Evaluating sources of mercury in Canada's Mackenzie River.

Arctic rivers may be the largest net sources of mercury (Hg) to the Arctic Ocean, yet riverine sources of Hg remain poorly characterized compared to atmospheric processes. This article reviews the current state of knowledge on Hg inputs to the Mackenzie River and Valley in Northern Canada from six point and non-point sources. Point sources include the locations of mines, fossil fuel extraction facilities, and retrogressive permafrost thaw slumps.

Recent advances in the study of mercury biogeochemistry in Arctic permafrost ecosystems.

Permafrost predominates in polar and high mountain regions, encompassing nearly 15 % of the exposed land in the Northern Hemisphere. It denotes soil or rock that remains at or below 0 °C for the duration of at least two consecutive years. These frozen soils serve as a barrier to contaminants that are stored and accumulated in permafrost over extended periods of time.

Predicting Behavior and Fate of Atmospheric Mercury in Soils: Age-Dating METAALICUS Hg Isotope Spikes with Fallout Radionuclide Chronometry.

Soils accumulate anthropogenic mercury (Hg) from atmospheric deposition to terrestrial ecosystems. However, possible reemission of gaseous elemental mercury (GEM) back to the atmosphere as well as downward migration of Hg with soil leachate influence soil sequestration of Hg in ways not sufficiently understood in global biogeochemical models. Here, we apply fallout radionuclide (FRN) chronometry to understand soil Hg dynamics by revisiting the METAALICUS experiments 20 years after enriched isotope tracers (Hg, Hg, Hg, and Hg) were applied to two boreal watersheds in northwestern Ontario, Canada.

Tracking mercury sources in the Wabigoon River: Use of stable mercury isotopes in bioindicator organisms.

Mercury concentrations remain elevated in sediments and biota of the Wabigoon River downstream from Dryden, Ontario, the home of a former chlor-alkali plant. Understanding the current extent and severity of mercury contamination downstream of this industrial legacy site is of great importance in managing the mercury contamination within the traditional territory of Asubpeeschoseewagong Anishinabek (Grassy Narrows First Nation), located downstream of Dryden. The objective of this study was to use mercury stable isotope ratio analysis to distinguish between legacy mercury from the former chlor-alkali plant and mercury from geogenic sources.

Assessment of mercury methylation and methylmercury demethylation potentials in water and sediments along the Wabigoon River system.

Monomethylmercury (MMHg) plays a crucial role in the accumulation of mercury (Hg) within aquatic food chains. Since ambient levels of methylmercury are governed by the balance of simultaneous methylation and demethylation processes, determining in situ methylation and demethylation rates is critically important to understand the dynamics of methylmercury in the environment. This is especially important in the Wabigoon River system in Ontario, Canada, which is severely contaminated with Hg by a chlor-alkali facility operating in the 1960s, and still exhibits some of the highest recorded fish mercury concentrations in Canada.