Relevant bibliographies by topics / Undisturbed environment

Academic literature on the topic 'Undisturbed environment'

Author: Grafiati
Published: 10 December 2022
Last updated: 19 February 2023

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Journal articles on the topic "Undisturbed environment"

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McDowell, J. J., and Marcia L. Caron. "MATCHING IN AN UNDISTURBED NATURAL HUMAN ENVIRONMENT." Journal of the Experimental Analysis of Behavior 93, no. 3 (May 2010): 415–33. http://dx.doi.org/10.1901/jeab.2010.93-415.

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Nuijens, Louise, Bjorn Stevens, and A. Pier Siebesma. "The Environment of Precipitating Shallow Cumulus Convection." Journal of the Atmospheric Sciences 66, no. 7 (July 1, 2009): 1962–79. http://dx.doi.org/10.1175/2008jas2841.1.

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Abstract Quantitative estimates of precipitation in a typical undisturbed trade wind region are derived from 2 months of radar reflectivity data and compared to the meteorological environment determined from soundings, surface flux, and airborne-lidar data. Shallow precipitation was ubiquitous, covering on average about 2% of the region and contributing to at least half of the total precipitation. Echo fractions on the scale of the radar domain range between 0% and 10% and vary greatly within a period from a few hours to a day. Variability in precipitation relates most strongly to variability in humidity and the zonal wind speed, although greater inversion heights and deeper clouds are also evident at times of more rain. The analysis herein suggests that subtle fluctuations in both the strength of the easterlies and in subsidence play a major role in regulating humidity and hence precipitation, even within a given meteorological regime (here, the undisturbed trades).
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Briard, L., C. Goujarde, C. Bousquet, and A. Dussutour. "Stress signalling in acellular slime moulds and its detection by conspecifics." Philosophical Transactions of the Royal Society B: Biological Sciences 375, no. 1802 (May 18, 2020): 20190470. http://dx.doi.org/10.1098/rstb.2019.0470.

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Unicellular organisms live in unpredictable environments. Therefore, they need to continuously assess environmental conditions and respond appropriately to survive and thrive. When subjected to rapid changes in their environment or to cellular damages, unicellular organisms such as bacteria exhibit strong physiological reactions called stress responses that can be sensed by conspecifics. The ability to detect and use stress-related cues released by conspecifics to acquire information about the environment constitutes an adaptive survival response by prompting the organism to avoid potential dangers. Here, we investigate stress signalling and its detection by conspecifics in a unicellular organism, Physarum polycephalum . Slime moulds were subjected to either biotic (i.e. nutritional) or abiotic (i.e. chemical and light) stressors or left undisturbed while they were exploring a homogeneous environment. Then, we observed the responses of slime moulds facing a choice between cues released by stressed clone mates and cues released by undisturbed ones. We found that slime moulds actively avoided environments previously explored by stressed clone mates. These results suggest that slime moulds, like bacteria or social amoeba, exhibit physiological responses to biotic and abiotic stresses that can be sensed by conspecifics. Our results establish slime moulds as a promising new model to investigate the use of social information in unicellular organisms. This article is part of the theme issue ‘Signal detection theory in recognition systems: from evolving models to experimental tests’.
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Yellajosula, Gayatri, Larry Cihacek, Tim Faller, and Christopher Schauer. "Soil Carbon Change Due to Land Conversion to Grassland in a Semi-Arid Environment." Soil Systems 4, no. 3 (July 16, 2020): 43. http://dx.doi.org/10.3390/soilsystems4030043.

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A 5-year study evaluated the change in the quantity of soil total C (STC), soil organic C (SOC), and soil inorganic C (SIC) stored in the surface 60 cm of the soil profile on two adjacent blocks of land with a long-term history of cropping (CH) or undisturbed grassland (NH) on similar soil types between 1999 and 2004. The NH area was tilled and a grass-legume species mix was seeded into plots on both the NH and the CH areas. Selected plots of restored grass were established so they could be grazed (GG) by livestock while other plots were left ungrazed (UG). Original undisturbed (and ungrazed) grassland plots within the NH area were used as a control treatment. Initially, STC and SOC in CH were lower than NH when compared under the semi-arid environmental conditions found in southwestern North Dakota. Over the study period, the undisturbed grass control plots had increases in STC and SOC levels in the soil profile of 3.90 kg·m−2 and 3.34 kg·m−2, respectively. Restored grass on the NH area with grazing showed increases in STC and SOC values of 2.11 and 1.26 kg·m−2, respectively, while without grazing, profile STC and SOC had values of 3.80 and 3.28 kg·m−2, respectively. Restored grass on the CH area showed increases in profile STC and SOC values of 0.55 and 1.96 kg·m−2, respectively, for the grazed plots and 0.78 and 2.11 kg·m−2, respectively, when left ungrazed. Soil inorganic C, though present in the soils, did not significantly change during the study. The lower C accumulation in the CH plots may be due to a lag time in the establishment of mycorrhizal associations with the seeded species, the inoculums of which were already present in the NH soils. Changes in STC were likely due to changes in water relationships in the soil profile where management changes affected water infiltration and its movement causing leaching of SIC below the 60 cm depth evaluated. Soils under undisturbed grassland continue to accumulate carbon while soils of the disturbed grassland or cropped prior to re-establishing grass showed losses that occurred due to either accumulating C at a lower rate or perhaps to C loss during the initial establishment period (1–2 years).
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Dias, Alesandra Martins, and Francisco Leonardo Tejerina-Garro. "Changes in the structure of fish assemblages in streams along an undisturbed-impacted gradient, upper Paraná River basin, Central Brazil." Neotropical Ichthyology 8, no. 3 (2010): 587–98. http://dx.doi.org/10.1590/s1679-62252010000300003.

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The João Leite River is located in the upper Paraná basin, Central Brazil. It drains areas covered by Cerrado vegetation interspersed with urban and agricultural areas. This study aims to asses changes of the fish assembleges structure along a undisturbed-impacted gradient in ten stream stretches using ecological descriptors, a similarity index and the abundance-biomass relationship (ABC curves). The fish were collected during the dry period using electrofishing gear in stretches of 50 m. Results show that the environmental variation observed along the undisturbed-impacted gradient considered influences on fish assemblage structure. Both richness and diversity differences between fish assemblages are partially influenced by stream stretch orthonian order and anthropogenic impacts. ABC curves classified six stream stretches located in preserved or impacted areas as undisturbed while four stretches were classified as disturbed. This is attributed to the influence of the undisturbed habitat within the conservation unit and the presence of K- or r- strategist species. This type of study contributes to an understanding of the effects of aquatic environment conservation on the Brazilian Cerrado core area, where the choice of conservation areas prioritizes terrestrial over aquatic aspects.
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Malash, Kateryna Mykolaiivna, and Andrii Bomba. "Modelling of an explosion impact on a deformable medium with rigid inclusions with quasiconformal mappings methods." Modeling, Control and Information Technologies, no. 4 (October 22, 2020): 19–22. http://dx.doi.org/10.31713/mcit.2020.04.

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The explosive process influence on the environment with the existing impenetrable fixed inclusion is investigated by quasiconformal mappings numerical methods and step-by-step parameterization of the environment and the process characteristics numerical methods. The boundaries of the crater formed by the explosion, pressed and undisturbed areas of soil are determined. Numerical experiments were performed on the basis of the developed algorithm
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Álvarez, Alberto, W. Owen McMillan, Néstor Pérez-Buitrago, Alberto Sabat, and Miguel García. "Spatial ecology of the Mona Island iguana Cyclura cornuta stejnegeri in an undisturbed environment." Applied Herpetology 4, no. 4 (2007): 347–55. http://dx.doi.org/10.1163/157075407782424575.

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Kullberg, Russell G. "Decreased diversity caused by differential inhibition among artificial phytoplankton communities in an undisturbed environment." European Journal of Phycology 30, no. 4 (November 1995): 267–72. http://dx.doi.org/10.1080/09670269500651041.

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Scheltema, MA, LK Abbott, and AD Robson. "Seasonal variation in the infectivity of VA mycorrhizal fungi in annual pastures in a Mediterranean environment." Australian Journal of Agricultural Research 38, no. 4 (1987): 707. http://dx.doi.org/10.1071/ar9870707.

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The seasonal variation in the rate and extent of formation of mycorrhizas in pasture soils from two sites in south-west Australia was examined. Undisturbed soil cores were taken on eight occasions throughout the year, sown with Trifolium subterraneum L. and maintained in a glasshouse. At each collection time the extent of formation of mycorrhizas was measured 3 and 6 weeks after sowing.There was no seasonal variation in the extent of mycorrhizas formed in undisturbed soil cores at one site, hut at the other site the extent of mycorrhizas decreased over time. The rate of formation of mycorrhizas was most rapid when cores were collected immediately after the opening rains of the season.Similar species of fungi were present at both sites; however, the rate and extent of infection formed by each species differed between the sites. At both sites the infectivity of A. laevis and fine endophyte decreased throughout the winter months, but the infectivity of Glomus spp. did not change. Neither the total spore number nor an estimate of the number of infective propagules reflected the infectivity of the total population of VA mycorrhizal fungi measured simultaneously at the two sites.
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Sazanova, K. V. "STATISTICAL MODELS OF THE METABOLOME OF LITHOBIONTIC COMMUNITIES IN NATURAL AND URBANIZED CONDITIONS." Ecology. Economy. Informatics.System analysis and mathematical modeling of ecological and economic systems 1, no. 6 (2021): 155–60. http://dx.doi.org/10.23885/2500-395x-2021-1-6-155-160.

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The composition of metabolites in various types of biolayering on the marble surface in natural outcrops and in an urban environment has been studied. Metabolomic profiling was performed by gas chromatographymass spectrometry. It was found that biolayering in the urban environment is much less diverse biochemically than in anthropogenically undisturbed conditions. The differences in metabolomic data were significantly greater between sampling sites than between community types. Lithobiontic communities of organisms are an interesting and promising for bioindication and biomonitoring of the environment.
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Dissertations / Theses on the topic "Undisturbed environment"

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Steinvall, Konrad. "Deriving the Undisturbed Near-surface Lunar Electric Field : Simulations of the electrostatic environment of the Umeå Lunar Venture electric field instrument." Thesis, Umeå universitet, Institutionen för fysik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-136268.

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The existence of an electric field on the Moon has been theorized since the end of the 1960s, when reports from astronauts suggested that charged particles from the lunar surface could be seen interacting with light at high altitudes. Today it is believed that an electric field drives the motion of charged particles on the Moon, and although a good number of simulations investigating the field have been made, the electric field has not been measured experimentally. Space Science Sweden and Umeå Lunar Venture have developed an electric field mill instrument that is to be attached to a lunar lander with the intention of measuring the electric field near the lunar terminators. The main problem that arises when this approach is used to measure electric fields is that the presence ofthe lunar lander, and of the instrument itself, distorts the ambient fields intended to be measured. A numerical electrostatic model treating the electric field distortions caused by conductive materials and their charge is developed in COMSOL Multiphysics, and is shown to agree well with both theoretical and experimental results. The model is then applied to a system consisting of a lunar lander with the electric field instrumen tattached, and the resulting field distortions are investigated. The system is calibrated for different locations of the field mill, as well as for different modifications of the instrument in order to find the optimal location and instrument that minimizes the errors in the calculated ambient fields. The results indicate that if the instrument consists of three field mills, and is placed near a corner of the lunar lander, it will be able to measure the ambient electric field larger than a few 100 mV/m, unless the potential of the lunar lander is around 10 V, in which case the charge induced field drowns out the ambient field. However, the model of the lunar lander that was used lacked information regarding its materials and solar panels. Consequently, the assumption that the surfaces of the lander were conductive and held at the same potential was made. Similarly, only very simplified models of the solar panels were used to estimate their importance. Because of these simplifications, the results should be seen as preliminary, and not conclusive. In order to obtain more reliable results that can be used together with actual lunar data, a few changes and additions should be made to the model. Specifically, a more detailed and accurate computer model of the lunar lander is necessary to obtain more correctly estimated field distortions. Additional information regarding the material and coating of the solar panel is required to properly model the solar panels and account for their effect on the ambient electric field.
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Xu, Youjie. "Dust emissions from undisturbed and disturbed soils: effects of off-road military vehicles." Thesis, Kansas State University, 2014. http://hdl.handle.net/2097/18726.

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Master of Science
Department of Biological & Agricultural Engineering
Ronaldo G. Maghirang
Military training lands can be significant sources of fugitive dust emissions due to wind erosion. This study was conducted to determine dust emission potential of soils due to wind erosion as affected by off-road military vehicle disturbance. Multi-pass traffic experiments using two types of vehicles (i.e., wheeled and tracked) were conducted on six soil textures at four military training facilities: Fort Riley, KS; Fort Benning, GA; Yakima Training Center, WA; and White Sands Missile Range (WSMR), NM. Prior to and after the preselected number of vehicle passes, soil samples at three locations were collected with minimum disturbance into trays. Adjacent to the location where tray samples were collected, a Portable In-Situ Wind Erosion Lab (PI-SWERL) was used to measure dust emission potential. The tray samples were tested in a laboratory wind tunnel (with sand abrader) for dust emission potential using a GRIMM aerosol spectrometer and gravimetric method with filters. Comparison of the PI-SWERL (with DustTrak™ dust monitor) and wind tunnel (with GRIMM aerosol spectrometer) measurement results showed significant difference in measured values but high correlation, particularly for soils with high sand content. Wind tunnel tests results showed that sampling locations significantly affected dust emissions for the tracked vehicles but not for the light-wheeled and heavy-wheeled vehicles. Also, soil texture, number of vehicle passes, and vehicle type significantly affected dust emissions. For the light-wheeled vehicles, dust emissions increased as the number of vehicle passes increased. From undisturbed conditions to 10 vehicle passes, there was a significant (P<0.05) increase in dust emissions (297%) on average for all light-wheeled vehicle tests. From 10 to 25 passes and 25 to 50 passes, an additional 52% and 62% increments were observed. For the tracked vehicle, for the straight section sampling location, dust emission increased as the number of vehicle passes increased. However, for the curve section, dust emissions at any level of pass were significantly higher than initial condition; beyond the first pass, no significant increase was observed.
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Angliviel, de La Beaumelle Axel Christian Luc. "Evaluation of SHANSEP strenth-deformation properties of undisturbed Boston blue clay from automated triaxial testing." Thesis, Massachusetts Institute of Technology, 1991. http://hdl.handle.net/1721.1/34311.

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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Civil Engineering, 1991.
Includes bibliographical references (v. 1, leaves 250-252).
by Axel Christian Luc Angliviel de La Beaumelle.
M.S.
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Wood, James Lindley. "Peatland Communities and Environmental Parameters in an Undisturbed Boreal Poor Fen and a Comparison with Haul Road Disturbances." OpenSIUC, 2010. https://opensiuc.lib.siu.edu/theses/272.

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In the boreal forest of Alberta, oil exploration has brought roads into previously undisturbed areas. Peatlands cover vast areas of the boreal forest, transmit water across the landscape, provide habitat for wildlife, and store carbon sequestered from the atmosphere. Roads crossing peatlands is inevitable, and little is known about how roads impact plant communities, water chemistry, and water tables. Few studies of large fen complexes have been conducted in the continental boreal forest, nor have many investigated the impact of roads. Understanding the relationships between species, water chemistry, and microtopography provides insight into the nature of continental fens and how they respond to disturbance. I examined plant communities and water chemistry characteristics of an undisturbed fen and compared the data to nearby peatlands that were disturbed by mineral haul roads. This study determined the control study site was an acidic fen with a pH generally less than 4.0 and four community types were recognized. Most of the complex was very wet, open, oligotrophic poor fen, with a treed, oligotrophic, species poor area extending between two water tracks. As the fen narrowed following its drainage, site type changed to mesotrophic poor fen, with mesotrophic rich fen communities in some marginal areas. The water table was very stable. The road sites showed signs of enriched water chemistry and changed plant communities within 50 meters of the road upstream. Downstream plant communities were less effected. Water tables appear to be influenced both upstream and downstream differently.
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Choubedar, Feraidoun. "The use of radio-nuclides (unsupported 210Pb, 7Be and 137Cs) in air, rain and undisturbed soil as environmental tools." Thesis, University of Edinburgh, 2000. http://hdl.handle.net/1842/13381.

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Soil inventories of atmospherically derived 210Pb (radioactive half lives 22.3 years) were used to determine deposition patterns of atmospherically derived aerosols averaged over decades at low altitude sites (51-6° N, 0.6° W) and quantify the enhancement in aerosol deposition by aerodynamically rough canopies (forest) relative to short vegetation (grass). 210Pb and 7Be (radioactive half life 53.4 days) in surface air and rain (55.6° N, 3.9° W) were measured to determine the concentration of these radionuclide isotopes in the environment. Non-destructive gamma-spectrometry was used for all 3 parts using high purity germanium (HPGe) detectors. From the soil samples 137Cs (radioactive half life 30.2 years) are being measured and reported. The average inventories to the canopies compared to the short vegetation for 210Pb and 137Cs for Geescroft forest were 25.7% and 60.8% higher than the open field inventories, respectively; the corresponding values for Broadbalk forest were 30.9% and 68.9% for 210Pb and 137Cs, respectively. Although these two forests are not far from each other and have the same altitude, the excess inventories for Broadbalk forest are larger than Geescroft forest and this could be due to the fact that this forest is acting as an edge, because of its width. The averaged flux for Rothamsted forest soils for 210Pb was determined as 211 ± 6 Bq m-2 y-1 per metre of rainfall, and for the soil and vegetation in the open area 167 ± 6 Bq m-2 y-1 per metre of rainfall. The annual average concentrations in surface air were 0.19 ± 0.06 and 2.71 ± 0.66 mBq m-3 for 210Pb and 7Be, respectively. The annual fluxes of 210Pb and 7Be in rain were determined as 68 ± 10 and 787 ± 29 Bq m-2 y-1 per metre of rainfall, respectively. There was a seasonal variation for 7Be concentrations in air and rain giving spring high. The highest concentrations for 210Pb were obtained when the air mass origin was from continent. From the air and rain data for 210Pb and 7Be, similar washout scavenging ratios (Ws) were obtained, indicating they are scavenged from the atmosphere with a similar rate. The dry deposition of 210Pb and 7Be carrier aerosols were estimated as 41 ± 13% and 35 ± 9% of the total deposition for 210Pb and 7Be, respectively.
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Garbark, Christopher J. "The Relationship of Red-Backed Salamander Abundance to the Direct and Indirect Use Value of Undisturbed Forest, a Timberland Mosaic of Forest, and Agriculture Land-Uses." Thesis, Indiana University of Pennsylvania, 2019. http://pqdtopen.proquest.com/#viewpdf?dispub=13810330.

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Plethodon salamanders may serve as important indicators of forest ecosystem integrity due to their niche, physiological sensitivity, abundance, site fidelity, and association with forest structures. Forest ecosystems provide direct and indirect services and products that benefit society. Monitoring the quality and status of these direct and indirect use values is important to manage and maximize the benefit to people. An ecological indicator is something that may indicate the state of a system. Indicators are widely used in a variety of fields including forestry, economics, and environmental management to monitor the state of desired systems. The IndVal method is a statistical analysis used to determine the efficacy of a species as an indicator species, by determining the association between the species of interest and site groups or habitats. I sought to determine if the red-backed salamander is an indicator of forests based on the IndVal method, and if the red-backed salamander may be used as an indicator of use values. I hypothesized that red-backed salamanders may be used as an indicator of standing mature forested areas. I hypothesized that salamander abundance would be highest in forested areas and may act as an indicator species of forest habitats. I hypothesized that red-backed salamander abundance would have a positive correlation with indirect use values and a negative correlation with direct use values. The study area consisted of Forestland, Timberland, and Agriculture land-uses within northwestern Pennsylvania. I used visual encounter surveys and drift fences for capturing of red-backed salamanders (Plethodon cinereus) for abundance estimates. Visual encounter surveys were done within area constrained (10 × 10m) plots and a time constraint of roughly 30 minutes. I measured environmental variables within each plot. An N-mixture model of P. cinereus was used to estimate abundance based on repeated counts data. I used a principal components analysis (PCA) to determine which environmental variables were associated with study sites. I used a Kruskal-Wallis test and post-hoc Dunn’s test to determine differences between land-use in red-backed salamander abundance. I applied the IndVal method to red-backed salamander abundance in association to land-use and habitat. I estimated indirect use values through cost replacement methods for water purification, water cycling production, nitrate treatment, and soil erosion. I obtained direct use values through land-owners and the U.S. Forest Service archives, which the cost of production and gross value of production were used to determine the net and gross value. I used a Spearman’s Rank correlation to determine the relationship between red-backed salamander abundance and the direct and indirect use values of land-uses. The PCA 1 axis described an environmental gradient of closed to open canopy. Forestland sites had the lowest sunlight values, Agriculture having the highest, and Timberland intermediate between the two. Canopy percent cover was the most informative variable in the N-mixture model. Red-backed salamander abundance was greatest, mean = 434, on Forestland sites and was significantly (p-value < 0.05) different from Timberland and Agriculture. The red-backed salamander was highly associated with Forestland with an indicator species value of 0.876, and 0.972 for forests. Red-backed salamanders held a significant strong positive relationship with indirect use values, rho = 0.84. P. cinereus abundance had a significant strong negative relationship with gross direct use values, rho = –0.95, and net direct use values, rho = –0.92. The strong correlation between P. cinereus abundance and indirect use values suggest that red-backed salamander abundance may have applications as an indicator of indirect use values for forest ecosystems.

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Silva, Joyce Tatiane Rodrigues da. "Chuva de sementes em ambientes perturbados e não-perturbados na Floresta de Mata Atlântica do sul da Bahia, Brasil." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/11/11150/tde-24072008-170722/.

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O nível de perturbação a que um ambiente está sujeito pode afetar profundamente o processo de regeneração natural, através de modificações nas fontes de regeneração. Os principais mecanismos de regeneração natural das florestas são a chuva de sementes (dispersão), o banco de sementes do solo e o estabelecimento de plântulas. O presente estudo tem como objetivo analisar uma das principais etapas da regeneração, a chuva de sementes, em áreas de perturbações naturais (clareiras) e antrópicas (área queimada) e áreas sem indícios de perturbação recente na Mata Atlântica do sul da Bahia. Para a amostragem, foram instalados coletores de sementes em ambientes de sub-bosque, de clareiras naturais e de uma área perturbada por fogo, num total de 144 coletores de 0,50 x 0,50 m, amostrados mensalmente. A chuva de sementes da Floresta Ombrófila Densa analisada foi contínua ao longo dos dois anos amostrados, mas apresentou flutuações entre períodos do ano e variações entre os ambientes analisados. Foram amostradas 41.910 sementes, pertencentes a 198 morfoespécies, sendo que as 120 que puderam ser identificadas foram distribuídas em 31 famílias e 57 gêneros. As 78 espécies indeterminadas representam apenas 256 sementes ou 0,6% do total de sementes amostradas. A menor quantidade total de sementes nesses dois anos foi observada no ambiente de clareiras (7.555, representando 1,25 sementes/m²/dia), enquanto o maior número de sementes foi observado na área queimada (13.656, ou seja, 2,17 sementes/m²/dia). Não foram constatadas diferenças significativas entre a proporção de espécies anemocóricas para os ambientes de clareiras e sub-bosque em nenhum dos anos analisados. Os ambientes mais similares foram o sub-bosque próximo à área queimada (MP) e o subbosque adjacente às clareiras (SB), seguido pelas clareiras (C) e pelo sub-bosque próximo à área queimada (MP). Os períodos de maior taxa de deposição de sementes estiveram concentrados principalmente no meio de ano para praticamente todos os ambientes. A chuva de sementes foi dominada por um pequeno número de espécies produzindo cerca de 98% do total de sementes amostradas, e com muitas espécies sendo representadas por poucas sementes ao longo do período de estudo. Essa dominância foi representada principalmente por três espécies arbóreas pioneiras nativas: Miconia mirabilis, Cecropia pachystachya e Henriettea succosa. Em análise mais detalhada da chuva de sementes destas espécies foi observado que as espécies Miconia mirabilis e Cecropia pachystachya mostraram um padrão anual de deposição de suas sementes, sugerindo que estas espécies possuem uma fenologia definida com longos períodos de deposição de sementes durante o ano. Henriettea succosa foi a espécie que obteve uma distribuição mais homogênea entre os quatros ambientes observados, porém sua maior deposição de sementes ocorreu exclusivamente no mês de abril de 1999.
The disturbance level to which a forest is exposed to may affect its dynamics, modifying the recruits sources. The main mechanisms of forest natural regeneration is seed rain (dispersion), soil seed bank and seedlings establishment. This study aims to analyze seed rain within fire and natural (gaps) disturbed areas and sites with no sign of recent disturb at Atlantic Forests of South Bahia. Sampling was taken monthly through seed rain collectors located under gaps, understorey and fire disturbed areas, in a total of 144 0,5x0,5 m collectors. Although seed rain sampling was continuous, fluctuations were noticed for distinct seasonal periods and environments. A total of 41.910 seeds were sampled, representing 198 morfo-species; 120 were identified and classified into 31 botanical families and 57 genera. The remaining 78 morfo-species were represented by 256 seeds or 0,6% of total sampled seeds. The lower quantities of seeds were observed within gaps environments (7.555 seeds, representing 1,25 seeds/m²/day), while the higher amounts were observed for the fire disturbed areas (13.656 seeds or 2,17 seeds/m²/day). No significant differences were found regarding anemochoric species occurrence between gaps and understorey environments. Similarities were found between fire disturbed areas (MP) and their surrounding understorey environments (SB) and also between gaps (C) and understorey close to fire disturbed areas (SB). The periods of seeds deposition higher rate had been mainly concentrated in the middle of the year for practically all environments. Seed rain was characterized by few species that produced around 98% of the total amount of sampled seeds, with most of the species being represented by few seeds during this study. The dominant species were represented by three native pioneer tree species: Miconia mirabilis, Cecropia pachystachya and Henriettea succosa. A more detailed analysis of the seed rain revealed that Miconia mirabilis and Cecropia pachystachya have an annual deposition pattern, suggesting that these species have a defined phenology, with long periods of seeds deposition along a year. Henriettea succosa presented the most homogeneous distribution among the observed environments, with higher levels of deposition during April 1999. Further studies are needed to understand the observed patterns of this study, especially on M. mirabilis and C. pachystachya phenology.
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Muller, Heike K. "Laboratory study of chromium sorption and desorption in undisturbed soil." Thesis, 1992. http://hdl.handle.net/1957/36308.

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Books on the topic "Undisturbed environment"

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Beylich, Achim A., John C. Dixon, and Zbigniew Zwolinski, eds. Source-to-Sink Fluxes in Undisturbed Cold Environments. Cambridge: Cambridge University Press, 2016. http://dx.doi.org/10.1017/cbo9781107705791.

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Source-To-Sink-Fluxes in Undisturbed Cold Environments. Cambridge University Press, 2016.

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Zbigniew Zwoliński, John C. Dixon, and Achim A. Beylich. Source-To-Sink Fluxes in Undisturbed Cold Environments. Cambridge University Press, 2016.

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Dixon, John C., Achim A. Beylich, and Zbigniew Zwoliński. Source-To-Sink Fluxes in Undisturbed Cold Environments. Cambridge University Press, 2016.

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L, Mosko Timothy, and Intermountain Research Station (Ogden, Utah), eds. Streamflow data for undisturbed, forested watersheds in central Idaho. Ogden, UT (324 25th Street, Ogden 84401): U.S. Dept. of Agriculture, Forest Service, Intermountain Research Station, 1990.

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Müller, Heike K. Laboratory study of chromium sorption and desorption in undisturbed soil. 1992.

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Book chapters on the topic "Undisturbed environment"

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Císlerová, Milena, Tomáš Vogel, Jana Votrubová, and Alice Robovská. "Searching below thresholds: Tracing the origins of preferential flow within undisturbed soil samples." In Environmental Mechanics: Water, Mass and Energy Transfer in the Biosphere, 265–74. Washington, D. C.: American Geophysical Union, 2002. http://dx.doi.org/10.1029/129gm22.

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Alewell, C., E. Matzner, and A. Lükewille. "Reversibility of Soil Acidification by Reduction of Acid Input: An Experiment with Undisturbed Soil Columns." In Responses of Forest Ecosystems to Environmental Changes, 789–90. Dordrecht: Springer Netherlands, 1992. http://dx.doi.org/10.1007/978-94-011-2866-7_163.

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Xu, Shicheng, Haijun Lu, Dinggang Li, Jixiang Li, and Weiwei Wang. "Experimental Study on the Compression and Pore Characteristics of Undisturbed Loess Polluted by Landfill Leachate." In Proceedings of the 8th International Congress on Environmental Geotechnics Volume 2, 145–53. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-13-2224-2_18.

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"Challenges for Diadromous Fishes in a Dynamic Global Environment." In Challenges for Diadromous Fishes in a Dynamic Global Environment, edited by Daniele Bevacqua, Paco Melià, Alain J. Crivelli, Marino Gatto, and Giulio A. De Leo. American Fisheries Society, 2009. http://dx.doi.org/10.47886/9781934874080.ch40.

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<em>Abstract</em>.-The European eel <em>Anguilla anguilla </em>stock has been declining since the early 1970s and is currently considered to be outside safe biological limits. In June 2007, the Council of the European Union approved a regulation establishing measures for the recovery of the European eel stock. Each member state is required to develop eel management plans (EMPs) in order to achieve an escapement of at least 40% of the potential spawner biomass (with respect to undisturbed conditions) from each river basin. A reliable estimate of the potential spawner output of local stocks is crucial for the development of EMPs. Given the complexity of the eel life cycle, the use of mathematical models explicitly accounting for specific demographic traits and incorporating fundamental socioeconomic information is necessary to thoroughly assess the effectiveness of alternative management strategies. Here, using a case study approach, we show how mathematical modeling, based on sound field data, can contribute to the assessment of potential spawning stock and to the development of sound management plans. Then, we discuss how a multi-objective approach can be used to examine trade-offs between conservation and fishery goals and to help decision makers identify effective management policies.
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Zhang, G., and H. Wu. "Characteristics of pore water pressure and deformation of an undisturbed sandy clay under high pressure triaxial unloading test." In Global View of Engineering Geology and the Environment, 777–82. CRC Press, 2013. http://dx.doi.org/10.1201/b15794-124.

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Benarroch, Eduardo E., Jeremy K. Cutsforth-Gregory, and Kelly D. Flemming. "Ventricular and Cerebrospinal Fluid System." In Mayo Clinic Medical Neurosciences, edited by Eduardo E. Benarroch, Jeremy K. Cutsforth-Gregory, and Kelly D. Flemming, 409–34. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780190209407.003.0012.

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The meninges, ventricular system, subarachnoid space, and cerebrospinal fluid (CSF) constitute a functionally unique system that has an important role in maintaining a stable environment within which the central nervous system can function. The membranes that constitute the meninges serve as supportive and protective structures for neural tissue. The CSF itself provides a cushioning effect during rapid movement of the head and mechanical buoyancy to the brain. In addition to providing a pathway for the removal of brain metabolites, it functions as a chemical reservoir that protects the local environment of the brain from changes that may occur in the blood, thus ensuring the brain’s continued undisturbed performance. The CSF system is present at the supratentorial, posterior fossa, and spinal levels. Because of this extensive anatomical distribution and function, pathologic alterations of the CSF system can occur in many neurologic disorders.
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McFarland, Ben. "The Triple-Point Planet." In A World From Dust. Oxford University Press, 2016. http://dx.doi.org/10.1093/oso/9780190275013.003.0008.

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Let’s move to a vantage point a little quieter: the surface of the moon. It is so still that Neil Armstrong’s footprints remain undisturbed. The only reason the US flag there appears to “fly” is that a wire holds it up. The moon and Mercury stayed still as Mars, Venus, and Earth moved on down the road of geological development. The moon is a “steady” environment, a word whose Middle English roots are appropriately tangled with the word for “sterile.” Nothing moves on the moon, but in its sky Mars, Venus, and Earth move in their orbits, just as they moved on in complexity 4 billion years ago. Out of the whole solar system, Mars and Venus are the most like Earth in size, position, and composition. Mars is smaller, but Venus could be Earth’s twin in size. If Earth and Venus were separated at birth, then something happened to obscure the family resemblance: liquid water brought life. To chemists, liquid is the third phase of matter, between solid and gas, and its presence made all the difference. Mars gleams a bright blood red even to the naked eye, while Venus is choked with thick yellow bands of clouds. Mars is cold enough to have carbon dioxide snow, while Venus is hot enough to melt tin and boil water. Earth’s blue oceans and green continents provide a bright, primary contrast. These three siblings have drastically different fortunes. At first, they looked the same, colored with black mafic basalt and glowing red magma. The original planets were all so hot that their atmospheres were driven off into space. The oceans and the air came from within. Steam condensed into oceans on each planet’s cool basalt surface. Oceans changed the planet. Water is a transformative chemical, small yet highly charged, seeping into the smallest cracks, dissolving what it can and carrying those things long distances. Venus, Earth, and Mars do not look like the moon because they have been washed in water. Mars is dry now, but the Curiosity rover left no doubt that the red planet was first blue with water.
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Val, Pedro, Jorge Figueiredo, Gustavo Melo, Suzette Flantua, Carlos Alberto Quesada, Ying Fan Reinfelder, James S. Albert, Juan Manuel Guayasamin, and Carina Hoorn. "Chapter 1: Geology and geodiversity of the Amazon: Three billion years of history." In Amazon Assessment Report 2021. UN Sustainable Development Solutions Network (SDSN), 2021. http://dx.doi.org/10.55161/pofe6241.

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This chapter explores how geodiversity evolved over three billion years of history. It shows that periods of continental breakup followed by mountain building ultimately led to the fundamental physiographic subdivisions of the Amazon, and a wealth of landscapes, soils, ore deposits, oil and gas reserves, and freshwater aquifers. Data on the Amazon’s geodiversity support a central theme of the environmental sciences, that the formation of most natural resources (like rare-earth ores, hydrocarbons, freshwater aquifers, and fertile soils) requires natural processes to operate undisturbed over immense periods of geological time and across broad spatial domains.
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Price, Trevor. "Species across Space." In Ecology of a Changed World, 273—C26.P20. Oxford University PressNew York, 2022. http://dx.doi.org/10.1093/oso/9780197564172.003.0026.

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Abstract Tropical regions contain more species than temperate regions, both on land and in the ocean. Recent efforts to measure total genetic diversity show similar patterns. Explanations for the presence of many species in the tropics are broadly divided into present-day conditions (e.g., land-based, warm, and wet environments with a long growing season enable the coexistence of multiple species) and past history (tropical environments have been large and undisturbed, allowing species to accumulate). Alternatives are difficult to separate, as both can account for the presence of many rare and small-ranged species in the tropics. The uneven distribution of rare and small-ranged species, as well as differences in the extent of current threats (habitat loss), have led to the identification of biodiversity hotspots, which contain a large fraction of all threatened species. They include the Brazilian Atlantic rainforest and Madagascar.
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Rowlands, Mark. "The Wildwood." In World on Fire, 226–38. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780197541890.003.0012.

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The three grave environmental threats that we face today are those of climate change, mass extinction, and pestilence. To mitigate these threats, the most important things we can do are (1) stop eating animals and their products and (2) afforest wherever and whenever we can. The first course of action makes possible the second. By no longer eating animals, we make available large areas of land suitable for afforestation. These twin policies will go a long way toward solving our three environmental threats. Afforested land will sequester significant amounts of carbon dioxide, arrest the changes in land use that are the most important cause of extinction, and provide a suitably undisturbed home for animal reservoirs of disease. In afforesting the land, we must let the past be our guide: restore the land to what it was before humans arrived and ruined the neighborhood.
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Conference papers on the topic "Undisturbed environment"

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Tian, Wei, Yongmei Qian, Xiaopen Su, and Ruozhu Wang. "Test method of damage mechanism of the half-section concrete expanded-plates pile with undisturbed soil model." In 2016 International Forum on Energy, Environment and Sustainable Development. Paris, France: Atlantis Press, 2016. http://dx.doi.org/10.2991/ifeesd-16.2016.50.

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Tian, Wei, Yongmei Qian, Tongjiang Lu, and Ruozhu Wang. "The undisturbed soil experiment of the comparison about the failure of the half and whole cross-section piles under the resistance compression." In 2016 International Forum on Energy, Environment and Sustainable Development. Paris, France: Atlantis Press, 2016. http://dx.doi.org/10.2991/ifeesd-16.2016.51.

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He, Yueru. "Constructive Exploration of Transforming STEM Library Group Study Room into Individual Study Room." In 2020 4th International Conference on Informatization in Education, Management and Business. Clausius Scientific Press, 2020. http://dx.doi.org/10.23977/iemb2020003.

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In recent years, with more and more faculties and students in school, the university has seen a growing demand for access to a variety of learning spaces. The White Memorial Chemistry Library and the Engineering and Physics Library (EPSL) merged to form the STEM library. Besides, STEM students do not have enough quiet and comfortable space to study. There is no doubt that an undisturbed and comfortable learning environment can improve students' concentration and study efficiency. Especially for STEM students, there is an urgent need for a quiet and comfortable learning environment. To solve the problem, this article provides a solution which creates a quiet and comfortable learning environment by soundproofing walls and converting group study rooms into individual study rooms without potential disturb, the method enables staffs and students to eliminate the interference and focus on their work in the library.
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Yap, Choon Hwai, Neelakantan Saikrishnan, Gowthami Tamilselvan, and Ajit P. Yoganathan. "Fluid Shear Stress Characteristics of the Ventricular Surface Versus the Aortic Surface of the Aortic Valve: An In Vitro Study." In ASME 2011 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2011. http://dx.doi.org/10.1115/sbc2011-53931.

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Aortic valve calcification is a degenerative disease with high prevalence, especially amongst the elderly, and is a major cause of morbidity and mortality. Ex vivo experiments has shown that aortic valve leaflets are sensitive to their mechanical environment in a magnitude dependent manner. Fluid shear stresses, specifically, has been shown to affect inflammatory and remodeling responses relevant to aortic valve calcification [1,2]. Consequently, it has been proposed that the phenomenon of diseased calcium nodules developing exclusively on the aortic surface as opposed to the ventricular surface is due to the exposure of the aortic surface to disturbed shear stresses, whereas undisturbed shear stresses on the ventricular surface do not trigger calcification [3,4]. Additionally, it has been observed that the non-coronary leaflet of the AV is more susceptible to calcification, which is hypothesized to be due to reduced shear stresses from the lack of diastolic coronary flow [5].
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Budimir, Vjekoslav, Armin Roduner, and Helene Hofmann. "Slope stabilisation using high-tensile stainless-steel wire mesh." In 6th International Conference on Road and Rail Infrastructure. University of Zagreb Faculty of Civil Engineering, 2021. http://dx.doi.org/10.5592/co/cetra.2020.1106.

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Slope stabilisation systems with meshes made of high-tensile steel wire have been in use for 20 years and have proven to be reliable systems on loose rock and soil slopes. The optimization of the nailing pattern thanks to the high load bearing capacity of the system permits a reduction of the overall costs and represents an economical solution as well as an ecological solution. The expected service life with regards to corrosion depends, in addition to the corrosion protection used, on the environmental conditions and the corresponding chemical wear. The definition of aggressive corrosive environments for slope stabilisation projects are for example: coastlines by the sea, aggressive ground (low pH-value, sulphur content) and roads with de-icing (salt). If the micro-climatic conditions on site are known, systems made of stainless steel can be installed to counteract the aggressiveness and keep up a long service life. Stainless steel is a steel alloy, with a minimum of 10.5% chromium and less than 1.2% carbon content. The chromium produces a thin layer of oxide on the surface of the steel known as the 'passive layer'. This prevents any further corrosion of the surface. In this contribution the pilot project for stainless steel-based slope stabilisation is presented, which has been installed 14 years ago in an aggressive environment, along the coastline in the UK. It was installed in 2007, with a stainless high-tensile steel wire mesh. Not only does the slope stabilisation mesh have to be made out of stainless steel, the additional components have to present the same protection to avoid the phenomenon of bi-metallic corrosion. Therefore, the nails, spike plates and press claws were as well made of stainless steel. After fourteen years, the slope is still undisturbed and the material in good conditions although exposed constantly to the sea breeze.
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Yamamoto, Marcio, Sotaro Masanobu, Joji Yamamoto, Katsuo Ban, Masayuki Ikenobu, Tamotsu Izumida, and Takashi Sakamoto. "Numerical Analysis of VIV on Drillstring During CPT in Shallow High-Current Sea." In ASME 2019 2nd International Offshore Wind Technical Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/iowtc2019-7534.

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Abstract To design the foundation of a fixed-type wind turbine, the geotechnical data of the region in different depths below the seafloor must be surveyed using a cone penetration test (CPT). A common methodology to carry out the CPT in shallow water is to use a drillstring to drill a well. Then the drillstring must be anchored and a cone probe is conveyed within the drillstring to survey the undisturbed soil a few meters below the bit. However, during the period the drillstring is anchored in a relative high-current environment, it will be exposed to the vortex-induced vibration (VIV). In this article, we will present the VIV numerical analysis to assess the stress and accumulate fatigue on the drillstring. The simulation was calculated in the frequency domain using commercial software for marine riser analysis used by the Petroleum Industry. We compared two different drillstrings, one composed by Bottom Hole Assembly (BHA) and drill pipe and the other using BHA and heavyweight drill pipe. The VIV results show slightly better performance of the string composed by heavy weight drill pipes.
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Sungur, Zerrin. "Social Impact of Sustainable Ecotourism: Cases from Turkey." In International Conference on Eurasian Economies. Eurasian Economists Association, 2012. http://dx.doi.org/10.36880/c03.00522.

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The concept of sustainability began to dominate tourism debates after the United Nations Conference on the Environment and Development, the Earth Summit in Rio de Janerio in 1992. Ecotourism is the fastest growing sector, with an estimated growth rate of 25 to 30 percent, of one of the largest industries in the world. The motto of Action Program for Sustainable Development was that “Only whatever can be sustained by nature and society in the long term permissible.” The World Conservation Union expanded this definition as follows: “Ecotourism is environmentally responsible travel and visitation to relatively undisturbed natural areas, in order to enjoy and appreciate nature that promotes conservation, has low negative visitor impact, and provides for beneficially active socio-economic involvement of local populations.” There are two major problems with respect to ecotourism: achieving ecologic integrity of the ecotourism resource and, increasing and ensuring consistency of quality of the recreation experience for the ecotourist. Economic, environmental and social impacts involved in ecotourism should be balanced within ethical principles. The first official reference to the concept of ecotourism in Turkey was made in the Eighth Five-Year Development Plan (2001-2005). The aim of this study is to explore social impacts of ecotourism in Turkey. Some projects and surveys related with ecotourism will be considered in order to get better understanding of social impacts of ecotourism on the lives of local people in Turkey.
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Basle, Nuša, Sonja Lebe, and Borut Milfelner. "Strengthening Guests’ Perceived Value Through Restaurants’ Innovativeness, Creativity, Sustainability and Local Features." In Challenges in Economics and Business in the Post-COVID Times. University of Maribor Press, 2022. http://dx.doi.org/10.18690/um.epf.5.2022.34.

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This research deals with a rarely discussed topic: upscale gastronomy. The field is under-researched due to the restrictions imposed by restaurant owners who primarily do not allow researchers to have direct contact with their guests, thus assuring them an undisturbed, private atmosphere. Despite this fact, the authors of this study were successful in assuring partners within upscale restaurants (among them holders of Michelin stars and holders of other awards) who agreed to cooperate. The aim was to verify the relationships between innovativeness, creativity, sustainability and local features as important competences of upscale gastronomy. The reliability, convergence and discriminant validity of the scales were tested by using exploratory and confirmatory factor analyses. The results confirmed that a) innovativeness and creativity could potentially be an important antecedent of the perceived sustainability of upscale restaurants, b) innovativeness and creativity also influence the level of included local features in upscale gastronomy, and c) if guests perceive a restaurant as more sustainable and more related to its local environment, they also perceive the upscale restaurant as having higher value. In this study, sustainability and local features played a mediating role in the impact of innovativeness and creativity on perceived value.
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Zhang, Qiong. "The Vertical Leaching Migration Research on 137Cs in Soil Around Shidaowan Plant of CAP1400." In 2021 28th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/icone28-64641.

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Abstract The risk of radioactive material leakage caused by nuclear accidents increased with the increasing of number of Nuclear Power Plants in China. One of the serious threat of radiation harm to the human body is believed to be 137Cs. It can exist in the environment for a long time, due to the half-life of which is as long as about 30 years. In this research, the brown soil and aeolian sandy soil were selected as two kinds of classic soil around the site of Shidaowan demonstration plant of CAP1400 to carry out the 137Cs migration model experiments. The source of radioactivity was put on the 16 of experiment columns that were filled by undisturbed soil, the simulated raining weather was according to the local rainfall amount with two sprinklers, and the sunlight was replaced by fluorescent lamp. The result showed that the vertical migration model of radionuclides in soil is one-dimensional convective dispersion equation. three-year experiments showed that most of 137Cs in soil were distributed in the range of 0–4cm. The simulation results using the Hydrus 1D with 10 years that most of 137Cs in soil were distributed in the range of 0–10cm, so the nuclear accident caused by the serious nuclides have little impact on groundwater.
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Pajic, Tanja, Natasa Todorovic, Dunja Stefanovic, Mihailo D. Rabasovic, Aleksandar Krmpot, and Miroslav Zivic. "THE INFLUENCE OF SELENITE ON FILLAMENTOUS FUNGI HYPHA MORPHOMETRY PARAMETERS." In 1st INTERNATIONAL Conference on Chemo and BioInformatics. Institute for Information Technologies, University of Kragujevac, 2021. http://dx.doi.org/10.46793/iccbi21.308p.

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Selenium salts have been known for long time to have a potential for both beneficial and harmful effects on living organisms. It is present in the environment, where it can be readily assimilated by plants and fungi, thus entering the food chain. We investigated the cell growth dynamics in the presence of selenite which is considered to have more toxic potential than selenate. The effects of selenite (1 mM) on the growth of fungi from the activated spores to the end of the exponential growth were measured on several hypha morphological parameters by microscopy in vivo. Phycomyces blaekesleneeanus was used as model filamentous fungus. The most striking effect of Se+4 treatment was inhibition of hypha growth, resulting in more than four times shorter hypha in Se+4 –treatment group than in the control (200 ± 50 µm, n = 50 vs 900 ± 100 µm, n = 40 respectively) at the end of exponential growth period under controlled conditions. The Se+4 effect was an inhibition and not a simple delay in growth, as hypha length did not change significantly from 27th to 30th hour of culture in Se+4-treatment group. Since the microscopy was performed on live cultured cells, undisturbed cytoplasmic streaming was observed, confirming that hyphae were alive at all time points measured. 30h old spore diameters were also significantly reduced by Se+4 treatment (p = 0.0365), while hypha diameters were not significantly altered.
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Reports on the topic "Undisturbed environment"

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Nimz, G., M. W. Caffee, and J. McAninch. Hydrologic and geochemical controls on the transport of radionuclides in natural undisturbed arid environments as determined by accelerator mass spectrometry measurements. Office of Scientific and Technical Information (OSTI), April 2000. http://dx.doi.org/10.2172/15013403.

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Nimz, Gregory J., Marc W. Caffee, and Jeffrey McAninch. Hydrologic and Geochemical Controls on the Transport of Radionuclides in Natural Undisturbed Arid Environments as Determined by Accelerator Mass Spectrometry Measurements. Office of Scientific and Technical Information (OSTI), December 1999. http://dx.doi.org/10.2172/827420.

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Mann, F. M. Computer code selection criteria for flow and transport code(s) to be used in undisturbed vadose zone calculations for TWRS environmental analyses. Office of Scientific and Technical Information (OSTI), January 1998. http://dx.doi.org/10.2172/10154262.

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Nimz, G. J., M. W. Caffee, R. C. Finkel, and J. E. McAninch. Hydrologic and geochemical controls on the transport of radionuclides in natural undisturbed arid environments as determined by accelerator mass spectrometry measurements. 1997 annual progress report. Office of Scientific and Technical Information (OSTI), January 1997. http://dx.doi.org/10.2172/13540.

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Nimz, G., M. Caffee, R. Finkel, and J. McAninch. Hydrologic and geochemical controls on the transport of radionuclides in natural undisturbed arid environments as determined by accelerator mass spectrometry measurements. 1998 annual progress report. Office of Scientific and Technical Information (OSTI), June 1998. http://dx.doi.org/10.2172/13541.

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VOOGD, J. A. Recommendations for computer code selection of a flow and transport code to be used in undisturbed vadose zone calculations for TWRS immobilized environmental analyses. Office of Scientific and Technical Information (OSTI), April 1999. http://dx.doi.org/10.2172/781694.

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Clausen, Jay, Susan Frankenstein, Jason Dorvee, Austin Workman, Blaine Morriss, Keran Claffey, Terrance Sobecki, et al. Spatial and temporal variance of soil and meteorological properties affecting sensor performance—Phase 2. Engineer Research and Development Center (U.S.), September 2021. http://dx.doi.org/10.21079/11681/41780.

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An approach to increasing sensor performance and detection reliability for buried objects is to better understand which physical processes are dominant under certain environmental conditions. The present effort (Phase 2) builds on our previously published prior effort (Phase 1), which examined methods of determining the probability of detection and false alarm rates using thermal infrared for buried-object detection. The study utilized a 3.05 × 3.05 m test plot in Hanover, New Hampshire. Unlike Phase 1, the current effort involved removing the soil from the test plot area, homogenizing the material, then reapplying it into eight discrete layers along with buried sensors and objects representing targets of inter-est. Each layer was compacted to a uniform density consistent with the background undisturbed density. Homogenization greatly reduced the microscale soil temperature variability, simplifying data analysis. The Phase 2 study spanned May–November 2018. Simultaneous measurements of soil temperature and moisture (as well as air temperature and humidity, cloud cover, and incoming solar radiation) were obtained daily and recorded at 15-minute intervals and coupled with thermal infrared and electro-optical image collection at 5-minute intervals.
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Russo, David, and William A. Jury. Characterization of Preferential Flow in Spatially Variable Unsaturated Field Soils. United States Department of Agriculture, October 2001. http://dx.doi.org/10.32747/2001.7580681.bard.

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Preferential flow appears to be the rule rather than the exception in field soils and should be considered in the quantitative description of solute transport in the unsaturated zone of heterogeneous formations on the field scale. This study focused on both experimental monitoring and computer simulations to identify important features of preferential flow in the natural environment. The specific objectives of this research were: (1) To conduct dye tracing and multiple tracer experiments on undisturbed field plots to reveal information about the flow velocity, spatial prevalence, and time evolution of a preferential flow event; (2) To conduct numerical experiments to determine (i) whether preferential flow observations are consistent with the Richards flow equation; and (ii) whether volume averaging over a domain experiencing preferential flow is possible; (3) To develop a stochastic or a transfer function model that incorporates preferential flow. Regarding our field work, we succeeded to develop a new method for detecting flow patterns faithfully representing the movement of water flow paths in structured and non-structured soils. The method which is based on application of ammonium carbonate was tested in a laboratory study. Its use to detect preferential flow was also illustrated in a field experiment. It was shown that ammonium carbonate is a more conservative tracer of the water front than the popular Brilliant Blue. In our detailed field experiments we also succeeded to document the occurrence of preferential flow during soil water redistribution following the cessation of precipitation in several structureless field soils. Symptoms of the unstable flow observed included vertical fingers 20 - 60 cm wide, isolated patches, and highly concentrated areas of the tracers in the transmission zone. Soil moisture and tracer measurements revealed that the redistribution flow became fingered following a reversal of matric potential gradient within the wetted area. Regarding our simulation work, we succeeded to develop, implement and test a finite- difference, numerical scheme for solving the equations governing flow and transport in three-dimensional, heterogeneous, bimodal, flow domains with highly contrasting soil materials. Results of our simulations demonstrated that under steady-state flow conditions, the embedded clay lenses (with very low conductivity) in bimodal formations may induce preferential flow, and, consequently, may enhance considerably both the solute spreading and the skewing of the solute breakthrough curves. On the other hand, under transient flow conditions associated with substantial redistribution periods with diminishing water saturation, the effect of the embedded clay lenses on the flow and the transport might diminish substantially. Regarding our stochastic modeling effort, we succeeded to develop a theoretical framework for flow and transport in bimodal, heterogeneous, unsaturated formations, based on a stochastic continuum presentation of the flow and a general Lagrangian description of the transport. Results of our analysis show that, generally, a bimodal distribution of the formation properties, characterized by a relatively complex spatial correlation structure, contributes to the variability in water velocity and, consequently, may considerably enhance solute spreading. This applies especially in formations in which: (i) the correlation length scales and the variances of the soil properties associated with the embedded soil are much larger than those of the background soil; (ii) the contrast between mean properties of the two subdomains is large; (iii) mean water saturation is relatively small; and (iv) the volume fraction of the flow domain occupied by the embedded soil is relatively large.
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