Natural stable isotopic compositions of mercury in aerosols and wet precipitations around a coal-fired power plant in Xiamen, southeast China

In this study, samples of 18 wet precipitations (WPs) and 38 aerosols were collected around a coal-fired power plant (CFPP) located in Xiamen, southeast China, which was equipped with a seawater flue gas desulfurization system. Total particulate mercury (TPM) in aerosol samples, and total mercury (WP-TM), dissolved mercury (WP-DM) and particulate mercury (WP-PM) in WP samples were analyzed for the natural isotopic compositions of mercury. For the first time, both mass dependent fractionation (MDF) and mass independent fractionation of odd (odd-MIF) and even (even-MIF) isotopes of WP-DM and WP-PM were reported and discussed. Both WP-TM and TPM displayed negative MDF and slightly positive even-MIF. Negative odd-MIF was observed in TPM and WP-PM, whereas positive odd-MIF was observed in WP-TM and WP-DM. It was found that the mercury budget in WP-PM samples was mainly controlled by atmospheric particles. Potential sources of mercury in samples were identified via analysis of mercury isotopic signatures and meteorological data with the NOAA HYSPLIT model. The results showed that TPM and WP-PM in solid samples were homologous and the isotopic compositions of WP-TM depended on those of WP-DM. The ratios of Δ199Hg/Δ201Hg resulting from photochemical reactions and positive Δ200Hg values (from -0.06‰ to 0.27‰) in all samples indicated that the mercury coming from local emission of the CFPP together with long-distance transportation were the two main contributing sources.