The Experts below are selected from a list of 2556 Experts worldwide ranked by ideXlab platform
Desmond E. Walling - One of the best experts on this subject based on the ideXlab platform.
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~(210)Pb_(ex) depth distribution in soil and calibration models for assessment of soil erosion rates from ~(210)Pb_(ex) measurements
Chinese Science Bulletin, 2003Co-Authors: Xinbao Zhang, Desmond E. Walling, Mingyi Feng, Anbang WenAbstract:Three soil cores collected from China and UK show the210Pbex and137Cs depth distribution on Uncultivated and cultivated Land. Depth distributions of the two nuclides are very similar. Those nuclide concentrations are higher in the top horizon and decrease exponentially with depth on Uncultivated Land while the concentrations are almost uniform throughout the plough layer as a result of mixing associated with cultivation on cultivated Land.210Pbex reference inventory in the Loess Plateau is 573 mBq▪cm−2, a little higher than 520.0 mBq▪cm−2 in UK. Distribution of artificial fallout137Cs, produced during the nuclear testing period of the late 1950s and 1960s, is in an unsteady state. In contrast, distribution of natural fallout210Pbex is in a steady state under constant conditions of Land environment and erosion processes for a long term, e.g. >100 years. Therefore, mass balances of137Cs and210Pbex in soil are different. According to its processes of continues deposition from the atmosphere, nature decay and losses with soil losses,210Pbex steady state mass balance models for cultivated Land as well as for Uncultivated Land are developed to estimate soil erosion rates in this paper. Besides, the proportion of freshly deposited210Pbex fallout removed by erosion on cultivated Land can also be calculated from210Pbex depth distribution at a reference site of uneroded permanent grass Land.
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The use of a numerical mass-balance model to estimate rates of soil redistribution on Uncultivated Land from 137Cs measurements
Journal of Environmental Radioactivity, 1998Co-Authors: Philip N. Owens, Desmond E. WallingAbstract:Abstract A numerical mass-balance model is developed which can be used to estimate rates of soil redistribution on Uncultivated Land from measurements of bombderived 137 Cs inventories. The model uses a budgeting approach, which takes account of temporal variations in atmospheric fallout of 137 Cs, radioactive decay, and net gains or losses of 137 Cs due to erosion and deposition processes, combined with parameters which describe internal 137 Cs redistribution processes, to estimate the 137 Cs content of topsoil and the 137 Cs inventory at specific points, from the start of 137 Cs fallout in the 1950s to the present day. The model is also able to account for potential differences in particle size composition and organic matter content between mobilised soil particles and the original soil, and the effect that these may have on 137 Cs concentrations and inventories. By running the model for a range of soil erosion and deposition rates, a calibration relationship can be constructed which relates the 137 Cs inventory at a sampling point to the average net soil loss or gain at that location. In addition to the magnitude and temporal distribution of the 137 Cs atmospheric fallout flux, the soil redistribution rates estimated by the model are sensitive to parameters which describe the relative texture and organic matter content of the eroded or deposited material, and the ability of the soil to retain 137 Cs in the upper part of the soil profile.
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Soil erosion and redistribution on cultivated and Uncultivated Land near las bardenas in the central Ebro river Basin, Spain
Land Degradation and Development, 1994Co-Authors: Timothy A. Quine, Ana Navas, Desmond E. Walling, J. MachínAbstract:The semiarid regions of Spain, including the central part of the Ebro River basin, are under threat due to desertification. Severe erosion, as a result of poor Land management, has led to degradation of the soil resource, and there is a clear need for quantitative erosion rate data to evaluate the problem. This study aimed to examine the potential for using caesium-137 to identify the patterns and rates of soil erosion and redistribution within this semiarid environment. Samples for the determination of caesium-137 were collected from Uncultivated slopes and cultivated valley floor sites near the head and outlet of a small representative basin in the Las Bardenas area. The measured patterns of caesium-137 mobilization, redistribution and export provide a semiquantitative indication of the variation in erosion within the study site. Calibration of the caesium-137 measurements, taking account of the differing behaviour of radiocaesium on cultivated and Uncultivated Land, allows estimation of the actual rates of erosion and deposition involved. The results show (1) the erosion rates on the cultivated Land (1.6–2.5 kg m−2 yr−1) are typically more than five times those seen on the Uncultivated Land (0.2–0.4 kg m−2 yr−1), and (2) erosion on the Uncultivated Land is significantly less severe at the head of the basin than at the outlet. Study of the vegetation cover suggests that lower growing shrubs and grasses may be more effective in reducing erosion in this environment than trees.
J. Machín - One of the best experts on this subject based on the ideXlab platform.
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Soil erosion and redistribution on cultivated and Uncultivated Land near las bardenas in the central Ebro river Basin, Spain
Land Degradation and Development, 1994Co-Authors: Timothy A. Quine, Ana Navas, Desmond E. Walling, J. MachínAbstract:The semiarid regions of Spain, including the central part of the Ebro River basin, are under threat due to desertification. Severe erosion, as a result of poor Land management, has led to degradation of the soil resource, and there is a clear need for quantitative erosion rate data to evaluate the problem. This study aimed to examine the potential for using caesium-137 to identify the patterns and rates of soil erosion and redistribution within this semiarid environment. Samples for the determination of caesium-137 were collected from Uncultivated slopes and cultivated valley floor sites near the head and outlet of a small representative basin in the Las Bardenas area. The measured patterns of caesium-137 mobilization, redistribution and export provide a semiquantitative indication of the variation in erosion within the study site. Calibration of the caesium-137 measurements, taking account of the differing behaviour of radiocaesium on cultivated and Uncultivated Land, allows estimation of the actual rates of erosion and deposition involved. The results show (1) the erosion rates on the cultivated Land (1.6–2.5 kg m−2 yr−1) are typically more than five times those seen on the Uncultivated Land (0.2–0.4 kg m−2 yr−1), and (2) erosion on the Uncultivated Land is significantly less severe at the head of the basin than at the outlet. Study of the vegetation cover suggests that lower growing shrubs and grasses may be more effective in reducing erosion in this environment than trees.
Timothy A. Quine - One of the best experts on this subject based on the ideXlab platform.
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Soil erosion and redistribution on cultivated and Uncultivated Land near las bardenas in the central Ebro river Basin, Spain
Land Degradation and Development, 1994Co-Authors: Timothy A. Quine, Ana Navas, Desmond E. Walling, J. MachínAbstract:The semiarid regions of Spain, including the central part of the Ebro River basin, are under threat due to desertification. Severe erosion, as a result of poor Land management, has led to degradation of the soil resource, and there is a clear need for quantitative erosion rate data to evaluate the problem. This study aimed to examine the potential for using caesium-137 to identify the patterns and rates of soil erosion and redistribution within this semiarid environment. Samples for the determination of caesium-137 were collected from Uncultivated slopes and cultivated valley floor sites near the head and outlet of a small representative basin in the Las Bardenas area. The measured patterns of caesium-137 mobilization, redistribution and export provide a semiquantitative indication of the variation in erosion within the study site. Calibration of the caesium-137 measurements, taking account of the differing behaviour of radiocaesium on cultivated and Uncultivated Land, allows estimation of the actual rates of erosion and deposition involved. The results show (1) the erosion rates on the cultivated Land (1.6–2.5 kg m−2 yr−1) are typically more than five times those seen on the Uncultivated Land (0.2–0.4 kg m−2 yr−1), and (2) erosion on the Uncultivated Land is significantly less severe at the head of the basin than at the outlet. Study of the vegetation cover suggests that lower growing shrubs and grasses may be more effective in reducing erosion in this environment than trees.
He China - One of the best experts on this subject based on the ideXlab platform.
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ASSESSMENT OF SOIL LOSS ON Uncultivated SLOPE Land BY USING ~(137)CS TECHNIQUE IN THE UPPER YANGTZE RIVER BASIN OF CHINA
2004Co-Authors: He ChinaAbstract:Radionuclides are used as tracers of sediments in areas where no plot data or field monitoring data are not available. Caesium-137 can provide important information on both soil loss rates and sediment sources. The 137Cs technique is employed to assess soil erosion rates in forest and grass Lands in the Upper Yangtze River Basin, China. The study area includes 6 forestLands and 4 grassLands in 8 counties and cities over the eastern part of the basin. The 137Cs reference inventories ranged from 620.9 Bq m-2 to 2560.3 Bq m-2. For the 6 forestLands, the average 137Cs inventory over a field ranges from 960.8 Bq m"2 to 2560.3 Bq m-2. The average erosion rate is estimated from the 137Cs measurements between 0 to 588 t km-2yr-1. For the 4 grassLands, the average 137Cs inventory ranges from 119.0 Bq m-2 to 869.7 Bq m-2. The average rate of erosion from grassLand varies from 0 to 4435 t km-2 yr-1. Where the erosion was more severe, the 137Cs inventory was lower. The results showed that there is no clear relationship between 137Cs inventory, slope length and slope gradient on Uncultivated Land. The erosion rates for Uncultivated Land and cultivated Land is compared. The result indicates that the erosion rates on Uncultivated Land is much lower than those on cultivated slopes and the severity of the soil erosion is closely related to vegetation cover.
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assessment of soil loss on Uncultivated slope Land by using 137 cs technique in the upper yangtze river basin of china
国际泥沙研究(英文版), 2004Co-Authors: He ChinaAbstract:Radionuclides are used as tracers of sediments in areas where no plot data or field monitoring data are not available. Caesium-137 can provide important information on both soil loss rates and sediment sources. The 137Cs technique is employed to assess soil erosion rates in forest and grass Lands in the Upper Yangtze River Basin, China. The study area includes 6 forestLands and 4 grassLands in 8 counties and cities over the eastern part of the basin. The 137Cs reference inventories ranged from 620.9 Bq m-2 to 2560.3 Bq m-2. For the 6 forestLands, the average 137Cs inventory over a field ranges from 960.8 Bq m"2 to 2560.3 Bq m-2. The average erosion rate is estimated from the 137Cs measurements between 0 to 588 t km-2yr-1. For the 4 grassLands, the average 137Cs inventory ranges from 119.0 Bq m-2 to 869.7 Bq m-2. The average rate of erosion from grassLand varies from 0 to 4435 t km-2 yr-1. Where the erosion was more severe, the 137Cs inventory was lower. The results showed that there is no clear relationship between 137Cs inventory, slope length and slope gradient on Uncultivated Land. The erosion rates for Uncultivated Land and cultivated Land is compared. The result indicates that the erosion rates on Uncultivated Land is much lower than those on cultivated slopes and the severity of the soil erosion is closely related to vegetation cover.
Carol Carpenter - One of the best experts on this subject based on the ideXlab platform.
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Women and livestock, fodder, and Uncultivated Land in Pakistan: A summary of role responsibilities
Society & Natural Resources, 1991Co-Authors: Carol CarpenterAbstract:Abstract This article presents a model of the relationships in rural Pakistan between women and livestock, fodder, and Uncultivated Land, and their importance to farming households in rainfed and irrigated fanning areas. In rainfed areas, fodder gathered by women from public, Uncultivated Land is a key natural resource, making possible the manure production that is essential to agriculture. This resource is reduced in irrigated areas, where agriculture has encroached upon Uncultivated Land. Women in Landed households in irrigated areas can harvest fodder from their own fields, but women in Land‐poor households must contend with fodder and fuel shortages that compel them to burn dung. This key natural resource, the fodder gathered by women from wasteLands, has not received the attention it deserves. As a result, it and the Land whose fertility it helps replenish are vulnerable to development efforts that overlook its existence.
