Wet deposition of total mercury at a suburban site in southern Italy (Calabria): Concentrations, fluxes and assessment of source areas

Accurate measurements of total mercury (HgT) in wet precipitation samples, collected in the suburban area of Cosenza (Southern Italy), over a 2-year period, from November 2013 to February 2016, were performed to study the distribution of rainwater HgT concentra ons and to evaluate the seasonal contribution of wet deposi on to the Hg flux . Precipitation samples were collected using a wet-only collector at the sampling site (39°21'N, 16°13'E, 217 m a.s.l.) inside the Campus of UniCal (University of Calabria) in Rende, Italy, following harmonized sampling procedures reported in the Standard Operating Procedures (SOPs) of the GMOS project. The volume weighted mean (VWM) of total mercury concentrations in 2014 and 2015 were 7.1 ± 3.9 ng L-1 and 15.1 ± 10.4 ng L-1 (mean ± SD), respectively, whilst the wet deposition flux of HgT in 2014 and 2015 were 6.1 ?g m-2 y-1 and 17.1 ?g m-2 y-1, respectively. Seasonal VWM HgT concentrations in 2014 shows highest values in spring followed by winter, summer, and fall. In 2015, VWM HgT concentrations were characterized by highest Hg levels in summer followed by spring, fall, and winter. In 2014, the wet deposition fluxes of HgT were in the order of spring > winter>fall>summer, while for the 2015 the largest wet deposition flux was observed in fall, due to the more abundant rainfall events, followed by winter, summer, and spring, respectively. In order to understand the potential mercury sources in precipitation during the period of this study, atmospheric pollutants (PM10, PM2.5, O3, NOx, SO2), local meteorological parameters, back trajectories (NOAA Hysplit) and satellite observation tools for wildfire/biomass burning events have been considered and their contribution was singled out. This work concerns Hg in wet deposition and an assessment of the occurrence and possible sources of rainwater HgT. This has been done using information that was not previously available to estimate the impact of mercury due to wet deposition in Southern Italy.