| The acidity of the precipitation is deteriorating, the proportion of acid rain takes theshare of90percents in all precipitation samples in recent years, The calcium hasdecreased for years, it should account for the pH value declining of these years. Themain ions includes sulfate, nitrate, calcium and ammonium, the sulfate in theprecipitation is decreasing, the nitrate is fluctuating. The ratio of sulfate and nitrate isalso decreasing, it indicates the acid rain is transforming to sulfate-nitrate-mixed acidrain from sulfate dominating acid rain. The value of pH fails to reveal the pollution ofrain water. According to the comparison of major ions concentration in four monitoringlocation precipitation in2006-2010, the concentrations in downtown area are superior tosuburb area. The major ions concentration seasonal difference in precipitation isdiscovered, the spring is the highest, followed by winter and summer, the autumn is thelowest. the local Climate characteristics of temperature inversion，gentle breeze，andless rain would be one contributing factor, another is the increase of pollutantsemission, such as plants produce more for the festival consumption, also most of thefireworks and cracker would be exploded in spring festival. Comparing to majorelement wet deposition flux in other regions, such as Beijing, Qingdao, Chongqing issignificant superior to their Historical highest flux.The sulfur dioxide emission of Chongqing urban area in2015was predicted as103205.83tons, it would have shrinked a quarter, accordingly the sulfate concentrationin the precipitation in2015would decrease continuously; due to the leap of vehiclepopulation in Chongqing urban area, the nitrate concentration would increase.The environmental policy has achieved its goal in a way, the sulfate is decreasingsignificantly. The implementation of“Model Creation” Project would bring down themajor ions.“Cape and emission-reduction”policy would exert an effect on the nitrate,sulfate and ammonium. The pilot implementation of emission trade would decrease thesulfate with uncertainties. |
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