At Harvard, Sunderland’s focus has been mercury pollution, a prime example of how the waste products people put into the oceans come back to harm human health. Mercury is a naturally occurring heavy metal that can be toxic to the nervous system of humans and other animals. Elemental mercury is most familiar to people in its liquid form, called quicksilver, but it also exists as a gas, and can interact with other chemicals to form organic and inorganic compounds. Most of the earth’s mercury stores are buried deep within the planet’s crust, but some is released to the environment naturally through processes such as volcanic activity, including through hydrothermal vents on the ocean floor. Humans have also been extracting and using mercury since antiquity; it’s been used to separate silver and gold from raw ore, and is present in many products, from batteries to light bulbs and paints.
Mercury is still used in mining. Small-scale, artisanal gold extraction, an informal industry practiced by an estimated 10 million to 19 million people in 70 countries, has become the biggest source of emissions today—one that causes grave pollution problems for local communities and ecosystems. Coal-fired power plants are another major source of oceanic mercury pollution. Annually, humanity burns several billion tons of coal. Thus, even though coal contains only trace amounts of mercury, the sheer volume combusted by humans—when combined with the metal’s unique properties—has created a global problem.
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