China, it turns out, is responsible for a lot of the mercury that's deposited into the Great Lakes.
That little fact was an aside in a press release I received today from the International Joint Commission, an organization that advises the US and Canadian governments on matters relating to shared water bodies. A 2011 report from the US National Oceanic and Atmospheric Administration estimated that 14 percent of the mercury in the Great Lakes basin came from China, second only to the 32 percent from the United States. Canada was only responsible for 3 percent.
Coal-fired power plants and industrial facilities are the major source of the mercury, which is spewed into the air when the coal is burned. Once it's in the atmosphere, the mercury can travel very long distances, which is how it winds up in the air around the Great Lakes and, subsequently, in the lakes themselves.
Thankfully, the US is cutting its use of coal; economics, pollution, and efforts to address climate change are playing a part in the fuel's decline.
In the press release, the IJC says it's concerned that some Great Lakes fish in some regions are showing up with increasing concentrations of mercury in their bodies. And it's worried that, in the future, some fish species may see more mercury in their bodies due to "significant increases in coal burning in Asia."
The IJC recommends that the Canadian and US governments commit to stable, long-term funding to monitor mercury deposition in the Great Lakes from the atmosphere. Between 1996 and 2010, there were 50 mercury monitoring sites across the Great Lakes. But 20 of those sites were out of commission by 2013. The IJC says that an adequate monitoring network would cost an estimated $250,000 a year.