Preliminary Study On The Chemistry Features Of Atmospheric Precipitation Of Three Typical Regions In Sichuan

Acid rain is one of major environmental issues in the world. Acid rain contains many harmful substances, it have potential harm to soils, forests, lakes and other ecosystems. Because of its unique topography and natural conditions and large number of sulfur dioxide emissions caused by industrial use of coal, acid rain pollution become a compelling question in Sichuan province.This study counducted a two years of precipitation observations by setting observation spots in Rainy area in west of China (Yucheng), the central area of Sichuan basin (Guanghan), mountains and canyons area in west of sichuan (Hanyuan).To find out type of Fallout from the air sedimentation to the ground, the main chemical composition,content and ratio of ions, component nature and content of some pollution from precipitation of three regions in the same time by observation and analysis of precipitation,pH values and NO3-, SO42-, NH4+, Ca2+, Mg2+, Na+, K+ ions.To provide a reference in studying the influence of environment by organic pollutants,N,S deposition.To provide the basis in responce and control of different character, different levels of air pollution in three regions. To provide the reference in selecting against harmful substances plant species in afforestation.The results showed that:1 Characteristics of atmospheric precipitationTotal precipitation of Yucheng was respectively 1772mm and 1703mm in 2008 and 2009,Guanghan was 817mm and 794mm,hanyuan was 768mm and 528mm. Three regions all showed seasonal variation trend of precipitation:precipitation in summer and autumn is high,in spring and winter is low.2 The dynamic characteristics of acid rain frequency, precipitation pH in Three regionsFrequency of acid rain is significantly different in three regions.Order as follows Yucheng> Guanghan> Hanyuan.Type of acid rain in yucheng is mainly moderate,Type of acid rain in Guanghan and Hanyuan is mainly mild,seasonal and annual pH value of Yucheng are both the lowest in three regions.3 Composition and the component relationship of ionicMajor ion of precipitation in three regions are all SO42-. The type of causing acid rain is respectively mixed in Yucheng and Hanyuan, sulfateorcoal-burning in Guanghan. descending order of∑annual value in the three regions was Guanghan (106.15mg/L)>Yucheng (103.23mg/L)> Hanyuan (29.23mg/L).Seasonal variation trend of precipitation in three regions:precipitation in summer and autumn is high, spring and winter is low.4 Seasonal, interannual settlement features of C, N, S and cationicC, N, S and cationic settlement of three regions have a trend of higher in summer and autumn and lower in spring and winter,but settlement concentration have the opposite trend.5 Association of precipitation factors in YuchengPrecipitation dilute the ion of atmospheric deposition in Yucheng,the size of pH have no necessarily relationship with the size of a single ion concentration,anions and cations showed significant positive correlation.