Man-made mercury levels in oceans triple
The amount of mercury near the surface of many of the world’s oceans has tripled as the result of our polluting activities, a study published Wednesday in the journal Nature show.
The increased levels of the toxic element, warn the researchers from Ohio’s Wright State University, may have serious implications for marine life, adding that further research could yield more advice on the potential angers to human health.
“This information may aid our understanding of the processes and the depths at which inorganic mercury species are converted into toxic methyl mercury and subsequently bioaccumulated in marine food webs,” the academics the prestigious Woods Hole Oceanographic Institution (WHOI) said in a statement.
The group found that mercury accumulation in the surface layers of the seas is happening faster than in the deep ocean, as humans pour the element into the atmosphere and seas from a variety of sources, including gold mining, coal-fired power plants and sewage.
Mercury is known for being toxic to humans and marine life, and accumulates in people’s systems over time as they are exposed to sources of it.
"It would seem that, if we want to regulate the mercury emissions into the environment and in the food we eat, then we should first know how much is there and how much human activity is adding every year," said WHOI marine chemist Carl Lamborg, who has been studying mercury for 24 years.
"At the moment, however, there is no way to look at a water sample and tell the difference between mercury that came from pollution and mercury that came from natural sources. Now we have a way to at least separate the bulk contributions of natural and human sources over time,” he added.
The north pole and the Arctic circle, because of the winds and ocean currents, are in an area where many pollutants released elsewhere across the globe accumulate: top predators such as polar bears have been found to have high levels of toxins in their bodies as a result. Indigenous Arctic peoples sometimes eat these animals.
“In the Arctic and Antarctic, you will be starting to see some of this now,” he said. “But with deep-sea fishing in the tropics you will not see it yet, but you will see it within a hundred years.”
Mercury emissions from coal-fired power plants can be reduced by using chemical filters, but while this is increasingly the norm in the rich world many developing countries have yet to catch up. Another source of the metal is from sewage. Developed countries have means to reduce this impact, but again developing countries are less likely to have in place the treatment systems necessary.
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