丹江口水库库边降雨径流中有机氯农药赋存及风险评价

在南水北调中线源头区丹江口水库典型区域,根据不同土地利用类型修建了5组径流场来收集径流,研究了降雨径流水相及颗粒相中有机氯农药的分布特征及来源,并对其进行了风险评价.采用GC/MS对降雨径流中美国EPA优先控制的20种有机氯农药(OCPs)进行了检测分析.结果表明,径流颗粒物中有α-HCH和DDE两种有机氯农药检测出,而水相中仅有α-HCH一种有机氯农药检测出,不同利用类型土地径流颗粒物中OCPs含量的基本趋势为: 耕地(137.35ng/g)>果园(43.74ng/g) >山林(26.89ng/g),水相中OCPs含量的基本趋势为:耕地(1.94ng/L) >果园(1.90ng/L)>山林(1.19ng/L),说明耕地和果园受人为污染的影响,这和当地的开发情况也非常符合;同种土地利用类型径流中OCPs含量的基本趋势为: 10~15°耕地>5~10°耕地>0~5°耕地,由此可知,径流中OCPs含量随坡度的增加而增加,可能是由于坡度增大径流量也随之增大,降雨冲刷对土壤中有机氯农药的影响较大.对降雨径流中α-HCH和DDE进行源解析,α-HCH可能来自早期残留,部分也可能来自大气沉降;而DDE可能源之早期施用的DDT农药在好氧条件下分解产物.

Distribution characteristics and risk evaluation of organoclorine pesticides in runoff from typical area of Danjiangkou Reservoir

Five groups of artificial runoff fields were built to collect runoff based on the different types of land-use in the Middle Line Source Area of South-to-North Water Diversion Project area around Danjiangkou Reservoir.The distribution characteristics of organ chlorine pesticides(OCPs) in runoff of aqueous phase and particles phase were studied.The contents of 20 USEPA priority OCPs in runoff were determined using GC/MS method.The results showed that α-HCH and DDE were detected in runoff particles,but only α-HCH was detected in soluble phase.The concentrations of OCPs of the particle phase in the collected runoff samples of different land-use types decreased in the order: cultivated land(137.35ng/g) >oak forest(43.74ng/g) >orchard(26.89ng/g),and in aqueous phase was: cultivated land(1.94 1.94ng/L) >oak forest(1.90 1.94ng/L) >orchard(1.19 1.94ng/L).The characteristics of OCPs components show that the arable land and orchards were polluted by human,which is also consistent with the local development.The content of OCPs in the same land-use types decreased in the order: 10～15°>5～10°>0～5°.The OCPs concentration increased with the slope in runoff,which is perhaps because the slope had great influences on the generation of the runoff.The source of α-HCH and DDE in the submerged soil and runoff were investigated,which indicated that α-HCH maybe come from the earlier residues and atmospheric deposition.While DDE maybe come from the early application of the pesticide DDT decomposition under aerobic conditions product.