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TitleInfluence of late-Holocene climate change on the solid-phase speciation and long-term stability of arsenic in sub-Arctic lake sediments
AuthorMiller, C M; Parsons, M BORCID logo; Jamieson, H E; Ardakani, O HORCID logo; Gregory, B R B; Galloway, J MORCID logo
SourceScience of the Total Environment vol. 709, 136115, 2019 p. 1-18, Open Access logo Open Access
Alt SeriesNatural Resources Canada, Contribution Series 20190286
Mediapaper; on-line; digital
File formatpdf; html; docx (Microsoft® Word®)
ProvinceNorthwest Territories
NTS75L/11; 75L/12; 75L/13; 75L/14; 75L/15; 75L/16; 75M; 75N; 75O/05; 75O/12; 75O/13; 76B/04; 76B/05; 76B/12; 76B/13; 76C; 76D/01; 76D/02; 76D/03; 76D/04; 76D/05; 76D/06; 76D/07; 76D/08; 76D/09; 76D/10; 76D/11; 76D/15; 76D/16; 85I/09; 85I/10; 85I/11; 85I/12; 85I/13; 85I/14; 85I/15; 85I/16; 85J/09; 85J/10; 85J/15; 85J/16; 85O/01; 85O/02; 85O/07; 85O/08; 85O/09; 85O/10; 85P; 86A/01; 86A/02; 86A/08
Lat/Long WENS-115.0000 -107.5000 65.0000 62.5000
Subjectsenvironmental geology; geochemistry; stratigraphy; paleontology; Nature and Environment; Science and Technology; Economics and Industry; Holocene; lake sediment geochemistry; arsenic geochemistry; climate effects; lake sediment cores; arsenopyrite; scorodite; bedrock geology; metamorphic rocks; metasedimentary rocks; greywackes; slates; igneous rocks; intrusive rocks; diabases; gabbros; quartz porphyries; diorites; volcanic rocks; andesites; basalts; rhyolites; dacites; pore water samples; mining; metals; limnology; paleoclimatology; climatology; grain size analyses; stratigraphic models; statistical analyses; electron probe analyses; scanning electron microscope analyses; iron geochemistry; sulphur geochemistry; chlorine geochemistry; carbon nitrogen ratios; palynological analyses; pollen; temperature; Courageous Lake Greenstone Belt; Slave Province; Tundra Mine; Salmita Mine; Tundra Zone; Boreal Forest Region; Climate change; environmental baseline studies; cumulative effects; paleolimnology; Phanerozoic; Cenozoic; Quaternary
Illustrationsprofiles; photomicrographs; location maps; geoscientific sketch maps; plots; tables; bar graphs
ProgramEnvironmental Geoscience Metal Mining: northern baselines
Released2019 12 14
AbstractSediment 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 micrograms/L and 15 micrograms/L) 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; range: 29 to 49 mg/kg) are observed in sediment coeval with the Holocene Thermal Maximum (ca. 5430 ± 110 to 4070 ± 130 cal. years BP); at these depths, authigenic As-bearing framboidal pyrite is the primary host of As in sediment and the influence of organic matter on the precipitation of As-bearing framboidal pyrite is apparent petrographically. These findings suggest that increased biological productivity and weathering of terrestrial OM associated with climate warming influences redox cycles in the near-surface sediment and enhances the mobility of As in northern lakes. Knowledge generated from this study is relevant for predicting future climate change-driven variations in metal(loid) cycling in aquatic systems and can be used to interpret trends in long-term environmental monitoring data at historical, modern, and future metal mines in northern environments.
Summary(Plain Language Summary, not published)
Climate change is influencing the cycling of naturally occurring metal(loid)s and long-term stability of mining-derived contaminants in northern lakes. In this study, sediment cores were collected from two lakes in the Northwest Territories to examine the influence of mid- to late-Holocene regional warming on arsenic speciation and mobility. The results show that increased biological productivity and weathering of terrestrial organic material, associated with climate warming, enhanced the mobility of arsenic in near-surface sediments. These results will help to inform long-term environmental monitoring of the nearby, and recently remediated, Tundra Mine and are also applicable to other northern mine sites. This knowledge is relevant for predicting future climate change-driven variations in metal(loid) cycling in aquatic systems and can be used to improve environmental monitoring and remediation strategies at current and future natural resource developments.

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