Gustavo A. B. da Fonseca is Director of Programs, Global Environment Facility.
I spent many fond moments as a child letting captive mercury droplets swirl from the palm of my hand to another as I waited for my father, a dentist, to finish working on his last patient of the day.
The element that goes by the symbol Hg in the periodic table of elements (from the Greek word hydrargyrum, or “liquid silver”) is still widely employed in fillings of dental cavities in the form of an amalgam with a blend of other metals. It has also found a breath of uses in the modern world including medicine, industrial manufacturing of chlorine, plastics, compact florescent lights and gold production.
It took a major calamity to wake society up to the health hazards brought about by the carefree use and handling of mercury. In 1956, at a remote fishing village of Japan, where a chemical plant was, for decades, dumping loads of mercury into the Minamata bay, the large-scale poisoning of people and animals was bought to the attention of the wider public.
Mercury bioaccumulates in the environment through the ingestion of food and water. Over time, the element then concentrates in individual organisms then through the contamination of their immediate environment. Described as the Minamata disease, this form of severe mercury poisoning is a debilitating neurological syndrome caused by the consumption of marine organisms heavily contaminated with mercury.
Because it can be easily vaporized, mercury can be transported through the air over large distances far removed from its original source of emission. With a significant amount of mercury being emitted as a bi-product of industrial processes such as coal burning, along with metal and cement manufacturing, it has now reached even the most remote corners of the planet, making its way into the air we breathe and the food we eat.
Small-scale gold mining is now the largest source of mercury released into the environment, being responsible for 37% of all global emissions. Mercury readily dissolves gold to form an amalgam, and as such is used for extracting the precious metal from gold bearing ores and sediments.
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