Sunlight triggers the entry of poisonous mercury into polar lakes, but it also removes most of the toxic compound before fish can consume it, a new study suggests. The researchers warn that increased warming in the Arctic might upset this delicate balance.
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With spring, light returns to the Arctic after a long, dark winter. That polar sunrise, however, has a dark side. It triggers a burst of photochemical reactions that mobilizes atmospheric mercury, speeding its fall into arctic lakes, where fish can consume it.