How climate change impacts contaminants in the sea
The ocean is warming, becoming more acidic, and losing oxygen – these are well-known effects of climate change. What has been less studied is how these changes are affecting contaminants in the seas. A new study titled “Impacts of Climate Change on the Transport, Fate, and Biogeochemistry of Contaminants in Coastal Marine Ecosystems” has investigated the interaction of trace elements with climate change. The findings have been published in the Nature journal Communications Earth & Environment.
Climate Events are Releasing More Contaminants
“We wanted to understand how trace elements are being affected by climate change – an area that has seen very little research so far,” explains Dr Rebecca Zitoun, marine chemist at GEOMAR Helmholtz Centre for Ocean Research Kiel and co-lead author of the study alongside her Croatian colleague Dr Saša Marcinek from the Ruđer Bošković Institute in Zagreb. “We examined both human-induced and natural sources.” Metals such as lead, mercury, and cadmium enter the oceans not only through human activities such as industry or fossil fuel burning. Natural sources are also changing due to climate change: rising sea levels, rivers overflowing or drying up, melting sea ice and glaciers – all these processes mobilise and increase contaminant flows.
The study summarises the findings of a working group of the UN Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection (GESAMP) focusing on metal contaminants in the ocean. The working group was initiated by Dr Sylvia Sander, Professor of Marine Mineral Resources at GEOMAR and former head of the Marine Environmental Studies Laboratories at the International Atomic Energy Agency (IAEA) in Monaco. Christoph Völker from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) is also contributing from Germany.
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Trace Elements in Seawater are Sensitive to Climate Change
Climate changes, such as rising sea temperatures, ocean acidification, and oxygen depletion, impact trace elements in various ways.
Higher water temperatures increase the bioavailability and uptake of trace elements such as mercury by marine organisms. This happens because higher temperatures boost metabolism, reduce oxygen solubility, and increase gill ventilation, leading to more metals entering organisms and accumulating in their bodies.
As the ocean absorbs most of the carbon dioxide (CO2) released by humans, it becomes more acidic – the pH level drops. This increases the solubility and bioavailability of metals such as copper, zinc, or iron. The effect is particularly pronounced with copper, which is highly toxic to many marine organisms at higher concentrations.
Furthermore, the growing depletion of oxygen, especially in coastal zones and on the seabed, enhances the toxic effects of trace elements. This stresses organisms that live directly in or on the seabed, such as mussels, crabs, and other crustaceans.
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Helmholtz Centre For Ocean Research Kiel (GEOMAR) (via EurekAlert!), 9 October 2024. Press release.
