The trouble with mercury

Researchers in the US have used laboratory simulations to reveal the two-faced nature of microbes that cycle toxic and less toxic mercury compounds in the environment. Microbial activity leads to the formation of highly toxic methylmercury. However, little is known about how environmental conditions and microbial activity generate less toxic forms.

Mercury has been distributed across the globe mainly because of the burning of coal, industrial activity and through natural processes such as volcanic eruptions. There are several different compounds of mercury found in sediments and water.

The team at the US Department of Energy's Oak Ridge National Laboratory have now shown that compounds from the decay of organic matter in aquatic settings can affect mercury cycling. They demonstrated that low concentrations of these compounds can chemically reduce mercury, but as those concentrations increase, the process is greatly inhibited.

'This study demonstrates that in anoxic sediments and water, organic matter is not only capable of reducing mercury, but also binding to mercury,' explains team member Liyuan Liang. 'This binding could make mercury less available to microorganisms for making methylmercury.' This research might one day lead to technology to address the global issue of mercury in global fish stocks and elsewhere.