珠三角地区环境空气PM2.5中重金属生态风险评估

Ecological Risk Assessment of Heavy Metalsin Ambient Air PM2.5 in the Pearl River Delta Region

以珠三角城市群(广州等9个城市)环境空气细颗粒物(PM2.5)为研究对象,利用电感耦合等离子体质谱法测定了PM2.5中重金属(Pb、Cd、Cr、Ni、As、Sb)含量,并采用地累积指数法和潜在生态风险评价对其进行风险评估。结果显示:珠三角地区城市环境空气PM2.5中重金属Cd、As和Sb的污染级别达到3级,即中度污染,Pb的污染程度为偏中度,Cr和Ni的污染程度为中度偏下;珠三角大部分城市夏季PM2.5中Pb、Cr及Ni的含量与兰州、北京等城市相比相对较低,Cd基本低于北京和武汉,就不同城市而言,佛山和肇庆夏季PM2.5中各重金属含量相对较高,惠州与江门相对较低。研究表明,珠三角地区城市大气PM2.5中重金属Cd和Sb所带来的生态风险较为严重。在评价珠三角地区城市群环境空气生态风险时,应密切关注Cd和Sb等低浓度但污染程度较高和生态危害极强的重金属元素可能带来的环境生态风险。

The content of heavy metals(Pb,Cd,Cr,Ni,As,Sb)in PM2.5 was determined by inductively coupled plasma mass spectrometry(ICP-MS)in the urban agglomeration of the Pearl River Delta(Guangzhou and other nine cities),and the risk assessment was carried out by land accumulation index method and potential ecological risk assessment.The results showed that the contents of heavy metals(Cd,As and Sb)in PM2.5 of urban ambient air in the Pearl River Delta were determined by ICPMS.The level of pollution reached grade 3,i.e.moderate pollution,moderate pollution of Pb,moderate pollution of Cr and Ni;the content of Pb,Cr and Ni in summer PM2.5 of most cities in the Pearl River Delta was relatively lower than that of Lanzhou,Beijing and other cities,and Cd was basically lower than that of Beijing and Wuhan.For different cities,the content of heavy metals in summer PM2.5 of Foshan and Zhaoqing was relatively high,and that of Huizhou and Jiangmen was relatively high.The study shows that the ecological risk of heavy metals Cd and SB in PM2.5 in the urban atmosphere of the Pearl River Delta is relatively serious.When evaluating the environmental air ecological risk of urban agglomeration in the Pearl River Delta,we should pay close attention to the environmental ecological risk of heavy metals such as Cd and SB with low concentration but high pollution and high ecological hazard.