广州市公园表层土壤中有机氯农药的分布特征

通过测定广州市典型公园的冬季和夏季表层土壤样品中有机氯农药(OCPs)含量,研究了OCPs的残留现状和潜在生态风险,并与附近地区相比较,结合当地所处的地理位置对土壤中OCPs的分布特征进行了探讨。冬季和夏季土壤中,六六六类(HCHs)的残留水平分别为0.29~6.26 ng/g和0.60~8.07ng/g,平均值分别为2.06和2.44 ng/g;滴滴涕类(DDTs)的残留水平分别为3.27~38.8 ng/g和1.46~35.5 ng/g,平均值分别为12.4和12.5 ng/g。两类OCPs都未超过国家土壤环境质量标准一级自然背景值。较低的α-HCH/γ-HCH比值和γ-HCH>β-HCH,有可能仍有林丹的使用所致。一些公园可能有新的外源DDTs的输入。历史悠久且距离市中心较近的公园土壤中OCPs含量明显偏高。对于大多数新建且相对偏僻的公园而言,表层土壤一般都未见明显的OCPs污染。

Distribution Characteristics of Organochlorine Pesticides in Top Soils from Parks in Guangzhou City

Samples of top soils from typical public parks in Guangzhou City in winter and summer seasons were collected and analyzed for organochlorine pesticides(OCPs).Comparison with residue levels in the other parts of Pearl River Delta area,the discussion was made to evaluate the characteristics of temporal and spatial distribution patterns and potential health risk of OCPs in the soils to the human.The hexachlorocyclohexane(HCHs) concentration in the soils in winter and summer seasons ranged from 0.29 to 6.26 ng/g and 0.60 to 8.07 ng/g,averaging 2.06 and 2.44 ng/g,respectively.Dichorodiphenyltricyloroechane(DDTs) concentrations were in the range of 3.27~38.8 ng/g and 1.46~35.5 ng/g,with average values of 12.4 and 12.5 ng/g,respectively.Both HCHs and DDTs do not exceed the Level Ⅰ(natural background level) of the National Soil Quality Criteria.The observed low α-HCH/γ-HCH ratios and the general phenomena of γ-HCH>β-HCH in these soil samples may be attributed to recent use of lindane.Higher concentrations of DDTs were found in old parks or within the old town of Guangzhou City,whereas DDT levels were lower in the new parks which located in unpopulated areas.