The ocean is warming, acidifying and losing oxygen; well-documented effects of climate change. But less attention has been paid to how these changes affect marine pollutants. A new study investigated the interaction of trace elements with climate change. The findings were published in the journal Nature Contact Earth and Environment.
Climate events cause more pollution
Dr. D., a marine chemist at the GEOMAR Helmholtz Center for Ocean Research in Kiel and co-author of the study. “We wanted to understand how climate change affects micronutrients, an area that has been understudied to date,” explains Rebecca Zitun. His Croatian colleague, Dr. from the Ružer Bošković Institute in Zagreb. Saša Marcinek. “We explored both anthropogenic and natural sources.”
Metals such as lead, mercury and cadmium do not enter the oceans only through human activities such as industry or the burning of fossil fuels. Natural resources are also changing due to climate change: rising sea levels, flooding or drying of rivers, melting of sea ice and glaciers – all these processes stimulate and increase pollutant flows.
The study summarizes the findings of a working group of the United Nations Joint Panel of Experts on Scientific Aspects of the Marine Environment (GESAMP) focused on metal pollutants in the oceans. The working group was led by Dr. Professor of Marine Mineral Resources at GEOMAR and former Head of the International Atomic Energy Agency (IAEA) Marine Environmental Laboratories in Monaco. Started by Sylvia Sander. Christoph Felker from the Alfred Wegener Institute and the Helmholtz Center for Polar and Marine Research (AWI) also contributes from Germany.
Dr. “Our working group focused on the effects of climate change and greenhouse gases on pollutants in the ocean,” Sander explains. One example of these effects is the increase in mercury levels in Arctic waters: melting glaciers, thawing permafrost, and coastal erosion lead to the release of more mercury from natural sources. This poses a particular threat to communities that rely on artisanal fishing, as mercury accumulates in the food chain and can reach our plates through the consumption of contaminated fish.
Sources of metals toxic to humans
“Human activities have increased the global flow of toxic metals such as lead and mercury by three to seven times compared to pre-industrial levels,” says Professor Sander, giving another example. “Toxic elements such as silver are increasingly being detected in coastal waters due to coal burning and the increasing use of silver nanoparticles in antibacterial products.” Additionally, the transportation and use of plastics also contributes to the spread of heavy metals. Plastics can bind metals such as copper, zinc and lead in water. These bound contaminants can also enter the food chain.
In the future, the human contribution of heavy metals may increase further due to increased use of the oceans.
Trace elements in seawater are sensitive to climate change
Climate changes such as rising sea temperatures, ocean acidification, and oxygen depletion affect micronutrients in a variety of ways.
Higher water temperatures increase the bioavailability and uptake of trace elements such as mercury by marine organisms. This is because high temperatures accelerate metabolism, reduce oxygen solubility, and increase gill ventilation, leading to more metals entering and accumulating in their bodies.
Since the ocean absorbs most of the carbon dioxide (CO 2 ), released by a person, becomes more acidic – the pH level decreases. This increases the solubility and bioavailability of metals such as copper, zinc or iron. This effect is especially pronounced with copper, which is highly toxic to many marine organisms at high concentrations.
In addition, increasing oxygen deficiency, especially in coastal areas and on the seabed, increases the toxic effect of trace elements. This creates stress for organisms that live directly in or on the seabed, 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: directly, through the release of pollutants into the environment, and indirectly, through the effects of human-induced climate change on natural resources.
But the study also shows that there is still not enough data on how climate change affects pollutants in the oceans. The working group calls for increased research into new and understudied pollutants. In addition, better models should be developed and legislation should be amended to improve the control of marine pollutants.
Dr. Rebecca Zitun: “To better understand impacts on ecosystems and human health, we need to address knowledge gaps about interactions between pollutants and climate change and develop standardized methods that provide globally comparable data.” This is an important step towards strengthening marine protection and developing sustainable solutions for sensitive coastal areas.
Source: Port Altele
