鄂东鸭儿湖地区大气中有机氯农药特征及土-气交换

Characteristics and Soil-air Exchange of Organochlorine Pesticides in the Atmosphere of Yaer Lake Area,Eastern Hubei

采用聚氨酯泡沫-被动采样法（PUF-PAS）采集鸭儿湖地区大气样，研究典型污染源地区大气中有机氯农药（OCPs）组成、来源及土-气交换现状。鸭儿湖地区大气中OCPs主要组成为艾氏剂（Aldrin）、滴滴涕（DDTs）、六六六（HCHs）、六氯苯（HCB）、甲氧滴滴涕（Methoxychlor）和a-硫丹（α-Endosulfan），约占OCPs总量的84%。较高浓度Aldrin（平均浓度为161.25 pg/m^3）广泛存在应引起高度重视。HCHs（平均浓度为89.64 pg/m^3）和DDTs（平均浓度为92.29 pg/m^3）普遍存在且含量高，污染程度比较明显。HCHs异构体中β-HCH高于α-HCH，远远高于γ-HCH和δ-HCH，说明HCHs经过长期降解已逐渐稳定下来；来源分析推测存在工业HCHs的使用或者受大气长距离传输影响。DDTs在各点位分布明显不同于HCHs，且各点位DDTs的六种组成均存在很大差别，可能由于点位地理位置以及农药使用情况导致；来源分析推测大气中DDTs主要来自历史残留。鸭儿湖地区OCPs土气交换研究表明，HCHs主要表现为从大气向土壤中沉降；DDTs在大多数点位源于土壤中历史残留的挥发，部分点位受到大气长距离传输影响。

Composition, source and soil-air exchange of organochlorine pesticides （OCPs） in the atmosphere of Yaer Lake area, a typical OCPs polluted area, were studied by sampling atmospheric samples with polyurethane foam-passive sampling method （PUF-PAS）. Results showed that Aldrin, DDTs, HCHs, HCB, Methoxychlor and α-Endosulfan were main OCPs components and accounted for 84% of the total amount of OCPs in the atmosphere. It should be noted that Aldrin existed extensively in high concentration （average of 161.25 pg/m^3）, and average concentrations of HCHs and DDTs in the atmosphere of study area were 89.64 and 92.29 pg/m^3, respectively, the pollution was remarkable compared with other areas. The concentration of β-HCH was higher than that of α-HCH and much higher than those of γ-HCH and δ-HCH, indicating that HCHs had been stabilized after a long degradation process and that HCHs came from industrial releasing and subjected the long-distant atmospheric transport. The spatial distribution of DDTs was different from that of HCHs, six DDTs isomers distributed differently at different sampling points since of the varied pesticide usages and geographical locations. The source identification inferred that DDTs were mainly from historical residues. The study of soil-air exchange of OCPs in the Yaer Lake area suggested that the predominant soil-air exchange of HCHs was the precipitation from air to soil, and the soil-air exchange of DDTs was mainly volatilization from soil to air at most of sampling points and was controlled by the long-distant atmospheric transport at others.