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Biogeochemical cycle of Hg in water and sediment in the Scheldt estuary and the Belgian Coastal Zone (BCZ).

Thursday 6th May, 4 PM CET

Tianhui Ma

Abstract: Mercury (Hg) is one of the primary health concerns in natural and urbanised environments. Coastal and estuarine zones are often sites of high Hg contamination due to the input from anthropogenic sources and the biogeochemistry of these systems. The Belgian Coastal Zone (BCZ) is a long-term, recurrent metallic pollution by atmospheric deposition, direct wastewater discharge from coastal industries and input of the Scheldt Estuary which is enriched in trace metals from the industrial site of Antwerp. In order to assess Hg contaminants in the Scheldt Estuary and the BCZ, a passive sampling technique: Diffusive Gradients in Thin-films (DGT) was used. It is a powerful tool to measure the bioavailable fraction of Hg in water and sediment porewater. Hg concentrations, distributions between different phases and fluxes between water and sediment systems are studied. Sediment can be seen as a sink for Hg and a source of Hg to surface water as well. A Belgica campaign took place in March of 2020, the Hg concentrations changing with salinity in water along the estuary, while the exchange of Hg between solid and dissolved phases can affect the labile Hg concentration both in water and sediment.