Isotopic composition for source identification of mercury in atmospheric fine particles

Q. Huang, J. B. Chen, W. L. Huang, P. Q. Fu, B. Guinot, X. B. Feng, L. H. Shang, Z. H. Wang, Z. W. Wang, S. L. Yuan, H. M. Cai, L. F. Wei (+1 others)
2016 Atmospheric Chemistry and Physics Discussions  
The usefulness of mercury (Hg) isotopes for tracing the sources and pathways of Hg (and its vectors) in atmospheric fine particles (PM<sub>2.5</sub>) is uncertain. Here, we measured Hg isotopic compositions in 30 potential source materials and 23 PM<sub>2.5</sub> samples collected in four seasons from the megacity Beijing (China), and combined the seasonal variation of both mass-dependent fractionation (represented by the ratio <sup>202</sup>Hg/<sup>198</sup>Hg, δ<sup>202</sup>Hg) and
more » ... p>Hg) and mass-independent fractionation of isotopes with odd and even mass numbers (represented by Δ<sup>199</sup>Hg and Δ<sup>200</sup>Hg, respectively) with geochemical parameters and meteorological data to identify the sources of PM<sub>2.5</sub>-Hg and possible atmospheric particulate Hg transformation. All PM<sub>2.5</sub> samples were strongly enriched in Hg and other heavy metals, and displayed large ranges of both δ<sup>202</sup>Hg (&minus;2.18 to 0.51 ‰) and Δ<sup>199</sup>Hg (&minus;0.53 to 0.57 ‰), and small positive Δ<sup>200</sup>Hg (0.02 to 0.17 ‰). The results indicated that the seasonal variation of Hg isotopic composition (and elemental concentrations) was likely derived from variable contributions from the anthropogenic sources, with continuous input due to industrial activities (e.g. smelting, cement production and coal combustion) in all seasons, while coal combustion dominated in Winter and biomass burning mainly in Autumn. The significant positive Δ<sup>199</sup>Hg of PM<sub>2.5</sub>-Hg in Spring and early Summer was likely derived from long-range transported Hg that had undergone extensive photochemical reduction. The study demonstrated that Hg isotopes are a powerful tool for tracing the sources of particulate Hg and its vectors in the atmosphere.
doi:10.5194/acp-2016-363 fatcat:e6u26eniqjapdgl4a36poja3uq