Recent mercury pollution on the rise, but quick to change, study shows

The analysis showed that the first major mercury pollution peak occurred during the North American Gold Rush of the late 19th century when mercury was used to extract gold and silver from ores and sediments. Following the end of the Gold Rush, mercury levels quickly returned to near natural levels. Starting in the middle of the 20th century, mercury pollution began an unprecedented increase to maximum levels in the early 1970s, most likely due to industrialization in the United States and Europe. Mercury pollution decreased through the late 1970s and 1980s as mercury was removed from many commercial products and emissions regulations were enacted in North America and Europe. But the ice core shows a renewed increase in mercury pollution since the early 1990s until the record ends in 1998 due to the rise of coal burning in Asia and small-scale gold mining in developing countries that is thought to have continued through at least 2008.
http://dailygreenworld.com/2015/09/07/recent-mercury-pollution-on-the-rise-but-quick-to-change-study-shows/