Soil erosion by wind is one of the most important processes in the changing the earth's surface in semi-arid areas,Thus it is of great importance to study soil-erosion action.Using integrated technologies of remot...Soil erosion by wind is one of the most important processes in the changing the earth's surface in semi-arid areas,Thus it is of great importance to study soil-erosion action.Using integrated technologies of remote sensing and geochemistry radioactivity iso-tope to extract regional soil-erosion information and to calculate quantity of soil erosion is accomplished successfully in this paper by means of beneficial experiments in the Talatan region of the Gonghe Basin,which is located in northeastern Qinghai-Tibet Pla-teau in China.The results show that the soil erosion by wind is not intensive in this region;the erosion types belong to the classes of very-soft erosion and soft-erosion type,which account for 47.12 percent and 35.58 percent,respectively,of the total study area.In total,two kinds of soil erosion account for 82.70 percent of the study area;only a small area belongs to the classes of severe erosion and very-severe erosion;this area is about 22.14 km2.Severe deposition activity has taken place in this region,and has appeared in a large area(322.67 km2),which accounts for 11.78 percent of the total study area.The results of this study show that soil erosion and deposition inventories are 870,000-1,150,000 tons and 550,000-780,000 tons,respectively,per year.The soil in-ventory shows about 320,000-370,000 tons from Talatan to Longyangxia reservoir per year.Using remote-sensing technology and 137Cs techniques is a valid means to analyze and to evaluate the quantity of soil erosion by wind in semi-arid environments.展开更多
Soil and water losses through erosion have been serious in the black soil region of Northeast China. Therefore, a sloping cultivated land in Songnen Plain was selected as a case study to： 1） determine the ^137Cs ref...Soil and water losses through erosion have been serious in the black soil region of Northeast China. Therefore, a sloping cultivated land in Songnen Plain was selected as a case study to： 1） determine the ^137Cs reference inventory in the study area; 2） calculate erosion and deposition rates of black soil on different slope locations; 3） conduct a sensitivity analysis of some model parameters; and 4） compare overall outputs using four different models. Three transects were set in the field with five slope locations for each transect, including summit, shoulder-slope, back-slope, foot-slope, and toe-slope. Field measurements and model simulation were used to estimate a bomb-derived ^137Cs reference inventory in the study area. Soil erosion and deposition rates were estimated using four ^137Cs models and percentage of ^137Cs loss/gain. The ^137Cs reference value in the study area was 2 232.8 Bq m^-2 with ^137Cs showing a clear topographic pattern, decreasing from the summit to shoulder-slope, then increasing again at the foot-slope and reaching a maximum at the toe-slope, Predicted soil redistribution rates for different slope locations varied. Among models, the Yang Model （YANG-M） overestimated erosion loss but underestimated deposition. However, the standard mass balance model （MBM1） gave predictions similar to a mass balance model incorporating soil movement by tillage （MBM2）. Sensitivity analysis of the proportion factor and distribution pattern of ^137Cs in the surface layer demonstrated the impact of ^137Cs enrichment on calculation of the soil erosion rate. Factors influencing the redistribution of fallout ^137Cs in landscape should be fully considered as calculating soil redistribution rate using ^137Cs technique.展开更多
Reservoir sedimentation dynamics were interpreted using Cs-137 activity, particle size and rainfall erosivity analysis in conjunetion with sediment profile coring. Two sediment cores were retrieved from the Changshou ...Reservoir sedimentation dynamics were interpreted using Cs-137 activity, particle size and rainfall erosivity analysis in conjunetion with sediment profile coring. Two sediment cores were retrieved from the Changshou reservoir of Chongqing, which was dammed in 1956 at the outlet of Longxi catchment in the Three Gorges Area using a gravity corer equipped with an aerylie tube with an inner diameter of 6 em. The extracted cores were sectioned at 2 cm intervals. All sediment core samples were dried, sieved （〈2 mm） and weighed. 137Cs activity was measured by y-ray spectrometry. The particle size of the core samples was measured using laser particle size granulometry. Rainfall erosivity was calculated using daily rainfall data from meteorological records and information on soil conservation history was collated to help interpret temporal sedimentation trends. The peak fallout of 137Cs in 1963 appeared at a depth of 84 cm in core A and 56 cm in core B. The peaks of sand contents were related to the peaks of rainfall erosivity which were recorded in 1982, 1989, 1998 and 2005, respectively. Sedimentation rates were calculated according to the sediment profile chronological controls of 1956, 1963, 1982, 1989, 1998 and 2oo5. The highest sedimentation rate was around 2.0 cm·a^-1 between 1982 and 1988 when the Chinese national reform and the Household Responsibility System were implemented, leading to accelerated soil erosion in the Longxi catchment. Since 1990s, and particularly since 2005, sedimentation rates clearly decreased, since a number of soil conservation programs have been carried out in the catchment. The combined use of ^137Cs chronology, particle size and rainfall erosivity provided a simple basis for reconstructing reservoir sedimentation dynamics in the context of both physical processes and soil restoration. Its advantages include avoiding the need for full blown sediment yield reconstruction and the concomitant consideration of core correlation and corrections for autochthonous inputs and reservoir trap efficiency.展开更多
This paper reports the concentrations of 137Cs, hexaehlorocyclohexane （HCH）, dichlorodiphenyltrichloroethanes （DDT） and its main degradation products, δ3C, and organic carbon in pond sediments （O-210 cm, section...This paper reports the concentrations of 137Cs, hexaehlorocyclohexane （HCH）, dichlorodiphenyltrichloroethanes （DDT） and its main degradation products, δ3C, and organic carbon in pond sediments （O-210 cm, sectioned by 2-20 cm interval） and surface soils （the 0-3 cm horizon） collected in 2OlO from Chenjia catchment, which is located in Yanting county in the hilly central Sichuan of China. α-, β-, and γ-HCH, DDT, and DDD were not detected throughout the sediment profile. Trace concentrations of δ-HCH （0.89-29.31 ng g^-1） and p,p＇- DDE （1.85-6.02 ng g^-1） were detected only in top 40 cm sediment. The 137Cs fallout peak in 1963 （corresponding to the 55-60 cm depth）, the sedimentary signature left by the last year of HCH use in 1989 （an additional indicator at 20-25 cm）, and the obvious original channel bed prior to the construction of the pond in 1956 were used as temporal markers to estimate changes in average sedimentation rate between different periods due to changes in land use. Continuous, marked decrease in average sedimentation rate （i.e., 3.79, 1.35 and 1.07 cm year-1 in 1956-1963, 1963-1989, and 1989-2010, respectively） over time was observed, probably due to the reforestation, abandoning of steep sloping farmland for afforestation and natural re-vegetation （implementation of the Grain for Green Program）, and the conversion of part of gently sloping farmlandterraces to orchard land since the 1980s, especially since the 1990s. This was corroborated by the observed decrease （more negative） in δ3C of sediment towards the surface, which indicates increased relative contribution of eroded soil particles coming from slopes with increased tree cover in sediment source area. Combined use of 137Cs, δ-HCH, and δ3C record in sediments has been demonstrated to be a powerful approach to reconstruction of response in sedimentation rate to historical land use changes.展开更多
The CMOS (Complementary Metal Oxide Semiconductor) image sensor of a smartphone has been known for its sensitivity to gamma-rays. In this research, some smartphones were selected and tested for measurement of gamma-ra...The CMOS (Complementary Metal Oxide Semiconductor) image sensor of a smartphone has been known for its sensitivity to gamma-rays. In this research, some smartphones were selected and tested for measurement of gamma-rays emitted from Cesium-137 and Iridium-192 sources. During measurements, the phones were set in video mode while the camera lenses were covered with black adhesive tape to prevent light exposure. Interaction of gamma-rays with the CMOS appeared as flashing bright spots on the image. The bright spots were then counted by using the freely available ImageJ software. Preliminary results indicated that the number of bright spots increased linearly with increase of gamma-ray dose rate. An in-house Android application software was then developed for real-time counting of the bright spots. The application software also allowed users to input a calibration equation so that the phones could simultaneously convert the count rate to display in dose rate. This research demonstrated that, after appropriate calibration, smartphones could be used as gamma-ray measuring devices for radiation safety control involving high activity sources such as in industrial radiography, gamma-ray irradiation facility and medical treatment.展开更多
基金financed by the Institute of Qinghai Salt Lakes,Chinese Academy of Sciences (contract KZCX2-SW-118)The open fund of State Key Laboratory of Estuarine and Coastal Research also supported this research.
文摘Soil erosion by wind is one of the most important processes in the changing the earth's surface in semi-arid areas,Thus it is of great importance to study soil-erosion action.Using integrated technologies of remote sensing and geochemistry radioactivity iso-tope to extract regional soil-erosion information and to calculate quantity of soil erosion is accomplished successfully in this paper by means of beneficial experiments in the Talatan region of the Gonghe Basin,which is located in northeastern Qinghai-Tibet Pla-teau in China.The results show that the soil erosion by wind is not intensive in this region;the erosion types belong to the classes of very-soft erosion and soft-erosion type,which account for 47.12 percent and 35.58 percent,respectively,of the total study area.In total,two kinds of soil erosion account for 82.70 percent of the study area;only a small area belongs to the classes of severe erosion and very-severe erosion;this area is about 22.14 km2.Severe deposition activity has taken place in this region,and has appeared in a large area(322.67 km2),which accounts for 11.78 percent of the total study area.The results of this study show that soil erosion and deposition inventories are 870,000-1,150,000 tons and 550,000-780,000 tons,respectively,per year.The soil in-ventory shows about 320,000-370,000 tons from Talatan to Longyangxia reservoir per year.Using remote-sensing technology and 137Cs techniques is a valid means to analyze and to evaluate the quantity of soil erosion by wind in semi-arid environments.
基金Project supported by the Hundred Talents Program of Chinese Academy of Sciences (No. K09Z3) the National Natural Science Foundation of China (Nos. 40271108 and 40471125).
文摘Soil and water losses through erosion have been serious in the black soil region of Northeast China. Therefore, a sloping cultivated land in Songnen Plain was selected as a case study to： 1） determine the ^137Cs reference inventory in the study area; 2） calculate erosion and deposition rates of black soil on different slope locations; 3） conduct a sensitivity analysis of some model parameters; and 4） compare overall outputs using four different models. Three transects were set in the field with five slope locations for each transect, including summit, shoulder-slope, back-slope, foot-slope, and toe-slope. Field measurements and model simulation were used to estimate a bomb-derived ^137Cs reference inventory in the study area. Soil erosion and deposition rates were estimated using four ^137Cs models and percentage of ^137Cs loss/gain. The ^137Cs reference value in the study area was 2 232.8 Bq m^-2 with ^137Cs showing a clear topographic pattern, decreasing from the summit to shoulder-slope, then increasing again at the foot-slope and reaching a maximum at the toe-slope, Predicted soil redistribution rates for different slope locations varied. Among models, the Yang Model （YANG-M） overestimated erosion loss but underestimated deposition. However, the standard mass balance model （MBM1） gave predictions similar to a mass balance model incorporating soil movement by tillage （MBM2）. Sensitivity analysis of the proportion factor and distribution pattern of ^137Cs in the surface layer demonstrated the impact of ^137Cs enrichment on calculation of the soil erosion rate. Factors influencing the redistribution of fallout ^137Cs in landscape should be fully considered as calculating soil redistribution rate using ^137Cs technique.
基金funded by the Chinese Academy of Sciences(Grant No.KZCX2-XB3-09)the Ministry of Science and Technology of China(Grant No.2011BAD31B03)the National Natural Science Foundation of China(Grant Nos.41101259,41102224 and 41201275)
文摘Reservoir sedimentation dynamics were interpreted using Cs-137 activity, particle size and rainfall erosivity analysis in conjunetion with sediment profile coring. Two sediment cores were retrieved from the Changshou reservoir of Chongqing, which was dammed in 1956 at the outlet of Longxi catchment in the Three Gorges Area using a gravity corer equipped with an aerylie tube with an inner diameter of 6 em. The extracted cores were sectioned at 2 cm intervals. All sediment core samples were dried, sieved （〈2 mm） and weighed. 137Cs activity was measured by y-ray spectrometry. The particle size of the core samples was measured using laser particle size granulometry. Rainfall erosivity was calculated using daily rainfall data from meteorological records and information on soil conservation history was collated to help interpret temporal sedimentation trends. The peak fallout of 137Cs in 1963 appeared at a depth of 84 cm in core A and 56 cm in core B. The peaks of sand contents were related to the peaks of rainfall erosivity which were recorded in 1982, 1989, 1998 and 2005, respectively. Sedimentation rates were calculated according to the sediment profile chronological controls of 1956, 1963, 1982, 1989, 1998 and 2oo5. The highest sedimentation rate was around 2.0 cm·a^-1 between 1982 and 1988 when the Chinese national reform and the Household Responsibility System were implemented, leading to accelerated soil erosion in the Longxi catchment. Since 1990s, and particularly since 2005, sedimentation rates clearly decreased, since a number of soil conservation programs have been carried out in the catchment. The combined use of ^137Cs chronology, particle size and rainfall erosivity provided a simple basis for reconstructing reservoir sedimentation dynamics in the context of both physical processes and soil restoration. Its advantages include avoiding the need for full blown sediment yield reconstruction and the concomitant consideration of core correlation and corrections for autochthonous inputs and reservoir trap efficiency.
基金supported by the National Key Technology R&D Program of the Ministry of Science and Technology of China (Grant No. 2011BAC09B05)the National Natural Science Foundation of China (Grant No. 41171372)+2 种基金International Atomic Energy Agency (15521/RO)the Hundred Talents Program of the Chinese Academy of Sciences and Sichuan Provincethe CAS-SAFEA International Partnership Program for Creative Research Team (Grant No. KZZD-EWTZ-06)
文摘This paper reports the concentrations of 137Cs, hexaehlorocyclohexane （HCH）, dichlorodiphenyltrichloroethanes （DDT） and its main degradation products, δ3C, and organic carbon in pond sediments （O-210 cm, sectioned by 2-20 cm interval） and surface soils （the 0-3 cm horizon） collected in 2OlO from Chenjia catchment, which is located in Yanting county in the hilly central Sichuan of China. α-, β-, and γ-HCH, DDT, and DDD were not detected throughout the sediment profile. Trace concentrations of δ-HCH （0.89-29.31 ng g^-1） and p,p＇- DDE （1.85-6.02 ng g^-1） were detected only in top 40 cm sediment. The 137Cs fallout peak in 1963 （corresponding to the 55-60 cm depth）, the sedimentary signature left by the last year of HCH use in 1989 （an additional indicator at 20-25 cm）, and the obvious original channel bed prior to the construction of the pond in 1956 were used as temporal markers to estimate changes in average sedimentation rate between different periods due to changes in land use. Continuous, marked decrease in average sedimentation rate （i.e., 3.79, 1.35 and 1.07 cm year-1 in 1956-1963, 1963-1989, and 1989-2010, respectively） over time was observed, probably due to the reforestation, abandoning of steep sloping farmland for afforestation and natural re-vegetation （implementation of the Grain for Green Program）, and the conversion of part of gently sloping farmlandterraces to orchard land since the 1980s, especially since the 1990s. This was corroborated by the observed decrease （more negative） in δ3C of sediment towards the surface, which indicates increased relative contribution of eroded soil particles coming from slopes with increased tree cover in sediment source area. Combined use of 137Cs, δ-HCH, and δ3C record in sediments has been demonstrated to be a powerful approach to reconstruction of response in sedimentation rate to historical land use changes.
文摘The CMOS (Complementary Metal Oxide Semiconductor) image sensor of a smartphone has been known for its sensitivity to gamma-rays. In this research, some smartphones were selected and tested for measurement of gamma-rays emitted from Cesium-137 and Iridium-192 sources. During measurements, the phones were set in video mode while the camera lenses were covered with black adhesive tape to prevent light exposure. Interaction of gamma-rays with the CMOS appeared as flashing bright spots on the image. The bright spots were then counted by using the freely available ImageJ software. Preliminary results indicated that the number of bright spots increased linearly with increase of gamma-ray dose rate. An in-house Android application software was then developed for real-time counting of the bright spots. The application software also allowed users to input a calibration equation so that the phones could simultaneously convert the count rate to display in dose rate. This research demonstrated that, after appropriate calibration, smartphones could be used as gamma-ray measuring devices for radiation safety control involving high activity sources such as in industrial radiography, gamma-ray irradiation facility and medical treatment.
