Dissolved gaseous mercury production and sea-air gaseous exchange in impacted coastal environments of the northern Adriatic Sea

Research reveals that dissolved gaseous mercury (DGM) production and sea-air exchange in the northern Adriatic Sea, impacted by historical Hg mining, are influenced more by water temperature and mixing conditions than DGM concentrations alone. While a highly contaminated fish farm (Val Noghera, Italy) showed substantial DGM production (126.0–711.3 pg L−1), driven by photoreduction and biotic processes, an open coastal zone (Bay of Piran, Slovenia) exhibited lower DGM levels (21.8–183.4 pg L−1). Surprisingly, Hg fluxes at both sites were comparable (VN: 7.43–41.17 ng m−2 h−1; PR: 0–81.49 ng m−2 h−1), attributed to enhanced gaseous exchange in the open coastal zone and stagnation-related limitations in the fish farm. The study, using a floating flux chamber and real-time Hg0 analyser, underscores that static saltwater conditions hinder Hg volatilisation, potentially increasing mercury availability for methylation and trophic transfer.

Floreani, F., Barago, N., Klun, K., Faganeli, J., & Covelli, S. (2023). Dissolved gaseous mercury production and sea-air gaseous exchange in impacted coastal environments of the northern Adriatic Sea. Environmental Pollution, 332, 121926. https://doi.org/10.1016/j.envpol.2023.121926