Atmospheric Arsenic Deposition in the Pearl River Delta Region, South China: Influencing Factors and Speciation.

This is a comprehensive study on mobilization/speciation and temporal/spatial variation of atmospheric arsenic (As) deposition in the Pearl River Delta (PRD) region. A set of experimental procedures was established for measuring the deposition fluxes of individual As species. The deposition carrying inorganic AsIII % was significantly higher than that contained in atmospheric particles. Compared with dry deposition, wet deposition was much more harmful to the regional ecosystem, as it contributed the majority of bulk deposition (>75%) and carried most of the mobilized iAsIII compounds. A stepwise linear regression model was utilized to identify the factors influencing total As deposition (wet: precipitation and PM2.5, dry: relative humidity, wind speed, and PM10, bulk: precipitation, PM2.5, and wind speed). By examining the representativeness of the study sites and comparison with the literature data, the statistic models were verified to explain the temporal/spatial variation of total As deposition in the entire PRD region, where significant seasonal variation was only found for wet deposition (wet season > dry season). The annual As load contributed from regional atmospheric deposition increased from 2013 to 2015, when the contributions of individual cities varied annually.