Coal

After decades of decreases, mercury rises in Great Lakes wildlife

Scientists are seeing an uptick of the legacy toxic in Great Lakes fish and birds. Warming waters are the suspected culprit. More coal will make it worse.

GL Merc Source 2

SAULT STE. MARIE, MI — “Toxic mercury is once again increasing in some Great Lakes fish and birds after decades of consistent, promising reductions.

Scientists are still trying to figure out what’s going on, but one of the suspected culprits in reversing decades of mercury reductions in wildlife is a climate change-induced increase in water temperatures.

Mercury is a known toxic—in wildlife it impairs reproduction, growth, behavior, or just flat-out kills them.  The reports of increases are a surprise as there’s been steady progress on mercury since the 1970s. Fewer domestic coal plants, accountable for about half of U.S. mercury emissions, helped decrease pollution.

From the 1970s to the early 2000s, Great Lakes wildlife saw regular, consistent reductions in mercury loads.

But mercury travels the globe, and as coal has taken off in places such as Asia over the past 20 years so, too, has the atmospheric export of toxic mercury. Those additions have offset coal reductions in the U.S. and Europe. In addition, climate change is altering how legacy chemicals are stored, transformed and transported in land, water and air.

Warmer water more quickly converts mercury to its more toxic form—methyl mercury. This form also more quickly accumulates in fish and birds, with each step of the food chain more contaminated than the previous.”

— Brian Bienkowski, The Daily Climate

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