2023-05-08 14:45:47
Mercury causes a great environmental impact as it is present both in the air (atmosphere) and in bodies of water (hydrosphere) and in living organisms (biosphere). It accumulates mainly in terrestrial ecosystems, especially in soils. Regarding its origin, mercury emissions into the atmosphere do not only have an anthropogenic origin, but the global mercury cycle is also controlled by natural sources, such as oceanic or volcanic emissions.
An international study, co-led by researchers from the Higher Council for Scientific Research (CSIC) in Spain, shows that mercury levels in the Arctic increased in correspondence with the increase in temperature during the climate transition between the Last Glacial Cycle and the Holocene ( 16,000-10,000 years before present). In the current context of climate change, this work highlights the link between melting ice and the increase in natural emissions of mercury into the atmosphere and, therefore, with a greater risk for the ecosystems of the Arctic region.
Researchers have used ice cores from Greenland, as part of the international East Greenland Ice Core Project, to examine the relationship between past climate variations and mercury levels in the Arctic. The objective was to understand the natural sources that determine the biogeochemical cycle of mercury (a global pollutant and a toxic element for the nervous system of living beings). The results show that mercury levels in the Arctic region increased during the transition from the Last Glacial Cycle to the current climatic period, the Holocene (last 11,000 years), due to the reduction in ice cover caused by the increase in temperature. temperature.
“This work reveals that the deposition of mercury on the surface of the Arctic ice tripled at the beginning of the Holocene compared to the Last Glacial Cycle”, emphasizes Delia Segato, a researcher at the Ca’Foscari University of Venice in Italy and co-author of this study. . “Thanks to the analysis and interpretation of paleoclimatic archives and the development of a numerical model of the atmospheric chemistry of mercury”, continues Segato, “we have concluded that the loss of Arctic ice due to global warming produced 11,700 years ago is the main cause of the increase of mercury deposition in arctic ecosystems”.
Greenland area where the ice core was extracted. (Photo: East Greenland Ice-core Project)
“In the polar regions, sea ice plays a fundamental role in controlling natural mercury emissions into the atmosphere,” explains Alfonso Saiz-López, a researcher at the Rocasolano Institute of Physical Chemistry (IQFR) dependent on the CSIC, and one of the two coordinators of this study. In fact, continues Saiz-López, “it has been shown that perennial ice, sometimes several meters thick, prevents the transfer of mercury from the ocean to the atmosphere, which otherwise occurs given the volatile nature of this metal.” ”.
Due to current global warming, the perennial ice extent in the Arctic has been reduced by more than 50% since the middle of the last century. “This work suggests that future Arctic melting may lead to a greater escape of mercury from the ocean into the atmosphere, with the consequent risk for Arctic populations and ecosystems,” concludes Saiz-López.
The study is titled “Climate control on Arctic mercury variability during the Last Glacial Termination”. And it has been published in the academic journal Nature Geoscience. (Source: Alejandro Parrilla García / CSIC)
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