The temporal and spatial variation in soil temperature play a significant role in energy and water cycle between land surface and atmosphere on the Tibetan Plateau.Based on the observed soil temperature data（hourly d...The temporal and spatial variation in soil temperature play a significant role in energy and water cycle between land surface and atmosphere on the Tibetan Plateau.Based on the observed soil temperature data（hourly data from 1 January 2001 to 31 December 2005）obtained by GAME-Tibet,the diurnal,seasonal and interannual variations in soil temperature at BJ site（31.37°N,91.90°E; 4509 m a.s.l.）near Naqu in the central Tibetan Plateau were analyzed.Results showed that the average diurnal variation in soil temperature at 4 and 20 cm depth can be described as sinusoidal curve,which is consistent with the variation of solar radiation. However,the average diurnal variation in soil temperature under 60 cm was very weak.The average diurnal amplitude in soil temperature decreased by the exponential decay function with the increase of soil depth（R2=0.92,p〈0.01）.It is demonstrated that the average diurnal maximum soil temperature decreased by the exponential decay function with the increase of soil depth（R2=0.78,p〈0.01）.In contrast, the average diurnal minimum soil temperature increased by the exponential grow function with increasing of soil depth（R2=0.86,p〈0.01）.There were a linear negative correlation between the average annual maximum Ts and soil depth（R2=0.96, p〈0.01）,a logarithmic function relationship between the average annual minimum soil temperature and soil depth（R2=0.92,p〈0.01）.The average seasonal amplitude in soil temperature followed the exponential decay function with the increase of soil depth（R2=0.98,p〈0.01）.The mean annual soil temperature in each layer indicated a warming trend prominently.During the study period,the mean annual soil temperature at 4,20,40,60,80,100,130, 160,200 and 250 cm depth increased by 0.034,0.041, 0.061,0.056,0.062,0.050,0.057,0.051,0.047 and 0.042℃/a,respectively.展开更多
Fuzzy classification combined with spatial prediction was used to assess the state of soil pollution in the peri-urban Beijing area. Total concentrations of As, Cr, Cd, Hg, and Pb were determined in 220 topsoil sampl...Fuzzy classification combined with spatial prediction was used to assess the state of soil pollution in the peri-urban Beijing area. Total concentrations of As, Cr, Cd, Hg, and Pb were determined in 220 topsoil samples （0-20 cm） collected using a grid design in a study area of 2 600 kin2. Heavy metal concentrations were grouped into three classes according to the optimum number of classes and fuzziness exponent using the fuzzy comean （FCM） algorithm. Membership values were interpolated using ordinary kriging. The polluted soils of the study area induced by the measured heavy metals were concentrated in the northwest corner and eastern part, especially the southeastern part close to the urban zone, whereas the soils free of pollution were mainly distributed in the southwestern part. The soils with potential risk of heavy metal pollution were located in isolated spots mainly in the northern part and southeastern corner of the study region. The FCM algorithm combined with geostatistical techniques, as compared to conventional single geostatistical kriging methods, could produce a prediction with a quantitative uncertainty evaluation and higher reliability. Successful prediction of soil pollution achieved with FCM algorithm in this study indicated that fuzzy set theory had great potential for use in other areas of soil science.展开更多
Agricultural land use and management practices may affect soil properties,which play a critical role in sustaining crop production.Since the late 1970s,several new agricultural land use types had been introduced in th...Agricultural land use and management practices may affect soil properties,which play a critical role in sustaining crop production.Since the late 1970s,several new agricultural land use types had been introduced in the rural areas of China.The purpose of this study is to evaluate the effect of these land use changes on the soil properties,nu-trient absorption rate,and nutrient use economic efficiency ratio in an agricultural area of Beijing.Specifically,the cropland,the orchard and the vegetable field were examined.Results of this study suggest that land use and farming management practices significantly affect the content of soil organic carbon (SOC),total nitrogen (TN),total phos-phorus (TP),and available phosphorus in the surface layer of 0-25 cm (p<0.05) in the Yanqing Basin,northwestern Beijing.Soil nutrients in each agricultural land use type decrease rapidly with the increasing soil depth.Orchard and vegetable field tend to have higher soil nutrients than the cropland does.However,the soil nutrient-absorption rate (NAR) of the orchard and vegetable field is lower than that of the cropland,even though orchard and vegetable field may provide much higher economic benefit.While increasing SOC,TN,and TP in the orchard and vegetable field by intensive farming may be a valuable option to improve soil quality,potential increase in the risk of nutrient loss,or agricultural non-point source pollution can be a tradeoff if the intensive practices are not managed appropriately.展开更多
The concentrations of polychlorinated biphenyls （PCBs） have been determined in soils collected in Beijing of China. According to Principle Component Analysis （PCA） of PCBs, the possible sources were studied. Relat...The concentrations of polychlorinated biphenyls （PCBs） have been determined in soils collected in Beijing of China. According to Principle Component Analysis （PCA） of PCBs, the possible sources were studied. Relationship between PCBs and soil organic materials revealed that higher chlorinated PCBs are more inclined to be adsorbed by particles rich of organic materials. But the low chlorinated homologues are dominant in Beijing soils, which is very different from the foreign studies. It was concluded that the application of relatively low chlorinated commercial PCBs in China was the main reason leading to this homologue composition character. Besides, the relatively short pollution history is also one of the main reasons. PCA of PCBs data in Beijing soil and atmospheric deposition samples revealed that some other emission sources such as atmospheric deposition, automobile exhaust; chemical and petrochemical industry and steel industry may be the important reasons of elevated PCBs concentrations in Beijing soil展开更多
Numerous efforts have been made to characterize forest carbon （C） cycles and stocks in various ecosystems. However, long-term observation on each component of the forest C cycle is still lacking. We measured C stock...Numerous efforts have been made to characterize forest carbon （C） cycles and stocks in various ecosystems. However, long-term observation on each component of the forest C cycle is still lacking. We measured C stocks and fluxes in three per- manent temperate forest plots （birch, oak and pine forest） during 2011-2014, and calculated the changes of the components of the C cycle related to the measurements during 1992-1994 at Mr. Dongling, Beijing, China. Forest net primary production in birch, oak, and pine plots was 5.32, 4.53, and 6.73 Mg C ha-1 a-1, respectively. Corresponding net ecosystem production was 0.12, 0.43, and 3.53 Mg C ha-1 a-1. The C stocks and fluxes in 2011-2014 were significantly larger than those in 1992-1994 in which the biomass C densities in birch, oak, and pine plots increased from 50.0, 37.7, and 54.0 Mg C ha-1 in 1994 to 101.5, 77.3, and 110.9 Mg C ha a in 2014; soil organic C densities increased from 207.0, 239.1, and 231.7 Mg C ha-1 to 214.8, 241.7, and 238.4 Mg C ha-l; and soil heterotrophic respiration increased from 2.78, 3.49, and 1.81 Mg C ha-1 a-1 to 5.20, 4.10, and 3.20 Mg C ha-1 a-l. These results suggest that the mountainous temperate forest ecosystems in Beijing have served as a carbon sink in the last two decades. These observations of C stocks and fluxes provided field-based data for a long-term study of C cycling in temperate forest ecosystems.展开更多
The economic benefit of sediment reduction by pine forest and black acacia forest at different age classes in Miyun reservoir watershed was studied using the approach of relocation cost based on the field survey from ...The economic benefit of sediment reduction by pine forest and black acacia forest at different age classes in Miyun reservoir watershed was studied using the approach of relocation cost based on the field survey from 1996 to 1999. The results show that if the transportation of eroded soil into Miyun reservoir was estimated as 100%, the economic benefit of sediment reduction by pine forest would be 59-164 RMB yuan/ha（RMB yuan = Renminbi yuan, or yuan） per year （US$1=8.27 RMB yuan during the period of research）, and 58-134 yuan/ha by black acacia forest. The average economic benefit of sediment reduction by forest is 130 yuan/ha per year. If r （the rate at which the eroded soil will enter a reservoir） varies, the economic benefits of sediment reduction also change. To estimate the economic benefit of sediment reduction more accurately, r should be measured from the field test. The results from this study provide information to help assess the feasibility of the environmental project in thids area.展开更多
基金sponsored jointly by the National Natural Science Foundation of China(41075007)the One Hundred Talent Program of the Chinese Academy of Sciences(29O827B11)the National Key Basic Research program of China(2010CB951404)
文摘The temporal and spatial variation in soil temperature play a significant role in energy and water cycle between land surface and atmosphere on the Tibetan Plateau.Based on the observed soil temperature data（hourly data from 1 January 2001 to 31 December 2005）obtained by GAME-Tibet,the diurnal,seasonal and interannual variations in soil temperature at BJ site（31.37°N,91.90°E; 4509 m a.s.l.）near Naqu in the central Tibetan Plateau were analyzed.Results showed that the average diurnal variation in soil temperature at 4 and 20 cm depth can be described as sinusoidal curve,which is consistent with the variation of solar radiation. However,the average diurnal variation in soil temperature under 60 cm was very weak.The average diurnal amplitude in soil temperature decreased by the exponential decay function with the increase of soil depth（R2=0.92,p〈0.01）.It is demonstrated that the average diurnal maximum soil temperature decreased by the exponential decay function with the increase of soil depth（R2=0.78,p〈0.01）.In contrast, the average diurnal minimum soil temperature increased by the exponential grow function with increasing of soil depth（R2=0.86,p〈0.01）.There were a linear negative correlation between the average annual maximum Ts and soil depth（R2=0.96, p〈0.01）,a logarithmic function relationship between the average annual minimum soil temperature and soil depth（R2=0.92,p〈0.01）.The average seasonal amplitude in soil temperature followed the exponential decay function with the increase of soil depth（R2=0.98,p〈0.01）.The mean annual soil temperature in each layer indicated a warming trend prominently.During the study period,the mean annual soil temperature at 4,20,40,60,80,100,130, 160,200 and 250 cm depth increased by 0.034,0.041, 0.061,0.056,0.062,0.050,0.057,0.051,0.047 and 0.042℃/a,respectively.
基金Project supported by the National Natural Science Foundation of China (Nos. 40571065 and 40235054)the National Key Basic Research Support Foundation of China (No. G1999045707).
文摘Fuzzy classification combined with spatial prediction was used to assess the state of soil pollution in the peri-urban Beijing area. Total concentrations of As, Cr, Cd, Hg, and Pb were determined in 220 topsoil samples （0-20 cm） collected using a grid design in a study area of 2 600 kin2. Heavy metal concentrations were grouped into three classes according to the optimum number of classes and fuzziness exponent using the fuzzy comean （FCM） algorithm. Membership values were interpolated using ordinary kriging. The polluted soils of the study area induced by the measured heavy metals were concentrated in the northwest corner and eastern part, especially the southeastern part close to the urban zone, whereas the soils free of pollution were mainly distributed in the southwestern part. The soils with potential risk of heavy metal pollution were located in isolated spots mainly in the northern part and southeastern corner of the study region. The FCM algorithm combined with geostatistical techniques, as compared to conventional single geostatistical kriging methods, could produce a prediction with a quantitative uncertainty evaluation and higher reliability. Successful prediction of soil pollution achieved with FCM algorithm in this study indicated that fuzzy set theory had great potential for use in other areas of soil science.
基金Under the auspices of Key Direction in Knowledge Innovation Programs of Chinese Academy of Sciences (No. KZCX2-YW-421)National Natural Science Foundation of China (No.40925003)
文摘Agricultural land use and management practices may affect soil properties,which play a critical role in sustaining crop production.Since the late 1970s,several new agricultural land use types had been introduced in the rural areas of China.The purpose of this study is to evaluate the effect of these land use changes on the soil properties,nu-trient absorption rate,and nutrient use economic efficiency ratio in an agricultural area of Beijing.Specifically,the cropland,the orchard and the vegetable field were examined.Results of this study suggest that land use and farming management practices significantly affect the content of soil organic carbon (SOC),total nitrogen (TN),total phos-phorus (TP),and available phosphorus in the surface layer of 0-25 cm (p<0.05) in the Yanqing Basin,northwestern Beijing.Soil nutrients in each agricultural land use type decrease rapidly with the increasing soil depth.Orchard and vegetable field tend to have higher soil nutrients than the cropland does.However,the soil nutrient-absorption rate (NAR) of the orchard and vegetable field is lower than that of the cropland,even though orchard and vegetable field may provide much higher economic benefit.While increasing SOC,TN,and TP in the orchard and vegetable field by intensive farming may be a valuable option to improve soil quality,potential increase in the risk of nutrient loss,or agricultural non-point source pollution can be a tradeoff if the intensive practices are not managed appropriately.
基金Acknowledgements： The research was supported by Beijing Natural and Science Foundation.
文摘The concentrations of polychlorinated biphenyls （PCBs） have been determined in soils collected in Beijing of China. According to Principle Component Analysis （PCA） of PCBs, the possible sources were studied. Relationship between PCBs and soil organic materials revealed that higher chlorinated PCBs are more inclined to be adsorbed by particles rich of organic materials. But the low chlorinated homologues are dominant in Beijing soils, which is very different from the foreign studies. It was concluded that the application of relatively low chlorinated commercial PCBs in China was the main reason leading to this homologue composition character. Besides, the relatively short pollution history is also one of the main reasons. PCA of PCBs data in Beijing soil and atmospheric deposition samples revealed that some other emission sources such as atmospheric deposition, automobile exhaust; chemical and petrochemical industry and steel industry may be the important reasons of elevated PCBs concentrations in Beijing soil
基金supported by National Natural Science Foundation of China(31321061,31330012)National Basic Research Program of China on Global Change(2014CB954001)
文摘Numerous efforts have been made to characterize forest carbon （C） cycles and stocks in various ecosystems. However, long-term observation on each component of the forest C cycle is still lacking. We measured C stocks and fluxes in three per- manent temperate forest plots （birch, oak and pine forest） during 2011-2014, and calculated the changes of the components of the C cycle related to the measurements during 1992-1994 at Mr. Dongling, Beijing, China. Forest net primary production in birch, oak, and pine plots was 5.32, 4.53, and 6.73 Mg C ha-1 a-1, respectively. Corresponding net ecosystem production was 0.12, 0.43, and 3.53 Mg C ha-1 a-1. The C stocks and fluxes in 2011-2014 were significantly larger than those in 1992-1994 in which the biomass C densities in birch, oak, and pine plots increased from 50.0, 37.7, and 54.0 Mg C ha-1 in 1994 to 101.5, 77.3, and 110.9 Mg C ha a in 2014; soil organic C densities increased from 207.0, 239.1, and 231.7 Mg C ha-1 to 214.8, 241.7, and 238.4 Mg C ha-l; and soil heterotrophic respiration increased from 2.78, 3.49, and 1.81 Mg C ha-1 a-1 to 5.20, 4.10, and 3.20 Mg C ha-1 a-l. These results suggest that the mountainous temperate forest ecosystems in Beijing have served as a carbon sink in the last two decades. These observations of C stocks and fluxes provided field-based data for a long-term study of C cycling in temperate forest ecosystems.
文摘The economic benefit of sediment reduction by pine forest and black acacia forest at different age classes in Miyun reservoir watershed was studied using the approach of relocation cost based on the field survey from 1996 to 1999. The results show that if the transportation of eroded soil into Miyun reservoir was estimated as 100%, the economic benefit of sediment reduction by pine forest would be 59-164 RMB yuan/ha（RMB yuan = Renminbi yuan, or yuan） per year （US$1=8.27 RMB yuan during the period of research）, and 58-134 yuan/ha by black acacia forest. The average economic benefit of sediment reduction by forest is 130 yuan/ha per year. If r （the rate at which the eroded soil will enter a reservoir） varies, the economic benefits of sediment reduction also change. To estimate the economic benefit of sediment reduction more accurately, r should be measured from the field test. The results from this study provide information to help assess the feasibility of the environmental project in thids area.
