广西大石围天坑群有机氯农药的大气干湿沉降

Atmospheric Deposition of OCPs in Dashiwei Karst Tiankeng Group in Guangxi

为研究大气有机氯农药(OCPs)的沉降对广西乐业大石围天坑群喀斯特生态环境的影响,选择典型的大石围天坑,采用大气干湿采样器分季节进行了为期一年(2007-03—2008-03)的大气干湿沉降样品采集,利用气相色谱-质谱联用仪(GC-MS)测定22种有机氯农药。结果表明,大气干湿沉降中PAHs的干湿沉降通量为10.236～88.728 ng(/m.2d),平均值为48.974 ng(/m.2d),研究期间大石围天坑的OCPs沉降量为2.986 g;OCPs沉降通量的空间分布为东垭口>南垭口>北哑口>西峰,与风的进出口密切相关;不同季节的沉降通量为春季>秋季>夏季>冬季,春、夏季OCPs沉降通量高于秋、冬季1.0倍,且春季以滴滴涕(DDTs)和六氯苯(HCB)为主,夏季以β-硫丹和HCB为主,秋季以HCHs和顺式-氯丹为主,冬季以HCHs为主。研究区大气OCPs沉降通量与季风、地理位置、降雨量和温度等因子密切相关;OCPs来源分析显示大石围天坑群春、夏季大气中OCPs主要来源于高气温、低海拔的水稻、水果主产区百色、南宁盆地的远距离传输,秋、冬季则来源于北部相邻的贵州省境内。

An investigation was conducted at Leye County,Guangxi Province,for studying impact of atmospheric deposits of organo-chlorine pesticides（OCPs） on ecological environment of the Dasiwei Karst Tiankeng Group,which involved collecting dry and wet deposit samples by seasons for a whole year and analyzing OCPs of 22 species by GC.Deposits of OCPs including PAH,DDT,HCB and β-endosulfan were measured in different seasons and at various places in terms of deposition flux and weight.It has been showed that OCPs deposition flux in this study area was closely related with monsoon,the wind direction,wind speed,precipitation and temperature,and that OCPs could be transported by atmospheric movement from the pollution sources to the study area through a long distance,e.g.from the agricultural regions of Baise and Nanning basins within the Province during spring and summer,while from neighboring Guizhou Province in north during winter and fall.