嘉兴市大气PM2.5中金属元素污染特征、生态风险评价及来源分析

为研究嘉兴市大气PM_2.5中金属元素的污染特征、生态风险和污染来源，使用嘉兴市善西超级站的24 h在线监测数据，对2019年3月1日—2020年2月29日嘉兴市大气PM_2.5和其中12种金属元素（K、Ca、Fe、Zn、Mn、Cd、Pb、Cr、Ni、Ba、Cu、V）进行分析。结果表明：观测期间嘉兴市PM_2.5平均浓度为30.94 μg/m³，优于GB 3095—2012《环境空气质量标准》二级标准（35 μg/m³），PM_2.5浓度季节分布为冬季>春季>秋季>夏季。金属元素总浓度为1.36 μg/m³，从高到低分别为K>Fe>Zn>Ca>Mn>Pb>Ba>Cu>Cr>Ni>Cd>V，其中Fe、Zn浓度的变化受到新型冠状病毒感染疫情暴发和春节的影响。随着大气污染程度的加重，PM_2.5中金属元素总浓度和各金属元素浓度都呈上升趋势，但大多数金属元素在PM_2.5中的占比呈下降趋势。富集因子法表明，K、Ca、Fe、Ba、V不存在富集，Zn、Cd存在极重富集。地累积指数结果显示，Cu、Pb、Zn、Cd受到人为源的影响较大。由金属元素的生态风险指数可知，Mn、Cr、Ni存在轻微潜在生态风险，Zn、Cu、Pb、Cd的生态风险较大。通过主成分分析得出，嘉兴市PM_2.5中金属元素主要来自工业源、燃煤源、交通源和自然源。

Pollution characteristics,ecological risk assessment and source apportionment of mental elements in PM2.5 in Jiaxing City

In order to study the pollution characteristics, ecological risks and pollution sources of metal elements in PM2.5 in Jiaxing, the 24-hour online monitoring data of Shanxi (SX) site in Jiaxing City from March 1, 2019 to February 29, 2020 were collected to investigate PM2.5 and 12 metal elements (K, Ca, Fe, Zn, Mn, Cd, Pb, Cr, Ni, Ba, Cu and V) in PM2.5 samples. The results indicated that the average concentration of PM2.5 was 30.94 μg/m3 during the sampling period, which was better than the secondary concentration standard of Ambient Air Quality Standard (GB 3095-2012) (PM2.5, 35 μg/m3). PM2.5 concentrations in the samples were in the following order: winter > spring > autumn > summer. Meanwhile, the concentrations of metal elements were ranked as follows: K > Fe > Zn > Ca > Mn > Pb > Ba > Cu > Cr > Ni > Cd > V (the total concentration being 1.36 μg/m3), in which concentrations of Fe and Zn were affected by the COVID-19 outbreak and the Spring Festival. It was found that both the total metal concentration and each metal element concentration in PM2.5 increased with the pollution increasing, while the proportion of most metal elements in PM2.5 decreased. The enrichment factor (EF) method results indicated that K, Ca, Fe, Ba and V were considered almost with no elements enrichment, while Zn and Cd showed extremely heavy enrichment. The geoaccumulation index (Igeo) results implied that Cu, Pb, Zn and Cd were strongly influenced by anthropogenic activities. In addition, the ecological risk index (Ei) results of mental elements indicated that Mn, Cr and Ni showed slight ecological risk, and Zn, Cu, Pb and Cd showed high ecological risk. In addition, the principal component analysis indicated that industrial processes, coal combustion, vehicle traffic and crustal sources were the main sources of these metal elements in PM2.5 in Jiaxing City.