Pollution characteristics of atmospheric particulate mercury near a coal-fired power plant on the southeast coast of China

Abstract

PM2.5 and PM10 samples were collected in a rural area from December 2014 to August 2015 near a coal-fired power plant on the southeast coast of China. The total mercury concentrations in PM2.5 ranged from 116.2 to 1070.9 pg/m3 and in PM10 from 173.4 to 1456.8 pg/m3, with averages of 309.5 ± 94.9 and 387.5 ± 133.5 pg/m3, respectively. These were much higher than those found in many foreign cities. The concentrations of mercury in PM2.5 and PM10 varied seasonally, with the highest average concentration in winter. This was probably due to the seasonal variation of meteorological conditions and concentration of particulates. The highest mass-based concentration of mercury in PM2.5 and PM10 was observed in spring. This result might be related to the prevailing sea winds in spring. The spatial variation of particulate mercury conformed to the concentration distribution characteristics of pollutant discharged from coal-fired power plant elevated source at the downwind area. The seasonal variation in the concentrations of the four mercury species (including exchangeable particulate mercury: EXPM, HCl-soluble particulate mercury: HPM, elemental particulate mercury: EPM, and residual particulate mercury: RPM) were all identical to the seasonal variation of total particulate mercury (TPM) in PM2.5 and PM10 (winter > spring > summer). Owing to the variation of meteorological conditions, the proportion of different mercury species in TPM followed different seasonal trends. In contrast to RPM, the percentage of both HPM and EPM in PM2.5 was higher than in PM10.