天津市采暖季不同气团来向PM_(2.5)中重金属污染特征及健康风险评价

Pollution Characteristics and Health Risk Assessment of Heavy Metals in PM_(2.5) of Different Air Masses During Heating Season in Tianjin

为了解天津市采暖季PM_(2.5)中重金属的污染特征及健康风险,使用Xact-625重金属在线分析仪于2020年11月至2021年3月对PM_(2.5)中的重金属元素进行连续采样,分析10种重金属元素(Pb、 Cd、 Cr、 As、 Zn、 Mn、 Co、 Ni、 Cu和V)的污染特征,利用HYSPLIT模型分析重金属元素的时空分布特征,并结合美国EPA健康风险评价模型对重金属健康风险展开研究.结果表明,采样期间天津市10种重金属元素的总浓度平均值为(261.56±241.74)ng·m^(-3),Cr[折算Cr(Ⅵ)]和As元素高于《环境空气质量标准》(GB 3095-2012)的年平均限值.后向轨迹分析表明,天津市主要受到来自西北部中距离气团(1号)、西北部长距离气团(2号)、西南部气团(3号)和东北部气团(4号)的影响.不同气团来向重金属元素呈现不同的污染特征和健康风险,3号气团PM_(2.5)浓度、10种重金属元素总浓度和5种重金属元素经呼吸途径暴露的终身致癌风险值之和均最高,2号气团10种重金属元素经呼吸途径暴露的非致癌风险值之和最高.健康风险评价显示,Mn元素对儿童存在一定的非致癌风险,Cr和As元素对人体存在一定的致癌风险,3号气团的Cd元素亦存在一定的致癌风险.

In order to explore the pollution characteristics and health risks of heavy metals in PM_(2.5)in Tianjin, heavy metal samples(Pb, Cd, Cr, As, Zn, Mn, Co, Ni, Cu, and V) in PM_(2.5)were analyzed from November 2020 to March 2021 using the Xact-625 heavy metal online analyzer. The spatial and temporal distribution characteristics were analyzed using the HYSPLIT model, and the health risks of heavy metals were analyzed using the US EPA risk assessment model. The results indicated that the average total concentration of the 10 heavy metal elements was(261.56±241.74) ng·m^(-3), among which the concentrations of Cr [converted Cr(Ⅵ)] and As were higher than the annual average limit of the National Ambient Air Quality Standard(GB 3095-2012). According to the back trajectory results, the medium-distance transmissions from northwest areas(NO.1), the long-distance transmissions from northwest areas(NO.2), the transmissions from southwest areas(NO.3), and the transmissions from northeast areas(NO.4) were the major sources in Tianjin City. The heavy metals of different air masses presented different pollution characteristics and health risks;the concentration of PM_(2.5), the total concentration of the 10 heavy metal elements, and the total carcinogenic risk of the five heavy metal elements of the NO.3 air mass were the highest, whereas the total non-carcinogenic risk of the 10 heavy metal elements of the NO.2 air mass was higher than that of the other two air mass. The health risk assessment showed that Mn posed non-carcinogenic risks to children, and Cr and As presented carcinogenic risk. Meanwhile, Cd of the NO.3 air masses also presented carcinogenic risk.