A Simplified Approach to Modeling the Dispersion of Mercury from Precipitation to Surface Waters—The Bay of Kaštela Case Study

Abstract

Wet deposition is the main source of mercury (Hg) from the atmosphere to the Earth’s surface. However, the processes that govern the dispersion of deposited Hg in seawater are currently not well understood. To address this issue, total mercury (THg) concentrations in surface seawaters and precipitation were determined on a monthly basis in the Bay of Kaštela (Central Adriatic Sea). Following the assumption that deposited THg is diluted in the seawater bulk due to mixing processes, an exponential decay-like model was developed and the wet deposition of THg was normalized based on periods between precipitation events and seawater sampling. Normalized wet deposition of THg showed significant correlation with the THg gradient in surface seawater after removal of an outlier. To explain the observed outlier, further data normalization included wind data to account for enhanced seawater mixing due to strong winds. Wind-normalized THg deposition of all datapoints showed significant correlation with the THg gradient in surface seawater. The correlation showed that the THg gradient in surface seawater of 0.378 pg L−1 m−1 corresponds to THg wet deposition of 1 ng m−2 after including the influence of wind speed on seawater mixing.

Measurement of Atmospheric Mercury: Current Limitations and Suggestions for Paths Forward

“…The atmosphere is the primary pathway for the global transport of mercury (Hg) . The chemical form of Hg in the atmosphere determines how quickly it is removed through wet or dry deposition. , Deposition of atmospheric Hg results in contamination of surface waters and ecosystems, and can have adverse effects on human and wildlife health . To monitor and mitigate future effects of global Hg contamination, the Minamata Convention was ratified by 147 countries and entered into force in 2017, with the objective of “protecting human health and the environment from the adverse effects of mercury”…”