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1
Smith, W. N., P. Rochette, C. Monreal, R. L. Desjardins, E. Pattey, and A. Jaques. "The rate of carbon change in agricultural soils in Canada at the landscape level." Canadian Journal of Soil Science 77, no. 2 (May 1, 1997): 219–29. http://dx.doi.org/10.4141/s96-113.
Анотація:
The Century model [a computer simulation of the dynamics of soil organic carbon (SOC)] was used to estimate the rate of SOC change in agricultural soil in Canada. The analysis was carried out on 180 Soil Landscapes of Canada (SLC) polygons, representing 15% of the SLC polygons within agricultural regions. The analysis was stratified into soil zones and into soil textural classes. For each sampled polygon, Century was run for 1 to 5 types of crop rotations under conventional-tillage as well as no-tillage, providing that no-till was used on at least 5% of the land. From the Century simulations, it was estimated that the overall rate of SOC loss from agricultural soils in Canada for 1990 was 39.1 kg ha−1 yr−1 This implies that 1.93 Mt of SOC (7.08 Mt of CO2) was lost from agricultural soils in Canada. Compared to 1990, the SOC loss was estimated to have been greater by 11.9 kg ha−1 yr−1 in 1980 and 9.1 kg ha−1 yr−1 in 1985. The lower loss in 1990 was primarily due to the incorporation of no-till practices and reduction of summer fallow in the mid 1980s. In 1990, at the provincial level, Alberta had the highest rate of SOC loss at 74.5 kg ha−1 yr−1 followed by Manitoba with 66.1 kg ha−1 yr−1 In Ontario, Quebec, and the Atlantic Provinces the average provincial rate of SOC loss was less than 35 kg ha−1 yr−1 Higher SOC loss rates were typically found in soils with coarser texture and greater native SOC content. Key words: Carbon dioxide, greenhouse gas, Century model
2
VandenBygaart, A. J., E. G. Gregorich, and D. A. Angers. "Influence of agricultural management on soil organic carbon: A compendium and assessment of Canadian studies." Canadian Journal of Soil Science 83, no. 4 (August 1, 2003): 363–80. http://dx.doi.org/10.4141/s03-009.
Анотація:
To fulfill commitments under the Kyoto Protocol, Canada is required to provide verifiable estimates and uncertainties for soil organic carbon (SOC) stocks, and for changes in those stocks over time. Estimates and uncertainties for agricultural soils can be derived from long-term studies that have measured differences in SOC between different management practices. We compiled published data from long-term studies in Canada to assess the effect of agricultural management on SOC. A total of 62 studies were compiled, in which the difference in SOC was determined for conversion from native land to cropland, and for different tillage, crop rotation and fertilizer management practices. There was a loss of 24 ± 6% of the SOC after native land was converted to agricultural land. No-till (NT) increased the storage of SOC in western Canada by 2.9 ± 1.3 Mg ha-1; however, in eastern Canada conversion to NT did not increase SOC. In general, the potential to store SOC when NT was adopted decreased with increasing background levels of SOC. Using no-tillage, reducing summer fallow, including hay in rotation with wheat (Triticum aestivum L.), plowing green manures into the soil, and applying N and organic fertilizers were the practices that tended to show the most consistent in creases in SOC storage. By relating treatment SOC levels to those in the control treatments, SOC stock change factors and their levels of uncertainty were derived for use in empirical models, such as the United Nations Intergovernmental Panel on Climate Change (IPCC). Guidelines model for C stock changes. However, we must be careful when attempting to extrapolate research plot data to farmers’ fields since the history of soil and crop management has a significant influence on existing and future SOC stocks. Key words: C sequestration, tillage, crop rotations, fertilizer, cropping intensity, Canada
3
Hossain, M. F., Yu Zhang, Wenjun Chen, Jixin Wang, and Goran Pavlic. "Soil organic carbon content in northern Canada: A database of field measurements and its analysis." Canadian Journal of Soil Science 87, no. 3 (May 1, 2007): 259–68. http://dx.doi.org/10.4141/s06-029.
Анотація:
Arctic and sub-arctic soils contain a large amount of organic carbon in their topsoil horizons and in the upper layers of permafrost. There is concern that climate warming could release this soil organic carbon (SOC) to the atmosphere as greenhouse gases. However, information about the profile features and spatial distribution of SOC in northern ecosystems are far less than for other regions. In this study, we compiled all the available field measurements of SOC in northern Canada and developed a database. Including our recent measurements, the database contains 438 profiles with 1473 soil horizons. We analyzed the profile features and the regional patterns of SOC in northern Canada based on this database. The results show that the SOC content of subsurface soils is relatively high in northern regions because of the alternate freeze-thaw actions. In the top 100 cm of soils, 40% of the SOC is located in the 50- to 100-cm layer. The SOC content is lower in northern Arctic and in mountainous regions. The average upland SOC content in northern Canada is higher than in other world biomes (i.e., croplands, temperate forest, tropical savannas, and tropical forest) except temperate grasslands and boreal forest. Key words: Soil organic carbon, northern Canada, database, arctic and sub-arctic.
4
VandenBygaart, A. J., E. Bremer, B. G. McConkey, H. H. Janzen, D. A. Angers, M. R. Carter, C. F. Drury, G. P. Lafond, and R. H. McKenzie. "Soil organic carbon stocks on long-term agroecosystem experiments in Canada." Canadian Journal of Soil Science 90, no. 4 (December 1, 2010): 543–50. http://dx.doi.org/10.4141/cjss10028.
Анотація:
Several long-term agroecosystem experiments (LTAEs) across Canada have been maintained for periods of up to a century. Much scientific knowledge of changes in soil properties through time has been learned from these few, highly productive LTAEs. We determined the effects of land management changes (LMC) on soil organic carbon (SOC) by re-sampling 27 LTAEs across Canada using identical sampling and laboratory protocols. Seven LTAEs were sampled comparing perennial to annual cropping and it was found that SOC stocks (0-30 cm) were 9.0 ± 1.5 Mg C ha-1 higher under perennial cropping after an average of 16.9 ± 2.1 yr. This yielded a SOC stock change factor of 0.6 Mg C ha-1 yr-1, comparing favourably to a modelling assessment and the Intergovernmental Panel on Climate Change (IPCC) default factor. In six LTAEs in western Canada, no-tillage increased SOC storage by 3.2 ± 1.3 Mg C ha-1 in the top 15 cm over a period of 23.3 ± 2.7 yr relative to conventional tillage, a rate of SOC storage of 0.14 Mg C ha-1 yr-1. This rate was also similar to that derived by simulation modelling and was slightly lower than the default IPCC rate for subhumid and semi-arid regions. In eastern Canada, where tillage is much deeper than western Canada, SOC storage was not significant differently between the two tillage systems. In six LTAEs in western Canada, removing fallow periods every second or third year in favour of continuous cropping increased SOC storage by 5.2 ± 1.1 Mg C ha-1 yr-1 over 21.8 ± 4.0 yr or an average SOC stock change factor of 0.23 Mg C ha-1 yr-1 to 15 cm depth. This was slightly higher than two independent meta-analyses and rates derived from simulation modelling. The results determined from a re-sampling of LTAEs across Canada provided an invaluable method of validating rates of SOC change concluded by other means.
5
Tan, S. Y., and J. Li. "An exploratory spatial analysis of soil organic carbon distribution in Canadian eco-regions." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XL-2 (November 11, 2014): 205–12. http://dx.doi.org/10.5194/isprsarchives-xl-2-205-2014.
Анотація:
As the largest carbon reservoir in ecosystems, soil accounts for more than twice as much carbon storage as that of vegetation biomass or the atmosphere. This paper examines spatial patterns of soil organic carbon (SOC) in Canadian forest areas at an eco-region scale of analysis. The goal is to explore the relationship of SOC levels with various climatological variables, including temperature and precipitation. The first Canadian forest soil database published in 1997 by the Canada Forest Service was analyzed along with other long-term eco-climatic data (1961 to 1991) including precipitation, air temperature, slope, aspect, elevation, and Normalized Difference Vegetation Index (NDVI) derived from remote sensing imagery. In addition, the existing eco-region framework established by Environment Canada was evaluated for mapping SOC distribution. Exploratory spatial data analysis techniques, including spatial autocorrelation analysis, were employed to examine how forest SOC is spatially distributed in Canada. Correlation analysis and spatial regression modelling were applied to determine the dominant ecological factors influencing SOC patterns at the eco-region level. At the national scale, a spatial error regression model was developed to account for spatial dependency and to estimate SOC patterns based on ecological and ecosystem factors. Based on the significant variables derived from the spatial error model, a predictive SOC map in Canadian forest areas was generated. Although overall SOC distribution is influenced by climatic and topographic variables, distribution patterns are shown to differ significantly between eco-regions. These findings help to validate the eco-region classification framework for SOC zonation mapping in Canada.
6
Osuoji, Roland I., and Michael A. Bankole. "Do Infants and Children have Measurable Inguinal Canals?" Journal of Nepal Paediatric Society 33, no. 3 (December 15, 2013): 182–85. http://dx.doi.org/10.3126/jnps.v33i3.8355.
Анотація:
Introduction: Herniotomy is a common procedure performed by Paediatric Surgeons. However, opinions differ as to whether to open the inguinal canal when performing this procedure or not. Those who advocate performing herniotomy without opening the inguinal canal believe that in early childhood, the superficial inguinal ring is directly superimposed on the deep inguinal ring, there being no appreciable inguinal canal in this age group. Our study was planned to open the inguinal canal and simply measure the distance between the pubic tubercle medially and the inferior epigastric vessels laterally. Finding a measurable inguinal canal in all cases studies debunks the belief that the superficial inguinal ring frequently overlaps the deep inguinal ring. Materials and Methods: From October 2007 to September 2008 and from May 2012 to April 2013 the inguinal canals of 75 children from 1 day to 2 years old were measured during herniotomies and orchidopexies. Premature babies were excluded from this study. The inguinal canals were all opened. Using a simple sterilized metallic ruler, the distance between the ipsilateral inferior epigastric vessels and the ipsilateral pubic tubercle was measured. Results: The lengths of the inguinal canals ranged from 1cm to 4.5 cm (mean 2.88cm+/-.71cm SD). The shortest inguinal canal length was 1 cm while the longest inguinal canal was 4.5 cm. Conclusion: Children with inguinal hernia up to the age of 2 years have a measurable inguinal canal and we suggest the excision of the hearnial sac superficial to the external inguinal ring runs the risk of leaving substantial sac behind proximal to the transfixing suture, even when some traction is applied to the sac before applying the transfixing suture. DOI: http://dx.doi.org/10.3126/jnps.v33i3.8355 J. Nepal Paediatr. Soc. 2013;33(3):182-185
7
VandenBygaart, A. J., E. G. Gregorich, D. A. Angers, and B. G. McConkey. "Assessment of the lateral and vertical variability of soil organic carbon." Canadian Journal of Soil Science 87, no. 4 (August 1, 2007): 433–44. http://dx.doi.org/10.4141/cjss06025.
Анотація:
Accurate predictions of changes in soil organic matter are difficult, at least in part, because of the lack of precision in measurements of soil organic carbon (SOC). This lack of precision is mostly due to the spatial variability in SOC that occurs with depth through the profile and laterally across the soil surface. The objective of this study was to assess the lateral and vertical variability of SOC in several pedologically distinct agricultural soils across Canada. Our goal was to determine the effect of different sampling methods on the precision of SOC measurements, namely: the effect of sampling either by fixed depth or by genetic soil horizon, the influence of compositing samples from different depth increments, and the number of cores required for a minimum detectable difference. Soils were sampled in increments down to 60 cm using a 4 × 3 m grid at six sites: two each from Ontario (Gleysol and Melanic Brunisol), Quebec (Humic Gleysol and Humo Ferric Podzol) and Saskatchewan (Dark Brown Chernozem). At four of the six sites, sampling by genetic soil horizon appeared to increase the precision of SOC measurements, but only when the surface 30 cm of the soil profile was considered. At the other two sites (soil types: Gleysol and Melanic Brunisol) sampling by fixed depth increments was more effective for increasing the precision of SOC measurements than sampling by genetic horizon. The effect of compositing samples from different depth increments had little influence on the precision of SOC measurements for all six soil types. These results suggest that sampling more than two depth increments per soil core has limited advantages for increasing statistical power to detect change in SOC. The high background SOC levels in the Gleysol soil would require a large number of soil cores in order to detect a small change in SOC such as that which would occur in a typical monitoring project. The Chernozem soils had lower spatial variability in SOC than the soil types in eastern Canada. Determining a statistically significant change in SOC of 5 Mg ha-1 would be difficult with the sampling design used in this study. Key words: Soil organic carbon, statistical power, sampling design, coefficient of variation, spatial variability, Canada
8
Hoff, R. M., and L. A. Barrie. "Air Chemistry Observations in the Canadian Arctic." Water Science and Technology 18, no. 2 (February 1, 1986): 97–107. http://dx.doi.org/10.2166/wst.1986.0019.
Анотація:
Arctic air chemistry measurements made in Canada since 1979 are reviewed. At Mould Bay, Alert and Igloolik, 25 aerosol constituents and aerosol light scattering have been measured routinely. Gas phase measurements of SO2, chlorinated pesticides, nitrogen species, and hydrocarbons have been measured during short-term intensive studies. CO2 has been routinely measured as part of the background air monitoring program at Mould Bay and Alert. Anthropogenic pollution typified by SO4= and V has a persistent seasonal cycle seen at all sites. Alert tends to have slightly higher concentrations than Mould Bay and Igloolik. It is shown that the seasonal cycle is dependent on the source of the aerosol. Anthropogenic pollutants (Cr, Cu, Mn, Ni, Pb, Sr, V, Zn, H+, NH4+ , SO4= and NO3−), halogens except Cl (Br, I, F) , sea salt (Na, Mg, Cl) and soil derived constituents (Al, Ba, Ca, Fe, Ti) have distinct seasonal cycles. Anthropogenic constituents (except SO4=) have peak concentrations in winter 1/2 to 1/4 of annual means in southern Sweden. SO4 is an exception to this being only 30% less in the Canadian Arctic than in southern Sweden, because of the production of SO4= from SO2. Light scattering observations indicate that SO4= varies from 10-70% of the total fine particle mass during the polluted winter months. Light scattering coefficients (bscat) greater than 5 × 10−5 m−1 at Mould Bay are associated with trans-polar air trajectories. Weekly-mean SO2 concentrations at Mould Bay between late 1983 and early 1984 ranged from 0.2-0.8 ppb and comprised 48-82% of the airborne sulphur. Recent measurements of chlordane in the Arctic atmosphere are presented.
9
Liu, Y. L., Z. H. Wu, Y. Y. Chen, and B. Z. Wang. "SOIL CARBON MAPPING IN LOW RELIEF AREAS WITH COMBINED LAND USE TYPES AND PERCENTAGES." ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences IV-3 (May 2, 2018): 285–92. http://dx.doi.org/10.5194/isprs-annals-iv-3-285-2018.
Анотація:
Accurate mapping of soil carbon in low relief areas is of great challenge because of the defect of conventional “soil-landscape” model. Efforts have been made to integrate the land use information in the modelling and mapping of soil organic carbon (SOC), in which the spatial context was ignored. With 256 topsoil samples collected from Jianghan Plain, we aim to (i) explore the land-use dependency of SOC via one-way ANOVA; (ii) investigate the “spillover effect” of land use on SOC content; (iii) examine the feasibility of land use types and percentages (obtained with a 200-meter buffer) for soil mapping via regression Kriging (RK) models. Results showed that the SOC of paddy fields was higher than that of woodlands and irrigated lands. The land use type could explain 20.5&thinsp;% variation of the SOC, and the value increased to 24.7&thinsp;% when the land use percentages were considered. SOC was positively correlated with the percentage of water area and irrigation canals. Further research indicated that SOC of irrigated lands was significantly correlated with the percentage of water area and irrigation canals, while paddy fields and woodlands did not show similar trends. RK model that combined land use types and percentages outperformed the other models with the lowest values of RMSE<sub>C</sub> (5.644&thinsp;g/kg) and RMSE<sub>P</sub> (6.229&thinsp;g/kg), and the highest R<sup>2</sup><sub>C</sub> (0.193) and R<sup>2</sup><sub>P</sub> (0.197). In conclusions, land use types and percentages serve as efficient indicators for the SOC mapping in plain areas. Additionally, irrigation facilities contributed to the farmland SOC sequestration especially in irrigated lands.
10
Howell, S. G., A. D. Clarke, S. Freitag, C. S. McNaughton, V. Kapustin, V. Brekovskikh, J. L. Jimenez, and M. J. Cubison. "An airborne assessment of atmospheric particulate emissions from the processing of Athabasca oil sands." Atmospheric Chemistry and Physics 14, no. 10 (May 23, 2014): 5073–87. http://dx.doi.org/10.5194/acp-14-5073-2014.
Анотація:
Abstract. During the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) campaign, two NASA research aircraft, a DC-8 and a P-3B, were outfitted with extensive trace gas (the DC-8) and aerosol (both aircraft) instrumentation. Each aircraft spent about a half hour sampling air around the oil sands mining and upgrading facilities near Ft. McMurray, Alberta, Canada. The DC-8 circled the area, while the P-3B flew directly over the upgrading plants, sampling close to the exhaust stacks, then headed downwind to monitor the aerosol as it aged. At short range, the plume from the oil sands is a complex mosaic of freshly nucleated ultrafine particles from a SO2- and NO2-rich plume, soot and possibly fly ash from industrial processes, and dust from dirt roads and mining operations. Shortly downwind, organic aerosol appears in quantities that rival SO4, either as volatile organic vapors condense or as they react with the H2SO4. The DC-8 pattern allowed us to integrate total flux from the oil sands facilities within about a factor of 2 uncertainty that spanned values consistent with 2008 estimates from reported SO2 and NO2 emissions, though there is no reason to expect one flyby to represent average conditions. In contrast, CO fluxes exceeded reported regional emissions, due either to variability in production or sources missing from the emissions inventory. The conversion rate of SO2 to aerosol SO4 of ~6% per hour is consistent with earlier reports, though OH concentrations are insufficient to accomplish this. Other oxidation pathways must be active. Altogether, organic aerosol and black carbon emissions from the oil sands operations are small compared with annual forest fire emissions in Canada. The oil sands do contribute significant sulfate and exceed fire production of SO2 by an order of magnitude.
11
Jarecki, Marek, Kumudinie Kariyapperuma, Bill Deen, Jordan Graham, Amir Behzad Bazrgar, Sowthini Vijayakumar, Mahendra Thimmanagari, Andrew Gordon, Paul Voroney, and Naresh Thevathasan. "The Potential of Switchgrass and Miscanthus to Enhance Soil Organic Carbon Sequestration—Predicted by DayCent Model." Land 9, no. 12 (December 10, 2020): 509. http://dx.doi.org/10.3390/land9120509.
Анотація:
Warm season perennial C4 grasses (WSGs), switchgrass (Panicum virgatum L.) and miscanthus species (Miscanthus spp.), have been reported to positively influence short-term (15–20 years) soil organic carbon (SOC). In this study, the DayCent model was used to predict changes in long-term SOC stocks under WSGs for moderate (Representative Concentration Pathway (RCP) 4.5) and high (RCP 8.5) warming climate change scenarios in southern Ontario, Canada, and to determine how long the enhanced SOC stock will last when WSGs are converted back to annual crop rotation. The model predicted that a consistent corn–corn–soybean–winter wheat (CCSW) rotation prevented SOC from depletion over the 21st century. Under WSGs, the model predicted high rates of SOC sequestration during the first 20–30 years which then tended to stabilize after 50–60 years. However, the rate of SOC sequestration over 90 years for RCP 4.5 was 0.26 and 0.94 Mg C ha−1 yr−1 for switchgrass and miscanthus, respectively. If 40-year stands of WSGs are converted back to CCSW, the model predicted SOC decline to the previous level in 40–50 years. DayCent predicted that under RCP 8.5 scenario in the second half of the 21st century and in the future, there will be a reduction in SOC stocks, especially under miscanthus stands.
12
Wu, Zihao, Yiyun Chen, Yuanli Zhu, Xiangyang Feng, Jianxiong Ou, Guie Li, Zhaomin Tong, and Qingwu Yan. "Mapping Soil Organic Carbon in Floodplain Farmland: Implications of Effective Range of Environmental Variables." Land 12, no. 6 (June 8, 2023): 1198. http://dx.doi.org/10.3390/land12061198.
Анотація:
Accurately mapping soil organic carbon (SOC) is conducive to evaluating carbon storage and soil quality. However, the high spatial heterogeneity of SOC caused by river-related factors and agricultural management brings challenges to digital soil mapping in floodplain farmland. Moreover, current studies focus on the non-linear relationship between SOC and covariates, but ignore the effective range of environmental variables on SOC, which prevents the revelation of the SOC differentiation mechanism. Using the 375 samples collected from the Jiangchang Town near Han River, we aim to determine the main controlling factors of SOC, reveal the effective range of environmental variables, and obtain the spatial map of SOC by using the gradient boosting decision tree (GBDT) model and partial dependence plots. Linear regression was used as a reference. Results showed that GBDT outperformed linear regression. GBDT results show that the distance from the river was the most important SOC factor, confirming the importance of the Han River to the SOC pattern. The partial dependence plots indicate that all environmental variables have their effective ranges, and when their values are extremely high or low, they do not respond to changes in SOC. Specifically, the influential ranges of rivers, irrigation canals, and rural settlements on SOC were within 4000, 200, and 50 m, respectively. The peak SOC was obtained with high clay (≥31%), total nitrogen (≥1.18 g/kg), and total potassium contents (≥11.1 g/kg), but it remained steady when these covariates further increased. These results highlight the importance of revealing the effective range of environmental variables, which provides data support for understanding the spatial pattern of SOC in floodplain farmland, achieving carbon sequestration in farmland and precision agriculture. The GBDT with the partial dependence plot was effective in SOC fitting and mapping.
13
Pennock, Dan, Angela Bedard-Haughn, and Valerie Viaud. "Chernozemic soils of Canada: Genesis, distribution, and classification." Canadian Journal of Soil Science 91, no. 5 (October 2011): 719–47. http://dx.doi.org/10.4141/cjss10022.
Анотація:
Pennock, D., Bedard-Haughn, A. and Viaud, V. 2011. Chernozemic soils of Canada: Genesis, distribution, and classification. Can. J. Soil Sci. 91: 719–747. Chernozemic soils in Canada have a characteristic biomantle that fully expresses the effect of organisms on soil formation. Additions of large amounts of below-ground biomass from grasses are transformed into complex organic compounds through the activities of meso- and macro-fauna, microbial degradation and combustion by fires. Degradation is regulated by (a) climatic influences on plant inputs and microbial activity, (b) the chemical and biochemical nature of the residues, (c) encapsulation of organic matter within aggregates by soil micro-faunal activities and freeze–thaw processes and (d) protection against decomposition by Ca2+ and clay minerals. These organic compounds are mixed with the mineral matrix through the action of organisms from mites to badgers. Regional differences in the regulators cause differences in soil organic carbon (SOC) storage and the colour value of the surface Chernozemic A horizon. The storage of SOC is lowest in the Brown soil zone (≈60 to 80 Mg ha−1) and greatest in the Black soil zone (≈120 to 150 Mg ha−1); this corresponds to a decrease in the annual water deficit from ≈200 mm (Brown) to 70 to 100 mm (Black). Where soil CaCO3 contents are high either through initial concentration in the parent material or by the precipitation of secondary CaCO3, substantially higher SOC storage than the regional norms can result. A repetitive catenary pattern occurs throughout the region. The primary controls on this pattern are hydrological – a lateral component to water flow in hillslopes leads to more developed horizonation downslope, and discharge surrounding wetlands causes precipitation of secondary carbonate minerals and more soluble salts in a fringe surrounding the wetlands. Chernozemic landscapes have been highly altered by humans through their conversion to agricultural production. Loss of the dense root network of the native grasslands causes a substantial decrease in SOC. This loss of carbon and reduction in A horizon thickness is accelerated by erosion; the effects of tillage erosion are now recognized as being ubiquitous through the agricultural region. The substantial amounts of SOC storage and our ability to increase storage through altered management practices make these soils a particular focus of interest in a future made more uncertain by the possibility of human-induced climatic change.
14
Laamrani, Ahmed, Aaron A. Berg, Paul Voroney, Hannes Feilhauer, Line Blackburn, Michael March, Phuong D. Dao, Yuhong He, and Ralph C. Martin. "Ensemble Identification of Spectral Bands Related to Soil Organic Carbon Levels over an Agricultural Field in Southern Ontario, Canada." Remote Sensing 11, no. 11 (May 31, 2019): 1298. http://dx.doi.org/10.3390/rs11111298.
Анотація:
The recent use of hyperspectral remote sensing imagery has introduced new opportunities for soil organic carbon (SOC) assessment and monitoring. These data enable monitoring of a wide variety of soil properties but pose important methodological challenges. Highly correlated hyperspectral spectral bands can affect the prediction and accuracy as well as the interpretability of the retrieval model. Therefore, the spectral dimension needs to be reduced through a selection of specific spectral bands or regions that are most helpful to describing SOC. This study evaluates the efficiency of visible near-infrared (VNIR) and shortwave near-infrared (SWIR) hyperspectral data to identify the most informative hyperspectral bands responding to SOC content in agricultural soils. Soil samples (111) were collected over an agricultural field in southern Ontario, Canada and analyzed against two hyperspectral datasets: An airborne Nano-Hyperspec imaging sensor with 270 bands (400–1000 nm) and a laboratory hyperspectral dataset (ASD FieldSpec 3) along the 1000–2500 nm range (NIR-SWIR). In parallel, a multimethod modeling approach consisting of random forest, support vector machine, and partial least squares regression models was used to conduct band selections and to assess the validity of the selected bands. The multimethod model resulted in a selection of optimal band or regions over the VNIR and SWIR sensitive to SOC and potentially for mapping. The bands that achieved the highest respective importance values were 711–715, 727, 986–998, and 433–435 nm regions (VNIR); and 2365–2373, 2481–2500, and 2198–2206 nm (NIR-SWIR). Some of these bands are in agreement with the absorption features of SOC reported in the literature, whereas others have not been reported before. Ultimately, the selection of optimal band and regions is of importance for quantification of agricultural SOC and would provide a new framework for creating optimized SOC-specific sensors.
15
Périé, Catherine, and Rock Ouimet. "Organic carbon, organic matter and bulk density relationships in boreal forest soils." Canadian Journal of Soil Science 88, no. 3 (May 2, 2008): 315–25. http://dx.doi.org/10.4141/cjss06008.
Анотація:
Relationships between soil organic carbon (SOC), organic matter (SOM), and bulk density (BD) were established in acidic loamy to sandy loam fine fractions of forest soils in Quebec (Canada). The interest of such relationships rests with the possibility of using simple and rapid techniques to estimate SOC and BD. It is also a crucial step in establishing the correspondence among several databases when SOC data are obtained using different measurement techniques. In this study, SOC was measuredby dry combustion (SOCNDC) and wet digestion (SOCWD) methods, and organic matter by loss-on-ignition (LOI). Our results suggest that, in these soils: (1) LOI can be used for estimating SOC (r2 = 0.95, RMSEP = 16%) and SOCDC/SOM significantly decreased with increasing depth from 0.49 to 0.27; (2) SOCDC and SOCWD were highly correlated. Even if SOCWD provided near complete recovery of SOCDC, dry combustion remains the preferred method for SOC analysis since recovery decreased with increasing depth from 100 to 83%. (3) BD was also strongly related to SOM(r2 = 0.81). We recommend using the organic density approach to estimate BD from SOM because it allows BD to be predicted without significant bias and with a degree of accuracy of 14%. Key words: Forest soils, soil organic carbon, soil organic matter, soil bulk density
16
Bolinder, M. A., A. J. VandenBygaart, E. G. Gregorich, D. A. Angers, and H. H. Janzen. "Modelling soil organic carbon stock change for estimating whole-farm greenhouse gas emissions." Canadian Journal of Soil Science 86, no. 3 (May 1, 2006): 419–29. http://dx.doi.org/10.4141/s05-102.
Анотація:
Modelling soil organic carbon (SOC) stock changes in agroecosystems can be performed with different approaches depending on objectives and available data. Our objective in this paper is to describe a scheme for developing a dynamic SOC algorithm for calculating net greenhouse gas emissions from Canadian farms as a function of management and local conditions. Our approach is flexible and emphasizes ease of use and the integration of available knowledge. Using this approach, we assessed the performance of several SOC models having two or more compartments for some common agroecosystems in Canada. Analysis of long-term data for conventional management practices at different sites (n = 36) in Canada, including recent model applications in the literature on some of those data, indicated that the results obtained with two-compartment models, such as the Introductory Carbon Balance Model (ICBM) and Modified Woodruff Model (MWM), yielded results comparable to those of a multi-compartment model (CENTURY). The analysis also showed that a model such as ICBM need stuning to be applied to management and conditions across Canada. Two-compartment models programmable in a simple spreadsheet format, though they may not supplant more complex models in allapplications, offer advantages of simplicity and transparency in whole-farm analyses of greenhouse gas emissions. Key words: Virtual Farm, soil organic carbon, soil disturbance, C inputs, Introductory Carbon Balance Model (ICBM), CENTURY, Modified Woodruff Model (MWM).
17
Zhao, Z., Q. Yang, G. Benoy, T. L. Chow, Z. Xing, H. W. Rees, and F. R. Meng. "Using artificial neural network models to produce soil organic carbon content distribution maps across landscapes." Canadian Journal of Soil Science 90, no. 1 (February 1, 2010): 75–87. http://dx.doi.org/10.4141/cjss08057.
Анотація:
Soil organic carbon (SOC) content is an important soil quality indicator that plays an important role in regulating physical, chemical and biological properties of soil. Field assessment of SOC is time consuming and expensive. It is difficult to obtain high-resolution SOC distribution maps that are needed for landscape analysis of large areas. An artificial neural network (ANN) model was developed to predict SOC based on parameters derived from digital elevation model (DEM) together with soil properties extracted from widely available coarse resolution soil maps (1:1 000 000 scale). Field estimated SOC content data extracted from high-resolution soil maps (1:10 000 scale) in Black Brook Watershed in northwestern New Brunswick, Canada, were used to calibrate and validate the model. We found that vertical slope position (VSP) was the most important variable that determines distributions of SOC across the landscape. Other variables such as slope steepness, and potential solar radiation (PSR) also had significant influence on SOC distributions. The prediction of the selected two-input-node SOC model (VSP and coarse resolution soil map recorded SOC as inputs) had a correlation coefficient of 0.92 with measured values, and model predicted SOC values had 47.9% of the total points within ±0.5% of the measured values and 70.6% within ±1% of the measured values. The prediction od the selected four-input-node model (VSP, slope steepness, PSR and coarse resolution SOC values as inputs) had a correlation coefficient of 0.98 with measured values and model predicted SOC values had 75% of the total points within ±0.5% of the measured values and 87% within ±1% of the measured values. The prediction of the five-input-nodes model with soil drainage as additional input had a correlation coefficient of 0.99 with measured values, and model predicted SOC values had 87% of the total points within ±0.5% of the measured values and 98% of the total points within ±1% of the measured values. The calibrated SOC prediction model was used to produce a high-resolution SOC map for the Black Brook Watershed and the resulting SOC distribution map is considered to be realistic. Results indicated that DEM-derived hydrological parameters together with widely available coarse resolution soil map data could be used to produce high-resolution SOC maps with the ANN method.Key words: Soil organic carbon, artificial neural network model, high-resolution soil maps, digital elevation model, vertical slope position
18
Howell, S. G., A. D. Clarke, S. Freitag, C. S. McNaughton, V. Kapustin, V. Brekovskikh, J. L. Jimenez, and M. J. Cubison. "An airborne assessment of atmospheric particulate emissions from the processing of Athabasca oil sands." Atmospheric Chemistry and Physics Discussions 13, no. 8 (August 15, 2013): 21301–43. http://dx.doi.org/10.5194/acpd-13-21301-2013.
Анотація:
Abstract. During the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) campaign, two NASA research aircraft, a DC-8 and a P-3B, were outfitted with extensive trace gas (the DC-8) and aerosol (both aircraft) instrumentation. Each aircraft spent about a half hour sampling air around the oil sands mining and upgrading facilities near Ft. McMurray, Alberta, Canada. The DC-8 circled the area, while the P-3B flew directly over the upgrading plants, sampling close to the exhaust stacks, then headed downwind to monitor the aerosol as it aged. At short range, the plume from the oil sands is a complex mosaic of freshly nucleated ultrafine particles from a SO2 and NO2-rich plume, fly ash and soot from industrial processes, and dust from dirt roads and mining operations. Shortly downwind, organic aerosol appears in quantities that rival SO4=, either as volatile organic vapors condense or as they react with the H2SO4. The DC-8 pattern allowed us to integrate total flux from the oil sands facilities within about a factor of two uncertainty that spanned values consistent with 2008 estimates from reported SO2 and NO2 emissions. In contrast, CO fluxes exceeded reported regional emissions, due either to variability in production or sources missing from the emissions inventory. The conversion rate of SO2 to aerosol SO4= of ~6% per hour is consistent with earlier reports, though OH concentrations are insufficient to accomplish this. Other oxidation pathways must be active. Altogether, organic aerosol and black carbon emissions from the oil sands operations are small compared with the forest fires present in the region during the summer. The oil sands do contribute significant sulfate and exceed fire production of SO2 by an order of magnitude.
19
Gestsdottir, Steinunn, G. John Geldhof, Tomáš Paus, Alexandra M. Freund, Sigrun Adalbjarnardottir, Jacqueline V. Lerner, and Richard M. Lerner. "Self-regulation among youth in four Western cultures." International Journal of Behavioral Development 39, no. 4 (July 20, 2014): 346–58. http://dx.doi.org/10.1177/0165025414542712.
Анотація:
We address how to conceptualize and measure intentional self-regulation (ISR) among adolescents from four cultures by assessing whether ISR (conceptualized by the SOC model of Selection, Optimization, and Compensation) is represented by three factors (as with adult samples) or as one “adolescence-specific” factor. A total of 4,057 14- and 18-year-old youth in Canada, Germany, Iceland, and the US participated. Confirmatory factor analyses did not confirm a tripartite model of SOC in any sample, whereas a single (nine-item) composite fit in all samples. A partial weak factorial invariance model showed a roughly equivalent meaning of the nine-item composite among German, Icelandic, and US youth. We discuss the need for further examination of the relative importance of items among Canadian youth, and possible problems using reverse-coded items with adolescents. The similarities that were observed across age and cultural groups suggest that a single factor structure of SOC, as measured by nine items, may be robust for youth in Western cultural settings and that SOC processes are not fully developed until adulthood.
20
Bazrgar, Amir Behzad, Aeryn Ng, Brent Coleman, Muhammad Waseem Ashiq, Andrew Gordon, and Naresh Thevathasan. "Long-Term Monitoring of Soil Carbon Sequestration in Woody and Herbaceous Bioenergy Crop Production Systems on Marginal Lands in Southern Ontario, Canada." Sustainability 12, no. 9 (May 10, 2020): 3901. http://dx.doi.org/10.3390/su12093901.
Анотація:
Enhancement of terrestrial carbon (C) sequestration on marginal lands in Canada using bioenergy crops has been proposed. However, factors influencing system-level C gain (SLCG) potentials of maturing bioenergy cropping systems, including belowground biomass C and soil organic carbon (SOC) accumulation, are not well documented. This study, therefore, quantified the long-term C sequestration potentials at the system-level in nine-year-old (2009–2018) woody (poplar clone 2293–29 (Populus spp.), hybrid willow clone SX-67 (Salix miyabeana)), and herbaceous (miscanthus (Miscanthus giganteus var. Nagara), switchgrass (Panicum virgatum)) bioenergy crop production systems on marginal lands in Southern Ontario, Canada. Results showed that woody cropping systems had significantly higher aboveground biomass C stock of 10.02 compared to 7.65 Mg C ha−1 in herbaceous cropping systems, although their belowground biomass C was not significantly different. Woody crops and switchgrass were able to increase SOC significantly over the tested period. However, when long term soil organic carbon (∆SOC) gains were compared, woody and herbaceous biomass crops gained 11.0 and 9.8 Mg C ha−1, respectively, which were not statistically different. Results also indicate a significantly higher total C pool [aboveground + belowground + soil organic carbon] in the willow (103 Mg ha−1) biomass system compared to other bioenergy crops. In the nine-year study period, woody crops had only 1.35 Mg C ha−1 more SLCG, suggesting that the influence of woody and herbaceous biomass crops on SLCG and ∆SOC sequestrations were similar. Further, among all tested biomass crops, willow had the highest annual SLCG of 1.66 Mg C ha−1 y−1.
21
Xie, H. T., X. M. Yang, C. F. Drury, J. Y. Yang, and X. D. Zhang. "Predicting soil organic carbon and total nitrogen using mid- and near-infrared spectra for Brookston clay loam soil in Southwestern Ontario, Canada." Canadian Journal of Soil Science 91, no. 1 (February 2011): 53–63. http://dx.doi.org/10.4141/cjss10029.
Анотація:
Xie, H. T., Yang, X. M., Drury, C. F., Yang, J. Y. and Zhang, X. D. 2011. Predicting soil organic carbon and total nitrogen using mid- and near-infrared spectra for Brookston clay loam soil in Southwestern Ontario, Canada. Can. J. Soil Sci. 91: 53–63. Mid-infrared (MIR) and near-infrared (NIR) spectroscopy of soils have been tested to estimate soil organic carbon (SOC) and total N (TN) concentrations at local, regional and national scales. However, these methods have rarely been used to assess SOC and TN concentrations of the same soil under different management practices. The objective of this study was to determine if models developed from infrared spectra of Brookston clay loam soils under different management practices could be used to estimate SOC, and TN concentrations and the C:N ratio. Soils used for model calibration included 217 samples from a long-term fertilization and crop rotation study and a long-term compost study, whereas 78 soil samples from a long-term tillage study on the same soil type were used for model validation. Soil organic carbon and TN concentrations of all samples were also analyzed using dry combustion techniques. Soil samples were scanned from 4000 to 400 cm−1 (2500–25 000 nm) for MIR spectra and from 8000 to 4000 cm−1 (1250–2500 nm) for NIR spectra. Partial least squares regression (PLSR) analysis was used for the calibration dataset to build prediction models for SOC, TN and C:N ratio. The SOC and TN concentrations determined using dry combustion techniques were compared with the prediction from the models using the calibration datasets. The predictions of SOC and TN concentrations by the PLSR method using infrared spectra were statistically sound, with high coefficient of determination with the calibration dataset (R2cal, SOCMIR=0.99 and SOCNIR=0.97, TNMIR=0.98 and TNNIR=0.97) and the validation dataset (R2val, SOCMIR=0.96 and SOCNIR=0.95, TNMIR=0.96 and TNNIR=0.95) and low root mean square error (RMSEPcal, SOCMIR=0.93 and SOCNIR=1.60, TNMIR=0.08 and TNNIR=0.12; RMSEPval, SOCMIR=1.40 and SOCNIR=1.75, TNMIR=0.11 and TNNIR=0.12). The predictions of SOC and TN concentrations in the 5 to 30 cm depth were better than the predictions for either the surface (0 to 5 cm) soils or for soils from lower depths (>30 cm). The models could be used as an alternative method for determining SOC and TN concentrations of Brookston clay loam soils; however, larger sample populations and improved model algorithms could further improve predictions.
22
Xu, Yanming, Carl Ngai Man Ho, Avishek Ghosh, and Dharshana Muthumuni. "Generalized Behavioral Modelling Methodology of Switch-Diode Cell for Power Loss Prediction in Electromagnetic Transient Simulation." Energies 14, no. 5 (March 9, 2021): 1500. http://dx.doi.org/10.3390/en14051500.
Анотація:
Modern wide-bandgap (WBG) devices, such as silicon carbide (SiC) or gallium nitride (GaN) based devices, have emerged and been increasingly used in power electronics (PE) applications due to their superior switching feature. The power losses of these devices become the key of system efficiency improvement, especially for high-frequency applications. In this paper, a generalized behavioral model of a switch-diode cell (SDC) is proposed for power loss estimation in the electromagnetic transient simulation. The proposed model is developed based on the circuit level switching process analysis, which considers the effects of parasitics, the operating temperature, and the interaction of diode and switch. In addition, the transient waveforms of the SDC are simulated by the proposed model using dependent voltage and current sources with passive components. Besides, the approaches of obtaining model parameters from the datasheets are given and the modelling method is applicable to various semiconductors such Si insulated-gate bipolar transistor (IGBT), Si/SiC metal–oxide–semiconductor field-effect transistor (MOSFET), and GaN devices. Further, a multi-dimensional power loss table in a wide range of operating conditions can be obtained with fast speed and reasonable accuracy. The proposed approach is implemented in PSCAD/ Electromagnetic Transients including DC, EMTDC, (v4.6, Winnipeg, MB, Canada) and further verified by the hardware setups including different daughter boards for different devices.
23
Campbell, C. A., A. J. VandenBygaart, R. P. Zentner, B. G. McConkey, W. Smith, R. Lemke, B. Grant, and P. G. Jefferson. "Quantifying carbon sequestration in a minimum tillage crop rotation study in semiarid southwestern Saskatchewan." Canadian Journal of Soil Science 87, no. 3 (May 1, 2007): 235–50. http://dx.doi.org/10.4141/s06-018.
Анотація:
Scientists and the agricultural community require methods of quantifying C sequestration in soils. This is important in assessing the impact of crop management practices on emission of greenhouse gases and for “C trading”. Using simulation models may be a more effective method of quantification as compared with in situ measurements. A 17-yr crop rotation experiment being conducted on a medium-textured Orthic Brown Chernozem at Swift Current, Saskatchewan, in which soil organic C (SOC) was being monitored periodically, was used to assess the effect on C sequestration of cropping frequency, wheat class, legume green manure (LGM), flexible cropping based on available water, and regrassing of crop land. Prior to the study, the experimental site had been cropped to fallow-wheat (F-W) for the previous 60 yr. Crop management in this experiment involved minimum tillage, snow trapping, and N + P fertilization based on soil tests. Three models [Century, the Introductory C Balance model (ICBM), and the Campbell model] were tested for their effectiveness in simulating SOC trends. Because growing season precipitation was average to above average, yields, and thus C inputs from residue, were also above average, and consequently SOC increased in most systems for the first 10 yr before reaching a new steady state. SOC gains (kg ha-1 yr-1) in the 0- to 15-cm depth in 17 yr were directly proportional to cropping frequency (F-W-W = 135, F-W-W-W = 332, and Cont W = 441); LGM-W-W gained SOC at a much higher rate than F-W-W (329 vs. 135 kg ha-1 yr-1 ); Canada Western Red Spring (CWRS) wheat (Triticum aestivum L.), although it yielded 26% less than Canada Prairie Spring (CPS) wheat, gained SOC at a higher rate than CPS wheat (135 vs. 0 kg ha-1 yr-1). Further, 2 yr of conventionally-tilled fallow in 17 yr (flexible system) markedly suppressed SOC gain by 46% compared with Cont W (441 vs. 236 kg ha-1 yr-1). There was a 282 kg ha-1 yr-1 gain in SOC under crested wheatgrass (Agropyron cristatum L.) (CWG) but most of this gain occurred in the last 7 yr. Though having their inherent weaknesses, the ICBM and Campbell models performed equally well in simulating SOC trends (r2 = 0.55**), but Century was less effective (r2 = 0.21*), in part because of its limited ability to simulate yields. Because C input, and thus yield, is one of the main factors influencing SOC gains, and since measured yields are used in the ICBM and Campbell models, while simulated yields are used by Century, the ICBM and Campbell models have an advantage over the Century model in this comparison. Efficiencies of conversion of input C to SOC increased with cropping frequency, and were higher for LGM-W-W than for F-W-W, and for systems with CWRS wheat rather than CPS wheat. Efficiency of conversion was 8% for F-W-W, 15% for LGM-W-W and 21% for Cont W. Key words: ICBM model, Century model, Campbell model, C sequestration, legume green manure, regrassing
24
Yang, X. M., and B. D. Kay. "Impacts of tillage practices on total, loose- and occluded-particulate, and humified organic carbon fractions in soils within a field in southern Ontario." Canadian Journal of Soil Science 81, no. 2 (May 1, 2001): 149–56. http://dx.doi.org/10.4141/s00-015.
Анотація:
The effects of no-tillage (NT) and moldboard plowing (MP) on the distribution and storage of soil organic carbon (SOC) and different C fractions were determined along a transect on a private farm in southern Ontario, Canada, where a paired NT and MP strip traversing three soil series had been in existence for 19 yr. Soil samples were collected to a depth of 60 cm in seven increments. SOC was determined in each sample and for the top 30 cm, the organic carbon was fractionated into loose-, occluded-particulate organic matter (loose-POM and occluded-POM) and humified fraction (HF). After 19 yr, soils under NT contained significantly (P < 0.05) more SOC than soils under MP on both an equivalent depth basis and an equivalent mass basis. Greater concentrations of loose- and occluded-POM were found in NT than MP surface soils (0-10 cm). MP favored higher loose-POM contents than NT practices at a depth of 10-20 cm. The HF fraction accounted for most of the increase in SOC in the Huron and Brady soils, whereas the occluded POM accounted for more of the increase in the Fox soil. Our results indicate that the extent of SOC sequestration under NT is strongly dependent on soil type and cropping history. Key words: Tillage practices, soil organic carbon, C fraction, C sequestration
25
Bolinder, M. A., O. Andrén, T. Kätterer, and L. E. Parent. "Soil organic carbon sequestration potential for Canadian Agricultural Ecoregions calculated using the Introductory Carbon Balance Model." Canadian Journal of Soil Science 88, no. 4 (August 1, 2008): 451–60. http://dx.doi.org/10.4141/cjss07093.
Анотація:
The potential for storage of atmospheric CO2-C as soil organic C (SOC) in agroecosystems depends largely on soil biological activity and the quantity and quality of annual C inputs to soil. In this study we used the Introductory Carbon Balance Model (ICBM) approach driven by daily standard weather station data, specific soil properties and crop characteristics at the scale of Canadian agricultural ecoregions. The objectives were to calculate a climate-dependent soil biological activity parameter representative for annual agricultural crop production systems (re_crop) and to estimate the effect of fallow (re_fallow). These parameters are based on the daily product of soil temperature and stored water that influence biological activity in the arable layer, and are used to adjust the decomposition rates of the ICBM SOC pools. We also tested re_crop and re_fallow on SOC stock change data for different site and treatment combinations from long-term field experiments located in some of the ecoregions. An re_crop value of 0.95 for western ecoregions was on average 0.23 units lower than that of the eastern ecoregions, indicating a lower decomposition rate of SOC. Although the estimated annual C inputs to soil for small-grain cereals were on average ≈7.5% higher in the eastern ecoregions (305 vs. 285 g C m-2 yr-1), the overall results suggest that the western ecoregions would have a greater potential to maintain high SOC levels in the long term. However, these parameters varied between ecoregions and, consequently, the SOC sequestration potential was not always higher for the western ecoregions. The effect of fallow was on average ≈0.04, i.e., SOC decomposed slightly faster under fallow. Predictions for 24 out of 33 site and treatment combinations across Canada were significantly improved (P = 0.003), compared with a previous application with the ICBM that did not differentiate between crops and fallow. The methodology used here enabled us to examine regional differences in the potential for SOC sequestration as a balance between annual C inputs to soil and soil biological activity. Key words: Annual C inputs, climate, fallow, soil biological activity, agroecosystems
26
Campbell, C. A., R. P. Zentner, F. Selles, V. O. Biederbeck, B. G. McConkey, B. Blomert, and P. G. Jefferson. "Quantifying short-term effects of crop rotations on soil organic carbon in southwestern Saskatchewan." Canadian Journal of Soil Science 80, no. 1 (February 1, 2000): 193–202. http://dx.doi.org/10.4141/s99-045.
Анотація:
Crop management practices can have a major influence on soil fertility and soil organic C (SOC) sequestration. We need to accurately measure and estimate changes in SOC in the short term (<20 yr). A 10-yr crop rotation experiment, conducted on a medium-textured Orthic Brown Chernozem at Swift Current, in southwestern Saskatchewan, was sampled in 1990 (3 yr after initiation of the study) and in 1993 and 1996, to measure SOC changes under nine crop rotation treatments. Minimum tillage practices were used. The stubble was cut high to enhance snow trap and N and P fertilizer applied based on soil tests. Grain and straw yields of the cereals, and hay yields of the crested wheatgrass (CWG) [Agropyron cristatum (L.) Gaeertn.] were measured annually. An empirical equation which uses two simultaneous first order kinetic expressions, one to estimate crop residue decomposition and the other to estimate soil humus C mineralization was used, together with crop residue (straw and estimated root) C inputs, to estimate SOC changes over the 1987 to 1996 period. The estimated SOC values for the 1990 to 1996 period were generally similar to the measured values (r2 = 0.64, P < 0.0001). Significant (P < 0.10) changes in SOC were not observed below 15 cm depth, perhaps because shallow tillage (10- to 12.5-cm depth) is practiced. A change from cropland to CWG did not increase SOC, and this treatment, chemical fallow-winter wheat (Triticum aestivum L.)-spring wheat (F-WW-W), and F-high-yielding (Hy) Canada Prairie Spring (CPS) wheat-Hy (F-Hy-Hy) rotations, had the lowest SOC gains among the rotations. The CPS wheat had a higher harvest index (0.46) than hard red spring (HRS) wheat (0.39), but it increased SOC less than the comparable HRS wheat rotation between 1990 and 1996 indicating that higher grain yields do not always equate to higher SOC. Weather conditions were favourable for cereals from 1990 to 1996 and we measured significant increases in SOC (up to 5.5 Mg ha−1 in 6 yr). This is encouraging for producers who may be contemplating participating in "C trading", although this also suggests that periods of less favourable weather will limit gains in SOC. Summerfallowing once in 4 yr in this semiarid environment did not reduce SOC gains compared to continuous wheat (Cont W). For example, a F-W-W-W rotation gained 4.88 Mg C ha−1 in 6 yr while continuous wheat gained 5 Mg ha−1. Growing Indianhead lentil (Lens culinaris Medikus) as a legume green manure crop (GM) with wheat in a GM-W-W rotation did not increase SOC more than F-W-W. The efficiencies of conversion of residue C to SOC were high, ranging between 9% for frequently fallowed systems to 29% for continuously cropped systems, likely due to the favourable weather conditions experienced. Key words: Carbon sequestration, legume green manure, crested wheatgrass, harvest index effect, C conversion efficiencies
27
Lussier, Jason M., Maja Krzic, Sean M. Smukler, Katarina R. Neufeld, Chantel J. Chizen, and Art A. Bomke. "Labile soil carbon fractions as indicators of soil quality improvement under short-term grassland set-aside." Soil Research 58, no. 4 (2020): 364. http://dx.doi.org/10.1071/sr19180.
Анотація:
Grassland set-asides (GLSA) are fields that are taken out of intensive annual crop production and seeded with a mixture of grasses and legumes for one to four years to improve soil quality. The objectives of this study were to evaluate (i) the relationships among soil organic carbon (SOC), permanganate oxidisable C (POXC), dilute-acid extractable polysaccharides (DAEP) and aggregate stability to determine if they may be used as proxies for one another, (ii) whether these indicators could be used to predict aggregate stability, (iii) if differences in soil quality after short-term GLSAs, detected with aggregate stability, could instead be detected with POXC or DAEP and (iv) potential use of diffuse Fourier transform spectroscopy (FT-MIR) to predict POXC, DAEP and aggregate stability in the Fraser River Delta region of British Columbia, Canada. There were strong relationships among SOC, POXC and DAEP, but the relationship between DAEP and SOC (R2 = 0.60, P < 0.0001) was less strong than that observed between POXC and SOC (R2 = 0.71, P < 0.0001). All three soil C fractions were significantly predicted with the 2–6 mm aggregate size fraction but the correlations for DAEP (R2 = 0.43) and POXC (R2 = 0.36) were stronger than that for SOC (R2 = 0.29). Predictions of soil quality indicators using FT-MIR produced R2 = 0.92 for POXC, R2 = 0.93 for DAEP and R2 = 0.62 for the 2–6 mm aggregate size fraction. These results suggest that FT-MIR holds promise as a low-cost method to determine labile soil C fractions that are better proxy soil quality indicators for aggregate stability than SOC.
28
Miller, J. J., M. L. Owen, X. M. Yang, C. F. Drury, W. D. Reynolds, and D. S. Chanasyk. "Long-term cropping and fertilization influences soil organic carbon, soil water repellency, and soil hydrophobicity." Canadian Journal of Soil Science 100, no. 3 (September 1, 2020): 234–44. http://dx.doi.org/10.1139/cjss-2019-0129.
Анотація:
Long-term (58 yr) cropping and fertilization effects on soil water repellency were determined for a clay loam soil in southwestern Ontario, Canada by measuring soil organic carbon (SOC), soil water repellency index (RI), and soil hydrophobicity (SH). The 12 treatments (non-replicated) included fertilized and non-fertilized legume-based crop rotation (ROT) with four phases (corn–oat–alfalfa–alfalfa), continuous corn (CC), and continuous Kentucky bluegrass (KBG). We hypothesized that SOC, RI, and SH would be greater for each phase of the ROT versus CC, KBG versus CC and ROT, and fertilized versus non-fertilized treatments. Surface (0–10 cm) soil samples were collected in the spring of 2017. Laboratory measurements were conducted to determine SOC, RI (ratio of soil sorptivity to ethanol and water), and SH (ratio of hydrophobic CH– to hydrophilic CO– functional groups). Mean SOC and SH were greater (P ≤ 0.05) for each phase of the ROT versus CC (33% to 2.4 times), KBG versus CC (3.2–6 times) and each phase of ROT (2.2–2.8 times), and fertilized versus non-fertilized rotation oats and KBG (15%–30%). Mean RI was greater for KBG versus CC (4.8 times) and KBG versus each phase of the ROT (3.0–5.5 times) under fertilization only, greater for fertilized versus non-fertilized KBG (6.8 times), but similar for each phase of ROT versus CC. In general, legume-based rotations, perennial grass, and fertilizer enhanced SOC and SH, and to a lesser extent soil RI.
29
Andrijašević, Nemanja. "George Radin on Bishop Dr. Nicholai Velimirovich and the Serbian Orthodox Church in America." Nicholai Studies: International Journal for Research of Theological and Ecclesiastical Contribution of Nicholai Velimirovich I, no. 2 (July 26, 2021): 369–94. http://dx.doi.org/10.46825/icholaistudies/ns.2021.1.2.369-394.
Анотація:
Abstract: George Radin (Đorđe Radin, 1896–1981) was one of the numerous Serbian emigrants in the USA in the period right before WW2. He studied at the most eminent American Universities and had become an attorney, then a lawyer and finally an expert in international law. He managed to achieve great success and expertise in the field of American foreign politics and diplomacy. In the period between the two World Wars, he met Bishop Dr. Nicholai Velimirovich who made a strong impression on him. He was the Bishop’s guide across the USA during his two visits there: in 1920 and in 1927. During his first visit to the continent, the Bishop had organized the life of the Serbian Orthodox Church (SOC), considering that at the time SOC didn’t have its residing bishop there. Radin was, according to his own testimony, one of the organizers of the Bishop’s arrival to America at the beginning of 1946. He had been of the opinion that this significant Bishop should live in one of the Protestant Churches and hold lectures at the Universities, thus serving SOC and its members. In other words, it was his conviction that the Bishop should have organized the church life in the same way he did in his previous two visits to the USA. However, the situation between the two World Wars was far more complicated. The Serbian Church had by that time appointed its ruling bishop in America and Canada — Dionisiye Milivoyevich (Dionisije Milivojević, 1898–1979), who parted ways with Bishop Nicholai soon after his arrival to the USA. Immense damage had been done to the SOC by the utter lack of cooperation between these two bishops. Bishop Nicholai found a “Solomon’s solution” for this by deciding to live and work in Saint Tikhon’s Orthodox Monastery in South Canaan, Pennsylvania. It was in this holy place that he reposed in 1956. Until the end of his life, Radin was of the opinion that a fundamental mistake had been made by the secession of the opportunity that through abiding in the Protestant communities Bishop Nicholai might do more for the SOC and the Serbs, especially through his acquaintances and contacts with the representatives of other Christian confessions, primarily Protestants. He mentioned this in his correspondence with Sliјepchevich (Đoko Slijepčević, 1908–1993). Also, Radin made all the efforts in his power to help overcome the current schism in the SOC. He wrote about his opinions, ideas and steps taken in that direction to the bishops of the Serbian Church, as well as the Patriarch German Djorich himself. Even though the Patriarch of the SOC also made efforts to help overcome the schism, at one point he told Radin that this unfortunate and extremely difficult issue is an internal matter of the SOC, and thus should be dealt with internally. In the appendix of this work, there are excerpts from the letters found in the Radin — Slijepchevich correspondence. They illustrate the enormous mutual trust and respect that these two acquaintances had for each other, having met by the mediation of Bishop Nicholai. The excerpts also present the opinions of the respectful lawyer and law expert — Radin who, in his own way, tried to contribute to the benefit of the SOC. They also convey his judgment on the importance of Bishop Nicholai as well as his discernment about the missed opportunity that the above mentioned bishop should have been presented with in order to contribute more to the SOC, its faithful people and all the Serbs in general — on the American continent, as well as in the whole world. It is clear that he remained hindered in that respect — among other factors — by the will of Bishop Dionisiye. Only a few years after the death of Bishop Nicholai, the most complicated problem of the SOC in diaspora unraveled — the schism. Radin directed all his attention and efforts towards the solution of this problem, in the ways he considered to be the most acceptable. In all this he had agreement with and support of Slijepchevich, with whom he had researched the best ways of achieving reconciliation. Fragments of his letters imply that the majority of his emigrant life he devoted to taking care of Bishop Nicholai, as well as fighting against schism and finding the possibilities of its overcoming.
30
Balint, Adina. "Transcultural Mobility and Contemporary Self-Narratives in Francophone Canada." Lublin Studies in Modern Languages and Literature 40, no. 2 (January 18, 2017): 136. http://dx.doi.org/10.17951/lsmll.2016.40.2.136.
31
Sorenson, Preston Thomas, Jeremy Kiss, and Angela Bedard-Haughn. "A Proposed Methodology for Determining the Economically Optimal Number of Sample Points for Carbon Stock Estimation in the Canadian Prairies." Land 13, no. 1 (January 20, 2024): 114. http://dx.doi.org/10.3390/land13010114.
Анотація:
Soil organic carbon (SOC) sequestration assessment requires accurate and effective tools for measuring baseline SOC stocks. An emerging technique for estimating baseline SOC stocks is predictive soil mapping (PSM). A key challenge for PSM is determining sampling density requirements, specifically, determining the economically optimal number of samples for predictive soil mapping for SOC stocks. In an attempt to answer this question, data were used from 3861 soil organic carbon samples collected as part of routine agronomic soil testing from a 4702 ha farming operation in Saskatchewan, Canada. A predictive soil map was built using all the soil data to calculate the total carbon stock for the entire study area. The dataset was then subset using conditioned Latin hypercube sampling (cLHS), both conventional and stratified by slope position, to determine the total carbon stocks with the following sampling densities (points per ha): 0.01, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, and 0.8. A nonlinear error function was then fit to the data, and the optimal number of samples was determined based on the number of samples that minimized soil data costs and the value of the soil carbon stock prediction error. The stratified cLHS required fewer samples to achieve the same level of accuracy compared to conventional cLHS, and the optimal number of samples was more sensitive to carbon price than sampling costs. Overall, the optimal sampling density ranged from 0.025 to 0.075 samples per hectare.
32
Chan, T. W., J. R. Brook, G. J. Smallwood, and G. Lu. "Time-resolved measurements of black carbon light absorption enhancement in urban and near-urban locations of southern Ontario, Canada." Atmospheric Chemistry and Physics 11, no. 20 (October 20, 2011): 10407–32. http://dx.doi.org/10.5194/acp-11-10407-2011.
Анотація:
Abstract. In this study a photoacoustic spectrometer (PA), a laser-induced incandescence instrument system (LII) and an Aerosol Mass Spectrometer were operated in parallel for in-situ measurements of black carbon (BC) light absorption enhancement. Results of a thermodenuder experiment using ambient particles in Toronto are presented first to show that LII measurements of BC are not influenced by the presence of non-refractory material thus providing true atmospheric BC mass concentrations. In contrast, the PA response is enhanced when the non-refractory material is internally mixed with the BC particles. Through concurrent measurements using the LII and PA the specific absorption cross-section (SAC) can be quantified with high time resolution (1 min). Comparisons of ambient PA and LII measurements from four different locations (suburban Toronto; a street canyon with diesel bus traffic in Ottawa; adjacent to a commuter highway in Ottawa and; regional background air in and around Windsor, Ontario), show that different impacts from emission sources and/or atmospheric processes result in different particle light absorption enhancements and hence variations in the SAC. The diversity of measurements obtained, including those with the thermodenuder, demonstrated that it is possible to identify measurements where the presence of externally-mixed non-refractory particles obscures direct observation of the effect of coating material on the SAC, thus allowing this effect to be measured with more confidence. Depending upon the time and location of measurement (urban, rural, close to and within a lake breeze frontal zone), 30 min average SAC varies between 9 ± 2 and 43 ± 4 m2 g−1. Causes of this variation, which were determined through the use of meteorological and gaseous measurements (CO, SO2, O3), include the particle emission source, airmass source region, the degree of atmospheric processing. Observations from this study also show that the active surface area of the BC aggregate, which is measured by the LII as the PPS, is an important parameter for inferring the degree of particle collapse of a BC particle. In addition, PPS could be a useful measurement for indicating the importance of recently emitted BC (e.g. from gasoline or diesel engines) relative to the total measured BC in the atmosphere.
33
Nimrod, Galit. "Aging Well in the Digital Age: Technology in Processes of Selective Optimization with Compensation." Journals of Gerontology: Series B 75, no. 9 (August 27, 2019): 2008–17. http://dx.doi.org/10.1093/geronb/gbz111.
Анотація:
Abstract Objectives Studies show that using information and communication technology (ICT) contributes significantly to elders’ subjective well-being (SWB). Drawing on the Selective Optimization with Compensation (SOC) model, this study aims at exploring the mechanism by which ICT use helps older adults remain engaged in valued life activities and maintain their SWB. Method Involving teams from seven countries (Canada, Colombia, Israel, Italy, Peru, Romania, Spain), 27 focus groups were conducted with a total of 184 grandmothers aged 65 years and older who use ICT. Results Analysis led to identification of a series of strategies related to ICT use that may be described in SOC terms. “Intentional limited use” and “Selective timing,”, for example, are clearly associated with selection. In addition, numerous optimizing strategies were found to be applied in “Instrumental” and “Leisure” activities, whereas some ICT uses offered compensation for “Aging-related” and “General” challenging circumstances. Discussion The study suggests that ICT is used in all three SOC processes and that its effective application facilitates adjustment and enhances SWB. It should therefore be regarded as a resource that supports existing personal and social resources and life management strategies, and even as a Quality of Life Technology that maintains or enhances functioning in older adulthood.
34
Degryse, Fien, Roslyn Baird, Rodrigo C. da Silva, Christopher B. Holzapfel, Claudinei Kappes, Monica Tysko, and Michael J. McLaughlin. "Sulfur Uptake from Fertilizer Fortified with Sulfate and Elemental S in Three Contrasting Climatic Zones." Agronomy 10, no. 7 (July 17, 2020): 1035. http://dx.doi.org/10.3390/agronomy10071035.
Анотація:
Field trials with labeled fertilizers can be used to provide information on fertilizer efficiency, residual value, and nutrient fate. We assessed the uptake from elemental S (ES) and sulfate S (SO4-S) in S-fortified monoammonium phosphate fertilizers by various crops at three sites in Argentina, Brazil, and Canada. The S sources were labeled with 34S, and the 34S abundance in the plant tissue was analyzed at an early stage and at maturity over two consecutive years. At the sites in Argentina and Canada, the recovery of ES in the crop was smaller than that of SO4-S in the first year, while the opposite was true in the second year. At the Brazilian site, the recovery of ES was similar to that of SO4-S in the first year, but higher in the second year. In the Argentina and Canada sites, the cumulative recovery of SO4-S was >65% and that of ES was 20−25%. In the Brazilian site, the cumulative recovery of SO4-S was 9% and that of ES 16%. The higher recovery of ES than of SO4-S in the Brazilian site was attributed to leaching of added SO4-S and relatively fast oxidation of ES due to the warm climate. These results suggest that ES may be more suitable than SO4-S as a fertilizer S source in warm humid climates, while inclusion of SO4-S in the fertilizer is recommended in colder climates as slow oxidation limits the initial availability of ES.
35
Stiglitz, Roxanne, Elena Mikhailova, Julia Sharp, Christopher Post, Mark Schlautman, Patrick Gerard, and Michael Cope. "Predicting Soil Organic Carbon and Total Nitrogen at the Farm Scale Using Quantitative Color Sensor Measurements." Agronomy 8, no. 10 (October 1, 2018): 212. http://dx.doi.org/10.3390/agronomy8100212.
Анотація:
Sensor technology can be a reliable and inexpensive means of gathering soils data for soil health assessment at the farm scale. This study demonstrates the use of color system readings from the Nix ProTM color sensor (Nix Sensor Ltd., Hamilton, ON, Canada) to predict soil organic carbon (SOC) as well as total nitrogen (TN) in variable, glacial till soils at the 147 ha Cornell University Willsboro Research Farm, located in Upstate New York, USA. Regression analysis was conducted using the natural log of SOC (lnSOC) and the natural log of TN (lnTN) as dependent variables, and sample depth and color data were used as predictors for 155 air dried soil samples. Analysis was conducted for combined samples, Alfisols, and Entisols as separate sample sets and separate models were developed using depth and color variables, and color variables only. Depth and L* were significant predictors of lnSOC and lnTN for all sample sets. The color variable b* was not a significant predictor of lnSOC for any soil sample set, but it was for lnTN for all sample sets. The lnSOC prediction model for Alfisols, which included depth, had the highest R2 value (0.81, p-value < 0.001). The lnSOC model for Entisols, which contained only color variables, had the lowest R2 (0.62, p-value < 0.001). The results suggest that the Nix ProTM color sensor is an effective tool for the rapid assessment of SOC and TN content for these soils. With the accuracy and low cost of this sensor technology, it will be possible to greatly increase the spatial and temporal density of SOC and TN estimates, which is critical for soil management.
36
Hall, Frederick A. "A Prince’s Sojourn in Eighteenth-Century Canada." Studies in Eighteenth-Century Culture 19, no. 1 (1990): 247–66. http://dx.doi.org/10.1353/sec.1990.0015.
37
Schut, Peter, Scott Smith, Walter Fraser, Xiaoyuan Geng, and David Kroetsch. "Soil Landscapes of Canada: Building a National Framework for Environmental Information." GEOMATICA 65, no. 3 (September 2011): 293–309. http://dx.doi.org/10.5623/cig2011-045.
Анотація:
The Soil Landscapes of Canada (SLC) is a national soil map and accompanying database of environmental information for all of Canada, produced and maintained by the Canadian Soil Information Service (CanSIS) which is a part of Agriculture and Agri-Food Canada. The SLC maps were originally published as a set of paper products for individual provinces and regions. The maps were digitized in CanSIS, using one of the first geographic information systems in the world, and linked to soil and landscape attribute tables to serve an evolving variety of spatial modelling applications. The SLCs form the lowest level of the National Ecological Framework for Canada. The latest public release of the SLC is version 3.2, which provides updated soil and landscape information for the agricultural areas of Canada. The SLC v3.2 digital coverage includes an extensive set of relational data tables. The component table lists the soil components in each agricultural polygon along with their predicted dominant slope, class, and extent. The soil component codes are also linked to soil attribute tables which define fundamental soil properties, such as classification and parent material, as well as a description of the soil horizons and key soil attributes to a depth of 100 cm. SLC v3.2 adds a new set of landform tables which identify the major landform type in each polygon and indicates the most likely soil components in the upper, mid slope, lower slope, and depressional positions. These soil and landform attributes are designed to support a wide variety of national and international environmental modelling applications, such as the prediction of soil quality change, soil carbon sequestration, and land productivity for different agricultural crops in response to agricultural policy, land management, and climate change scenarios. Future versions of the SLC are under development that will have improved spatial resolution and include soils data for areas beyond the present agricultural zone of Canada.
38
Lynch, D. H., R. D. H. Cohen, A. Fredeen, G. Patterson, and R. C. Martin. "Management of Canadian prairie region grazed grasslands: Soil C sequestration, livestock productivity and profitability." Canadian Journal of Soil Science 85, no. 2 (May 1, 2005): 183–92. http://dx.doi.org/10.4141/s04-053.
Анотація:
The GrassGro model (a computer simulation of management-induced changes in range and pasture forage and livestock productivity) was combined with spreadsheet analyses to estimate the influence of improved grazing practices on soil organic carbon (SOC), and farm profitability, across native rangelands and tame pastures of the southern Canadian Prairies. Improved practices included complementary grazing (CG) and reduced stocking density (RSD) on rangeland; and N fertilization (FERT), seeded grass/legumes grazed continuously (GLGC) or rotationally (GLGR), and RSD on tame pastures. The analysis was stratified into three ecoregions on the basis of similarities in climate and soil type. Averaged over 30 yr and ecoregions, SOC rates of gain through improved management were 5 (RSD) to 26 (CG) kg C ha-1yr-1 for rangelands, and 86 (RSD), 75 (GLGC), 62 (GLGR) and 222 (FERT) kg C ha-1yr-1 for tame pastures. Gains with FERT were considered largely negated by associated energy (C) costs, N2O emissions, and shifts in grassland species. The CG system alone improved net returns to the producer. The estimated potential combined SOC gain on prairie grazinglands (11.5 Mha) was 1.63 MMT CO2 yr-1 (or 0.465 MMT C yr-1), slightly less than the 1.70 MMT CO2 yr-1 currently emitted from agricultural soils in Canada. Key words: Soil carbon, GrassGro model, grazing management, rangeland, tame pasture
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Andrijasevic, Nemanja. "Letters of the highest ranking church officials to the author of the first volume of the History of the Serbian Orhtodox Church, Prof dr. Djoko Slijepcevic." Prilozi za knjizevnost, jezik, istoriju i folklor, no. 88 (2022): 135–49. http://dx.doi.org/10.2298/pkjif2288135a.
Анотація:
The year 2022 marks the 60th anniversary of the publication of the first comprehen?sive History of the Serbian Orthodox Church. Its author, Professor of the Belgrade University - Dr. Djoko Slijepcevic, was an ecclesiastical historian who published this work as a political emigrant in Munich, from his own financial resources. Several highly ranked church dignitaries, including the Patriarch of the Serbian Orthodox Church (SOC), decided to send him letters of gratitude, even though well aware that all correspondence at the time had been under sur?veillance. The appendix of this work contains letters written by the Serbian Patriarch German Djoric, Bishop of Bachka Nikanor Ilichic, dissident and spiritual elder Archimandrite Prof Dr. Justin Popovic (who had been canonized as saint by the SOC), Archimandrite Dr. Firmilian Otsokolyic, as well as protopriest Stevan Lastavitsa. The last two had been later ordained as bishops of SOC in America and Canada in 1963. These short letters which express gratitude and recognition of the author`s diligent work across several decades provide an opportunity to understand how the highest ranking officials of the Church reacted to the publication of the exiled authors`s History of the Serbian Orthodox Church in emigration. Up until late 1980s, this work had been unwanted and hard to find in Yugoslavia and had not been accessible in the state libraries, nor at the historical Institutes.
40
Thevathasan, Naresh, Andrew Gordon, Amir Bazrgar, and Moira Ijzerman. "Quantification of the Carbon Sequestration Potential of a 31-year-old Tree-based Intercropping System in Southern Ontario, Canada." Advances in Environmental and Engineering Research 03, no. 04 (October 25, 2022): 1–14. http://dx.doi.org/10.21926/aeer.2204043.
Анотація:
Carbon (C) storage potential was quantified for four tree species which are commonly incorporated into tree-based intercropping (TBI) systems and compared with conventional agricultural systems in southern Ontario, Canada. In the 31-year-old TBI system at the University of Guelph’s Agroforestry Research Station, Norway spruce (<em>Picea abies</em>), white cedar (<em>Thuja occidentalis</em>), black walnut (<em>Juglans nigra</em>) and red oak (<em>Quercus rubra</em>) were planted in tree rows, intercropped with soybean (<em>Glycine max</em>). In the conventional agricultural field, soybean was grown in a monocropping system. Above and belowground tree and crop C content, soil organic C (SOC) and system level C was quantified for each tree species as well as the conventional agricultural system. Red oak TBI systems had the highest SOC followed by black walnut, Norway spruce and white cedar with values of 93.2, 83.9, 78.1, and 72.2 t C ha<sup>-1</sup>, respectively. Red oak TBI systems also had the highest mean tree C content, followed by black walnut, Norway spruce and white cedar, with values of 299.7, 285.8, 255.4 and 70.1 kg C tree<sup>-1</sup>, respectively. Total system level C, which incorporated SOC, tree C content and tree planting densities was 134.8, 126.4, 115.7, 95.6 and 75.6 t C ha<sup>-1</sup> respectively for spruce, oak, walnut and cedar TBI systems and the agricultural field. TBI systems provide higher C sequestration potentials than conventional agricultural fields, and Norway spruce and red oak should be included into TBI systems in southern Ontario to maximize C sequestration benefits.
41
Tawfik, Kareem O., Brittany A. Leader, Zoe A. Walters, and Daniel I. Choo. "Relative Preservation of Superior Semicircular Canal Architecture in CHARGE Syndrome." Otolaryngology–Head and Neck Surgery 160, no. 6 (January 22, 2019): 1095–100. http://dx.doi.org/10.1177/0194599818824306.
Анотація:
Objectives (1) Describe common patterns of semicircular canal (SCC) anomalies in CHARGE syndrome (CS) and (2) recognize that in CS, the architecture of the superior SCC may be relatively preserved. Study Design This is a retrospective review of temporal bone imaging studies. Setting Quaternary care center. Subjects and Methods A sample of 37 patients with CS. All subjects met clinical diagnostic criteria for CS. The presence/absence of anomalies of the middle ear, mastoid, temporal bone venous anatomy, inner ear, and internal auditory canal was recorded. Anomalies of each SCC were considered separately and by severity (normal, dysplasia, aplasia). Results Thirty-seven subjects (74 temporal bones) were reviewed. Thirty-four (92.0%) patients demonstrated bilateral SCC anomalies. Three (8.0%) had normal SCCs. In patients with SCC anomalies, all canals demonstrated bilateral abnormalities. Thirty-two (86.5%) patients had bilateral horizontal SCC aplasia. These 32 patients also demonstrated posterior SCC aplasia in at least 1 ear. Of 74 temporal bones, 37 (50.0%) had superior SCC dysplasia. All dysplastic superior SCCs showed preservation of the anterior limb. Complete superior SCC aplasia was found in 28 (37.8%) temporal bones. Conclusion SCC anomalies occur with high frequency in CS. Complete absence of the horizontal and posterior canals is typical and usually bilateral. By contrast, the superior SCC often demonstrates relative preservation of the anterior limb.
42
Jeffries, D. S., D. CL Lam, I. Wong, and M. D. Moran. "Assessment of changes in lake pH in southeastern Canada arising from present levels and expected reductions in acidic deposition." Canadian Journal of Fisheries and Aquatic Sciences 57, S2 (September 7, 2000): 40–49. http://dx.doi.org/10.1139/f00-128.
Анотація:
An integrated acid rain assessment model was used to estimate pH for six clusters of lakes in southeastern Canada and scenarios of sulphate deposition that reflect the situation (a) before implementation of the SO2 emission controls required by the Canada/U.S. Air Quality Agreement, (b) after implementation of Canadian controls, and (c) after implementation of Canadian and U.S. controls. Modelled lake pHs were always less than their estimated original values. To assess the ecological significance of the pH reduction, scenario "damage" was quantified as the percentage of cluster lakes having pH < 6, a threshold criterion sufficient to protect most aquatic biota. Care was taken to account for naturally acidified lakes. The integrated acid rain assessment model predicted that Canadian SO2 controls will reduce damage in Ontario and Quebec but have little effect in Atlantic Canada. Implementation of U.S. SO2 controls will further reduce damage throughout all regions, although it is conservatively estimated that from 5 to 24% of the lakes will still have pH < 6 depending on cluster. Extrapolating to the inventory of acid-sensitive lakes in southeastern Canada suggests that ~76 000 lakes and ~970 000 ha of lake area will remain chemically damaged unless additional reductions in SO2 emissions are implemented beyond those required by the Air Quality Agreement.
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Laamrani, Ahmed, Paul R. Voroney, Daniel D. Saurette, Aaron A. Berg, Line Blackburn, Adam W. Gillespie, and Ralph C. Martin. "An Extensive Field-Scale Dataset of Topsoil Organic Carbon Content Aimed to Assess Remote Sensed Datasets and Data-Derived Products from Modeling Approaches." Remote Sensing 14, no. 21 (November 2, 2022): 5519. http://dx.doi.org/10.3390/rs14215519.
Анотація:
The geosciences suffer from a lack of large georeferenced datasets that can be used to assess and monitor the role of soil organic carbon (SOC) in plant growth, soil fertility, and CO2 sequestration. Publicly available, large field-scale georeferenced datasets are often limited in number and design to serve these purposes. This study provides the first publicly accessible dataset of georeferenced topsoil SOC measurements (n = 840) over a 26-hectare (ha) agricultural field located in southern Ontario, Canada, with a sampling density of ~32 points per ha. As SOC is usually influenced by site topography (i.e., slope and landscape position), each point of the database is associated with a wide range of remote sensing topographic derivatives; as well as with normalized difference vegetation index (NDVI) based value. The NDVI data were extracted from remote sensing Sentinel-2 imagery from over a five-year period (2017–2021). In this paper, the methodology for topsoil sampling, SOC measurement in the lab, as well as producing the suite of topographic derivatives is described. We discuss the opportunities that the database offers in terms of spatially explicit and continuous soil information to support international efforts in digital soil mapping (i.e., SoilGrids250m) as well as other potential applications detailed in the discussion section. We believe that the database with very dense point location measurements can help in conducting carbon stocks and sequestration studies. Such information can be used to help bridge the gap between ground data and remotely sensed datasets or data-derived products from modeling approaches intended to evaluate field-scale rates of agricultural carbon accumulation. The generated topsoil database in this study is archived and publicly available on the Zenodo open-access repository.
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D’Souza, Neil, Gerard Morton, and Hans T. Chung. "Radiation treatment of bladder squamous cell carcinoma in a patient." Canadian Urological Association Journal 6, no. 3 (February 26, 2013): E125—E128. http://dx.doi.org/10.5489/cuaj.395.
Анотація:
Bladder cancer is the sixth most common cancer in Canada. Whilemost patients present with transitional cell carcinoma, few presentwith squamous cell carcinoma (SCC). Risk factors for SCC includea history of chronic urinary tract infection, urothelial inflammationand indwelling catheters. We present the management of a patientwith locally advanced SCC of the bladder.
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Kumar, Shaji K., Brian G. M. Durie, Zhuo Su, Joris Diels, Brian Hutton, Annette Lam, and Ito Tetsuro. "Adjusted Comparisons Suggest Daratumumab Is Associated with Prolonged Survival Compared with Standard of Care Therapies in Patients with Heavily Pre-Treated and Highly Refractory Multiple Myeloma." Blood 128, no. 22 (December 2, 2016): 4517. http://dx.doi.org/10.1182/blood.v128.22.4517.4517.
Анотація:
Abstract Objective: To fully contextualize the benefit of novel agents such as daratumumab (DARA) monotherapy for the treatment of patients with heavily pre-treated and highly refractory multiple myeloma (MM), it is critical to understand the real-world outcomes of this patient population on current standard of care (SOC) therapies. The objective of this study was to perform adjusted comparisons to determine the comparative effectiveness of DARA monotherapy versus real-world SOC therapies. Methods: Data for patients treated with DARA 16 mg/kg monotherapy were available from clinical trials MMY2002 (n=106) and GEN501 (n=42), while patients treated with SOC therapies were derived from the International Myeloma Foundation (IMF) chart review of patients with MM who had ≥3 prior lines of therapy and were double refractory to a proteasome inhibitor (PI) and an immunomodulatory drug (IMiD) (n=543) (Kumar et al., ASH 2016; submitted). The pooled DARA studies demonstrated a median overall survival (OS) of 20.1 months versus 13.0 months for SOC based on the IMF cohort (Usmani et al., Blood 2016; Kumar et al., ASH 2016; submitted). The relative treatment effect of DARA versus SOC was estimated using two adjusted comparison methodologies, propensity score matching (PSM) and multivariate Cox regression analyses. Both methodologies utilized individual patient data to compare OS. Modeled covariates for the PSM were age, gender, prior lines of therapy, albumin, and refractory status to bortezomib (BOR), carfilzomib (CAR), lenalidomide (LEN), and pomalidomide (POM). PSM was performed using caliper matching with a caliper width 25% of the standard deviation of the logit-transformed propensity score, using sampling without replacement. For the regression analysis, the covariates included in the multivariate proportional hazards regression model were age, gender, prior lines of therapy, albumin, beta-2 microglobulin, prior exposure to POM and CAR, and PI/IMiD refractory status. Clustering of observations at the treatment-line level within patients was controlled for using the robust sandwich estimate for the covariance matrix, making confidence intervals (CIs) more conservative. For both PSM and regression, statistical significance testing was performed using a two-tailed p-value of <0.05, and all comparisons between treatment groups were reported with hazard ratios (HRs) and 95% CIs. Results: Prior to PSM, imbalances between the DARA and SOC groups were significant for prior lines of therapy and proportions of patients refractory to POM, CAR, BOR, and LEN. After PSM, the DARA and SOC groups were well balanced for all covariates included in propensity score calculations. After PSM, comparisons found significant improvement in favor of DARA relative to SOC for OS (HR=0.44 [95% CI 0.31-0.63]) (Figure 1). Regression analyses revealed consistent results. After adjustment for differences in all covariates included in regression between the DARA and SOC groups, results showed significant improvement in favor of DARA compared with SOC for OS (HR=0.43 [95% CI 0.32-0.59]) (Figure 2). Conclusions: Findings from both PSM and regression analyses were consistent and suggest that DARA is associated with significant gains in OS compared with SOC therapies for patients with heavily pre-treated and highly refractory MM. References: 1. Usmani SZ, Weiss BM, Plesner T, Bahlis NJ, Belch A et al. (2016) Clinical efficacy of daratumumab monotherapy in patients with heavily pretreated relapsed or refractory multiple myeloma. Blood 128 (1): 37-44. 2. Kumar SK, et al. (2016) Natural history of relapsed myeloma, refractory to immunomodulatory drugs and proteasome inhibitors: a multicenter IMWG study. The 58th Annual Meeting of the American Society of Hematology: submitted. Disclosures Kumar: Celgene: Consultancy, Research Funding; Noxxon: Consultancy, Honoraria; Janssen: Research Funding; AbbVie: Research Funding; BMS: Consultancy; Amgen: Consultancy, Research Funding; Takeda: Consultancy, Research Funding; Sanofi: Consultancy, Research Funding; Skyline: Consultancy, Honoraria. Durie:Amgen: Consultancy; Takeda: Consultancy; Janssen: Consultancy. Su:Janssen: Research Funding. Diels:Johnson & Johnson: Employment, Equity Ownership. Hutton:Essai Canada: Consultancy; Cornerstone Research Group: Consultancy; Janssen: Research Funding. Lam:Janssen: Employment. Tetsuro:Johnson & Johnson: Equity Ownership; Janssen: Employment.
46
Hamilton, Erika P., Miguel Martin, Ciara Catherine O'Sullivan, Giuseppe Curigliano, Joohyuk Sohn, Junji Tsurutani, Konstantinos Tryfonidis, Libero Santarpia, Shan Yang, and Véronique Diéras. "HER2CLIMB-05: Phase 3 study of tucatinib or placebo in combination with trastuzumab and pertuzumab as maintenance therapy for HER2+ metastatic breast cancer." Journal of Clinical Oncology 41, no. 16_suppl (June 1, 2023): TPS1115. http://dx.doi.org/10.1200/jco.2023.41.16_suppl.tps1115.
Анотація:
TPS1115 Background: The current first-line (1L) standard of care (SOC) for human epidermal growth factor receptor 2-positive (HER2+) metastatic breast cancer (MBC) is trastuzumab (T) plus pertuzumab (P) and a taxane. Despite advances in 1L SOC, most patients progress during maintenance therapy with T + P. Tucatinib is a tyrosine kinase inhibitor (TKI) approved in combination with T and capecitabine for adults with HER2+ MBC, with and without brain metastases (BM). In HER2CLIMB, the addition of tucatinib significantly prolonged progression-free survival (PFS) and overall survival (OS) in patients with HER2+ MBC and was well tolerated. Adding tucatinib also reduced the risk of disease progression or death in patients with untreated and/or active BM (Murthy et al. 2020, Curigliano et al. 2021). HER2CLIMB-05 investigates whether adding tucatinib to 1L SOC as maintenance therapy will extend PFS while maintaining quality of life (QOL). Methods: HER2CLIMB-05 (NCT05132582) is a phase 3, randomized, double-blind study evaluating tucatinib plus T + P as maintenance therapy for HER2+ MBC. Approximately 650 patients will be enrolled. Eligible patients will have advanced HER2+ disease, no progression on 4–8 cycles of prior 1L SOC, Eastern Cooperative Oncology Group Performance Status of 0 or 1, and no or asymptomatic BM. Exclusion criteria include prior treatment with anti-HER2 and/or anti-epidermal growth factor receptor TKI (prior SOC for early BC is permitted) or inability to undergo contrast magnetic resonance imaging of the brain. Patients will be randomized 1:1 to receive either tucatinib or placebo twice daily, with T + P once every 21 days. Patients with hormone receptor-positive disease may receive endocrine therapy. The primary endpoint is investigator-assessed PFS. Secondary endpoints include OS (key endpoint), PFS by Blinded Independent Central Review (BICR), time to deterioration of health-related QOL, central nervous system PFS, safety, and pharmacokinetic (PK) parameters. PFS and OS will be compared using a 2-sided stratified log-rank test between treatment groups. Time-to-event endpoints will be summarized using the Kaplan–Meier method. PK and safety data will be summarized using descriptive statistics. Enrollment is ongoing in the US, Canada, Brazil, APAC and EU countries with additional sites planned. Clinical trial information: NCT05132582 .
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Chan, Anthony T. C., Victor Ho Fun Lee, Ruey-Long Hong, Myung-Ju Ahn, Wan Qin Chong, Anna Spreafico, Sung-Bae Kim, et al. "Abstract PO-008: Association of plasma Epstein-Barr virus DNA and clinical response in patients with recurrent and/or metastatic nasopharyngeal cancer treated with pembrolizumab or standard-of-care chemotherapy in KEYNOTE-122." Clinical Cancer Research 29, no. 18_Supplement (September 15, 2023): PO—008—PO—008. http://dx.doi.org/10.1158/1557-3265.aacrahns23-po-008.
Анотація:
Abstract Introduction: Plasma Epstein-Barr virus (EBV) DNA has been shown to be a sensitive and specific biomarker for prognosis, surveillance of recurrence, and treatment response of nasopharyngeal cancer (NPC). The phase 3 KEYNOTE-122 trial (NCT02611960) was conducted to evaluate pembrolizumab (pembro) vs standard of care (SOC) chemotherapy (chemo) in patients with platinum-pretreated recurrent/metastatic (R/M) NPC. This exploratory analysis was designed to evaluate association between plasma EBV DNA load and clinical response in patients treated with pembro or SOC in KEYNOTE-122. Materials and Methods: Patients who received ≥1 prior platinum-based chemo with histologically confirmed EBV-positive R/M NPC measurable per RECIST v1.1 and an ECOG PS ≤1, were randomly assigned 1:1 to receive pembro 200 mg IV Q3W for ≤35 cycles or investigator’s choice of SOC chemo (capecitabine, gemcitabine, or docetaxel). Association between baseline plasma EBV DNA load, as measured using a high-sensitivity qPCR assay, and clinical outcomes (ORR, PFS, OS) was evaluated within each treatment arm. Significance of continuous EBV DNA load was prespecified at 0.05 for 1-sided P values from logistic (ORR) and Cox proportional hazard regression (PFS, OS) adjusted for ECOG PS. Additional assessments included association between clinical outcomes and plasma EBV DNA load fold change from baseline at cycle 2, day 1 (C2D1), after baseline adjustment, and descriptive comparison between baseline plasma EBV DNA load and tumor volume in predicting clinical outcomes. Clinical data cutoff: November 30, 2020. Results: 215/228 (94.3%) treated patients had evaluable plasma EBV DNA load data at baseline (pembro, 111; SOC, 104). Baseline plasma EBV DNA load (as a continuous variable) was significantly associated with PFS and OS for pembro and SOC (both P < 0.005) but not ORR (P = 0.105, pembro; 0.473, SOC). Association between plasma EBV DNA load fold change from baseline at C2D1 and ORR, PFS, or OS was P ≤ 0.005 for both pembro and SOC. Baseline plasma EBV DNA load was numerically more predictive of OS and PFS than tumor volume for both pembro (C index [95% CI]: EBV DNA [OS: 0.71, 0.64-0.77; PFS: 0.67, 0.60-0.74] vs tumor volume [OS: 0.47, 0.41-0.54; PFS: 0.42, 0.35-0.49]) and SOC (EBV DNA [OS: 0.67, 0.60-0.73; PFS: 0.64, 0.56-0.71] vs tumor volume [OS: 0.58, 0.51-0.65; PFS: 0.54, 0.46-0.62]). Conclusions: In this post hoc exploratory analysis of KEYNOTE-122, higher baseline plasma EBV DNA load was negatively associated with PFS and OS in patients with NPC treated with pembro or SOC. Independent of baseline association, a larger decrease in plasma EBV DNA load at C2D1 relative to baseline was associated with improved clinical outcomes to both treatments. EBV DNA was more predictive of clinical outcomes than tumor volume. While definitive conclusions are limited, these findings provide additional support for plasma EBV DNA as a prognostic biomarker for NPC, which could guide treatment decisions. Citation Format: Anthony T. C. Chan, Victor Ho Fun Lee, Ruey-Long Hong, Myung-Ju Ahn, Wan Qin Chong, Anna Spreafico, Sung-Bae Kim, Gwo Fuang Ho, Priscilla B. Caguioa, Nuttapong Ngamphaiboon, Ramona F. Swaby, Bo Wei, Andrea Webber, John Kang, Burak Gumuscu, Jianda Yuan, Lillian Siu. Association of plasma Epstein-Barr virus DNA and clinical response in patients with recurrent and/or metastatic nasopharyngeal cancer treated with pembrolizumab or standard-of-care chemotherapy in KEYNOTE-122 [abstract]. In: Proceedings of the AACR-AHNS Head and Neck Cancer Conference: Innovating through Basic, Clinical, and Translational Research; 2023 Jul 7-8; Montreal, QC, Canada. Philadelphia (PA): AACR; Clin Cancer Res 2023;29(18_Suppl):Abstract nr PO-008.
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Cohen, S. B., H. Schulze-Koops, J. Pope, D. Gold, M. J. Cadatal, G. Schroeder, A. Diehl, E. Nagy, S. Duench, and A. Rubbert-Roth. "POS0827 CLINICAL OUTCOMES OF PATIENTS WITH RHEUMATOID ARTHRITIS WHO DISCONTINUED TOFACITINIB OR TUMOUR NECROSIS FACTOR INHIBITORS: RESULTS FROM ORAL SURVEILLANCE." Annals of the Rheumatic Diseases 82, Suppl 1 (May 30, 2023): 710–11. http://dx.doi.org/10.1136/annrheumdis-2023-eular.2670.
Анотація:
BackgroundSwitching or discontinuing therapy may occur in patients (pts) with rheumatoid arthritis (RA) with an inadequate response/intolerance to treatment. In ORAL Surveillance, a post-authorisation safety study of tofacitinib vs tumour necrosis factor inhibitors (TNFi) in pts with RA despite methotrexate aged ≥50 years with ≥1 additional cardiovascular risk factor,[1]pts could discontinue the assigned study drug and switch to local standard of care (SOC) treatment and, in contrast to previous randomised controlled trials, were encouraged to remain in the study.ObjectivesTo assess efficacy/safety in the SOC period in pts who discontinued study drug and started SOC treatment.MethodsThis post hoc analysis included randomised pts from ORAL Surveillance (NCT02092467) who received ≥1 dose of study drug (tofacitinib 5 or 10 mg twice daily [BID], or TNFi) and initiated SOC treatment per-protocol after discontinuing study drug. SOC treatment could include disease-modifying antirheumatic drugs (DMARDs; biologic, targeted synthetic, or conventional synthetic [cs]), or glucocorticoids. Efficacy outcomes included mean observed and change from randomisation/SOC baseline (BL; Δ) in Simplified Disease Activity Index (SDAI) over time. Adverse events (AEs) and serious AEs (SAEs) were reported; incidence rates (IRs; pts with events/100 pt-years [PY]) were estimated for AEs of special interest (AESI). Data were analysed for the periods in which pts who discontinued study drug received 1) tofacitinib or TNFi (randomised period) and 2) SOC treatment (SOC period). Pts were analysed in their original treatment group (ex-tofacitinib 5/10 mg BID, or ex-TNFi). Analyses were descriptive.ResultsOf 4362 randomised and treated pts, 718 (16.5%) stopped study drug (50.7, 59.3 and 47.8% due to AEs; 15.1, 5.8 and 21.9% due to insufficient clinical response for tofacitinib 5 mg BID, 10 mg BID and TNFi, respectively); most received csDMARDs only in the SOC period (73.1–79.6% across groups). In general, BL characteristics in pts who switched to SOC treatment were numerically similar across groups. Mean duration of randomised and SOC periods was 21.9–26.0 and 15.0–18.6 months, respectively. ΔSDAI over time was similar across groups in the randomised period (data not shown) with modest improvements in the SOC period (Figure 1) and with SDAI score generally reflecting moderate disease activity (data not shown). In general, AE and SAE rates were similar across groups but numerically higher in the randomised vs SOC period (data not shown). AESI rates were generally similar across groups in the SOC period (Table 1).Table 1.IRs (95% CIs) of AESI in the SOC period (SASa, total On-SOC time)Ex-tofacitinib 5 mg BID (N=219)Ex-tofacitinib 10 mg BID (N=275)Ex-TNFib(N=224)Major adverse cardiovascular eventscn (%), PY3 (1.4), 285.78 (2.9), 394.85 (2.2), 357.5IR (95% CI)1.1 (0.2, 3.1)2.0 (0.9, 4.0)1.4 (0.5, 3.3)Malignancies excluding NMSCcn (%), PY4 (1.8), 286.19 (3.3), 391.74 (1.8), 359.3IR (95% CI)1.4 (0.4, 3.6)2.3 (1.1, 4.4)1.1 (0.3, 2.9)NMSCcn (%), PY1 (0.5), 286.62 (0.7), 395.42 (0.9), 357.7IR (95% CI)0.4 (0.0, 1.9)0.5 (0.1, 1.8)0.6 (0.1, 2.0)Venous thromboembolismcn (%), PY1 (0.5), 287.12 (0.7), 395.41 (0.5), 361.1IR (95% CI)0.4 (0.0, 1.9)0.5 (0.1, 1.8)0.3 (0.0, 1.5)Serious infectionsn (%), PY16 (7.3), 276.215 (5.5), 375.617 (7.6), 332.4IR (95% CI)5.8 (3.3, 9.4)4.0 (2.2, 6.6)5.1 (3.0, 8.2)All-cause deathsn (%), PY7 (3.2), 288.813 (4.7), 396.38 (3.6), 361.2IR (95% CI)2.4 (1.0, 5.0)3.3 (1.8, 5.6)2.2 (1.0, 4.4)aSame as FASbUnited States, Puerto Rico and Canada: adalimumab; Rest of World: etanerceptcAdjudicatedCI, confidence interval; n, number of pts with event; NMSC, non-melanoma skin cancer; SAS, safety analysis setConclusionIn ORAL Surveillance, pts with RA who discontinued tofacitinib or TNFi and switched to SOC treatment had modest improvements in efficacy over time without increased risk of AEs. Limitations included that this analysis was post hoc.Reference[1]Ytterberg et al. N Engl J Med 2022; 386: 316-26AcknowledgementsThis study was sponsored by Pfizer. Medical writing support, under the direction of the authors, was provided by Maisie Camm, BSc, CMC Connect, a division of IPG Health Medical Communications, and was funded by Pfizer, New York, NY, USA, in accordance with Good Publication Practice (GPP 2022) guidelines (Ann Intern Med 2022;175:1298-1304).Disclosure of InterestsStanley B. Cohen Consultant of: AbbVie, Amgen, Boehringer Ingelheim, Gilead Sciences, Merck and Pfizer Inc, Hendrik Schulze-Koops Consultant of: AbbVie, Amgen, Biogen, Bristol Myers Squibb, Celgene, Eli Lilly, Gilead Sciences, Hexal Sandoz, Hospira, Janssen-Cilag, MSD, Novartis, Pfizer Inc, Roche and UCB, Grant/research support from: Novartis and Pfizer Inc, Janet Pope Consultant of: AbbVie, Actelion, Amgen, Bayer, Bristol Myers Squibb, Eli Lilly, Merck, Novartis, Pfizer Inc, Roche, Sandoz, Sanofi and UCB, Grant/research support from: Bristol Myers Squibb, Roche, Seattle Genetics and UCB, David Gold Shareholder of: Pfizer Inc, Employee of: Pfizer Inc, Mary Jane Cadatal Shareholder of: Pfizer Inc, Employee of: Pfizer Inc, Georgene Schroeder Employee of: Syneos Health, who were paid contractors to Pfizer Inc, Annette Diehl Shareholder of: Pfizer Inc, Employee of: Pfizer Inc, Edward Nagy Shareholder of: Pfizer Inc, Employee of: Pfizer Inc, Stephanie Duench Shareholder of: Pfizer Inc, Employee of: Pfizer Inc, Andrea Rubbert-Roth Speakers bureau: AbbVie, Amgen, Bristol Myers Squibb, Eli Lilly, F. Hoffmann-La Roche, Janssen and Sanofi Pasteur, Consultant of: AbbVie, Amgen, Chugai, Eli Lilly, F. Hoffmann-La Roche, Gilead Sciences, Novartis and Sanofi Pasteur.
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Ghahreman, Roya, Wanmin Gong, Paul A. Makar, Alexandru Lupu, Amanda Cole, Kulbir Banwait, Colin Lee, and Ayodeji Akingunola. "Modeling below-cloud scavenging of size-resolved particles in GEM-MACHv3.1." Geoscientific Model Development 17, no. 2 (January 26, 2024): 685–707. http://dx.doi.org/10.5194/gmd-17-685-2024.
Анотація:
Abstract. Below-cloud scavenging (BCS) is the process of aerosol removal from the atmosphere between cloud base and the ground by precipitation (e.g., rain or snow), and affects aerosol number or mass concentrations, size distribution, and lifetime. An accurate representation of precipitation phases is important in treating BCS as the efficiency of aerosol scavenging differs significantly between liquid and solid precipitation. The impact of different representations of BCS on existing model biases was examined through implementing a new aerosol BCS scheme in the Environment and Climate Change Canada (ECCC) air quality prediction model GEM-MACH and comparing it with the existing scavenging scheme in the model. Further, the current GEM-MACH employs a single-phase precipitation for BCS: total precipitation is treated as either liquid or solid depending on a fixed environment temperature threshold. Here, we consider co-existing liquid and solid precipitation phases as they are predicted by the GEM microphysics. GEM-MACH simulations, in a local-area domain over the Athabasca oil sands areas, Canada, are compared with observed precipitation samples, with a focus on the particulate base cation NH4+; acidic anions NO3-, SO4=, HSO3- in precipitation; and observed ambient particulate sulfate, ammonium, and nitrate concentrations. Overall, the introduction of the multi-phase approach and the new scavenging scheme enhances GEM-MACH performance compared to previous methods. Including a multi-phase approach leads to altered SO4= scavenging and impacts the BCS of SO2 into the aqueous phase over the domain. Sulfate biases improved from +46 % to −5 % relative to Alberta Precipitation Quality Monitoring Program wet sulfate observations. At Canadian Air and Precipitation Monitoring Network stations the biases became more negative, from −10 % to −30 % for the tests carried out here. These improvements contrast with prior annual average biases of +200 % for SO4=, indicating enhanced model performance. Improvements in model performance (via scores for correlation coefficient, normalized mean bias, and/or fractional number of model values within a factor of 2 of observations) could also be seen between the base case and the two simulations based on multi-phase partitioning for NO3-, NH4+, and SO4=. Whether or not these improvements corresponded to increases or decreases in NO3- and NH4+ wet deposition varied over the simulation region. The changes were episodic in nature – the most significant changes in wet deposition were likely at specific geographic locations and represent specific cloud precipitation events. The changes in wet scavenging resulted in a higher formation rate and larger concentrations of atmospheric particle sulfate.
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Van Eerd, Laura L., Katelyn A. Congreves, Adam Hayes, Anne Verhallen, and David C. Hooker. "Long-term tillage and crop rotation effects on soil quality, organic carbon, and total nitrogen." Canadian Journal of Soil Science 94, no. 3 (August 2014): 303–15. http://dx.doi.org/10.4141/cjss2013-093.
Анотація:
Van Eerd, L. L., Congreves, K. A., Hayes, A., Verhallen, A. and Hooker, D. C. 2014. Long-term tillage and crop rotation effects on soil quality, organic carbon, and total nitrogen. Can. J. Soil Sci. 94: 303–315. Long-term studies allow for quantification of the effects of crop production practices, such as tillage and crop rotation, on soil quality and soil C and N stores. In two experiments at Ridgetown, ON, we evaluated the long-term (11 and 15 yr) effect of tillage system and crop rotation on soil quality via the Cornell Soil Health Assessment (CSHA) at 0–15 cm and soil organic C (SOC) and total N at 5-, 10-, and 20-cm increments to 120 cm depth. The CSHA soil quality score and SOC and total N were higher with no-till (NT) than fall moldboard plough with spring cultivation (conventional tillage, CT) and rotations with winter wheat [soybean–winter wheat (S-W) and soybean–winter wheat–corn (S-W-C)] compared with rotations without winter wheat. In both long-term trials, NT had ca. 21 Mg ha−1more or 14% higher SOC than CT in the 0- to 100-cm soil profile, a trend which contrasts previous research in eastern Canada. Thus, the two long-term trial results at Ridgetown suggest that to improve soil quality and storage of C and N, growers on clay loam soil in southwestern Ontario should consider adopting NT production practices and including winter wheat in the rotation.