"Mercury found in high levels in deep Pacific Ocean fish such as swordfish has a chemical fingerprint, and it implicates coal-burning power plants in Asia, according to a new study."
"A research team from the universities of Hawaii and Michigan looked at mercury in the flesh of nine species common to the massive North Pacific Subtropical Gyre, the largest ecosystem on the planet, at 7 million square miles.
Four years ago, the team found that mercury levels in such fish as tuna increased with the depth of the fish’s habitat. This time, they set out to find out why, and what forces were at play. On the way, however, they found evidence implicating coal. The results were published online in Nature Geoscience."