Characterization of atmospheric arsenic wet deposition transport pathways and potential sources areas in the Pearl River Delta region.

This study tracked the characteristics of atmospheric wet deposition of the toxic element arsenic (As) at both urban (Guangzhou (GZ)) and forested (Dinghushan Natural Reserve (DHS)) sites within the Pearl River Delta (PRD) region between 2016 and 2019, examining its correlation with rainfall patterns. Additionally, by employing backward trajectory analysis and the potential source contribution function (PSCF) in conjunction with pertinent emission inventories, we pinpointed the main pathways of atmospheric arsenic transport and evaluated the emission contributions from priority source areas. The study revealed that the atmospheric arsenic wet deposition fluxes at the GZ and DHS sites exhibited a trend of increase followed by a decrease over the four-year period. Wet season deposition fluxes were more than triple those of the dry season, with urban site showing a difference of over four times. Notably, wet season As deposition at both sites was predominantly affected by heavy rainfall from marine air masses, constituting 31 % of the total deposition. The predominant trajectory directions contributing to arsenic deposition at GZ and DHS were northeast (55 %) and south (53 %), respectively. The primary source areas for both sites were largely outside the PRD region, with the GZ site having 80 % to 95 % of its source area in the non-PRD region, compared to 69 % to 88 % at the DHS site. Furthermore, non-PRD areas contributed approximately 65 % to arsenic emissions for both sites, with the industrial sector being the dominant emission source, exceeding 97 % of the total emissions.