Heavy metal toxicity in the ocean increases: How climate change will affect ocean pollutants

Toxic trace elements such as lead, mercury, arsenic, and cadmium occur naturally in small amounts in coastal waters. However, the contribution of human activities such as industry and agriculture is much greater.

A new study investigated how climate change is already affecting the distribution and accumulation of these elements, and how it may affect it in the future. One of the findings is that climate-related natural phenomena are releasing more pollutants, posing risks to both human and animal health. However, we still do not have enough knowledge about how these pollutants will behave in the future.

Ocean warming, acidification, and oxygen loss are well-known effects of climate change. How these changes are affecting ocean pollutants is less well studied. The new study, titled “Impacts of climate change on the transport, fate, and biogeochemistry of pollutants in coastal marine ecosystems,” investigates the interactions between trace elements and climate change. The results of this study were published in the journal Communications Earth & Environmental.

Climate change is releasing more pollutants

“We wanted to understand how trace elements are being affected by climate change, an area that has so far been little studied,” said GEOMAR Helmholtz Center for Marine Research. Dr. Rebecca Zitoun, a marine chemist and co-lead author of Keel, explains. I am working with my Croatian colleague Dr. Saša Marcinek at the Ružer Bošković Institute in Zagreb. “We investigated both anthropogenic and natural sources.”

Metals such as lead, mercury, and cadmium enter the oceans as well as through industry and human activities such as burning fossil fuels. Natural sources are also changing due to climate change. Rising sea levels, flooding and drying of rivers, melting of sea ice and glaciers, all these processes are mobilizing and increasing pollutant flows.

This study summarizes the findings of a working group of the Joint United Nations Group of Experts on Scientific Aspects of Marine Environmental Protection (GESAMP), which focused on marine metal pollutants.

The working group was founded by Dr. Sylvia Sander, Professor of Marine Mineral Resources at GEOMAR and former Director of the International Atomic Energy Agency’s (IAEA) Marine Environment Laboratory in Monaco. Christoph Fölker of the Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research (AWI) also contributed from Germany.

“Our working group has focused on the effects of climate change and greenhouse gases on marine pollutants,” explains Dr. Sander. An example of these effects is rising mercury levels in the Arctic Ocean. Melting glaciers, thawing permafrost, and coastal erosion are releasing more mercury from natural sources.

This poses a particular threat to communities that rely on traditional fishing, as mercury accumulates in the food chain and can end up on our plates by eating contaminated fish. .

Human sources of toxic metals

“Human activities have increased global emissions of toxic metals such as lead by a factor of 10 and mercury by a factor of 3 to 7 compared to pre-industrial times,” Professor Sander said. “Toxic elements like silver are increasingly being detected in coastal waters due to coal combustion and the increased use of silver nanoparticles in antimicrobial products.”

Additionally, transportation and the use of plastics also contribute to the spread of heavy metals. Plastics can bind metals such as copper, zinc, and lead from water. These combined contaminants can also enter the food chain.

In the future, increased ocean exploitation may further increase the anthropogenic contribution of heavy metals.

Trace elements in seawater are susceptible to climate change

Climate change, such as rising sea temperatures, ocean acidification, and oxygen depletion, affects trace elements in many ways.

Higher water temperatures increase the bioavailability and uptake of trace elements such as mercury by marine organisms. This happens because higher temperatures accelerate metabolism, reduce the solubility of oxygen, increase gill ventilation, and more metals enter the organism and accumulate in the body.

The ocean absorbs most of the carbon dioxide (CO2) that humans emit, making it more acidic and lowering pH levels. This increases the solubility and bioavailability of metals such as copper, zinc, and iron. This effect is particularly pronounced in the case of copper, which is highly toxic to many marine organisms at high concentrations.

In addition, the toxic effects of trace elements are increasing due to increasing oxygen depletion, especially in coastal areas and on the ocean floor. This puts stress on organisms that live directly on the ocean floor, such as mussels, crabs, and other crustaceans.

Double Burden: Pollutants and Climate Change

Human activities affect the amount of pollutants in coastal areas in two ways. One is direct, through the release of pollutants into the environment, and the other is indirect, through the effects of anthropogenic climate change on natural sources.

However, the study also found that there is still insufficient data on how climate change will affect marine pollutants. The working group calls for increased research on new and understudied pollutants. Furthermore, better models should be developed and legislation should be adjusted to improve the management of pollutant impacts in the ocean.

Dr. Zitoun said, “To better understand the impacts on ecosystems and human health, we need a standardized system that fills knowledge gaps on the interactions between pollutants and climate change and provides globally comparable data.” We need to develop methods.”

This is an important step towards strengthening ocean protection and developing sustainable solutions for vulnerable coastal areas.