长江口北岸南通地区酸雨污染及组分变化趋势分析

Analysis of Acid Rain Pollution and Composition Change Trend in Nantong Area on the North Bank of the Yangtze River Estuary

分析2007~2019年南通市各子站降水监测点位数据得出,近10年来,全市酸雨污染大幅减轻,酸雨发生率渐趋下降,强中度酸雨逐渐消除,降水酸度和酸雨酸度均有减弱,现阶段酸雨污染以弱酸性酸雨污染为主。近年来全市硫酸根离子当量浓度呈现逐年明显降低的趋势,机动车尾气排放的大量致酸物质使降雨中NO^(-)_(3)占比明显上升,SO^(2-)_(4)与NO^(-)_(3)浓度的比值已降至1.25∶1,南通市酸雨已由硫酸型向硫酸与硝酸并重混合型过渡。全市酸雨区域分布格局总体变化不大,主要呈现东南沿江沿海略高于西北部区域。

Based on the analysis of the data of precipitation monitoring points in each station of Nantong City from 2007 to2019,it is concluded that in the past 10 years,the acid rain pollution in the city has been greatly reduced,the occurrence rate of acid rain has been gradually reduced,the strong and medium acid rain has been gradually eliminated,the acidity of precipitation and acid rain has been weakened.At present,the acid rain pollution is mainly weak acid rain pollution.In recent years,the equivalent concentration of sulfate ions in the city has been decreasing year by year.A large number of acid-causing substances from vehicle exhaust emissions have increased the proportion of NO^(3-) in rainfall significantly,and the ratio of SO^(2-)_(4) to NO^(3-) concentration has been reduced to 1.25∶1.The acid rain in Nantong City has changed from sulfuric acid type to mixed type of sulfuric acid and nitric acid.The overall distribution pattern of acid rain in the whole city has little change,and showing that the southeast coastal area is slightly higher than the northwest area.