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Zhao, Gengxing, Chao Dong, Xiaona Chen y Baowei Su. "Scale Characteristics and Effects on Spatial Variability of Soil Available Nutrients". Applied Engineering in Agriculture 35, n.º 2 (2019): 221–30. http://dx.doi.org/10.13031/aea.12963.
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Abstract.The spatial variability of farmland soil nutrients on different scales is important for farming as it forms the basis for the efficient utilization of soil nutrients and precision fertilization. Survey points were distributed throughout the study area on three different scales (county, field, and block). Research on the scale effect of the spatial variability of available nitrogen (AN), available phosphorus (AP), and available potassium (AK) involved a combination of classical statistics, geostatistics, and Geographic Information System (GIS) techniques. Results indicated that the three kinds of nutrients presented moderate variation intensity on the three scales. All of the nutrients tested exhibited strong spatial autocorrelation, indicating that spatial variability was primarily affected by structural factors, including climate, soil type and topography. As the sampling scale decreased, the nutrients showing weak variation at the large scale exhibited great variation at the small scale; the spatial autocorrelation of these three nutrients first became greater and then weakened; the distance of the spatial autocorrelation shortened gradually. Furthermore, the patch density value of the soil nutrient map increased, which indicated that the distribution of nutrients tended to be more fragile. When combined, sampling methods on the multi-scale allowed us to obtain real and systematic soil information. This study explored scale characteristics and the effects of spatial variability with regards to the primary nutrients available on farmland and provided a theoretical basis to effectively understand the nutrient status of regional farmland and improve the efficacy of soil sampling. Keywords: Multi-scale, Geostatistics, Patch density, Fractal dimension, Kriging interpolation.
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Qin, Zi Han. "Research on the Spatial Variability of Soil Nutrients Prediction Based on GIS". Advanced Materials Research 791-793 (septiembre de 2013): 1681–85. http://dx.doi.org/10.4028/www.scientific.net/amr.791-793.1681.
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Soil is a necessary nutrition library of crop growth, its nutrient spatial variability exists the whole crop growth period with the characteristics of long and complex, so the spatial variability of soil nutrient prediction is one of the hot research problems to be urgently solved in precision agriculture. This paper first introduces GIS and statistical analysis organic combination of research method and model, on the basis of this, based on GIS spatial data level of analysis and point-line-side buffer, we will accurate analysis of point-line-sides mutation interval through the variation Euclidean distance and distance weighting interpolation method. Finally through the comparison of mean value and T test, we can predict the approximate interval of soil nutrients spatial variability, to a certain extent, it can provide theory and technology support for the scientific prediction of soil nutrients spatial variability.
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Zhao, Yue Ling, Hai Yan Han, Li Ying Cao y Gui Fen Chen. "The Nutrients Spatial Variability of Black Soil Based on GIS". Applied Mechanics and Materials 694 (noviembre de 2014): 580–83. http://dx.doi.org/10.4028/www.scientific.net/amm.694.580.
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The precision agriculture (PA) is the end product of the modern high tech's information technology and the agricultural production technology union. The soil nutrients are not only an important component of soil research, but also a critical determinant of its productivity. Some soil nutrients spatial distribution pictures were established based on important factors that affect crops production. The soil nutrient situation was understood by the paper in Jilin province black soil. The results can realized some information opening and sharing and helped some farmer and manager to understand some soil nutrient spatial distribution. They can speed up the development of Jilin province’s precision agriculture.
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Long, Linli, Ying Liu, Xiaoyang Chen, Junting Guo, Xinhui Li, Yangnan Guo, Xuyang Zhang y Shaogang Lei. "Analysis of Spatial Variability and Influencing Factors of Soil Nutrients in Western China: A Case Study of the Daliuta Mining Area". Sustainability 14, n.º 5 (27 de febrero de 2022): 2793. http://dx.doi.org/10.3390/su14052793.
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An understanding of the spatial variation and influence factors of soil nutrients in mining areas can provide a reference for land reclamation and ecological restoration. Daliuta was used as the study area. The spatial variability of soil nutrients was analyzed using traditional statistics and geostatistics. The effects of topography, mining history, and soil erosion were discussed. The results indicate that the soil pH of the Daliuta mining area is slightly acidic to slightly alkaline, and the soil organic matter, available nitrogen, available phosphorus, and available potassium belonged to the five levels (very low), six (extremely low), five (extremely low), and four (moderately low), respectively. The soil water and salt content indicated that the soil environment in the mining area is arid and has normal levels of salinity. The organic matter, available nitrogen, available phosphorus, available potassium, and soil salt varied moderately, and the pH did not change much, while the soil water varied strongly. The organic matter, pH, and soil salinity are moderately spatially autocorrelated, and the available nitrogen, available phosphorus, available potassium, and soil water are weakly spatially autocorrelated. Each nutrient index had a certain spatial trend effect. The slope, aspect, elevation, and topographic wetness index are the primary topographic factors that control the spatial distribution of soil nutrients. The organic matter, pH, and soil salinity are moderately spatially autocorrelated, and the available nitrogen, available phosphorus, available potassium, and soil water are weakly spatially autocorrelated. Each nutrient index had a certain spatial trend effect. The slope, aspect, elevation, and topographic wetness index are the primary topographic factors that control the spatial distribution of soil nutrients. Soil erosion and mining history are also important factors that lead to the spatial variation of soil nutrients.
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Carr, Geneviève M., Patricia A. Chambers y Antoine Morin. "Periphyton, water quality, and land use at multiple spatial scales in Alberta rivers". Canadian Journal of Fisheries and Aquatic Sciences 62, n.º 6 (1 de junio de 2005): 1309–19. http://dx.doi.org/10.1139/f05-044.
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The ability of land use to replace water quality variables in predictive models of periphyton chlorophyll a was tested with a 21-year data set for Alberta rivers. Nutrients (total dissolved P and NO2 + NO3) explained 23%24% of the variability in seasonal chlorophyll a, whereas land use (human population density) explained 25%28% of the variability. The best models included the combination of total dissolved P and population density, explaining 32%34% of periphyton chlorophyll a variability. However, analysis of variance of chlorophyll a by ecoregions and ecozones explained about as much variability (28%30%), and the inclusion of an ecoregion term into the regression models showed a diminished importance of land use as a predictor of chlorophyll a, with best models based on the combination of nutrients and ecoregion and explaining up to 43%44% of periphyton chlorophyll a variability. Within ecoregions, land use was sometimes a good surrogate for nutrient data in predicting chlorophyll a concentrations. Overall, land use is a suitable surrogate for nutrients in regression models for chlorophyll a, but its inclusion in general models may reflect regional differences in nutrientchlorophyll relationships rather than true land use effects on chlorophyll a.
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Behera, S. K., K. Suresh, K. Ramachandrudu, K. Manorama y B. N. Rao. "Mapping spatial variability of leaf nutrient status of oil palm (Elaeis guineensis Jacq.) plantations in India". Crop and Pasture Science 67, n.º 1 (2016): 109. http://dx.doi.org/10.1071/cp15029.
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Spatial variability of leaf nutrients in oil palm (Elaeis guineensis Jacq.) plantations in Goa, Karnataka, Mizoram and Gujarat states of India were examined for implementation of site-specific fertilisation programs. Georeferenced leaf samples were collected randomly for the oil palm plantations. The leaf nutrient concentrations were assessed and analysed statistically and geostatistically. The concentrations of leaf nutrients such as nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S) and boron (B) in oil palm plantations varied widely at different locations. Leaf P concentration was positively and significantly correlated with S concentration at Goa, Karnataka and Gujarat. Positive and significant correlation between leaf Ca and Mg concentration was recorded at Mizoram and Gujarat. Geostatistical analysis of leaf nutrients showed different distribution patterns at different locations. This study revealed the need to determine spatial variability of nutrient status of oil palm plantations before planning a differential fertiliser program. Therefore, saving of nutrients could be achieved by adopting site-specific nutrient-management strategies.
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Kumar, Hemendra, Puneet Srivastava, Jasmeet Lamba, Brenda V. Ortiz, Thomas R. Way, Laljeet Sangha, Bijoychandra S. Takhellambam, Guilherme Morata y Roberto Molinari. "Within-Field Variability in Nutrients for Site-Specific Agricultural Management in Irrigated Cornfield". Journal of the ASABE 65, n.º 4 (2022): 865–80. http://dx.doi.org/10.13031/ja.15042.
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HighlightsPhosphorus and nitrogen in soil and plants varied during the growing season across the cornfield.Spatial variability in nutrients caused spatial variability in plant growth and crop yield across the cornfield.Hydrological characteristics and soil hydraulic properties were responsible for spatial variability in nutrients.Need to consider spatial variability in nutrients in delineating management zones before adopting management practices.Abstract. The adoption of precision agricultural practices in Alabama has been increasing in recent years. Although challenging, understanding nutrient variability in agricultural fields is important for site-specific management. This study investigated phosphorus (P) and nitrogen (N) variability in an irrigated cornfield located in the Town Creek Watershed of Tennessee Valley Region of Alabama, USA during the 2019 growing season. Three different irrigation management zones (high yield-HY, moderate yield-MY, and low yield-LY) were delineated based on ten years of historical records of crop yield, soil texture, and measured topography using the Management Zone Analyst (MZA) software. The soil samples at 0 to 15 cm, 15 to 30 cm, and 30 to 60 cm depths were collected five different times during the 2019 growing season. Both manure and inorganic fertilizer were uniformly applied during the growing season. At all soil depths, HY and MY zones had higher soil nutrient concentrations than the field average nutrient concentration. However, the LY zone had below field average soil nutrient concentration in the entire soil profile. The plants (above-ground) in HY and MY zones had higher than average nutrient concentrations and the plants in the LY zone had lower than average nutrient concentrations throughout the cornfield. This site-specific nutrient variation in these zones was due to within-field terrain attributes, differences in soil properties, and surface runoff losses. A significant difference was recorded in the corn yield in the HY and LY zones of the field. Two extreme groups of nutrients were found in the cornfield similar to irrigation management zones (HY and LY). A zone with a higher yield also had higher soil and plant nutrients in the zone (HY), and a zone with a lower yield also had lower soil and plant nutrients in the zone (LY). Incorporating nutrient variability for site-specific management in management zone delineation can help with reducing nutrient application, nutrient loss, and improving yield. This study supports the adopting of precision agricultural management practices based on in-field nutrient variability. Keywords: Corn, Crop yield variability, Irrigation, Management zones, Nitrogen, Nutrient variability, Phosphorus, Site-specific management, Topographical wetness index (TWI).
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Siswanto, Eko, MD Latifur Rahman Sarker y Benny N. Peter. "Spatial variability of nutrient sources determining phytoplankton Chlorophyll-a concentrations in the Bay of Bengal". APN Science Bulletin 2022, n.º 1 (30 de julio de 2022): 56–64. http://dx.doi.org/10.30852/sb.2022.1834.
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Primary production is a key marine ecosystem driver in the Bay of Bengal and is important for the societies and economies of the surrounding countries. Although the availability of inorganic nutrients is known to control primary production in this region, the specific nutrient sources that affect primary production in different parts of the bay have not been identified. In this study, we assess the importance of nutrients from different sources in determining chlorophyll-a concentration, an indicator of primary production, in the Bay of Bengal by conducting multiple linear regression of satellite-derived chlorophyll-a concentration, sea surface height anomaly, and sea surface temperature; modelled dust deposition; and in situ river discharge from 1997 to 2016. River-borne nutrients were important up to approximately 200 km from the coast. Deep-ocean nutrients influenced chlorophyll-a concentrations mainly in the south-western and western bay, whereas wind-borne nutrients were more important in the central and eastern bay. Any attempt to understand the impact of nutrients from a certain source should also consider the potential impacts of other nutrient sources. Although climate impacts on chlorophyll-a concentrations through river discharge were observed in our study, future studies should investigate climate-change impacts through atmospheric aerosols and mesoscale eddies.
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Neatrour, Matthew A., Robert H. Jones y Stephen W. Golladay. "Correlations between soil nutrient availability and fine-root biomass at two spatial scales in forested wetlands with contrasting hydrological regimes". Canadian Journal of Forest Research 35, n.º 12 (1 de diciembre de 2005): 2934–41. http://dx.doi.org/10.1139/x05-217.
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We investigated the relationship between soil nutrients and fine-root biomass at broad (among ecosystem types) and fine (within a 20 m × 20 m plot) spatial scales in forested wetlands of the southeastern United States. We selected three replicates each of high-fertility floodplain swamps, low-fertility depressional swamps, and intermediate-fertility river swamp sloughs and measured soil nutrient availability (NO3-N, NH4-N, and PO4-P) and fine-root biomass. At one replicate of each wetland type, a dense network of sampling points was used to measure variability (variance and coefficient of variation) of soil nutrients and fine-root biomass. At the broad scale, fine-root biomass was lower in floodplain swamps than in either river swamp sloughs or depressional swamps. Also, multiple linear regression and Spearman's rank correlations indicated a negative relationship between soil nutrient availability and fine-root biomass. Fine-scale correlates between soil nutrient availability and fine-root biomass were generally weak. Fine-scale variability of NO3-N and NH4-N was greatest in the floodplain swamps, but nutrients were not spatially patchy at any of the sampled sites. We conclude that soil nutrient availability may control fine-root biomass at the broad scale, but it is unclear if the same is true at fine spatial scales.
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Kambale, J. B. y H. V. Rudramurthy. "Application of Geographical Information System to Understand Spatial Variability of Soil Available Nutrients in Northern Karnataka, India". Current World Environment 12, n.º 1 (25 de abril de 2017): 169–73. http://dx.doi.org/10.12944/cwe.12.1.20.
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It is very important to distinguish the spatial variability in soil fertility for site specific nutrient application. To know the status, 25 soil samples were collected from Vandurga Village, Yadgir District, Karnataka, India. Samples were analysed for electrical conductivity (EC), power of hydrogen (pH), organic carbon (OC), Nitrogen (N), Phosphorous (P2O5) and Potassium (K2O). Further, SPSS (ver. 19) was used to execute conventional statistical analysis and ArcGIS to get the information about distribution and spatial variability of soil available nutrients. The analysis results showed that the EC of soil varied from 0.13 to 0.25 dS/m with a mean of 0.18 dS/m. The PH ranged from 6.62 to 8.82 with an average of 7.89. Available OC ranged from 0.14 % to 1.90 % with mean of 0.78 %. Similarly mean values for N, P2O5 and K2O observed 215.3 kg/ha, 31.5 kg/ha, and 513.4 kg/ha, respectively. The SD and CV for EC was 0.031 and 16.69%, respectively, while for pH, OC, N, P2O5 and K2O it was found to be 0.56 and 7.04, 0.39 and 51.16, 100.9 and 46.86, 19.12 and 60.61, 160.88 and 31.33 respectively. Spatial variability maps for various nutrients prepared shows the huge variation in the soil nutrients availability. This variability appeared due to lack of balanced application of fertilizers. It was suggested that an appropriate applications of nutrients necessary for selected land based on soil nutrients.
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Tokareva, Irina V. y Anatoly S. Prokushkin. "Seasonal and Spatial Variability of Dissolved Nutrients in the Yenisei River". Water 14, n.º 23 (3 de diciembre de 2022): 3935. http://dx.doi.org/10.3390/w14233935.
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The accelerated rates of warming in high latitudes lead to permafrost degradation, enhance nutrient cycling and intensify the transport of terrestrial materials to the Arctic rivers. The quantitative estimation of riverine nutrient flux on seasonal and spatial scales is important to clarify the ongoing changes in land–ocean connectivity in the Arctic domain. This study is focused on a multiyear (2015–2021) analysis of concentrations of dissolved nutrients in the Yenisei River. Applying stationary water sampling, we studied seasonal variations in concentrations of phosphate, nitrate, nitrite and ammonia ions in the Yenisei River in the upper (56.0° N), middle (60.9° N) and lower (67.4° N) sections of the river. The waters of the upper river section demonstrated significant and steady nutrient enrichment throughout the hydrological year, reflecting the influence of the Krasnoyarsk reservoir. The downstream reaches of the Yenisei River had more apparent seasonal patterns of nutrient concentrations. Particularly, winter-season nutrient levels in the middle and lower river sections were the highest during the hydrological year and close to the upper section. At snowmelt, and especially the summer–fall seasons, all inorganic nutrient concentrations dropped dramatically after the inflow of the Angara River. On the other hand, the peak nitrite content observed during the early spring flood was most pronounced in the lower section of the river basin, reflecting the specific characteristics of the nitrogen cycle in permafrost soils. The spring flood plays the major role in the annual nutrient fluxes, except for nitrates, for which the maximum occurred in the winter season. The summer–fall season, despite its duration and considerable water runoff, demonstrated the lowest fluxes of dissolved inorganic phosphorus and nitrogen in comparison to other periods of the hydrological year, suggesting strong biological uptake and chemostasis.
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Artamonova, K. V., I. A. Gangnus, L. A. Dukhova, V. V. Maslennikov y N. A. Lavinen. "Spatial hydrochemical structure in surface waters of the Southern ocean between Africa and Antarctica". Arctic and Antarctic Research 67, n.º 4 (9 de diciembre de 2021): 328–47. http://dx.doi.org/10.30758/0555-2648-2021-67-4-328-347.
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Some hydrochemical characteristics and, first of all, the main nutrients (phosphorus, nitrogen, silicon) can be used as markers for distinguishing different types of water masses and positions of the main fronts of the Southern Ocean. The seasonal and interannual variability of these characteristics also reflects the character of biological processes in the surface layer of the ocean, which is important for assessing biological productivity. The aim of this study was to analyze the main features of the spatial distribution of hydrochemical characteristics in the surface layer in the Atlantic and Indian Ocean sectors of the Southern Ocean between the Subantarctic Front and the shores of Antarctica and assess their seasonal (spring–autumn) and interannual variability for the observation period from 2008 to 2020. We describe the surface nutrient concentrations between Africa and Antarctica along the transects that cross the Subantarctic Front (SAF) in the north, the Polar Frontal Zone (PFS), Polar Front (PF) and Antarctic Zone water in the south. The findings revealed an increase in dissolved oxygen and nutrients towards the south. Nitrates changed values within the SAF from 15 μM to 24 μM, whereas values from 1.2 μM to 1.7 μM were observed for phosphates. Silicate increased considerably within the Polar Front, from 6.6 μM to 20.8 μM. An analysis was carried out of the seasonal and interannual variability of the hydrochemical conditions in the surface layer of the Southern Ocean. The interannual variability of the nutrients was determined by the spatial variability of the main fronts of the Antarctic Circumpolar Current (ACC) and the intensity of the largescale Weddell Gyre (WG). Since 2017, there has been an increase in the meridional transfer of waters: in the Antarctic Summer 2017–2018, there was a spreading of high-nutrient WG waters toward the north, and in the Summer 2019–2020, the low-nutrient waters anomaly was transferred far to the south (up to 60°S).According to the data obtained, the seasonal dynamics of the nutrients in the surface layer of the Southern Ocean was rather weakly expressed. An exception is the high-latitude waters of the Cooperation and Davis Seas, where maximum seasonal variability of the hydrochemical characteristics was observed. The highest rate of nutrient consumption was observed in the coastal area of the Cooperation Sea near the fast ice edge from mid–December to early January and reached 3.2 μM per day for silicate, 1.8 μM per day for nitrates, and 0.12 μM per day for mineral phosphorus. The results of the long-term monitoring of the hydrochemical conditions in the Cooperation Sea made it possible to distinguish conditionally “warm” years with early vegetation (at the end of December) and intensive consumption of nutrients by phytoplankton, and “cold” years, when the formation of high-latitude “oases” in December–January was not observed.
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Cereja, Rui, Paula Chainho, Vanda Brotas, Joana P. C. Cruz, Giulia Sent, Marta Rodrigues, Frederico Carvalho, Sara Cabral y Ana C. Brito. "Spatial Variability of Physicochemical Parameters and Phytoplankton at the Tagus Estuary (Portugal)". Sustainability 14, n.º 20 (17 de octubre de 2022): 13324. http://dx.doi.org/10.3390/su142013324.
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The estuarine phytoplankton communities are known to respond rapidly to environmental changes, being considered an important water quality indicator; thus, it is crucial to fully understand its natural variability. The objective of the present study was to assess the spatial variability of both physicochemical variables and the phytoplankton community, to understand how such variability is influenced by seasonality and to evaluate how the anthropogenic sources affect such patterns. The Tagus estuary was used as a case study, since it is one of Europe’s largest estuaries, with high spatial and seasonal variations and a high level of human pressure associated with large urban and industrial areas. To achieve this goal, environmental parameters, nutrients concentration, bivalve biomass (filter feeders) and phytoplankton pigments were quantified in a single summer sampling campaign with high spatial resolution and in monthly campaigns in eight sampling stations through the Tagus estuary, in one year. In general, suspended particulate matter and nutrients decreased from the upper part of the estuary to the estuary mouth; however, relevant local inputs were also observed in more downstream locations, near outfalls of wastewater treatment plants (WWTP). The chlorophyll-a concentrations were higher over the southern intertidal mudflats, probably due to resuspension of microphytobenthos, associated with higher nutrient concentrations. Through a grazing indicator, it was observed that grazers are important drivers of variability of the phytoplankton community composition. All water bodies achieved “good” and “high” water quality classifications for both physicochemical and biological indicators, with the worst results reported for the water bodies located at the upper estuary. Therefore, this estuary presents a decreasing trend of nutrients and chlorophyll-a in the upstream–downstream direction, except for the estuary channels and the outfall in the northern margin, which lead to an increase in nutrient concentrations. However, these increases did not affect the water quality of the three analyzed water bodies, presenting at least good ecological status, considering the nutrient and chlorophyll-a indicators.
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Kroulík, M., M. Mimra, F. Kumhála y V. Prošek. "Mapping spatial variability of soil properties and yield by using geostatic method". Research in Agricultural Engineering 52, No. 1 (7 de febrero de 2012): 17–24. http://dx.doi.org/10.17221/4875-rae.
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The Czech University of Agriculture in Prague (CUA) Farm at Lány started with precision farming technology several years ago. In the first step the yield and nutrients content were monitored. For precision application development, detailed description of soil conditions and interrelationship will be necessary. Pulling force and soil electric conductivity measurement as indirect measuring methods were used for mapping spatial soil variability. These methods demonstrate other ways for description of complex soil media.
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Tamburi, Vinod, Amba Shetty y S. Shrihari. "Geostatistical Analysis on Spatial Variability of Soil Nutrients in Vertisols of Deccan Plateau Region of North Karnataka, India". International Journal of Mathematical, Engineering and Management Sciences 5, n.º 2 (1 de abril de 2020): 283–95. http://dx.doi.org/10.33889/ijmems.2020.5.2.023.
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Different methods of land use and management have a significant effect on soil properties distribution. Understanding of variations in soil nutrients in agricultural land use is important. An increase in extraction of nutrients, soil degradation, and management of nutrients is leading to a decline in quality of vertisols across the Deccan plateau of India. Though there are studies on spatial variability of vertisols macronutrients, studies on available calcium (Ca) and available magnesium (Mg) are rare. This study is conducted in Gulbarga taluk, north Karnataka, India, to evaluate the variability of soil pH, Ca, Mg, and Zinc (Zn). A total of 78 samples of soils are collected at 0 to 15 cm depth based on the accessibility and distribution of field patterns. Four subsamples represent a single composite sample. Agilent 4200 MP-AES (Microwave Plasma-Atomic. Emission Spectrometer) was used for determining the concentration of soil nutrients. The soil nutrients represent wide variation in coefficient of variation (CV) with a value of 6 % (for pH) to 70.9 % (for Zn). The soil pH showed a significantly positive correlation to Ca and a negative correlation to Mg. Geostatistical investigation indicates spherical model is the best fit for all nutrients. Except for Ca, all nutrients showed moderate spatial dependence. Ordinary kriging is used to generate spatial variability maps. The maps of spatial variability are highly variable in nutrients content and indicate that site-specific management needs to be taken by local authorities and improve the livelihood of marginal farmers and also for sustainable agriculture.
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Zhang, Qiang, Zhiping Yang, Yong Li, Deli Chen, Jianjie Zhang y Mingchang Chen. "Spatial variability of soil nutrients and GIS-based nutrient management in Yongji County, China". International Journal of Geographical Information Science 24, n.º 7 (2 de junio de 2010): 965–81. http://dx.doi.org/10.1080/13658810903257954.
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Jin, Jiyun y Cheng Jiang. "Spatial variability of soil nutrients and site-specific nutrient management in the P.R. China". Computers and Electronics in Agriculture 36, n.º 2-3 (noviembre de 2002): 165–72. http://dx.doi.org/10.1016/s0168-1699(02)00099-6.
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Khan, MZ, MA Islam, M. Sadiqul Amin y MMR Bhuiyan. "Spatial variability and geostatistical analysis of selected soil". Bangladesh Journal of Scientific and Industrial Research 54, n.º 1 (25 de marzo de 2019): 55–66. http://dx.doi.org/10.3329/bjsir.v54i1.40731.
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A study was conducted to explore the spatial variability of major soil nutrients of Agricultural fields in South-western region of Bangladesh. From the study area, 40 surface soil samples were collected by a random sampling strategy using GPS. Then soil physico-chemical properties i.e., pH, electrical conductivity (EC), organic matter (OM), total nitrogen (TN) N, soil available nutrients (P, K and S) were measured in laboratory. After data normalization, classical and geo-statistical analyses were used to describe soil properties and spatial correlation of soil characteristics. Spatial variability of soil physico-chemical properties was quantified through semi-variogram analysis and the respective surface maps were prepared through ordinary Kriging. Spherical model fits well with experimental semi-variogram of pH, EC, OM, TN, available P, K and S. Soil pH, available phosphorus (Av P), potassium (Av K) and sulfur (Av S) have the moderate spatial dependence, with nugget/sill ratios of 41.13% to 72.21%. The others have the strong dependence with nugget/sill ratios of less than 25%. The spatial variability of estimating soil properties varies within range of 0.0142 for Av P to 0.0383 for Av S and this model can calculate the un-sampled within neighboring distance of about 12.65 m for Av S to 150.82 m for TN, respectively. Cross validation of kriged map shows that spatial prediction of soil nutrients using semi-variogram parameters is better than assuming mean of observed value for any un-sampled location. Therefore, it is a suitable alternative method for accurate estimation of chemical properties of soil in un-sampled positions as compared to direct measurement which has time and costs concerned.
Bangladesh J. Sci. Ind. Res.54(1), 55-66, 2019
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Su, Xiaomei, Alan D. Steinman, Yunlin Zhang, Hong Ling y Dan Wu. "Significant Temporal and Spatial Variability in Nutrient Concentrations in a Chinese Eutrophic Shallow Lake and Its Major Tributaries". Water 14, n.º 2 (12 de enero de 2022): 217. http://dx.doi.org/10.3390/w14020217.
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Sediment nutrients can be released to the surface water when hydraulic disturbance becomes strong in shallow lakes, which contributes to nutrient enrichment and subsequent lake eutrophication in the water column. To explore the seasonal variations and spatial distributions exhibited by nutrients in the water column, surface sediment, and pore water of Lake Yangcheng and its major tributaries, we determined the concentrations of nitrogen (N) and phosphorus (P) throughout the lake in different seasons of 2018. Total N (TN) and total P (TP) concentrations in the connected rivers were much greater than those in the lake, indicating that external loading greatly contributed to the nutrient enrichment. TN concentration in the water column was highest in the winter, whereas TP peaked in the summer. A similar temporal pattern was observed for TN and TP in the sediment with maxima in the winter and minima in the summer; however, nutrients in the pore water were highest in the summer, in contrast to the temporal variation in the sediment. Additionally, high TN values in the water column and high TP in the three compartments were distributed primarily in the west part of the lake, while high TN concentrations in the sediment and pore water were observed mainly in the east portion of the lake. According to the enrichment factor index (an indicator evaluating the nutrient enrichment by comparing the detected contents and standard values), nutrients in the lake sediment were severely enriched with TN and TP averaging 2195.8 mg/kg and 543.0 mg/kg, respectively. The vertical distribution of TN and TP generally exhibited similar decreasing patterns with an increase in sediment depth, suggesting mineralization of TN and TP by microbes and benthic organisms. More attention and research are needed to understand the seasonality of nutrient exchange across the sediment–water interface, especially in eutrophic lakes.
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Yan, Ping, Hua Peng, Luobin Yan, Shaoyun Zhang, Aimin Chen y Kairong Lin. "Spatial variability in soil pH and land use as the main influential factor in the red beds of the Nanxiong Basin, China". PeerJ 7 (30 de enero de 2019): e6342. http://dx.doi.org/10.7717/peerj.6342.
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Soil pH is the main factor affecting soil nutrient availability and chemical substances in soil. It is of great significance to study the spatial variability of soil pH for the management of soil nutrients and the prediction of soil pollution. In order to explore the causes of spatial variability in soil pH in red-bed areas, the Nanxiong Basin in south China was selected as an example, and soil pH was measured in the topsoil by nested sampling (0–20 cm depth). The spatial variability characteristics of soil pH were analyzed by geostatistics and classical statistical methods, and the main factors influencing spatial variability in soil pH are discussed. The coefficient of variation in the red-bed areas of Nanxiong Basin was 17.18%, indicating moderate variability. Geostatistical analysis showed that the spherical model is the optimal theoretical model for explaining variability in soil pH, which is influenced by both structural and random factors. Analysis of the spatial distribution and pattern showed that soil pH is relatively high in the northeast and southwest, and is lower in the northwest. These results indicate that land use patterns and topographic factors are the main and secondary influencing factors, respectively.
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Syam, Tamaluddin. "Spatial Variability of Soil Nutrients Content Related to Rice Yield". Jurnal TANAH TROPIKA (Journal of Tropical Soils) 15, n.º 2 (1 de mayo de 2010): 153–57. http://dx.doi.org/10.5400/jts.2010.15.2.153.
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Zhao, Zhonghe, Gaohuan Liu, Qingsheng Liu, Chong Huang, He Li y Chunsheng Wu. "Distribution Characteristics and Seasonal Variation of Soil Nutrients in the Mun River Basin, Thailand". International Journal of Environmental Research and Public Health 15, n.º 9 (23 de agosto de 2018): 1818. http://dx.doi.org/10.3390/ijerph15091818.
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Based on soil sampling data from the dry season and the rainy season, the spatial heterogeneity and spatial pattern of soil nutrients in the Mun River Basin, Thailand, were studied and the seasonal variation in soil nutrients was analyzed using classical statistical methods and geostatistical methods. The soil nutrient content in the Mun Basin showed moderate and strong variations, and the descending order of soil variability was as follows: available phosphorous (AP) > electric conductivity (EC) > soil organic matter (SOM) > total nitrogen (TN) > pH value in the dry season, with AP showing strong variation, and EC > AP > SOM > TN > pH in the rainy season, with EC showing strong variation. Different soil nutrients and different soil properties had different spatial variation characteristics, and their corresponding best-fitting models were also different. Based on the nugget (C0), sill (C0 + C), and range (A), spatial analysis was performed for the soil nutrients, pH, and EC in the dry season and in the rainy season. Analysis based on kriging spatial interpolation data showed that pH, SOM, TN, and EC had convex or concave distributions, whereas AP had a patchy distribution. Terrain, vegetation, and human disturbance are the main factors that contribute to the differences in the soil nutrient pattern of the Mun River Basin.
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Zhao, Zhonghe, Gaohuan Liu, Qingsheng Liu, Chong Huang y He Li. "Studies on the Spatiotemporal Variability of River Water Quality and Its Relationships with Soil and Precipitation: A Case Study of the Mun River Basin in Thailand". International Journal of Environmental Research and Public Health 15, n.º 11 (5 de noviembre de 2018): 2466. http://dx.doi.org/10.3390/ijerph15112466.
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Human activities can affect soil nutrients, thereby influencing river water quality. The spatial pattern of precipitation also impacts distributions of water quality. In this paper, we employed a method that combines point survey, soil, and water quality data to analyze the spatial relationships between precipitation, soil nutrient and water quality in the basin on the basis of field surveys and laboratory analysis. The ordinary kriging method was applied to interpolate the precipitation and soil data, and the spatial pattern was analyzed. The water samples on the main stream and soil samples in the field were collected during both the dry and rainy seasons to analyze the water quality and soil nutrients. The results indicate: (1) The water quality in the dry season is better than that in the rainy season, the water quality in the upper reaches is better than that in the lower reaches, and agricultural activity is the direct source of water pollution. (2) The precipitation in the rainy and dry seasons is differente and the dilution effect of precipitation on pollutant concentrations and transport of water flow affect the spatial distribution of water quality. (3) There is a significant difference in the spatial pattern of soil nutrients between the dry and rainy seasons, and the soil nutrient content and the surface runoff directly affect the water quality. Soil nutrients are affected by human activities, and they potentially act as nonpoint source (NPS) pollution in this river basin. To improve the water quality, suitable agriculture measures need to be implemented.
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SOUVERMEZOGLOU, Ε., Ε. KRASAKOPOULOU y A. PAVLIDOU. "Temporal and spatial variability of nutrients and oxygen in the North Aegean Sea during the last thirty years". Mediterranean Marine Science 15, n.º 4 (31 de diciembre de 2014): 805. http://dx.doi.org/10.12681/mms.1017.
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Inorganic nutrient and dissolved oxygen data collected in the North Aegean Sea during 1986 - 2008 were analyzed in order to evaluate the role of the inflowing Black Sea originated surface water (BSW) in the nutrient regime of the area. In periods of high buoyancy inflow from Dardanelles strait, a reduction of inorganic nutrients in the surface layer is observed along the north-west route of the BSW; in parallel, the underlying layer of Levantine intermediate water revealed an increase of inorganic nutrients, receiving the degradation material from the surface layer. The above spatial patterns suggest a contribution of the BSW to the observed enhanced production of the North Aegean Sea. Anomalously low buoyancy inflow of BSW combined with severe winter meteorological conditions promote deep water formation events. The physical and chemical characteristics of the deep waters found in the different basins of the North Aegean Sea in 1997 (following the deep water formation in winters of 1992-1993) differed from those observed after the formation in winter 1987. These differences were probably related to the drastic changes occurred in the deep waters of the Eastern Mediterranean in the early 1990, by the Eastern Mediterranean Transient. Considering that deep water formation processes provide occasionally inorganic nutrients to the euphotic layer, it seems that BSW through its uninterrupted supply of small quantities of nutrients should play an additional role in the production in the North Aegean Sea.
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Ghimire, Deepak, Bandhu Raj Baral y Dinesh Panday. "Assessment of Spatial Variability of Soil Chemical Properties under Small-holder Farmers’ Field: a Case Study from Kavrepalanchowk District of Nepal". Current Agriculture Research Journal 6, n.º 3 (25 de diciembre de 2018): 337–43. http://dx.doi.org/10.12944/carj.6.3.12.
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A proper understanding of variability of soil chemical properties over an area is important for identifying the soil nutrients related production constraints. The suggestions for remedial measures and execution of appropriate nutrient management strategies are also based on the good knowledge of variation in soil nutrients. A case study was undertaken with an objective of assessing spatial variability of selected soil chemical properties of agricultural land. Soil samples from the surface (0 to 15 cm) were collected from farmers’ field in the central part of Kavrepalanchowk district of Nepal in February 2018. Soil samples were analyzed for soil pH, total organic carbon (TOC), total nitrogen (N), phosphorous (P), and potassium (K). Descriptive statistics revealed that the soil in the study area was slightly acidic and contained the low status of TOC, P, and K, while the N content was medium. Coefficient of variation (CV) indicated that soil pH was the least variable (CV= 9.37% with values ranging from 5.3 to 7.7) among the investigated soil samples while N was the most variable (CV= 98.81% with content values ranging from 0.03% to 0.67%). Other selected properties (TOC, P, and K) were found to be highly variable (CV= 49.94%, 94.89%, and 57.53% respectively). These variations in soil chemical properties were mostly related to the different cropping systems and soil management practices, including nutrient management carried out in the study area. Owing to the higher variability of nutrients, the results suggested to take into account various soil and nutrient management practices for sustained soil fertility and enhanced productivity.
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Fu, Weijun, Keli Zhao, Peikun Jiang, Zhengqian Ye, Hubert Tunney y Chaosheng Zhang. "Field-scale variability of soil test phosphorus and other nutrients in grasslands under long-term agricultural managements". Soil Research 51, n.º 6 (2013): 503. http://dx.doi.org/10.1071/sr13027.
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Field-scale variation of soil nutrients in grassland is becoming important because of the use of soil-nutrient information as a basis for policies such as the recently introduced EU Nitrates Directive. This study investigates the field-scale variability of soil-test phosphorus (STP) and other nutrients in two grasslands with a long-term history of poultry litter application. Two fields (field 1 for silage and field 2 for grazing pasture) were selected, and soil samples were collected based on 12 m by 12 m (field 1) and 15 m by 15 m (field 2) grids. Data were analysed using conventional statistics, geostatistics, and a geographic information system (GIS). In field 1, STP values ranged from 12.4 to 90 mg L–1 (average 38.5 mg L–1). In field 2, STP values ranged from 4.3 to 130.0 mg L–1 (average 21.4 mg L–1). Attention should be paid to long-term poultry application, as the average STP values in both fields were much greater than the recommended agronomic optimum STP status in Ireland of 8 mg L–1. Coefficient of variation values of soil nutrients in field 2 were much higher than those in field 1. Log-transformation and Box–Cox transformation were applied to achieve normality. Statistically significant (P < 0.01), positive correlations between P and other nutrients were found in both fields. Exponential and spherical models were fitted to the experimental variograms of STP in fields 1 and 2, respectively. Compared with the counterparts in field 1, soil nutrients in field 2 had larger ‘nugget-to-sill’ values, revealing that sheep grazing could weaken the spatial auto-correlation of soil nutrients. A grid of 60 m by 60 m was recommended for soil sampling in grassland, based on this study. High STP concentrations in field 1 were in the north-eastern side, which was related to uneven poultry litter application. Strong spatial similarity of low STP, magnesium, and pH values in their spatial distribution were found in field 2, confirming their strong statistical correlation.
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Rochon, P., D. Paré y C. Messier. "Development of an improved model estimating the nutrient content of the bole for four boreal tree species". Canadian Journal of Forest Research 28, n.º 1 (1 de enero de 1998): 37–43. http://dx.doi.org/10.1139/x97-176.
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An improved model for estimating nutrient contents of the commercial portion of tree boles was developed for four boreal tree species (Populus tremuloides Michx., Betula papyrifera Marsh., Picea glauca (Moench) Voss, and Abies balsamea (L.) Mill.). This model considers the spatial pattern of variation of nutrient concentrations inside the bole and its relationships with tree size. For all species-nutrient combinations, no significant pattern was found for vertical variations in nutrient concentrations, while two types of nonlinear models, using distance from the tree periphery as the independent variable, fit the pattern of horizontal (or radial) variations. These patterns of variability were used to estimate the global nutrient concentration of the bole by using mathematical integration. The values obtained with this method were generally lower, especially for large stems, than values obtained with traditional methods that do not consider the variability of nutrient concentrations inside the bole. This improved model would permit better estimates of the amounts of nutrients lost in biomass upon forest harvesting, as well as internal cycling of nutrients within the bole.
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Wang, Z. M., K. S. Song, B. Zhang, D. W. Liu, X. Y. Li, C. Y. Ren, S. M. Zhang, L. Luo y C. H. Zhang. "Spatial variability and affecting factors of soil nutrients in croplands of Northeast China: a case study in Dehui County". Plant, Soil and Environment 55, No. 3 (6 de abril de 2009): 110–20. http://dx.doi.org/10.17221/323-pse.
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This paper addressed the spatial distribution characteristics of organic matter, total nitrogen, extractable phosphorus and extractable potassium in agricultural soils of Northeast China. The related factors were explored using geostatistics and geographic information systems. The results showed that the log-transformed data of the four soil nutrients followed a normal distribution. Soil extractable phosphorus had a higher coefficient of variation. The experimental variogram of the log-transformed data of soil organic matter, total nitrogen and extractable phosphorus was fitted with an exponential model, while soil extractable potassium was fitted to a spherical model. Soil samples from smaller slope gradients had higher organic matter and total nitrogen. Soil type affected the four soil nutrients significantly. Soil samples from dry farming land had significantly higher total nitrogen and extractable potassium than soil from paddy fields, while the contrary was found for extractable phosphorus. Along the Yinma River, soil samples from the western part have statistically higher values for organic matter, total nitrogen and extractable potassium than those collected from the eastern part.
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Adame, Maria Fernanda, Ruth Reef, Alistair Grinham, Glen Holmes y Catherine E. Lovelock. "Nutrient exchange of extensive cyanobacterial mats in an arid subtropical wetland". Marine and Freshwater Research 63, n.º 5 (2012): 457. http://dx.doi.org/10.1071/mf11133.
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Cyanobacterial mats cover extensive areas of subtropical arid coastal wetlands and are sites of active nutrient exchange. To assess spatial (low v. high in the intertidal zone) and temporal (day v. night) variability in nitrogen (N) exchange in arid Exmouth Gulf, Western Australia, we measured nutrient exchange (NOx–-N, NH4+ and soluble reactive phosphorus) during tidal inundation and N fixation of cyanobacterial mats before and during an unusual period of heavy rainfall. Additionally, we investigated the species composition within the cyanobacterial mat. We hypothesised that nutrients are released to the floodwater during tidal inundation, that N fixation is a significant path of N incorporation, that highest N fixation rates occur in the low intertidal zone at night, and that the cyanobacterial mat community composition varies across the intertidal zone. Our results showed that nutrients were removed from the floodwater during tidal inundation. N fixation accounted for 34% of N incorporation, with highest rates in the lower intertidal zone during the day. The cyanobacterial mat was dominated by Microcoleus chthonoplastes, but composition varied across the intertidal zone. The present study provided evidence of temporal and spatial variability in nutrient exchange and implied an important role of cyanobacterial mats in coastal production.
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Geetha, R., N. Chandramohanakumar y Lizen Mathews. "Seasonal Variability of Dissolved Nutrients in Mangrove Ecosystems along South West Coast of Kerala, India." Journal of Wetlands Ecology 3 (21 de diciembre de 2009): 32–42. http://dx.doi.org/10.3126/jowe.v3i0.2264.
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The mangroves of Kerala are fast disappearing due to developmental activities. There are very few studies conducted in the chemical aspects of these ecosystems. The main objective of this study is to assess the spatial and seasonal variation of hydrographical as well as nutrients in mangrove ecosystems along Kerala coast. Five sampling sites least intervened by industries were selected for the study. Sampling was done for a period of six months in monthly intervals. A monsoonal hike of dissolved nutrients was observed in all ecosystems except in the constructed mangrove wetland. The constructed wetland exhibited a different hydrography and nutrient level in all seasons. The mangrove forest in this area consists of the species Bruguiera gymnorrhiza which has been planted since forty years. Key words: wetlands; mangroves; nutrients; season; constructed wetland DOI: 10.3126/jowe.v3i0.2264 Journal of Wetlands Ecology, (2009) Vol. 3, pp 32-42
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Silva, Marinoé Gonzaga da, Anderson Nascimento do Vasco, Cleide Cruz Soares, Ramiro Joaquim de Jesus Neves, Carlos Alexandre Borges Garcia y Antenor de Oliveira Aguiar Netto. "Spatial modeling of nitrogen and phosphorus in an agricultural basin in northeastern Brazil". Research, Society and Development 11, n.º 15 (23 de noviembre de 2022): e475111537047. http://dx.doi.org/10.33448/rsd-v11i15.37047.
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Hydrological models can help in predicting the behavior of aquatic systems in watershed, and are able to simulate both hydrological processes and nutrient dynamics. The SWAT model is used in water resource management to estimate the production of water, sediments, and nutrients, as well as to identify diffuse sources of pollution. The objective of this work was to evaluate spatial and temporal variability in the dynamics of the nutrients nitrogen and phosphorus derived from agricultural activities, at the sub-basin level, in the watershed of the Poxim-Açu River. The model was subjected to tests of sensitivity, calibration, and validation in terms of the discharge and the behavior of the nutrients. Statistical analysis showed that the performance of the model was satisfactory. It was found that more than 40% of the areas of the main subbasins that produced sediments and nutrients was occupied by pasture, and that the predominant soil types were Red-Yellow Argisols and Gleysols. These subbasins corresponded to 30% of the hydrographic basin studied and produced 65% of the sediments, 84% of the total nitrogen, 93% of the phosphate, and 86% of the total phosphorus.
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Whitehouse, M. J., C. Symon y J. Priddle. "Variations in the distribution of chlorophyll a and inorganic nutrients around South Georgia, South Atlantic". Antarctic Science 5, n.º 4 (diciembre de 1993): 367–76. http://dx.doi.org/10.1017/s0954102093000495.
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Data collected on four large-scale surveys around the subantarctic island of South Georgia provide information on the variability in the distribution of chlorophyll and inorganic nutrients during the austral summer and winter. During three summer surveys, surface water cholorophyll and nutrient concentrations were highly patchy over scales ranging from a few to hundreds of kilometres. The highest measurement of chlorophyll a was 8 mg m−3 and a wide range of nutrient concentrations were found; 5–32 mmol m−3 NO3−N, 1.1–2.2 mmol m−3 PO4−P and 8–60 mmol m−3 Si(OH)4−Si. In winter, chlorophyll and nutrient levels were far more uniform, with chlorophyll concentrations lower and nutrient concentrations generally higher than in summer. The spatial variability in nutrient concentrations was due to a variety of factors acting over a range of scales, however biological processes appeared most important in creating the mesoscale patchiness around the island. Although phytoplankton abundance and nutrient concentrations were not directly correlated, the scales of variability were clearly similar.
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Falqueto Jorge, Ricardo, Cinara Xavier de Almeida, George Deroco Martins, Danilo Ferreira Mendes, Juliano Marques Pinto y Luana Karolina Pena. "RFJ Spatial variability in fertigated coffee yields and plant nutrients in soil saturation extracts". International Journal for Innovation Education and Research 7, n.º 11 (30 de noviembre de 2019): 347–60. http://dx.doi.org/10.31686/ijier.vol7.iss11.1888.
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The spatial distribution and levels of available plant nutrients (elements) in the soil can limit coffee yield and must be evaluated for effective crop management. Therefore, we analyzed spatial variability in yield and plant nutrients in the saturation extract of a clayey Oxisol cropped with fertigated coffee. The experiment was carried out on 14 hectares of coffee in Monte Carmelo, Minas Gerais, Brazil. Soil samples were collected (0 - 0.2m layer) at 61 regular grid points (spaced 50x50m) and used to determine plant nutrients in the saturation extract. Coffee yield was also determined at these points. Descriptive statistics were calculated for each variable and geostatistics were used to build a spatial variability model representing the physical attributes of the soil. Variographic analysis was performed using semivariograms. These showed that yield and soil chemistry varied throughout the study site. Thus, the maps generated from geostatistics can be useful tools for soil management in fertigated coffee crops.
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Gray, Sarah, Grady Hanrahan, Ian McKelvie, Alan Tappin, Florence Tse y Paul Worsfold. "Flow Analysis Techniques for Spatial and Temporal Measurement of Nutrients in Aquatic Systems". Environmental Chemistry 3, n.º 1 (2006): 3. http://dx.doi.org/10.1071/en05059.
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Environmental Context.Eutrophication is a growing problem globally, and it has significant ecological and socio-economic consequences. Understanding the causes of eutrophication requires a knowledge of nutrient biogeochemistry in aquatic systems. Owing to the high spatial and temporal variability of nutrients in these systems, there is a need for autonomous in situ measurement techniques with rapid response and the ability to collect long-term data. Flow injection analysis is one technique that meets these demands. Abstract.Flow analysis offers a versatile and powerful approach to monitoring of the aquatic environment. The present review highlights the drivers for determining macro- and micro-nutrients in marine and fresh waters, and outlines the instrumental requirements for in situ instrumentation. The principles of flow analysis, specifically flow injection and derivative techniques, and the chemical bases for macro- and micro-nutrient detection are discussed, and key examples of suitable approaches are considered. The successful deployment of flow analysis nutrient monitoring systems for spatial and temporal measurements is illustrated by specific examples relating to surface transects, depth profiles and temporal deployments. Finally, the challenges and imperatives of research in this area are outlined.
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Trotter, Mark, Chris Guppy, Rebecca Haling, Tieneke Trotter, Clare Edwards y David Lamb. "Spatial variability in pH and key soil nutrients: is this an opportunity to increase fertiliser and lime-use efficiency in grazing systems?" Crop and Pasture Science 65, n.º 8 (2014): 817. http://dx.doi.org/10.1071/cp13449.
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Nutrient-use efficiency is a key issue for grazing systems in Australia. Spatial variability in soil pH and nutrients at the sub-paddock scale may affect the efficiency of utilisation of, and provide an opportunity for, site-specific management (SSM) of fertiliser and soil ameliorants. However, there has been little research exploring the potential for SSM in grazing systems. This study examines the spatial variability of soil test pH, phosphorus (P), potassium (K) and sulfur (S) in two typical pasture fields (a native and an improved) on the Northern Tablelands of New South Wales and evaluates the potential for SSM based on a comparison with critical values. In both fields, the overall paddock mean from a grid survey containing >80 samples for pH, P, K and S (0–10 cm) exceeded the critical values, suggesting that the addition of fertiliser or lime was not required. However, considerable sub-paddock-scale variability was observed, with CV ranging from 35% to 66% for the key nutrients (P, K and S). The Sprengel–Liebig Law of the Minimum was applied to evaluate the proportion of each field constrained by one or more soil characteristics. Up to 55% of the improved paddock and 78% of the native pasture was potentially responsive to amendments. The results of this study suggest that SSM of fertilisers and ameliorants could provide substantial improvements in productivity and possibly reductions in fertiliser use. The development and application of appropriate systems and tools to effectively quantify this spatial variability remain a challenge, coupled with management strategies that optimise the placement of amendments and account for the variability in other production limiting factors.
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DeCarlo, Thomas M., Laura Gajdzik, Joanne Ellis, Darren J. Coker, May B. Roberts, Nicholas M. Hammerman, John M. Pandolfi, Alison A. Monroe y Michael L. Berumen. "Nutrient-supplying ocean currents modulate coral bleaching susceptibility". Science Advances 6, n.º 34 (agosto de 2020): eabc5493. http://dx.doi.org/10.1126/sciadv.abc5493.
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With predictions that mass coral bleaching will occur annually within this century, conservation efforts must focus their limited resources based on an accurate understanding of the drivers of bleaching. Here, we provide spatial and temporal evidence that excess nutrients exacerbate the detrimental effects of heat stress to spark mass coral bleaching in the Red Sea. Exploiting this region’s unique oceanographic regime, where nutrients and heat stress vary independently, we demonstrate that the world’s third largest coral reef system historically suffered from severe mass bleaching only when exposed to both unusually high temperature and nutrients. Incorporating nutrient-supplying ocean currents and their variability into coral bleaching forecasts will be critical for effectively guiding efforts to safeguard the reefs most likely to persist in the Anthropocene.
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Sun, Guojun, Haijun Liu, Dong Cui y Chunmei Chai. "Spatial heterogeneity of soil nutrients in Yili River Valley". PeerJ 10 (3 de mayo de 2022): e13311. http://dx.doi.org/10.7717/peerj.13311.
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Soil nutrients are a vital reference index of soil fertility and are essential in studying spatial variability for the development of land resources. The traditional statistical methods including correlation analysis and geostatistical analysis, were used to explore the spatial variability of nutrients and its influencing factors in the Yili River Valley. The results showed that soil total potassium (STK) had a weak variation, soil organic carbon (SOC), soil total nitrogen (STN) and soil total phosphorus (STP) showed a moderate degree of variation. Correlation analysis showed that SOC had a significant correlation with STN, STP, STK, silt, soil water content (SWC), Cos a and altitude (p < 0.01). In contrast, negative correlations were found between the SOC and sand, soil bulk density (SBD) and pH (p < 0.01), the same as STN. STP had a significant correlation with STK, silt (p < 0.01) and Cos a (p < 0.05), whereas negative correlations were found between the STP, sand and SBD (p < 0.01). STK had a significant correlation with silt, whereas negative correlations were found between the STK, sand and SBD. Ordinary Kriging interpolation showed that the distribution of SOC and STN had a high value in the northeast, northwest and southeast, and a low value in the central and southwest. STP was high in the northwest and southeast and low in the northeast and southwest. STK was high in the northwest and northeast and low in the central and southeast regions. This is helpful for the rational exploitation of land resources in ecological economy development in the Yili River Basin.
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Sundarambal, P., P. Tkalich y R. Balasubramanian. "Modelling the effect of atmospheric nitrogen deposition on marine phytoplankton in the Singapore Strait". Water Science and Technology 61, n.º 4 (1 de febrero de 2010): 859–67. http://dx.doi.org/10.2166/wst.2010.357.
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Atmospheric deposition is an important source of nutrients to the ocean, potentially stimulating primary production, but its relative effect on coastal eutrophication remains largely unknown. This paper presents data generated by the 3-D modelling program NEUTRO to assess the proportion of atmospheric nutrient fluxes, allowing a quantification of the relative contribution of atmospheric and ocean fluxes in the Singapore Strait. This work included an assessment of the importance of high concentration episodic inputs of nitrate-nitrogen associated with transport of polluted air onto the surface water. The NEUTRO model features a nutrient-fuelled food web composed of nutrients, plankton, and dissolved oxygen dynamics. Model simulations show that atmospheric deposition fluxes alone might contribute nitrate-nitrogen mass up to 15% into the Singapore Strait. This amount might be a significant contributor toward regional eutrophication when the system is under nutrient-depleted conditions. Model calibrations for temporal and spatial variability of nutrients qualitatively and quantitatively agreed with available measurements.
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Tagore, G. S., G. D. Bairagi, R. Sharma y P. K. Verma. "Spatial variability of Soil Nutrients Using Geospatial Techniques: A case study in soils of Sanwer Tehsil of Indore district of Madhya Pradesh". ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XL-8 (23 de diciembre de 2014): 1353–63. http://dx.doi.org/10.5194/isprsarchives-xl-8-1353-2014.
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A study was conducted to explore the spatial variability of major soil nutrients in a soybean grown region of Malwa plateau. From the study area, one hundred sixty two surface soil samples were collected by a random sampling strategy using GPS. Then soil physico-chemical properties i.e., pH, EC, organic carbon, soil available nutrients (N, P, K, S and Zn) were measured in laboratory. After data normalization, classical and geo-statistical analyses were used to describe soil properties and spatial correlation of soil characteristics. Spatial variability of soil physico-chemical properties was quantified through semi-variogram analysis and the respective surface maps were prepared through ordinary Kriging. Exponential model fits well with experimental semi-variogram of pH, EC, OC, available N, P, K, S and Zn. pH, EC, OC, N, P, and K has displayed moderate spatial dependence whereas S and Zn showed weak spatial dependence. Cross validation of kriged map shows that spatial prediction of soil nutrients using semi-variogram parameters is better than assuming mean of observed value for any un-sampled location. Therefore it is a suitable alternative method for accurate estimation of chemical properties of soil in un-sampled positions as compared to direct measurement which has time and costs concerned.
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Tolu, Julie, Johan Rydberg, Carsten Meyer-Jacob, Lorenz Gerber y Richard Bindler. "Spatial variability of organic matter molecular composition and elemental geochemistry in surface sediments of a small boreal Swedish lake". Biogeosciences 14, n.º 7 (3 de abril de 2017): 1773–92. http://dx.doi.org/10.5194/bg-14-1773-2017.
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Abstract. The composition of sediment organic matter (OM) exerts a strong control on biogeochemical processes in lakes, such as those involved in the fate of carbon, nutrients and trace metals. While between-lake spatial variability of OM quality is increasingly investigated, we explored in this study how the molecular composition of sediment OM varies spatially within a single lake and related this variability to physical parameters and elemental geochemistry. Surface sediment samples (0–10 cm) from 42 locations in Härsvatten – a small boreal forest lake with a complex basin morphometry – were analyzed for OM molecular composition using pyrolysis gas chromatography mass spectrometry for the contents of 23 major and trace elements and biogenic silica. We identified 162 organic compounds belonging to different biochemical classes of OM (e.g., carbohydrates, lignin and lipids). Close relationships were found between the spatial patterns of sediment OM molecular composition and elemental geochemistry. Differences in the source types of OM (i.e., terrestrial, aquatic plant and algal) were linked to the individual basin morphometries and chemical status of the lake. The variability in OM molecular composition was further driven by the degradation status of these different source pools, which appeared to be related to sedimentary physicochemical parameters (e.g., redox conditions) and to the molecular structure of the organic compounds. Given the high spatial variation in OM molecular composition within Härsvatten and its close relationship with elemental geochemistry, the potential for large spatial variability across lakes should be considered when studying biogeochemical processes involved in the cycling of carbon, nutrients and trace elements or when assessing lake budgets.
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Gbolo, P. y P. Gerla. "Statistical analysis to characterize transport of nutrients in groundwater near an abandoned feedlot". Hydrology and Earth System Sciences 17, n.º 12 (6 de diciembre de 2013): 4897–906. http://dx.doi.org/10.5194/hess-17-4897-2013.
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Abstract. Surface water from a lagoon and groundwater samples from 17 wells within and near an abandoned feedlot in northwestern Minnesota, USA, were analyzed for carbon, nutrients, and field parameters. The feedlot is surrounded by wetlands that act as receptors of nutrients from the feedlot. Q- and R-mode multivariate analyses performed on total carbon (TC), inorganic carbon (IC), total organic carbon (TOC), nitrite-nitrogen (NO2-N), nitrate-nitrogen (NO3-N), ammonium-nitrogen (NH4-N), soluble or dissolved reactive phosphorus (DRP), and total phosphorus (TP) indicated three groups of the chemical species, which reflected variability in groundwater chemistry. Factor analysis indicated approximately 82% of the variability in factor 1 was caused by TC, IC, TOC, and DRP, while in factor 2 approximately 79% of the variability was caused by NO2-N, NO3-N, and TP. In factor 3, only NH4-N contributed 31% of the variability. Groundwater isotope and spatial distribution analysis indicated reduced nitrate concentration from the source to the wetlands, with variation in NO2-N, NO3-N, and NH4-N concentrations attributed to the plant nutrient uptake, high rate of denitrification and/or the dissimilatory nitrate reduction to ammonium. This study indicated the value of multivariate analyses in characterizing variability in groundwater quality.
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Akbas, F., H. Gunal y N. Acir. "Spatial variability of soil potassium and its relationship to land use and parent material". Soil and Water Research 12, No. 4 (9 de octubre de 2017): 202–11. http://dx.doi.org/10.17221/32/2016-swr.
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Information on the spatial distribution of plant nutrients is a prerequisite to predict their behaviour and to monitor the fertility in a watershed. This study was conducted to evaluate variations of plant available potassium (PAK) and non-exchangeable potassium (NEK) of a watershed with different land use and parent materials. Eight hundred soil samples were taken from 0–30 and 30–60 cm depths across the Kazova watershed of 20 656 ha in size. Average PAK was 152.8 mg/K kg in surface layers and 167.2 mg/kg in subsurface layers. NEK was 925 mg K/kg in surface and 167.2 mg K/kg in subsurface layers. All forms of K were the lowest in soils formed over serpentinite. Soils in pastures had the highest PAK and NEK. Both K forms were positively related to clay content. Spatial variability patterns of PAK and NEK were similar and consistent at both soil depths. The variation in parent material and land use is considered as the main cause for large variations of potassium forms.
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Šilha, J., P. Hamouz, V. Táborský, K. Štípek, J. Šnobl, K. Voříšek, L. Růžek, L. Brodský y K. Švec. "Case studies for precision agriculture". Plant Protection Science 38, SI 2 - 6th Conf EFPP 2002 (31 de diciembre de 2017): 704–10. http://dx.doi.org/10.17221/10595-pps.
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The results of spatial variability of plant-available soil nutrients (P, K, Mg) and soil pH are described in this paper. Experiment was realized on the field of area 72 ha (orthic luvisol), located in the area of Český Brod. The use of coefficient of variation as a criterion of variability of soil agrochemical properties and yield on the field showed the following: the highest variability was observed in available P, the second highest variability was in available K, and the lowest variability of main non-mobile nutrients was in the available Mg. Soil pH was the lowest of all measured soil properties. Although the highest correlation coefficient between the soil available P content and soil pH was established, the process of spatial dependence was not detected. Detailed field scouting and others data can be important elements, as can complex decision rules, taking into account additional factors such as the characteristics of crop protection agents and preferences of the farm manager. This paper illustrates, how to plant nutritions, crop protection, crop production might be integrated to support these diseases and weeds management decisions.
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Bernardi, A. C. C., G. M. Bettiol, G. G. Mazzuco, S. N. Esteves, P. P. A. Oliveira y J. R. M. Pezzopane. "Spatial variability of soil fertility in an integrated crop livestock forest system". Advances in Animal Biosciences 8, n.º 2 (1 de junio de 2017): 590–93. http://dx.doi.org/10.1017/s2040470017001145.
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Knowledge on spatial variability of soil properties is useful for the rational use of inputs, as in the site specific application of lime and fertilizer. Crop-livestock-forest integrated systems (CLFIS) provide a strategy of sustainable agricultural production which integrates annual crops, trees and livestock activities on a same area and in the same season. Since the lime and fertilizer are key factors for the intensification of agricultural systems in acid-soil in the tropics, precision agriculture (PA) is the tool to improve the efficiency of use of these issues. The objective of this research was to map and evaluate the spatial variability of soil properties, liming and fertilizer need of a CLFIS. The field study was carried out in a 30 ha area at Embrapa Pecuária Sudeste in São Carlos, SP, Brazil. Soil samples were collected at 0–0.2 m depth, and each sample represented a paddock. The spatial variability of soil properties and site-specific liming and fertilizer needs were modeled using semi-variograms, the soil fertility information were modeled. Spatial variability soil properties and site specific liming and fertilizer need were modeled by kriging and inverse distance weighting (IDW) techniques. Another approach used was based on lime and fertilizer recommendation considering the paddocks as the minimum management unit. The results showed that geostatistics and GIS were useful tools for revealing soil spatial variability and supporting management strategies. Soil nutrients were used to classify the soil spatial distribution map and design site-specific lime and fertilizer application zones. Spatial analyses of crop needs and requirement can provide management tools for avoiding potential environmental problems, caused by unbalanced nutrient supplies.
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Li, Cangyu, Xinhui Wang y Mingzhou Qin. "Spatial variability of soil nutrients in seasonal rivers: A case study from the Guo River Basin, China". PLOS ONE 16, n.º 3 (16 de marzo de 2021): e0248655. http://dx.doi.org/10.1371/journal.pone.0248655.
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Agricultural non-point source pollution refers that substance such as nitrogen and phosphorus cause water environment pollution through surface runoff and underground leakage in agricultural production activities. Water environment pollution related to agricultural non-point source pollution in the Huaihe River Basin is becoming more and more prominent. Therefore, it is necessary to analyze the characteristic of soil nutrient in cultivated land and explore the spatial variation and influencing factors of soil nutrients at the watershed scale. A total of 239 topsoil samples were collected from the Guo river basin, and the related factors of soil organic matter (SOM), total carbon (TC), total nitrogen (TN), total phosphorous (TP), total potassium (TK) and potential of hydrogen (PH) were studied by using descriptive statistics and geostatistical methods. The results showed that TK and PH were weak variation, while SOM, TC, TN and TP were medium variation. Soil pH, TP, TK, TC and SOM had moderate spatial variability, which was caused by both random factors and structural factors such as soil texture, soil type, fertilization and local ecological restoration management. Soil TN showed a strong spatial correlation, mainly due to soil texture and soil type. If the recommended fertilization amount is still given based on the average value of soil nutrients ignoring the spatial heterogeneity, it will not only affect crop production efficiency and fertilizer utilization, but may also cause greater environmental pollution. This study can provide a theoretical basis for the management of agro-ecological environments throughout the basin area.
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Szatmári, Gábor, Mihály Kocsis, András Makó, László Pásztor y Zsófia Bakacsi. "Joint Spatial Modeling of Nutrients and Their Ratio in the Sediments of Lake Balaton (Hungary): A Multivariate Geostatistical Approach". Water 14, n.º 3 (26 de enero de 2022): 361. http://dx.doi.org/10.3390/w14030361.
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Eutrophication, water quality, and environmental status of lakes is a global issue that depends not only on external loadings from industrial, agricultural, and municipal sources but often also on internal loadings from lake sediments. In the latter case, in addition to the quality and quantity of nutrients stored in sediments, their relative content may be an important factor. In the example of Lake Balaton, we jointly modeled the spatial distribution of the nutrients nitrogen (N) and phosphorus (P) and their ratio (i.e., N:P) in the sediments of the lake and then provided spatial predictions at different scales (i.e., point, basin, and entire lake) with the associated uncertainty. Our aim was to illustrate the merits of applying multivariate geostatistics when spatial modeling of more than one variable is targeted at various scales in water ecosystems. Variography confirmed that there is a spatial interdependence between the nutrients. The results revealed that multivariate geostatistics allows this interdependence to be taken into account and exploited to provide coherent and accurate spatial models. Additionally, stochastic realizations, reproducing the joint spatial variability, can be generated that allow providing spatially aggregated predictions with the associated uncertainty at various scales. Our study highlighted that it is worthy of applying multivariate geostatistics in case spatial modeling of two or more variables, which jointly vary in space, is targeted in water ecosystems.
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Corredor-Acosta, Andrea, Náyade Cortés-Chong, Alberto Acosta, Matias Pizarro-Koch, Andrés Vargas, Johanna Medellín-Mora, Gonzalo S. Saldías, Valentina Echeverry-Guerra, Jairo Gutiérrez-Fuentes y Stella Betancur-Turizo. "Spatio-Temporal Variability of Chlorophyll-A and Environmental Variables in the Panama Bight". Remote Sensing 12, n.º 13 (4 de julio de 2020): 2150. http://dx.doi.org/10.3390/rs12132150.
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The analysis of synoptic satellite data of total chlorophyll-a (Chl-a) and the environmental drivers that influence nutrient and light availability for phytoplankton growth allows us to understand the spatio-temporal variability of phytoplankton biomass. In the Panama Bight Tropical region (PB; 1–9°N, 79–84°W), the spatial distribution of Chl-a is mostly related to the seasonal wind patterns and the intensity of localized upwelling centers. However, the association between the Chl-a and different physical variables and nutrient availability is still not fully assessed. In this study, we evaluate the relationship between the Chl-a and multiple physical (wind, Ekman pumping, geostrophic circulation, mixed layer depth, sea level anomalies, river discharges, sea surface temperature, and photosynthetically available radiation) and chemical (nutrients) drivers in order to explain the spatio-temporal Chl-a variability in the PB. We used satellite data of Chl-a and physical variables, and a re-analysis of a biogeochemical product for nutrients (2002–2016). Our results show that at the regional scale, the Chl-a varies seasonally in response to the wind forcing and sea surface temperature. However, in the coastal areas (mainly Gulf of Panama and off central-southern Colombia), the maximum non-seasonal Chl-a values are found in association with the availability of nutrients by river discharges, localized upwelling centers and the geostrophic circulation field. From this study, we infer that the interplay among these physical-chemical drivers is crucial for supporting the phytoplankton growth and the high biodiversity of the PB region.
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Melendez-Pastor, I., E. M. Isenstein, J. Navarro-Pedreño y M.-H. Park. "Spatial variability and temporal dynamics of cyanobacteria blooms and water quality parameters in Missisquoi Bay (Lake Champlain)". Water Supply 19, n.º 5 (24 de enero de 2019): 1500–1506. http://dx.doi.org/10.2166/ws.2019.017.
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Abstract Cyanobacteria bloom events have been associated with eutrophication processes, along with hydrologic and climate factors. Missisquoi Bay is a portion of Lake Champlain (USA–Canada) that is highly eutrophic and prone to cyanobacteria blooms and cyanotoxins. This study assessed the spatial–temporal influence of nutrients, turbidity and temperature in cyanobacteria distributions during a bloom event in the summer of 2006. Correlations, generalized linear models (GLMs), geostatistics and local indications of spatial association (LISA) autocorrelation analysis tested the influence of nutrient and non-nutrient explanatory variables in cyanobacteria biovolume. Total phosphorus exhibited a high direct correlation with cyanobacteria biovolume. The best performing GLMs included total phosphorus, total nitrogen, Secchi depth (as turbidity) and temperature as explanatory variables of cyanobacteria biovolume. Variogram analysis of those variables resulted in a better understanding of the underlying spatial variation process of the cyanobacteria bloom event. The LISA test revealed a moderate but stable autocorrelation between cyanobacteria biovolume and total phosphorus from 180 to 1,000 m of weight distance, suggesting the possibility of up-scaling the current results to coarse-resolution satellite imagery for more frequent monitoring of bloom events. The LISA test also revealed the spatial–temporal dynamic (movement of cyanobacteria scums) of high cyanobacteria blooms with high total phosphorus concentration.
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Prayitno, Hanif Budi y Afdal. "SPATIAL DISTRIBUTIONS OF NUTRIENTS AND CHLOROPHYLL-A: A POSSIBLE OCCURRENCE OF PHOSPHORUS AS A EUTROPHICATION DETERMINANT OF THE JAKARTA BAY". Jurnal Ilmu dan Teknologi Kelautan Tropis 11, n.º 1 (1 de abril de 2019): 1–12. http://dx.doi.org/10.29244/jitkt.v11i1.21971.
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Phytoplankton blooms due to nutrient enrichment (eutrophication) have been considered as the primary factor causing several massive fish kills occurred in the Jakarta Bay. This study aims to determine the spatial variation of phytoplankton abundance based on chlorophyll-a concentration and its relationship with nutrient level and composition. A field observation was conducted in July 2015 measuring chlorophyll-a and nutrient concentrations. Chlorophyll-a was measured using fluorometer Trilogy AU-10 while nutrients was using spectrophotometer Shimadzu UV-1800. The result showed that chlorophyll-a concentration was relatively higher in the western compared to the eastern region of the Jakarta Bay. In addition, the western region was high in orthophosphate, nitrate and silicate while the eastern region was high in ammonium and nitrate. Statistical analysis shows that chlorophyll-a had the highest significant correlation against orthophosphate in the western region and chlorophyll-a had no significant correlation with nutrients in the eastern region. It seems that phosphorus was the primary determinant of chlorophyll-a variability with a concentration of orthophosphate of more than 0.028 mg P/L is required to increase chlorophyll-a concentration. In addition, low orthophosphate concentration (0.014 mg P/L) below its minimum requirement for maximum phytoplankton growth was likely the factor causing the absence of chlorophyll-a and nutrients relationship in the eastern region. In summary, phosphorus is seemingly the primary eutrophication determinant in the Jakarta Bay.
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Auger, Pierre-Amaël, Thomas Gorgues, Eric Machu, Olivier Aumont y Patrice Brehmer. "What drives the spatial variability of primary productivity and matter fluxes in the north-west African upwelling system? A modelling approach". Biogeosciences 13, n.º 23 (30 de noviembre de 2016): 6419–40. http://dx.doi.org/10.5194/bg-13-6419-2016.
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Abstract. A comparative box analysis based on a multi-decadal physical–biogeochemical hindcast simulation (1980–2009) was conducted to characterize the drivers of the spatial distribution of phytoplankton biomass and production in the north-west (NW) African upwelling system. Alongshore geostrophic flow related to large-scale circulation patterns associated with the influence of coastal topography is suggested to modulate the coastal divergence, and then the response of nutrient upwelling to wind forcing. In our simulation, this translates into a coastal upwelling of nitrate being significant in all regions but the Cape Blanc (CB) area. However, upwelling is found to be the dominant supplier of nitrate only in the northern Saharan Bank (NSB) and the Senegalo-Mauritanian (SM) regions. Elsewhere, nitrate supply is dominated by meridional advection, especially off Cape Blanc. Phytoplankton displays a similar behaviour with a supply by lateral advection which equals the net coastal phytoplankton growth in all coastal regions except the Senegalo-Mauritanian area. Noticeably, in the Cape Blanc area, the net coastal phytoplankton growth is mostly sustained by high levels of regenerated production exceeding new production by more than twofold, which is in agreement with the locally weak input of nitrate by coastal upwelling. Further offshore, the distribution of nutrients and phytoplankton is explained by the coastal circulation. Indeed, in the northern part of our domain (i.e. Saharan Bank), the coastal circulation is mainly alongshore, resulting in low offshore lateral advection of nutrients and phytoplankton. Conversely, lateral advection transports coastal nutrients and phytoplankton towards offshore areas in the latitudinal band off the Senegalo-Mauritanian region. Moreover, this latter offshore region benefits from transient southern intrusions of nutrient-rich waters from the Guinean upwelling.