1997～2011年北京市空气中酸性物质与降水组分变化趋势的相关性分析

Correlation Between Acidic Materials and Acid Deposition in Beijing During 1997-2011

依据北京市环境保护监测中心1997～2011年降水监测资料、大气环境质量监测资料,结合北京经济发展和能源结构变化,分析了酸雨前体物的排放与环境空气中酸性物质及降水中组分的相关性,为政府部门评定大气污染治理效果,制定未来防控政策和规划提供科学决策依据.研究表明,环境空气中NO2、NOx、SO2年均浓度显著相关,说明北京地区环境空气中氮与硫的来源基本相同,均来自化石燃料燃烧排放,这也是酸雨形成的根本原因.北京市大气中的污染物主要来自局地排放源,而降水中硫、氮的湿沉降量与环境空气中SO2、NO2、NOx浓度变化趋势的相关性较差,表明降水中各离子浓度受局地源和外来大气输送共同作用的影响.同时发现降水中硝酸根浓度与机动车数量呈现相同变化趋势,反映出机动车尾气排放的NOx与降水中硝酸根浓度增长密切相关.

Based on the environment monitoring data and the ambient air quality data during the period of 1997-2011 from Beijing municipal environmental monitoring center,the correlations between primary pre-cursors of acid deposition,acidic materials and precipitation in Beijing area were analyzed in detail by taking economic development and energy mix into account.These results will be helpful for assessing the performance of environment quality improvement,as well as supplying scientific supporting information to make policies for national and local environment protection authorities.The main findings included as follows： there are significant correlations between the concentrations of NO2,NOx and SO2 in the atmosphere,which indicated that both N and S in ambient air of Beijing came from fossil fuels combustion;acidic pollutants in the air are mainly discharged from local emission sources in Beijing,while there is no obvious correlation between S and N in wet deposition and concentrations of SO2,NO2 and NOx in the atmosphere,which demonstrated that concentrations of different ions in the acid deposition were influenced by both local sources as well as the inputs from other surrounding districts.Besides,the concentration of NO-3 appeared to be correlative with the amount of motor vehicles,implying that the NOx from motor vehicles have contributed the increase of NO-3 concentration of substantially.