Influence of late-Holocene climate change on the solid-phase speciation and long-term stability of arsenic in sub-Arctic lake sediments

• Published in: Science of The Total Environment
• Main Authors: Miller, C.B. (Clare B.), Parsons, M.B. (Michael B.), Jamieson, H.E. (Heather E.), Ardakani, O.H. (Omid H.), Gregory, B.R.B. (Braden R.B.), Galloway, J.M. (Jennifer M.)
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2020
• Subjects: Arsenic; Climate change; Holocene; Lake sediment; Organic matter; Arctic; Arctic Lake; Canada; Courageous Lake; Northwest Territories
• Online Access: https://ir.library.carleton.ca/pub/26050; https://doi.org/10.1016/j.scitotenv.2019.136115

Sediment cores were collected from two lakes in the Courageous Lake Greenstone Belt (CLGB), central Northwest Territories, Canada, to examine the influence of late-Holocene warming on the transport and fate of arsenic (As) in sub-Arctic lakes. In both lakes, allochthonous As-bearing minerals (i.e. arsenopyrite and scorodite) were identified in sediment deposited during times of both regional warming and cooling, suggesting that weathering of bedrock and derived surficial materials provides a continual source of As to lakes of the CLGB. However, maximum porewater As (84 μg·L−1 and 15 μg·L−1) and reactive organic matter (OM; aquatic and terrestrial-derived) concentrations in each lake are coincident with known periods of regional climate warming. It is inferred that increased biological production in surface waters and influx of terrigenous OM led to the release of sedimentary As to porewater through reductive dissolution of As-bearing Fe-(oxy)hydroxides and scorodite during episodes of regional warming. Elevated sedimentary As concentrations (median: 36 mg·kg−1; range: 29 to 49 mg·kg−1) are observ