杭州市临安区冬季PM_(2.5)化学组成特征和来源解析

Characteristics of chemical compositions and sources of PM_(2.5)in winter at Lin′an

为研究杭州市临安区PM_(2.5)的污染特征及来源,于2021年12月23日至2022年2月28日在线监测临安区的PM_(2.5),并运用正交矩阵因子分解法(PMF)进行来源解析。结果表明,观测期间临安区PM_(2.5)平均质量浓度为53.91μg·m^(-3),NO_(3)^(-)和有机物对PM_(2.5)的贡献较大,分别占31.07%和19.66%。氮氧化率(NOR)、硫氧化率(SOR)和二次有机物(SOC)浓度的分析结果表明,临安区冬季PM_(2.5)的二次转化较明显,对PM_(2.5)有重要贡献。来源解析结果表明,临安区冬季PM_(2.5)主要有七类来源,分别为二次硝酸盐(52%)、二次硫酸盐(16%)、机动车尾气(14%)、燃煤(6%)、扬尘(5%)、工业排放(5%)和生物质燃烧(2%)。在污染过程中,二次硝酸盐和机动车尾气的贡献有所上升,建议当地政府在污染期间控制机动车尾气排放,降低PM_(2.5)浓度。

In order to study the pollution characteristics and source contributions of PM_(2.5)at Lin'an,located in Hangzhou City,the PM_(2.5)component online monitoring was conducted from December 23,2021,to February 28,2022,and the sources apportionment of PM_(2.5)was conducted using positive matrix factorization(PMF).The mean concentration of PM_(2.5)was 53.91μg·m~(-3)in winter,with NO_3~-and organic matter contributing the most,which accounted for 31.07%and 19.66%,respectively.NOR,SOR and SOC analysis showed that the secondary formation of PM_(2.5)was obvious in winter,which contributed largely to local PM_(2.5).Source apportionment showed that the air of Lin'an in winter was mainly affected by seven sources,namely secondary nitrate(52%),secondary sulfate(16%),vehicle exhaust(14%),coal(6%),dust(5%),industrial(5%)and biomass combustion(2%).During the episode,the contribution of secondary nitrate and vehicle exhaust increased,suggesting that local governments should control the impact of vehicle exhaust emissions on PM_(2.5)during pollution periods.