Mercury in suspended matter of the Gulf of Gdańsk: Origin, distribution and transport at the land-sea interface.

The coastal regions of inland seas are particularly vulnerable to Hg pollution. An important carrier of toxic Hg in the marine environment is suspended matter originating from multiple sources. The present study was conducted in the Gulf of Gdańsk and its adjoining land in the years 2011-2013. The results indicated that the Hg (Hg bound with suspended particulate matter) concentrations varied horizontally and vertically and were dependent on the water dynamics and the composition of organic matter. Conditions favourable for the accumulation of matter and adsorption of reactive gaseous mercury led to increasing Hg levels, which are especially hazardous in the case of semi-enclosed areas such as estuaries. These conditions also increase the Hg loads into the trophic chain through suspension feeders. Moreover, the Hg concentration was significantly affected by seasonal phenomena (mainly coastal erosion) and the quantity and quality of primary production (phytoplankton blooms, mainly Mesodinium rubrum).