深圳市大气中PM2.5载带金属污染特征及健康风险

于2020年3月～2021年2月对深圳市道路环境空气中PM_2.5载带的15种金属元素的质量浓度进行时间分辨率为1h的全年在线观测.结果显示,深圳市道路环境空气中PM_2.5载带金属元素的总平均浓度为(1062.3±434.6) ng/m³,其中Fe、Al、K、Ca和Zn为主要贡献元素,在金属元素中总贡献达到95.5%.Fe的浓度较高,受到与道路扬尘和机动车排放的强烈影响.金属浓度存在着显著的季节性差异,冬季浓度最高(1709.3ng/m³),夏季最低(644.1ng/m³).Mn、Fe、Cr、Zn和Ca元素呈现明显的双峰日变化分布,与机动车流量高峰一致.昼夜浓度分布结果显示,夜间船舶排放V和Ni的浓度高值得关注,而Mn、Zn和Ca的浓度白天较夜晚高,与白天机动车流量较高有关.高污染日总金属日间浓度和夜间浓度均为全年日间和夜间平均浓度的1.9倍.成年人与儿童暴露于深圳市道路环境空气的非致癌风险均低于阈值1,但是总致癌风险(6.5×10^-6)超过阈值10

Characteristics and health risks of ambient PM2.5-bound metals in Shenzhen

In this study, mass concentrations of 15PM_2.5-bound metals in Shenzhen's road ambient air were online observed with a resolution of 1h from March 2020 to February 2021. Results showed that: total average concentration of PM_2.5-bound metals in the road ambient air in Shenzhen was 1062.3±434.6ng/m³, and Fe, Al, K, Ca and Zn were the main contributor, which contribute 95.5% of total metals. Higher concentration of Fe was strongly affected by road dust and vehicle emissions. Significant seasonal differences happened in of metals. The concentration was the highest in winter (1709.3ng/m³) and lowest in summer (644.1ng/m³). Mn, Fe, Cr, Zn and Ca obtained obvious diurnal variation, which were consistent with traffic peaks for vehicles. Diurnal variation analysis revealed that: high concentrations of V and Ni from ship emissions at night deserve attention, while the concentrations of Mn, Zn and Ca were higher during the day than at night, which was related to the higher traffic flow of vehicles during the day. The daytime and nighttime concentrations of total metals on high pollution days were both 1.9times the average daytime and nighttime concentrations throughout the year. Non-carcinogenic risks of adults and children exposed to the road ambient air in Shenzhen were lower than the threshold of 1. However, total carcinogenic risks (6.5×10^-6) exceeded the carcinogenic risk threshold of 10^-6, and the sum of the carcinogenic risks of As and Cr (mainly from vehicle emissions) accounted for 88.9% of the total carcinogenic risk, indicating that the carcinogenic risk in PM_2.5-bound metals of traffic deserves attention and needs to be controlled continuously.