Mercury loads into the sea associated with extreme flood

Review of Mercury Circulation Changes in the Coastal Zone of Southern Baltic Sea

“…The high water level, persisting for a long time, apart from washing of Hg out of land, contributed to the deposition of suspension (enriched with mercury) close to and in the riverbed. This is of considerable significance as, under the influence of another rise in the water level, either due to a flood, flooding, or seasonal meltdown, it is very likely that mercury, in the form of methylmercury (the most toxic form), will be released from the bed and transported into the sea [27,39,40]. Such a situation was observed in July and September 2010 [25].…”

“…The mercury introduced into the coastal zone of the sea during the flood in 2010 was adsorbed by phytoplankton, contributing to a fourfold increase in its concentration in algae in the period between two flood waves reaching the Gdansk Basin, compared to the period before and after the flood [27]. Mercury bound to the fine sediment fraction, particulate suspended matter, and in its dissolved form was transported by the strong flood current from the river mouth far into the southern Baltic.…”

“…As a consequence, the concentration of Hg in the sediments of the southern Baltic following the flood increased by as much as 500% compared to the period before the flood and, in relation to the fine fraction content, by as much as 1500%. This state persisted for nearly 2 years [27].…”

“…During the largest flood (2010) on the River Vistula, within a relatively short time (31 days), 1.2 tonnes of Hg penetrated into the Baltic, amounting to 75% of the annual load in 2010 [27]. Such a large mass of mercury introduced was caused not only by the large volume of water (12 km 3 , which amounted to 21% of the yearly flow of the Vistula) but also by a several-fold increase in the Hg concentration compared to the time before the flood ( Figure 5).…”

Factors determining the accumulation of pentachlorophenol — a precursor of dioxins in bottom sediments of the Gulf of Gdańsk (Baltic Sea)

“…Sediment samples in the present study were collected in 2011 and as reported by Saniewska et al (2014), the levels of other contaminants (e.g. heavy metals) multiplied in this period as a consequence of the increased inflow of the river water into the Gulf of Gdańsk.…”