2001—2018年浙江省酸雨变化特征及影响因素分析

利用2001—2018年浙江省32个城市酸雨观测资料,结合数理统计和GIS空间插值,分析了全省降水酸度变化、化学组分特征及其影响因素。研究结果表明,以2009年为拐点,浙江省酸雨污染呈先加重后减轻的趋势,降水酸度和酸雨率均得到显著改善。2009年后,轻酸雨城市的比例不断上升。至2018年,全省大部分城市均处于轻酸雨区,并有部分非酸雨城市出现。降水中的硫酸根离子浓度呈显著下降趋势,硝酸根离子浓度呈波动变化,但变化不显著。硫酸根离子与硝酸根离子的当量浓度比值呈显著下降趋势,由2002年的3.48降至2018年的1.35,酸雨类型由硫酸主导型向复合型转变。二氧化氮、硝酸根离子和可吸入颗粒物是影响降水pH的主要因素,氮氧化物对浙江省降水酸度的影响不断增大。因此,在加强区域硫氮协同控制的同时,着力加强氮氧化物深度减排是进一步改善浙江省酸雨状况的关键。

Analysis on Tempo-Spatial Variation Characteristics and Influence Factors of Acid Rain in Zhejiang Province from 2001 to 2018

Considering the statistical analysis and interpolation of GIS, the acidity variation characteristics, chemical composition and influence factors of precipitation were investigated based on the precipitation data from 32 cities in Zhejiang province (2001 to 2018). The results showed that the effect of acid rain increased from 2001 to 2009 and decreased from 2009 to 2018. Both precipitation acidity and acid rain frequency significantly turned to better. Proportion of cities in light acid rain areas has been increasing since 2009. The majority of the province was suffering the light acid rain in 2018, accompanied with several non-acid rain areas. The concentration of SO₄^2- in precipitation decreased significantly, while NO₃^- concentration fluctuated without significant difference. The ratio of equivalent concentration of SO₄^2- to NO₃^- showed an overall downward trend from the highest of 3.48 in 2002 to 1.35 in 2018. The acid rain transformed from sulfuric acid type to complex type. Nitrogen dioxide, nitrate ion and inhalable particles were the main influence factors of precipitation pH value. The contribution of nitrogen oxide to acid rain was increasing in Zhejiang province. While reinforcing regional control of sulfur and nitrogen, strengthening emission reduction of nitrogen oxides is the key to further improve environmental quality.