东莞大气PM_(2.5)中金属元素污染特征与生态风险

The Pollution Characteristic and Ecological Risk of Atmospheric Fine-particle-bound Metals in Dongguan

该研究根据2019年1月-2020年2月东莞城区大气超级站PM_(2.5)中金属元素(Pb、Cd、Cr、Ni、As等15种)的在线监测数据,分析其污染特征与富集程度,并评估疫情防控期间的变化。结果显示:东莞城区大气PM_(2.5)中金属K、Fe、Ca、Al和Zn含量相对较高。K、Fe、Al、Ca、Zn、Pb、Mn、Cu、As和Se的月均浓度高值主要出现在11月、12月和1月。K、Pb、Cu、As、Ba和V日变化规律总体呈夜间高-白天低特征;Al、Fe、Zn、Ca和Mn则在早晚通勤交通高峰期间出现双峰。以Al为参比,除Ba和Fe外,其他元素富集因子均>10,富集明显;其中Cd、Se、Zn、Cu、As和Pb的富集因子大于100,富集非常严重。东莞大气总金属元素潜在生态危害程度为很强,Cd贡献为主。与2020年防控前和2019年同期相比,2020年疫情防控期12种以上元素浓度均有不同程度的下降;除K和Ba外,12种元素的富集因子亦显著下降,受人类活动影响程度剧减;疫情防控期大气总金属元素潜在生态危害较2019年同期相比下降14.8%。

Based on the online observation of 15 kinds of metals,including Pb,Cd,Cr,Ni,As,etc.,in PM_(2.5)at the suppersite in Dongguan urban area from January 2019 to February 2020,their pollution properties and enrichment conditions were analyzed,and their variations to the impact of 2019-nCoV epidemic prevention and control were discussed.The results showed that the contents of K,Fe,Ca,Al and Zn in PM_(2.5)in Dongguan urban air were relatively high.Generally,K,Fe,Al,Ca,Zn,Pb,Mn,Cu,As and Se showed higher mass concentration in November,December,and January.K,Pb,Cu,As,Ba and V showed a high-at night-low-in-day-time average diurnal variation,while Al,Fe,Zn,Ca and Mn had two peaks during morning and evening rush hours.With Al as reference,except Ba and Fe,the enrichment factor of the other 12 metals were over 10 with obvious enrichment,especially those of Cd,Se,Zn,Cu,As and Pb were higher than 100,indicating serious enrichment.The potential ecological risk of total metals was high in Dongguan with Cd as the major contributor.Compared with those during the period before 2019-nCoV epidemic prevention and control in 2020 and the same period in 2019,the mass concentrations of more than 12 kinds of metals decreased,and except K and Ba,the enrichment factor of the other 12 kinds of metals significantly decreased,in consistent with a marked decline in human activity.The potential ecological risk of total metals during the control period decreased by 14.8%compared with the same period in 2019.