Mercury concentrations and mercury isotope composition in lake sediment cores from the vicinity of a metal smelting facility in Flin Flon, Manitoba

The Flin Flon copper–zinc smelter is a site of concern as it has been the largest single source of atmospheric mercury emissions in Canada. Variations in total mercury concentration and mercury isotopic composition were determined in three lake sediment cores at different distances from the Flin Flon smelter. Total mercury concentrations ranged from 90 to 19,000 ng/g and were much higher in cores obtained closer to the smelter. The observed mass dependent mercury isotope fraction (MDF) varied significantly among sediment cores collected closer to the smelter (− 0.67 to − 1.48‰) and cores collected from further away (− 1.44 to − 2.71‰). Mass independent fraction (MIF) was detectable in some but not all samples (− 0.05 to 0.14‰). A simple binary mixing model showed that mercury in all sediment samples investigated in this study originated in variable proportions from the Flin Flon smelter. The study demonstrated that mercury isotope ratio measurements could serve as an effective tool for tracing mercury contamination caused by atmospheric emissions from metal smelting activities.

► Atmospheric mercury emission from metal smelting caused contamination in nearby lakes.
► Mercury contamination is evidenced by elevated concentrations.
► Pollution source is further distinguished from natural background by mercury isotope ratio measurements.
► Two source mixing model is successfully applied to predict smelter contribution to overall mercury in lake sediment.