江西鄱阳湖地区水稻土中DDTs和HCHs的残留分布研究

Distribution of residues of DDTs and HCHs in paddy soil from Poyang lake area,Jiangxi Province

采集江西鄱阳湖地区0~20 cm深度水稻土样品40件,分析样品中DDTs和HCHs的四种异构体及衍生物,绝大部分样品中均不同程度检出HCHs和DDTs,其中HCHs残留量为0.37~7.52 ng/g,异构体以B-HCH为主,次为A-HCH;DDTs残留量为0~43.04 ng/g,衍生物中p,p’-DDE占主要优势,次为p,p’-DDT。水稻土中的DDTs平均残留量高于HCHs数倍,但总量均小于国家一级土壤环境质量标准限量值,总体上是安全的。通过样品中AHCH/C-HCH比值,确定该地区HCHs来自历史污染的工业HCH,无新的HCH污染源。DDTs是在有氧环境下降解,0,p’-DDT/p,p’-DDT比值大多数小于1,说明整个地区DDT来源以工业品DDT为主,极个别样品来自三氯杀螨醇。DDE+DDD/DDT比值表明大部分样品为历史遗留的DDT污染物,但是少量地区仍有新的污染源输入,其来源既有土壤风化产物,也有新的工业DDT污染。

40 paddy soil samples in depths of 0-20 em from Poyang lake area of Jiangxi Province have been ana- lyzed for four types of isomers and derivatives of DDTs and HCHs in this paper. DDTs and HCHs have been detected in most samples. Residues of HCHs range from 0.37 to7. 52 ng/g, with dominant ^-HCH and less a-HCH of isomers. Residues of DDTs are 0-43.04 ng/g, with dominant p, p＇-DDE and less p,p＇- DDT of derivatives. Although the averaged residues of DDTs are higher than those of HCHs, they do not exceed the limit of national standard of the first class soil environmental quality, so the soil is safe as a whole. Ratio of a-HCH/γ-HCH indicates that the source of HCS may come from the previous contamina- tion of industrial HCH, without any new source of HCH. DDTs were degraded in the aerobic environ- ment, and the ratio of 0,p＇-DDT/p, p＇-DDT is mostly less than 1, indicating that DDT may come from industrial sources, with few samples being caused by dieofol. The ratio of DDE＋DDD/DDT indicates that DDT in most samples was caused by historical contamination. However, new sources of DDT contamination exist in some area, partially coming from the weathering of soil and partially from industry.