Li Jun, Zhang Gan, Qi Shihuan, Li Xiangdong, Peng Xiangzhi
State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
Sci Total Environ. 2006 Dec 15;372(1):215-24. doi: 10.1016/j.scitotenv.2006.09.023. Epub 2006 Oct 30.
Concentrations, and enantiomeric compositions of HCH, DDT and chlordane in 74 soils of the Pearl River Delta, South China were investigated. The mean concentrations of HCHs and DDTs descended in the order: crop soils>paddy soils>natural soils. The concentrations (ng/g dw) of p,p'-DDE, p,p'-DDT, p,p'-DDD and o,p'-DDT in crop soils were 0.14-231, 0.07-315, <DL-96.7 and 0.06-73.8, respectively, while those of chlordane were generally below 0.78 for trans-chlordane (TC) and 0.75 for cis-chlordane (CC). Enantiomeric factors (EF value) were determined for o,p'-DDT, alpha-HCH, TC and CC. Both preferential depletions of (-) enantiomer and (+) enantiomer were observed for o,p'-DDT and alpha-HCH, indicated by EF values either <0.5 or >0.5. An EF value >0.5 generally suggested a preferential degradation of the (-) enantiomers of both TC and CC. The racemic alpha-HCH observed in the soils with higher HCH concentrations indicated that the transformation from gamma-HCH (e.g. lindane) to alpha-HCH may be an important process in the soils. The isomer ratios of p,p'-DDT/(DDE+DDD), o,p'-DDT/p,p'-DDT and enantiomeric compositions of o,p'-DDT suggested that both illegal use of technical DDT and the DDT impurity in dicofol may be responsible for the freshly DDT input in the region. The sources of DDTs were drawn by principal component analysis-multiple linear regression (PCA-MLR). The relative contributions of dicofol-type DDT, residues, and fresh technical DDT were estimated to be 55%, 21% and 17%, respectively. In addition, CC was found to degraded faster than TC in soils from the Pearl River Delta. The study demonstrated that the combination of isomer ratios and enantiomeric composition analysis may provide critical information on the potential sources and fate of organochlorine pesticides in soil.
对中国南方珠江三角洲74份土壤中六氯环己烷（HCH）、滴滴涕（DDT）和氯丹的浓度及对映体组成进行了调查。六氯环己烷和滴滴涕的平均浓度顺序为：作物土壤＞稻田土壤＞天然土壤。作物土壤中p,p'-二氯二苯醚（p,p'-DDE）、p,p'-滴滴涕（p,p'-DDT）、p,p'-二氯二苯乙酮（p,p'-DDD）和o,p'-滴滴涕的浓度（ng/g干重）分别为0.14 - 231、0.07 - 315、＜检测限 - 96.7和0.06 - 73.8，而氯丹中反式氯丹（TC）的浓度一般低于0.78，顺式氯丹（CC）的浓度一般低于0.75。测定了o,p'-滴滴涕、α-六氯环己烷、反式氯丹和顺式氯丹的对映体分数（EF值）。o,p'-滴滴涕和α-六氯环己烷均观察到（-）对映体和（+）对映体的优先消耗，EF值＜0.5或＞0.5表明了这一点。EF值＞0.5通常表明反式氯丹和顺式氯丹的（-）对映体优先降解。在六氯环己烷浓度较高的土壤中观察到外消旋α-六氯环己烷，这表明从γ-六氯环己烷（如林丹）向α-六氯环己烷的转化可能是土壤中的一个重要过程。p,p'-滴滴涕/（二氯二苯醚+二氯二苯乙酮）、o,p'-滴滴涕/p,p'-滴滴涕的异构体比例以及o,p'-滴滴涕的对映体组成表明，该地区新输入的滴滴涕可能是由工业用滴滴涕的非法使用和三氯杀螨醇中的滴滴涕杂质造成的。通过主成分分析 - 多元线性回归（PCA - MLR）确定了滴滴涕的来源。估计三氯杀螨醇型滴滴涕、残留和新鲜工业用滴滴涕的相对贡献分别为55%、21%和17%。此外，发现珠江三角洲土壤中顺式氯丹比反式氯丹降解得更快。该研究表明，异构体比例和对映体组成分析相结合可以提供有关土壤中有机氯农药潜在来源和归宿的关键信息。
