The study was conducted in Zhifanggou Watershed,Shaanxi Province,China,to evaluate the effect of different vegetation types on hot-water extractable C,N and P fractions,with the aim to determine whether hot-water extr...The study was conducted in Zhifanggou Watershed,Shaanxi Province,China,to evaluate the effect of different vegetation types on hot-water extractable C,N and P fractions,with the aim to determine whether hot-water extractable fractions could be used as indicators of soil quality change in Loess Plateau.The six vegetation types established in 1975 were（i） Robinia pseudoacacia L.,（ii） Caragana korshinkii Kom.,（iii） Pinus tabulaeformis Carr.,（iv） P.tabulaeformis-Amorpha fruticosa L.,（v） R.pseudoacacia-A.fruticosa,and（vi） grassland.A cropped hillslope plot and a Platycladus orientalis L.native forest plot were used as references.The results indicated that the conversion of native forest to cropland resulted in a significant decline in the hot-water extractable C,N and P fractions.Hot-water extractable C,N,and P increased when cultivated land was revegetated,but after 30 years the amount of hot-water extractable C,N,and P in revegetated fields was still much lower compared to native forest.Hot-water extractable fractions increased more under mixed-forest than under pure-forest stands.Furthermore,there was a significant correlation between the hot-water extractable fractions and soil chemical and microbiological properties.The results showed that hot-water extractable fractions could be used as indicators of soil quality change on the Loess Plateau.展开更多
Modified BCR sequential extraction, single equilibrium-based EDTA extraction and kinetic fractionation were used for estimating the Pb and Cd availability in a series of soil samples from 3 sites located in urban area...Modified BCR sequential extraction, single equilibrium-based EDTA extraction and kinetic fractionation were used for estimating the Pb and Cd availability in a series of soil samples from 3 sites located in urban areas of Hanoi (Vietnam). These schemes were compared to identify a simple, rapid and cheap protocol for routine estimation of Pb and Cd remobilizable fraction and the related potential risk. The comparison of these three approaches revealed their convergence in terms of mobility patterns observed for Pb and Cd. Cd was characterized by higher extractibality and mobility whatever the approach. Pb was distinguished of Cd by its high association to Feoxides, lower extractability, lower rate of desorption and then lower mobility. For this environmental scenario, EDTA single scheme at equilibrium could be suggested as the best suited and a simple protocol for determination of the labile pool of Cd and Pb. The pseudo-total concentrations of Pb and Cd are actually below the Vietnamese standard level, contrary to the results obtained by other authors for agricultural soils at other urban sites of Hanoi.展开更多
Nitrogen(N) isotope ratio(δ^(15)N) of soil extractable NO_3^- plays a pivotal role in the study of N biogeochemical circulation in ecosystems. However, the NO_3^-concentration and its isotope composition of soil samp...Nitrogen(N) isotope ratio(δ^(15)N) of soil extractable NO_3^- plays a pivotal role in the study of N biogeochemical circulation in ecosystems. However, the NO_3^-concentration and its isotope composition of soil samples are unstable, making sample storage critical for preserving the N isotope composition of extracted soil NO_3^-. Nevertheless, studies on the appropriate selection of storage methods after soil sampling are scarce. In this study, we compared two commonly used methods for storing soil samples and investigated the stability of N isotopes of soil NO_3^-. The results demonstrated that no significant changes in the NO_3^-concentration and δ^(15)N value occurred in the samples stored at-18?C. However, the soil NO_3^-concentration markedly increased, and NO_3^-δ^(15)N value significantly changed after air-drying storage. Meanwhile, we also found that NO_3^-and its δ^(15)N were well preserved in the filtered soil extracts after 1 month. In contrast, the NO_3^-concentration gradually decreased and the^(15)N in NO_3^-was gradually enriched in the bactericidal agent-containing soil mixture solution during the storage period. Overall, our results indicated that N isotopes of NO_3^-could be effectively preserved in frozen-stored soil samples or filtered soil extracts. For field investigations conducted in remote areas and continued for a long-time period(and lacking a refrigerant supply), soil extraction/filtration using a CaSO_4-saturated solution may be a superior preparation and storage method for analyzing N isotopes of soil NO_3^-.展开更多
采用0.05mol.L-1的EDTA作为萃取剂,在一定的萃取条件下,对2种尾矿土壤中重金属进行土壤柱萃取实验,并采用优化的BCR(European Community Bureau of Reference)连续萃取方案对萃取前后的Pb、Zn、Cu和Cd进行形态分析.研究EDTA对4种金属的...采用0.05mol.L-1的EDTA作为萃取剂,在一定的萃取条件下,对2种尾矿土壤中重金属进行土壤柱萃取实验,并采用优化的BCR(European Community Bureau of Reference)连续萃取方案对萃取前后的Pb、Zn、Cu和Cd进行形态分析.研究EDTA对4种金属的萃取效率及萃取前后的形态变化特征.结果表明,EDTA能有效的从土壤中萃取该4种金属,萃取效率依次为:Cd>Zn>Cu>Pb;金属的4种形态均能被EDTA萃取;在浅层土壤中,EDTA对酸可提态的金属的萃取效果尤为显著;在深层土壤中,酸可提取态、氧化物结合态、有机结合态和残余态4种形态的金属萃取效果,随着土壤柱深度的增加而降低.展开更多
基金financially supported by the Strategic Technology Project of Chinese Academy of Sciences,China(XDA05060300)the Science and Technology Research and Development Program of Shaanxi Province,China(2011KJXX63)the Fundamental Research Funds for the Central Universities,China(ZD2013021)
文摘The study was conducted in Zhifanggou Watershed,Shaanxi Province,China,to evaluate the effect of different vegetation types on hot-water extractable C,N and P fractions,with the aim to determine whether hot-water extractable fractions could be used as indicators of soil quality change in Loess Plateau.The six vegetation types established in 1975 were（i） Robinia pseudoacacia L.,（ii） Caragana korshinkii Kom.,（iii） Pinus tabulaeformis Carr.,（iv） P.tabulaeformis-Amorpha fruticosa L.,（v） R.pseudoacacia-A.fruticosa,and（vi） grassland.A cropped hillslope plot and a Platycladus orientalis L.native forest plot were used as references.The results indicated that the conversion of native forest to cropland resulted in a significant decline in the hot-water extractable C,N and P fractions.Hot-water extractable C,N,and P increased when cultivated land was revegetated,but after 30 years the amount of hot-water extractable C,N,and P in revegetated fields was still much lower compared to native forest.Hot-water extractable fractions increased more under mixed-forest than under pure-forest stands.Furthermore,there was a significant correlation between the hot-water extractable fractions and soil chemical and microbiological properties.The results showed that hot-water extractable fractions could be used as indicators of soil quality change on the Loess Plateau.
文摘Modified BCR sequential extraction, single equilibrium-based EDTA extraction and kinetic fractionation were used for estimating the Pb and Cd availability in a series of soil samples from 3 sites located in urban areas of Hanoi (Vietnam). These schemes were compared to identify a simple, rapid and cheap protocol for routine estimation of Pb and Cd remobilizable fraction and the related potential risk. The comparison of these three approaches revealed their convergence in terms of mobility patterns observed for Pb and Cd. Cd was characterized by higher extractibality and mobility whatever the approach. Pb was distinguished of Cd by its high association to Feoxides, lower extractability, lower rate of desorption and then lower mobility. For this environmental scenario, EDTA single scheme at equilibrium could be suggested as the best suited and a simple protocol for determination of the labile pool of Cd and Pb. The pseudo-total concentrations of Pb and Cd are actually below the Vietnamese standard level, contrary to the results obtained by other authors for agricultural soils at other urban sites of Hanoi.
基金supported by the Key Deployment Project from Chinese Academy of Sciences (No. KZZDEW-04-06)the National Natural Science Foundation of China (No. 41373022)the National Basic Research Program of China (No. 2013CB955900)
文摘Nitrogen(N) isotope ratio(δ^(15)N) of soil extractable NO_3^- plays a pivotal role in the study of N biogeochemical circulation in ecosystems. However, the NO_3^-concentration and its isotope composition of soil samples are unstable, making sample storage critical for preserving the N isotope composition of extracted soil NO_3^-. Nevertheless, studies on the appropriate selection of storage methods after soil sampling are scarce. In this study, we compared two commonly used methods for storing soil samples and investigated the stability of N isotopes of soil NO_3^-. The results demonstrated that no significant changes in the NO_3^-concentration and δ^(15)N value occurred in the samples stored at-18?C. However, the soil NO_3^-concentration markedly increased, and NO_3^-δ^(15)N value significantly changed after air-drying storage. Meanwhile, we also found that NO_3^-and its δ^(15)N were well preserved in the filtered soil extracts after 1 month. In contrast, the NO_3^-concentration gradually decreased and the^(15)N in NO_3^-was gradually enriched in the bactericidal agent-containing soil mixture solution during the storage period. Overall, our results indicated that N isotopes of NO_3^-could be effectively preserved in frozen-stored soil samples or filtered soil extracts. For field investigations conducted in remote areas and continued for a long-time period(and lacking a refrigerant supply), soil extraction/filtration using a CaSO_4-saturated solution may be a superior preparation and storage method for analyzing N isotopes of soil NO_3^-.
文摘采用0.05mol.L-1的EDTA作为萃取剂,在一定的萃取条件下,对2种尾矿土壤中重金属进行土壤柱萃取实验,并采用优化的BCR(European Community Bureau of Reference)连续萃取方案对萃取前后的Pb、Zn、Cu和Cd进行形态分析.研究EDTA对4种金属的萃取效率及萃取前后的形态变化特征.结果表明,EDTA能有效的从土壤中萃取该4种金属,萃取效率依次为:Cd>Zn>Cu>Pb;金属的4种形态均能被EDTA萃取;在浅层土壤中,EDTA对酸可提态的金属的萃取效果尤为显著;在深层土壤中,酸可提取态、氧化物结合态、有机结合态和残余态4种形态的金属萃取效果,随着土壤柱深度的增加而降低.
