2012—2017年京津冀区域酸雨变化特征

利用2012-2017年京津冀区域26个酸雨观测站观测资料，基于GIS插值方法研究平均降水pH值和酸雨频率空间分布特征，分析酸雨区月、季和不同降水量等级下酸雨变化特征，探讨该区域酸雨的成因。结果表明：2012-2017年京津冀区域酸雨污染面积呈下降趋势，2012-2014年重酸雨区和2012-2013年酸雨频发区主要分布在承德、唐山、秦皇岛三市交界；2017年酸雨区面积（占比为15%）和酸雨频率多发区以上面积（占比为17%）比2012年分别减少了63%和52%；较弱酸雨频率出现最高，83%的特强酸雨出现在2012年和2013年。酸雨区秋季平均降水pH值最小，酸雨频率最高，秋季酸雨污染最为严重；冬季空气中污染物增多导致降水K值增大。中雨量级的平均降水pH值最小，小雨量级酸雨出现次数占比和降水K值最大；暴雨过程后减轻酸雨污染的程度。2011年后NO_x排放量超过了SO₂排放量，酸雨污染由"硫酸-硝酸型"逐步向"硝酸型"转变；减少SO₂和NO_x排放是降低京津冀区域酸雨污染的重要举措。

Characteristics of acid rain in the Beijing-Tianjin-Hebei region from 2012 to 2017

Using the observation data of 26 acid rain stations in the Beijing-Tianjin-Hebei region from 2012 to 2017,the spatial distribution characteristics of precipitation pH value and acid rain frequency were studied based on the GIS interpolation method.The variation characteristics of acid rain in different months,seasons and at different precipitation grades in the acid rain area were analyzed.The causes of acid rain formation were studied.The results show that from 2012 to 2017,the area of acid rain influencing in this region decreases.The areas with severe acid rain from 2012 to 2014 and with a high frequency of acid rain from 2012 to 2013 are both mainly distributed in the junction region of Chengde,Tangshan and Qinhuangdao cities.Compared with 2012,the acid rain area (accounting for 15% of the total region area) and the area with a high frequency of acid rain (accounting for 17% of the total region area) in 2017 decrease 63% and 52%,respectively.Generally,the frequency of relatively weak acid rain is the highest.83% of the extraordinarily strong acid rain occurs in 2012 and 2013.Compared with other seasons,the average pH value of in autumn precipitation is the lowest,its frequency of acid rain occurrence is the highest,and its pollution extent is the most serious.The increase of air pollutants in winter leads to the increase of K value in precipitation.The average pH value in the moderate-graded precipitation is the smallest.For the light-graded precipitation,the ratio of acid rain occurrence times to the total acid rain occurrence times reaches the maximum,and the corresponding K value in precipitation is the largest.After a rainstorm,acid rain pollution is reduced.After 2011,the emission of NO_x exceeds that of SO₂.The acid rain pollution has gradually changed from sulfuric acid-nitric acid type to nitric acid type.Reducing the emission of SO₂ and NO_x is an important measure to reduce the acid rain pollution in the Beijing-Tianjin-Hebei region.