Bromine and mercury, cycles and transport processes on the Antarctic plateau

The so-called atmospheric mercury depletion events (AMDE) are caused principally by reactions caused by bromine radicals and occur mainly in the coastal area of Antarctica. The discovery of these events also occurring on the plateau has pushed further study aimed at evaluating the physiochemical processes that characterise the mercury cycle in Polar Regions and its dependence on the cycles of halogen radicals. Reactions in the atmosphere can change the chemical form of mercury making it more soluble, bioavailable and potentially more dangerous for polar ecosystems. The objective of this project is to continue the measurement of mercury together with bromine and other halogens presents in the snow pack to understand better the deposition and re-emissions processes that occur on a daily and seasonal basis on the Antarctic plateau. We also hope to understand the scavenging role of precipitation and diamond dust. The chemistry of bromine is very active in coastal areas, in particular in zones with sea ice where production processes of Br radicals are highest; this in turn can affect the deposition of mercury. We hope to start to evaluate the processes governing the transport of air masses versus the interior of the continent, the hypothetical fractionation of Br compared to its abundance in seawater, and how these processes contribute to the deposition and distribution of Hg further inland in the Antarctic continent. These measurements will enhance our ability to understand the geochemical cycles of mercury in polar environments where the chemistry of Br seems to be a key component. This project is designed to continue and build upon the results of the PNRA Pd2013/AC3.03 project and complement with snow measurements the aims of ERANET planet and the GMOStral project of IPEV carrying out mercury air monitoring at 4 sites in the southern hemisphere, 2 in Antarctica, of which one is Concordia Station. The project proposal unites under one-umbrella experts on transport processes, as well as mercury and halogen chemistry and modelling.