荆州市降水污染特征及变化趋势分析

Analysis of Pollution Characteristics and Variation Tendency of Precipitation in Jingzhou City

根据湖北省荆州市1997～2010年大气降水监测资料,对降水pH、酸雨频率、阴阳离子组成及变化趋势进行分析,探讨了荆州市酸雨类型及成因。结果表明:荆州市酸雨污染总体呈现减轻趋势;酸雨类型主要为硫酸型;酸雨污染冬季最重,秋季次之,春季较轻,夏季最轻,其中1月份污染最重,12月份次之,7月份污染最轻;降水化学组成的主要离子为SO42-、Ca2+和NO3-,占全部离子的75%;SO42-与NO3-的比值为3.8∶1,表明大气降水的离子组成中SO42-是降水致酸的主要原因;总体上看,SO42-浓度上升趋势不显著,而NO3-浓度却呈显著上升,酸雨污染正在由硫酸型向混合型转变。

According to the monitoring data of atmospheric precipitation in Jingzhou City during 1997 to 2010,the pH of precipitation,frequency of acid precipitation,composition and variation tendency of zwitterion was analyzed,the type and genesis of acid precipitation in Jingzhou City is probed.The results turns out that acid precipitation pollution in Jingzhou City shows a reducing trend in general,mainly sulfuric acid type;pollution level was the heaviest in Winter,heavier in Autumn,lighter in Spring and lightest in Summer,among January was the worst,December better,and July the best;main ions chemical composed in precipitation is SO2-4,Ca2+ and NO-3,about 75% of all ions composed,ratio between SO2-4 and NO-3 is 3.8∶1,which indicates the primary cause of precipitation acidification is SO2-4 in atmospheric precipitation ions composition;general trend shows that,the uptrend of SO2-4 potency is not obvious,meanwhile the potency of NO-3 is rising significantly,the pollution of acid precipitation is changing from sulfuric acid type to mixed type.