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

Marko Štrok; Pascale Anabelle Baya; Dörthe Dietrich; Brian Dimock; Holger Hintelmann

doi:10.1016/j.scitotenv.2019.03.424

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

Sci Total Environ. 2019 Jun 25:671:655-665. doi: 10.1016/j.scitotenv.2019.03.424. Epub 2019 Mar 27.

Authors

Marko Štrok¹, Pascale Anabelle Baya², Dörthe Dietrich³, Brian Dimock⁴, Holger Hintelmann⁵

Affiliations

¹ Trent University, Department of Chemistry, 1600 West Bank Drive, Peterborough, Ontario K9J7B8, Canada; Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia. Electronic address: marko.strok@ijs.si.
² Trent University, Department of Chemistry, 1600 West Bank Drive, Peterborough, Ontario K9J7B8, Canada.
³ Trent University, Department of Chemistry, 1600 West Bank Drive, Peterborough, Ontario K9J7B8, Canada; University of Münster, Inorganic and Analytical Chemistry, Corrensstrasse, 30, D-48149 Münster, Germany. Electronic address: d_diet03@uni-muenster.de.
⁴ Trent University, Department of Chemistry, 1600 West Bank Drive, Peterborough, Ontario K9J7B8, Canada. Electronic address: briandimock@trentu.ca.
⁵ Trent University, Department of Chemistry, 1600 West Bank Drive, Peterborough, Ontario K9J7B8, Canada. Electronic address: hhintelmann@trentu.ca.

PMID: 30939318
DOI: 10.1016/j.scitotenv.2019.03.424

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.

Keywords: Anthropogenic mercury inputs; Arctic; Hg; Marine sediment cores.