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Deciphering processes controlling the methylmercury burden in oxygen deficient coastal seas

Research project In the project we study how the chemical speciation of mercury, community structure of microbes producing methylmercury, and molecular composition of organic matter vary across static and dynamic pelagic redoxclines and clarify how these processes control methylmercury formation in the different redox zones.

Head of project

Project overview

Project period:

2018-01-01 2021-12-31

Funding

Formas

Carl Tryggers Stiftelse

Participating departments and units at Umeå University

Department of Chemistry

Research area

Chemical sciences, Environmental chemistry, Marine science

Project description

Mercury (Hg) accumulates in aquatic biota as neurotoxic methylmercury (MeHg) and is considered one of the top ten chemicals of public health concern. Oxygen deficiency is spreading in coastal waters and the global ocean and causes redox stratifications and pelagic redoxclines. This process could potentially increase the MeHg burden on the ecosystems and threat fishery as an ecosystem service in many regions. Quantitative predictions of an altered MeHg burden have been hindered by critical knowledge gaps on the control that pelagic redoxclines have on MeHg formation, flux and exposure to biota.

We combine key competences in Hg biogeochemistry and molecular biology and use recently developed state-of-the-art methodologies to resolve these long-term outstanding research questions. We characterize how the chemical speciation of Hg, community structure of microbes producing MeHg, and molecular composition of organic matter vary across static and dynamic pelagic redoxclines and clarify how these processes control MeHg formation in the different redox zones. We also study MeHg flux and exposure to biota. The studies are carried out in the Baltic Sea region, but the findings from the project will be applicable to many coastal and marine ecosystems.

The project serves society by providing the missing knowledge required to understand and predict how MeHg burdens in different marine ecosystems and geographical region can be impacted by declining oxygen in water.