Increased carbon dioxide levels due to human activities elevate terrestrial mercury levels.

Natali, SM, SA Sañudo-Wilhelmy, RJ Norby, H Zhang, AC Finzi and MT Lerdau. 2008. Increased mercury in forest soils under elevated carbon dioxide. Oecologia online 4 September.

What do global warming, carbon footprint, and fossil fuel dependent energy systems really mean for human health? A recent study of mercury deposition in atmospheres with elevated carbon dioxide levels suggests that it could mean higher levels of mercury in our soil and ground in the future. Specifically, scientists found a thirty percent increase in the concentration of mercury in the soil of forests with artifically elevated carbon dioxide levels. By carefully eliminating all possible external sources of mercury which could be accounting for this increase, the authors conclude that the elevated carbon dioxide levels most likely cause changes in the soil chemistry that increase its ability to retain or store mercury, rather than increased deposition of atmospheric mercury. Thus, this study suggests that human activities that affect global warming may influence the planetary mercury cycle in two ways. First, coal burning releases mercury into the atmosphere, thus continued use of fossil fuels for our energy needs will increase the mercury present in our atmosphere. Secondly, elevated CO2 levels produced by fossil fuels affect the chemistry of ground and soil, leading to elevated absorption of mercury. While this research is preliminary, the outcome suggests potential consequences on ground level pollution, potentially impacting both the quality and supply of food and water.