Dissolved Gaseous Mercury Production at a Marine Aquaculture Site in the Mercury-Contaminated Marano and Grado Lagoon, Italy.

Dissolved gaseous mercury (DGM) production was examined in relation to ultraviolet radiation within a marine aquaculture site in the contaminated Marano and Grado Lagoon (Italy). The measured rates of DGM production relative to time elapsed (17.06 and 20.68 pg h ^-1 , respectively) were substantially (6-20 times) higher than what has been observed in other marine Hg studies. We measured similar levels of DGM relative to dissolved total mercury (THg _D ) (0.84%-8.91%) at these sites in comparison to uncontaminated marine sites, however relative to other moderately-contaminated marine sites in Portugal the % DGM/THg _D was high. These results suggest a substantial capacity for Hg volatilization from these highly contaminated lagoons to the atmosphere due to photoreduction mechanisms.