成都经济区有机氯农药异常区大气影响推断

以成都经济区中德阳绵竹有机氯农药异常区为重点,选取跨越异常区主风向(西北-东南)的长剖面,采集大气颗粒物样品和降水样品以及与大气采样点相对应的土壤样进行测试分析。采样自2007年6月18日起,每三个月(一个季度)收集一次,为期一年。研究表明表层土壤中HCH最高含量值均位于海拔400～700m之间,大气降水对土壤HCH的贡献量很大,是去除大气中HCH的有效形式。由于山脉阻碍和改变气流的活动情况,空气对流强度增加,温度下降显著,形成大量山前降水,使得有机氯农药沉降效率较高。高海拔地区有机氯农药含量的多少取决于有机氯农药本身的挥发性、蒸汽压、距离有机氯农药源区的距离以及传输通道的环境条件(高程变化、风向、温度、降水量、降水频度等)。

Deducing Atmospheric Impact in Abnormal Region of Organochlorine Pesticides in Chengdu Economic Region

Abnormal region of organochlorine pesticides (OCPs) in Deyang and Mianzhu in Chengdu Economic Region was selected as study object. Due to main wind direction in the region,a long section spanning the whole abnormal region was chosen to sample gas phase,particle phase and topsoil samples respectively. From June 18,2007,the samples were collected every three months (one season) for one year. Results showed that at the altitude of 400～700m,HCH's level of topsoil samples revealed the highest. Precipitation which contributed a lot of HCH to topsoil was effective to wipe off HCH in the atmosphere. Due to mountains affected the activity of air current,air convection intensity increased,temperature descend prominently,precipitation comes into being,which improved the efficiency of OCPs deposition. Level of OCPs at high attitude lied on volatility and steam pressure of OCPs,distance from the fountain and circumstance conditions of transmission channels including altitude changing rate,wind direction,temperature,measure and frequency of precipitation.