北京官厅水库周边土壤DDTs和HCHs暴露特征与风险评价

围绕北京水源地官厅水库周边2～10km范围于2009年系统布点,利用超声-振荡提取技术,使用气相色谱-电子捕获检测器(GC-ECD)分析方法测定了样品中的DDTs和HCHs含量.并利用GIS技术和地统计分析方法,研究其空间变异特征.结果表明,2009年官厅水库周边土壤中HCHs和DDTs的含量分别为n.d.～14.97ng·g-1(平均值0.73ng·g-1)、n.d.～64.91ng·g-1(平均值6.46ng·g-1).HCHs的残留以β-HCH为主,占总量的94.5%,DDTs的残留以p,p′-DDE为主,占总量的78.5%.不同土地利用类型中有机氯农药残留也不同,表现为果园农田荒地的趋势.Levene'sTest齐性检验结果显示,3种土地利用方式下HCHs和DDTs的残留差异并不显著.空间分析表明,其暴露格局受土地利用方式的影响,基本呈库北高于库南的趋势,高风险区集中在东部延庆县、中部的北辛堡镇以及西部的怀来县城附近.通过与我国土壤环境质量标准及荷兰土壤修复标准对比,并结合单因子污染指数法评价,本地区土壤中农药类POPs暴露仍处于较低的水平,环境风险较小.

DDTs and HCHs Residues in Soils Around Guanting Reservoir and Related Environmental Risk Assessment

Surface soil samples around Guanting Reservoir ranging from 2-10 km were measured for pesticide residues(HCHs and DDTs)concentrations in 2009.Occurrences and related environmental risk were analyzed; furthermore, GIS and geostatistical techniques were applied to analyze the spatial variation of organochlorine pesticides. The results show that concentrations of HCHs in soils range from n.d. to 14.97 ng·g^-1 with a mean value of 0.73 ng·g^-1 , and DDTs range from n.d. to 64.91 ng·g^-1 with a mean value of 6.46 ng·g^-1. According to the isomers of HCHs and metabolites of DDTs, HCHs and DDTs residues in soils were primarily from historical use. The land use showed great effect on the degradation of HCHs and DDTs, with the residual level sequence of orchard >> crop land > barren land. Based on kriging interpolation, the spatial distribution of HCHs and DDTs around Guanting Reservoir was observed. Spatial variability indicated how HCHs and DDTs had been applied and distributed in the past. Compared with those in other national or international regions, the concentrations of HCHs and DDTs in soils around Guanting Reservoir were very low.