Toxic mercury found in Antarctic sea ice: Australian study

Australian scientists have discovered a toxic form of mercury in the Antarctic atmosphere and sea ice.

The study, led by a team from the University of Melbourne, found significant amounts of methylmercury, an especially dangerous strain of mercury, in the Southern Ocean.

Caitlin Gionfriddo, a PhD student at the University of Melbourne who worked on the project, said the study reveals that methylmercury released by Antarctic ice into the ocean could be contaminating the food chain.

"There are high levels of methylmercury in our ecosystems, especially in the marine environment, but we don't know how it's being produced," Gionfriddo told a University of Melbourne publication on Tuesday.

"We're seeing it accumulate in the food web and most of it likely comes from atmospheric deposition of mercury onto sea water."

The research, published in the journal Nature Microbiology, said the atmospheric dumping of the mercury occurs all year but is most evident during the Antarctic spring when the most sea ice melts and releases the toxicant.

Researchers associated with the project expressed concerns that as global warming continues humans will be subject to greater exposure to mercury by consuming fish from the region.

Methylmercury can travel easily from the stomach to the bloodstream when ingested by humans, eventually reaching the brain and potentially causing developmental problems in fetuses, infants and children.

John Moreau, lead author of the study, said it is still unknown why the bacteria in methylmercury can cause developmental problems.

"After half a century of research, we still don't know why. Most people think it's just an accidental side reaction, some people think it's a reaction to toxicity," Moreau said.

The next step in the research is to study what environmental factors are creating the methylmercury and the extent of the contamination in Antarctic waters. Endit