I had a conversation the other day with a friend of mine who is an environmental attorney. I was telling her about the Environmental Protection Agency’s regulations to reduce mercury emissions from coal burning power plants. Her area of legal expertise is not air regulation so it was news to her that the Environmental Protection Agency had written and issued the regulations. Actually her area of expertise is international environmental law. She asked me a very logical question coming from someone who has a global perspective. What portion of global emissions is coming from the U.S. compared to countries like China who burn lots more coal than the U.S. and who have about zilch in the way of emission controls. I said mercury emissions from the U.S. are pretty small in comparison to the industrializing countries like China and on top of that the largest mercury air emissions are actually coming from small gold mining operations in Africa and South America. Yes, can you believe it? It is the 21st century and yet these mostly unregulated and often illegal mining operations are still using mercury to produce gold.
Go back to my previous blog post on “Where is All This Mercury Coming From?” and take a look at the chart showing mercury emissions over the last couple of hundred years. You will notice a big old slug of mercury air emissions between the years of 1850 to 1884. Those were the years of the Gold Rush. If you are an American, you will probably have studied the Gold Rush in school. The famous location where it all started was Sutter’s Mill on the South Fork of the American River in Coloma, California. James Marshall’s discovery of gold in the South Fork at Sutter’s Mill in 1848 is an iconic event in American History and Sutter’s Mill is now a California State Park. The event set off gold fever in the U.S. and thousands of people migrated west to try their luck at getting rich by mining gold. History books even have a name for these migrants – the 49ers. Yes, San Francisco named their football team after a bunch of gold miners.
As we have seen, mercury is a unique metal with some highly unusual properties. One of these properties is that it binds readily with other metals in what is called an amalgam. The 49ers learned pretty quickly that mercury was the perfect way to extract gold from the river sediments and the rock and soils they washed out of the Sierra hillsides through hydraulic mining. They washed the gold through mercury lined sluices and over mercury coated metal plates the size of houses. Mercury from these gold extraction processes can still be found today in the American River. Fortunately the use of mercury in gold extraction was replaced by another toxic favorite – cyanide. Cyanide has its problems but at least it degrades rapidly. Mercury is forever.
I took a look at the United Nations Environment Programme report “Global Mercury Assessment 2013: Sources, Emissions, Releases and Environmental Transport.” According to the report, small gold mining operations are now the largest source of man-made mercury emissions. The U.N. has calculated contributions from world-wide mercury sources to annual mercury emissions. The numbers in the report are from 2010. In 2010 global estimates were 1960 tons of mercury released into the air. Seven hundred and twenty seven tons of the mercury came from small gold mining operations. That is 37 percent of all mercury emissions. Worldwide in 2010 only 475 tons of mercury came from burning coal in power plants. Sure that is a big figure too. Twenty four percent of all annual emissions in 2010 came from power plants. It is the second biggest source.
Here’s the answer to my friend the environmental attorney. The whole of North America (remember Canada and Mexico are included in with the U.S.) only contributed 60.7 tons or 3.1 percent of mercury to the global atmosphere. That is from all sources, not just power plants. Even the European Union contributed more mercury to the atmosphere (4.5 percent). What about China. There were not specific numbers for China in the U.N. report, but Asia contributed nearly 50 percent of the global mercury emissions. East and Southeast Asia were 40 percent and South Asia was 8 percent.