10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
Mercury Stable Isotope Compositions of PM2.5 in Chinese Cities
HONGMEI XU, Ruoyu Sun, Junji Cao, Xi’an Jiaotong University
Abstract Number: 32 Working Group: Aerosol Chemistry
Abstract Atmospheric pollution by fine particulates and mercury (Hg) in emerging economies is a serious environmental concern. Here, we present Hg concentrations and isotope compositions during one month (January 2014) of 24-hour integrated fine particulate matter (PM2.5) samples from four large Chinese cities (Beijing, Changchun, Chengdu and Hong Kong) to identify Hg sources and transformation processes. Mean concentrations of PM2.5 (171±62 μg m-3) and PM2.5-bound Hg (1.3±1.1 ng m-3) in Chengdu were the highest. Overall, PM2.5 samples were characterized by moderately negative δ202Hg (-1.08±0.64‰, 1σ, n=64), slightly negative Δ199Hg (-0.13±0.28‰, 1σ, n=64) and insignificant Δ200Hg (0.03±0.05‰, 1σ, n=64). On average, δ202Hg of PM2.5 was the highest in Chengdu (-0.74±0.67‰, 1σ, n=29), followed by Beijing (-1.11±0.26‰, 1σ, n=17) and Changchun (-1.60±0.45‰, 1σ, n=18). PM2.5 from Beijing showed the most negative Δ199Hg (-0.31±0.40‰, 1σ, n=17) that was significantly lower than Changchun (-0.12±0.21‰, 1σ, n=18) and Chengdu (-0.02±0.15‰, 1σ, n=29). Coal combustion and cement production were identified to be the dominant sources of PM2.5-bound Hg in these cities, with additional Hg sources from non-ferrous metal smelting in Chengdu. Besides, Hg emissions from biomass burning were evident during short periods. The negative Δ199Hg and near-unity slope of Δ199Hg vs. Δ201Hg in PM2.5 from different cities indicate that the PM2.5-bound Hg was extensively photo-reduced in the local atmosphere following emission from sources.