Mianzhu--Aba profile, east of the Tibetan Plateau, was selected to study the occurrence of organo- chlorine pesticides （OCPs） along an altitudinal gradient. Dichlorodiphenyltrichloroethanes （DDTs）, hexachlorocy- c...Mianzhu--Aba profile, east of the Tibetan Plateau, was selected to study the occurrence of organo- chlorine pesticides （OCPs） along an altitudinal gradient. Dichlorodiphenyltrichloroethanes （DDTs）, hexachlorocy- clohexanes （HCHs） and Aldrin, Dieldrin and Endrin （Drins） in surface soils were detected in winter （March） and summer （July）. Soil concentrations （ng.g-1, dw） in winter and summer ranged as follws： DDTs, 0.37-179.16 and 0.32-42.57; HCHs, 0.14-10.76 and 0.55-32.71; Drins, N.D-3.99 and 0.02-6.93, respectively. Main soil OCPs were p,p＇-DDT, p,p＇-DDE, fl-HCH and Drins, among which Drins were rarely reported in current literature of the Tibetan Plateau. Higher OCP concentra- tions in the profile were attributed close to the agricultural fields of the Sichuan Basin, current lindane and non- dicofol DDTs inputs, and also long-range atmospheric transport from abroad. Soil OCP concentrations underwent obvious seasonal variation, with higher DDTs in winter and higher HCHs and Drins in summer. It may be caused by climatic conditions, summer monsoon type, and physico-chemical properties of such contaminants. Though ＂rest＂ phenomenon occurred in some sampling sites, HCHs and Drins showed an increasing trend with increasing altitude, while DDTs showed an evident decrease with increasing altitude. The altitudinal distribu- tions of OCPs were all consistent with previous findings in other mountainous regions. A primary fugacity analysis on OCPs soil-air exchange indicated that the profile may be secondary sources for HCHs and Endrin. As with Aldrin,Dieldrin, and DDTs, the profile may be both secondary sources and sinks.展开更多
Soil-air partitioning is an important diffusive process that affects the environmental fate of organic compounds and human health. In this review, factors affecting the soil-air partitioning of polychlorinated bipheny...Soil-air partitioning is an important diffusive process that affects the environmental fate of organic compounds and human health. In this review, factors affecting the soil-air partitioning of polychlorinated biphenyls （PCBs） and total dichloro-diphenyl-trichloroethanes （p,p＇- and o,p＇- isomers of DDT, DDD, and DDE） are discussed. Hydrophobicity is an important factor that influences soil-air partition coefficients （KsA）, and its effect can be explained through enthalpy of phase change for soil-air partitioning transfer （AHsA）. For more hydrophobic compounds, a sharp increase in the KSA of PCBs and organochlorines can be seen in the early aging period. During the aging period, the temperature has a significant effect on the more hydrophobic organic compounds. The content and properties of soil or- ganic matter influence the KSA of the target compounds. Generally, KSA decreases with increasing rela- tive humidity in soils. The linear trend between KSA and temperature （T） changes at 0 ~C. Freezing the air or soil in experiments would change the research results. On the basis of factors influencing soil-air partitioning, a multipleparameter （T, organic carbon fraction （foe）, and octanol-air partition coefficient （KoA）） model is put forward to predict the KSA values for PCBs and total DDTs.展开更多
文摘Mianzhu--Aba profile, east of the Tibetan Plateau, was selected to study the occurrence of organo- chlorine pesticides （OCPs） along an altitudinal gradient. Dichlorodiphenyltrichloroethanes （DDTs）, hexachlorocy- clohexanes （HCHs） and Aldrin, Dieldrin and Endrin （Drins） in surface soils were detected in winter （March） and summer （July）. Soil concentrations （ng.g-1, dw） in winter and summer ranged as follws： DDTs, 0.37-179.16 and 0.32-42.57; HCHs, 0.14-10.76 and 0.55-32.71; Drins, N.D-3.99 and 0.02-6.93, respectively. Main soil OCPs were p,p＇-DDT, p,p＇-DDE, fl-HCH and Drins, among which Drins were rarely reported in current literature of the Tibetan Plateau. Higher OCP concentra- tions in the profile were attributed close to the agricultural fields of the Sichuan Basin, current lindane and non- dicofol DDTs inputs, and also long-range atmospheric transport from abroad. Soil OCP concentrations underwent obvious seasonal variation, with higher DDTs in winter and higher HCHs and Drins in summer. It may be caused by climatic conditions, summer monsoon type, and physico-chemical properties of such contaminants. Though ＂rest＂ phenomenon occurred in some sampling sites, HCHs and Drins showed an increasing trend with increasing altitude, while DDTs showed an evident decrease with increasing altitude. The altitudinal distribu- tions of OCPs were all consistent with previous findings in other mountainous regions. A primary fugacity analysis on OCPs soil-air exchange indicated that the profile may be secondary sources for HCHs and Endrin. As with Aldrin,Dieldrin, and DDTs, the profile may be both secondary sources and sinks.
基金supported by the National Natural Science Foundation of China (No. 41172223)the Fundamental Research Funds for the Central Universities (No. 2652012089)the Commonwealth and Environmental Protection Project of the Ministry of Environmental Protection of the People’s Republic of China (No. 201209053)
文摘Soil-air partitioning is an important diffusive process that affects the environmental fate of organic compounds and human health. In this review, factors affecting the soil-air partitioning of polychlorinated biphenyls （PCBs） and total dichloro-diphenyl-trichloroethanes （p,p＇- and o,p＇- isomers of DDT, DDD, and DDE） are discussed. Hydrophobicity is an important factor that influences soil-air partition coefficients （KsA）, and its effect can be explained through enthalpy of phase change for soil-air partitioning transfer （AHsA）. For more hydrophobic compounds, a sharp increase in the KSA of PCBs and organochlorines can be seen in the early aging period. During the aging period, the temperature has a significant effect on the more hydrophobic organic compounds. The content and properties of soil or- ganic matter influence the KSA of the target compounds. Generally, KSA decreases with increasing rela- tive humidity in soils. The linear trend between KSA and temperature （T） changes at 0 ~C. Freezing the air or soil in experiments would change the research results. On the basis of factors influencing soil-air partitioning, a multipleparameter （T, organic carbon fraction （foe）, and octanol-air partition coefficient （KoA）） model is put forward to predict the KSA values for PCBs and total DDTs.
