Deposition of Mercury Species in the Ny-Ålesund Area (79°N) and Their Transfer during Snowmelt

Abstract

Arctic snowpacks are often considered as temporary reservoirs for atmospheric mercury (Hg) deposited during springtime deposition events (AMDEs). The fate of deposited species is of utmost importance because melt leads to the transfer of contaminants to snowmelt-fed ecosystems. Here, we examined the deposition, fate, and transfer of mercury species (total Hg (THg) and methylmercury (MeHg)) in an arctic environment from the beginning of mass deposition of Hg during AMDEs to the full melt of the snow. Following these events, important amounts of THg were deposited onto the snow surface with concentrations reaching 373 ng·L⁻¹ and estimated deposition fluxes of 200−2160 ng·m⁻². Most of the deposited Hg was reemitted to the atmosphere via photochemical reactions. However, a fraction remained stored in the snow and we estimated that the spring melt contributed to an input of 1.5−3.6 kg·year⁻¹ of THg to the fjord (i.e., 8−21% of the fjord’s THg content). A monitoring of MeHg in snow using a new technique (DGT sensors) is also presented.