intense cold, sea spray and long dark winters are stripping toxic mercury from the atmosphere and pushing it into the fragile Arctic food chain where it is accumulating, new research suggests.

The sudden burst of sunlight after long polar winters drives chemicals in sea salt to react with normally inert mercury vapour in the air, depositing it onto snow, report Julia Lu and colleagues at the Meteorological Service of Canada and Toronto, Canada. On melting, this snow injects a pulse of mercury into the Arctic ecosystem at a time when it is most vulnerable to contamination