Environmental Health - Toxic Substances
Environmental Mercury Cycling and Global Change
Rising global temperatures and changing human actions will significantly affect the environmental distribution of mercury worldwide, according to a recent article in Science by U.S. Geological Survey (USGS) and Harvard University scientists. Higher temperatures and weaker air circulation patterns from climate change will likely have significant impacts on the atmospheric lifetime and patterns of mercury deposition.
In most climate change scenarios, storms will be less frequent but more intense, resulting in larger amounts of mercury being released from the soil through erosion that may end up in rivers, lakes and oceans, the scientists said. mercury that reaches these surface waters, can be processed by naturally occurring bacteria into methylmercury an extremely toxic form of mercury that bioaccumulates in the food web.
A majority of present mercury releases to the environment are atmosphere emissions from human activities and reemissions of previously deposited mercury from soils and the oceans. The largest sources of man-made mercury emissions are small-scale gold mining and burning coal for electrical generation.
Changes in human behavior also will have substantial impacts on global mercury, according to the scientists. Current human emissions of mercury total 2,000 metric tons per year. Under the best-case scenario of curbing human emissions, that number could fall to 800 metric tons per year by 2050. If no actions are taken, the number will likely increase to 3,400 metric tons per year by 2050.
"The intersection of the complex behavior of mercury in the environment with the myriad of aspects of global change provided a significant challenge to describe in this paper," said USGS scientist David Krabbenhoft, the article’s lead author. "Although the science behind mercury research has exponentially increased in the past couple decades, providing reliable information to resource managers and decision makers on such complex topics remains a significant research challenge."
This study was funded by the USGS Toxic Substances Hydrology Program and Department of Environmental Health, Harvard University.
Krabbenhoft, D.P., and Sunderland, E.M., 2013, Global change and mercury: Science, v. 341, no. 6153, p. 1457-1458, doi:10.1126/science.1242838.