Mercury levels rise in oceans

Man has pumped tens of thousands of tons of mercury into the world’s oceans in the last 500 years, nearly tripling the amount of the toxic heavy metal in sea water, according to a study published online Wednesday in the journal Nature.

The study, the first to be based on widespread and long-term sampling of ocean waters, found that the increase in mercury content in Earth’s waters follows the same pattern as the post-industrial increase in carbon dioxide in the planet’s atmosphere — an exponential rise often described as a “hockey stick” graph.