关键词: PM_2.5, 重金属, 风险评估

Abstract: Objective To understand the pollution level of water-soluble heavy metals in atmospheric PM_2.5 in different urban areas of Guangzhou in 2017 and assess health risks to the population. Methods According to the regional characteristics of air pollution in Guangzhou, sampling sites were set up in districts of Yuexiu, Panyu, and Conghua. PM_2.5 samples were collected monthly from January to December 2017. The mass of the main metals （Al, As, Cd, Pb, Mn） in PM_2.5 was determined by inductively coupled plasma mass spectrometry. The health risk assessment model recommended by USEPA was used to evaluate the health risks, and the non-carcinogenic risk （hazard quotient, HQ） was used to evaluate the non-cancer risk of a single pollutant. The cancer risk of a single pollutant was evaluated, setting 10^-6 as an acceptable risk level. Results The median PM_2.5 concentrations in the three districts in Guangzhou were 0.048 mg/m³ in Yuexiu, 0.048 mg/m³ in Panyu, and 0.040 mg/m³ in Conghua（P>0.05）. The concentration of Al, which was the highest among the five heavy metal elements, was 105.0 ng/m³ in Yuexiu, 63.9 ng/m³ in Panyu, and 78.6 ng/m³ in Conghua （ P<0.01）.The concentration of Mn was 32.2 ng/m³ in Yuexiu, 24.2 ng/m³ in Panyu, and 15.0 ng/m³ in Conghua, respectively （P<0.01 for all）. The concentration of As was 6.57 ng/m³ in Yuexiu, 5.85 ng/m³ in Panyu, and 5.04 ng/m³ in Conghua. The concentration of Cd was 1.15 ng/m³ in Yuexiu, 0.95 ng/m³ in Panyu, and 0.91 ng/m³ in Conghua. The concentration of Pb was 33.0 ng/m³ in Yuexiu, 28.0 ng/m³ in Panyu, and 29.8 ng/m³ in Conghua. The differences of concentrations of As, Cd, and Pb among the three regions were not significant （P>0.05 for all）. The non-carcinogenic risk of Mn was the highest in Yuexiu and Panyu （HQ>1.0）, but it posed only health risks to children. There was no non-carcinogenic risk for heavy metals in PM_2.5 in Conghua. The carcinogenic risk values ??of As and Cd in three districts ranged from 3.7×10^-6 to 4.9×10^-5 which was higher than the acceptable risk level 10^-6 and had potential risk. Conclusion PM_2.5 pollution in Guangzhou urban area was relatively light, but heavy metal pollution can not be ignored. The combined effects of heavy metals on children's non-carcinogenic health risks should be highly valued.

Key words: PM_2.5, Heavy metals, Health risk assessment