高速公路PM2.5中重金属季节变化特征及健康风险评估

以往的研究较多关注于城市环境空气PM2.5的重金属污染特征和健康风险,而以交通源为主的相关分析较为匮乏。为探索高速公路环境空气PM2.5中重金属季节变化特征,评价高速公路工作人员健康风险,于2018年3-10月分4次集中采集南昌市周边3条高速公路(昌樟、昌铜和温厚)服务区、收费站中环境空气的PM2.5样品,运用电感耦合等离子体质谱联用仪(ICP-MS)监测了PM2.5中6种重金属(Cu、Zn、Pb、Cd、Cr和Ni)质量浓度,分析其季节变化特征,并利用地累积指数法(Igeo)、美国环保局推荐的健康风险评价模型,对环境空气PM2.5中6种重金属的污染特征及人体健康风险进行评价。结果表明高速公路服务区和收费站环境空气PM2.5质量浓度的季节变化特征表现为春季>秋季>夏季,PM2.5中不同重金属元素质量浓度的季节变化表现出显著性差异。总体上,不同季节PM2.5中重金属质量浓度表现为Zn>Pb>Cr>Cu>Ni>Cd,其中Cr的平均质量浓度为4.07×10^-2μg·m^-3,远高于城市水平。地累积指数评价结果表明6种重金属均受到不同程度的交通源污染,其中Zn和Cd的污染程度分级为严重污染,而Cu、Cr和Ni在秋季表现出更为严重的污染程度。健康风险评价结果表明,高速公路收费站和服务区环境空气的PM2.5中重金属不存在非致癌风险,而致癌风险评价中,PM2.5中Cr的致癌风险评价值超过阈值10^-4,具有致癌风险,Ni的致癌风险评价超过10^-5,具有潜在致癌风险。环境空气PM2.5中重金属的污染特征及致癌风险均表现为秋季高于春季和夏季,交通源引起的大气Cr和Ni污染应受到重视。

Seasonal Change Characteristic and Health Risk Assessment of Heavy Metals in PM2.5 Near Highway

Previous studies primarily focus on the pollution charactieristic and health risk in heavy metals of urban ambient air PM2.5,while less studies focus on the traffic source.Here we discuss the pollution characteristics of heavy metals of ambient air PM2.5 near highways.Three rounds of cluster sampling of ambient air PM2.5 were conducted on three highways,Changzhang,Changtong,and Wenhou,in peri-urban areas near Nanchang from March to October 2018.Sampling sites included service areas,toll stations in the highways.The concentrations of six heavy metals,Cu,Zn,Pb,Cd,Cr,and Ni,in PM2.5 were measured using ICP-MS,the seasonal change characteristic were analyzed,pollution characteristics and health risk of them were evaluated using Geoaccumulation Index(Igeo)and the US EPA risk assessment model,respectively.The mass concentration of ambient air PM2.5 had appeared the obvious seasonal characteristics,showed in the following order of spring>autumn>summer,heavy metal mass concentration of different seasons in highways decreased in the following order:Zn(3.88μg·m^-3)>Pb(6.48×10^-2μg·m^-3)>Cr(4.07×10^-2μg·m^-3)>Cu(2.64×10^-2μg·m^-3)>Ni(1.05×10^-2μg·m^-3)>Cd(0.13×10^-2μg·m^-3),the mass concentration of Cr in the highways was greater than in the cities,and the mass concentrations of heavy metals had a significant seasonal variation.Igeo results showed Cu,Zn,Pb,Cd,Cr,Ni were derived from traffic sources with different degrees,Zn and Cd were extremely contaminated,Cu,Cr and Ni were greater contamination in autumn than in spring and summer.Health risk assessment results showed that,heavy metals of PM2.5 had no non-carcinogenic risk in service areas,toll stations,but in carcinogenic risk.The carcinogenic risk assessment of Cr was greater than the threshold value of 10-4,indicating carcinogenic risk,carcinogenic risk assessment of Ni was greater than 10-5,had potential carcinogenic risk.Overall,carcinogenic risk of heavy metal in autumn was greater than in spring and summer,and traffic source caused Cr and Ni pollution should be appreciated.