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Mercury speciation and mercury stable isotope composition in sediments from the Canadian Arctic Archipelago

Author:
Štrok, Marko, Baya, Pascale Anabelle, Dietrich, Dörthe, Dimock, Brian, Hintelmann, Holger
Source:
The Science of the total environment 2019 v.671 pp. 655-665
ISSN:
0048-9697
Subject:
burning, coal, mercury, methylmercury compounds, organic matter, sediments, stable isotopes, Arctic region
Abstract:
Total mercury (THg) and monomethylmercury (MMHg) concentrations as well as mercury (Hg) isotope ratios were determined in sediment cores sampled from six locations from the Canadian Arctic Archipelago (CAA). At most sites, THg concentrations showed a decreasing trend with depth, ranging from 5 to 61 ng/g, implicating possible increased Hg deposition and/or riverine inputs in top sediment layers. MMHg values showed large oscillations within the top 10 cm of the cores. This variability decreased at the bottom of the cores with MMHg concentrations ranging from less than12 to up to 1073 pg/g. Average concentrations of THg and MMHg in the top 10 cm were linearly correlated, whereas no correlation was observed with organic matter (loss on ignition). Mercury isotope ratios showed negative values for both δ202Hg (−1.59 to −0.55‰) and Δ199Hg (−0.62 to −0.01‰). δ202Hg values became more negative with depth, while the opposite was observed for Δ199Hg. The former is consistent with predicted historical atmospheric Hg trends as a result of increased coal burning worldwide. Hg isotope ratio measurements in CAA sediments offer additional opportunities to trace Hg processes and sources in the Arctic.
Agid:
6358145