An international team of scientists from Germany, Brazil and Croatia has found that the toxicity of heavy metals entering the ocean increases as seawater warms. The study was published in the scientific journal Communications Earth & Environment (CEE).
Toxic trace elements such as lead, mercury, arsenic and cadmium occur naturally in small quantities in coastal waters.
In the new study, the team looked at how climate change is affecting the distribution and accumulation of these substances, and how it might affect them in the future.
Experts summarized the findings of the UN Joint Panel of Experts on the Scientific Aspects of Marine Environmental Protection, which is studying metal pollutants in the ocean.
Warmer water temperatures increase the uptake of mercury and other toxins by marine organisms, the analysis found. This occurs due to increased metabolism, decreased oxygen solubility, and increased gill ventilation in fish and other animals.
As the ocean absorbs most of the carbon dioxide released by humans, it becomes more acidic. Because of this, the solubility and bioavailability of copper, zinc and iron in water increases. The effect is especially pronounced in the case of copper, which is very toxic to many aquatic life in high concentrations.
In addition, increasing oxygen depletion in coastal areas and on the seabed increases the toxic effects of trace elements. This puts stress on bottom-dwelling organisms, including mussels, crabs and other crustaceans, the report's authors noted.
