Abstract:
Objective To explore the composition and main sources of heavy metals pollution in atmospheric PM2.5 in the main urban area of Haikou.
Methods From 2020 to 2022, the atmospheric PM2.5 in the main urban area of Haikou was regularly monitored month by month, and the atmospheric PM2.5 samples were collected from 10th to 16th days of each month, and the daily sampling time was not less than 22 hours. Twenty-five heavy metals in PM2.5 samples were measured by inductively coupled plasma mass spectrometry (ICP-MS). Main sources of sixteen heavy metals in PM2.5, which have high detection rate in PM2.5 were analyzed by positive matrix factorization model (PMF).
Results During 2020 to 2022, the median and quartile range of PM2.5 mass concentrations was 17.00 (14.25)μg/m3, mass concentrations of PM2.5 ranged from 4.00 to 64.00 (20.48±12.88)μg/m3, and there was no statistically significance yearly difference in the PM2.5 24-hour average concentrations (χ2=1.24, P>0.05). The PM2.5 24-hour average concentrations had a statistically significant quarterly difference (χ2=44.86, P < 0.01), which was highest in winter, followed by autumn and spring, and lowest in summer. The mass concentrations of the sixteen heavy metals ranged from 0.01-1 008.00 ng/m3, and the medians of mass concentrations in sixteen heavy metals were Fe>Al>Zn>Mn>Pb>Ba>Cu>Sr>Ni>Se>V>As>Sn>Cr>Cd>Li from the highest to the lowest. The analysis results of PMF model showed that the main contribution sources of sixteen heavy metals in the main urban area of Haikou were road and soil dust (49.82%), traffic exhaust (36.96%), mixed combustion (9.61%), construction dust (2.51%), and ship oil combustion (1.10%).
Conclusion The mass concentrations of atmospheric PM2.5 in Haikou from 2020 to 2022 is lower than the 24-hour average concentration secondary limit value (75 μg/m3) of the Ambient Air Quality Standards (GB 3095-2012). The heavy metals in PM2.5 are mainly Fe, Al, Zn, Mn and Pb. The main contribution sources are road and soil dust sources and traffic exhaust sources.