城区大气颗粒物中有机氯农药的含量与分布

采用FA-3型气溶胶粒度分布采样器采样,对北京和天津2个样点夏季大气中不同粒径颗粒物上有机氯农药残留量进行分析.在所有分级样品中均检测出δ-HCH,p,p'-DDD和p,p'-DDT,其他有机氯农药只在部分样品中被检出.北京样中HCHs(α-HCH+β-HCH+γ-HCH+δ-HCH)含量为0.240ng/m3,DDTs(p,p'-DDT+p,p'-DDD+p,p'-DDE)含量为0.962ng/m3,天津样品中HCHs含量为0.581 ng/m3,DDTs含量为1.874ng/m3.天津样中有机氯农药残留明显高于北京样.大气颗粒物上的有机氯农药粒径分布特征为:北京样中HCHs和DDTs含量随粒径均呈单峰分布,而天津样中HCHs呈三峰态分布,DDTs呈较弱的单峰态分布.HCHs和DDTs两类化合物的质量中值直径和分散度分别在2.1～2.5μm和3.1～3.7μm范围内. 

Residues and Distribution of Organochlorine Pesticides in Airborne Particles of Different Sizes from Urban Areas

Airborne particles were collected from urban areas of Beijing and Tianjin using an FA-3 aerosol cascade sampler in summer 2002. Organochlorine pesticides residues in various size fractions of the samples were measured.δ-HCH,p,p′-DDD and p,p′-DDT were all detectable.Concentrations of HCHs(α-HCH+β-HCH+γ-HCH+δ-HCH)were 0.240 ng/m 3 and 0.581 ng/m 3,and DDTs(p,p′-DDT,p,p′-DDD+p,p′-DDE) were 0.962 ng/m 3 and 1.874 ng/m 3 in the samples from Beijing and Tianjin,respectively.The levels of organochlorine pesticide residues in the sample from Tianjin were much higher than those from Beijing.The size distributions of HCHs in both samples and DDTs in the sample from Beijing were unimodal,while the size distribution of DDTs in the sample from Tianjin was trimodal.The median diameter and dispersion degree of HCHs and DDTs were at 2.1～2.5 μm and 3.1～3.7 μm respectively.