2011—2021年浙江省酸雨分布及变化特征

Distribution and variation characteristics of acid rain in Zhejiang Province during 2011—2021

关键词:  酸雨  空间分布  成因分析  浙江省  酸雨频率

Key words:  acid rain  spatial distribution  cause analysis  Zhejiang Province  acid rain frequency

摘要:

为了解浙江省酸雨污染的演变特征及成因，结合浙江省2011—2021年酸雨观测资料，分析了浙江省酸雨的分布情况及年际、月际的时间变化和强度变化特征。结果表明：2011—2021年，浙江省酸雨污染状况持续改善，酸雨发生频率从43.2%下降到21.6%。酸雨污染状况存在明显的季节变化，夏季酸雨污染多发生于浙江东部沿海地区但程度较轻；冬季酸雨污染最严重，酸雨发生频率达45%。二氧化硫 （SO₂ ） 和氮氧化物 （NO_x ） 是酸雨形成的重要前体物。“十三五”期间浙江省SO₂排放量降幅远超NO_x， 达到91.9%，然而降水pH值增幅弱，由此说明浙江省的酸雨污染类型已经从过去的硫酸型逐步向硫酸-硝酸型过渡。与此同时，浙西南地区酸雨污染趋势加剧，可能与工业发展水平逐年上升有关。

Abstract:

Background, aim, and scope At present, the growth of industrial production activities and motor vehicle ownership has caused acid rain pollution frequently to threaten human health. Zhejiang Province, as one of the important urban agglomerations in the Yangtze River Delta region, has a high industrial production output value and urbanization level. However, the long-term evolution process of acid rain pollution and its distribution characteristics in this region have not been sufficiently studied. This study covers the period from 2011 to 2021, utilizing data from 13 rain observation stations across Zhejiang Province, namely Shaoxing Station, Zhoushan Dinghai Station, Taizhou Hongjia Station, Wenzhou Station, Lishui Station, Yunhe Station, Jinhua Station, Jinhua Yiwu Station, Quzhou Station, Hangzhou Station, Hangzhou Lin’an Station, Huzhou Station, and Jiaxing Station, to analyze spatial and temporal variations of acid rain pollution and its underlying causes through mathematical statistical methods, and attempts to investigate the spatial and temporal characteristics of acid rain pollution in the region and to analyze the potential causes. Materials and methods The data of thirteen rain observation stations in Zhejiang Province was obtained to discuss the evolution of acid rain pollution from 2011 to 2021 through a series of mathematical statistical methods. Results The results showed that from 2011 to 2021, the acid rain pollution situation in Zhejiang Province continued to improve, the frequency of acid rain decreased from 43.2% to 21.6%. There are obvious seasonal changes in the acid rain pollution status. In summer, the acid rain pollution was light and occurred mostly in the eastern coastal areas of Zhejiang; winter was the most serious season for acid rain pollution, with a frequency of occurrence of 45%. Discussion The acidity of the province’s precipitation was gradually weakening, and the phenomenon of worsening acid rain pollution was still occurring in individual years, but such a phase did not last long. With the accelerated progress of urbanization and industrialization, the phenomenon of acid rain has been aggravated in the southwest of Zhejiang, continuously optimizing the structure of energy consumption is an important measure to improve the province’s acid rain pollution. Meteorological conditions, on the other hand, directly affect the diffusion and transportation of pollutants, leading to differences in the chemical composition of acid rain. In summer, southeast winds from the East China Sea prevail in Zhejiang, and the air masses were relatively clean, which played a role in alleviating acid rain pollution in the inland areas of Zhejiang. However, a large number of sulfate ions were carried by marine aerosols, thus still causing serious acid rain pollution in the coastal areas of Zhejiang. The most important precursors of acid rain formation are SO₂ and NOx. The SO₂ emissions in Zhejiang Province decreased much more than NO_x, reaching 91.9% during the 13th Five-Year Plan period. However atmospheric NOx will titrate ozone and control the atmospheric ozone concentration to some extent. Excessive pursuit of NOx emission reduction may increase the oxidizable of the ambient atmosphere and promote the formation of acidic pollutants. Conclusions Although the emission of SO₂ was decreased dramatically, the increase in precipitation pH was not obvious, indicating that the type of acid rain pollution was gradually transitioning to sulfuric acid-nitric acid type. Meanwhile, the increasing trend of acid rain pollution in southwest Zhejiang may be related to the increasing level of industrial development from year to year. Recommendations and perspectives This study provide the valuable insight into the causes of acid rain pollution in Zhejiang Province, and highlight the importance of reducing SO₂ and NOx emissions in order to alleviate acid rain pollution in the future.