Mercury concentration and isotopic composition on different atmospheric particles (PM_(10) and PM_(2.5)) in the subtropical coastal suburb of Xiamen Bay, Southern China

摘要

The concentration and isotopic composition of particulate-bound mercury (PBM) on both PM_(2.5) and PM_(10) were simultaneously measured (24 months) in a typical subtropical coastal suburb of Xiamen bay (SCXB), southern China. The results showed that most mercury was concentrated in PM_(2.5) and small particulates enriched heavier isotopes of mercury more than lighter ones. Negative △~(199)Hg values and slightly positive △~(200)Hg values were observed in both PM_(2.5) and PM_(10). PBM input sources were identified with isotopic compositions and meteorological data using the NOAA HYSPLIT model. It revealed that biomass combustion is the main source of paniculate mercury in SCXB, and the two other sources are urban anthropogenic emissions and potential marine sources. Seasonal variations in isotopic com- position and correlation analysis suggested that PBM in SCXB mainly originate from inland after long-distance transportation in spring and under the influence of oceanic air masses in summer. The △~(199)Hg/△~(201)Hg ratios in all samples (1.01 ± 0.05, 2SE) indicated that the photoreduction of Hg(Ⅱ) in the aerosol was the main reaction process of PBM transformation in the atmosphere. Seasonal variations in △~(200)Hg values were also found, indicating the possibility of even mass independent fractionation in tracing the mercury sources.