They went to the biggest dumpyard in the country where children lived amidst burning trash, scavenging for metal.

FORBES: The Disease of More

Dr McConnell believes the picture of the last few years captured by his Greenland core suggests this renewed interest in coal burning is leading to an upturn in heavy metal input to the part of the Arctic he has studied.

BBC: Coal's toxic legacy to the Arctic

Mercury can be released into the environment through a number of industrial processes including mining, metal and cement production, and the burning of fossil fuels.

BBC: Nations agree on legally binding mercury rules