Determining the effects of past gold mining using a sediment palaeotoxicity model

Cheney, Cynthia L.; Eccles, Kristin M.; Kimpe, Linda E.; Thienpont, Joshua R.; Korosi, Jennifer B.; Blais, Jules M.

doi:10.1016/j.scitotenv.2020.137308

Cited by 24 publications

(16 citation statements)

References 56 publications

(82 reference statements)

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“…This has important implications for the use of short cores (<30 cm) for estimating pre-mining background conditions of redox sensitive elements, such as As and Sb. In addition, Cheney et al (2020) recently proposed that background levels of sedimentary As in many lakes from the Yellowknife region may be elevated relative to others regions in Canada and the world due to solubility and geogenic sources of As in the region. The data from this study highlight the importance of considering the downward mobilization of metals(oids) like As in lake sediments.…”

Section: Anthropogenic Impactsmentioning

confidence: 99%

Late-Holocene diatom community response to climate driven chemical changes in a small, subarctic lake, Northwest Territories, Canada

et al. 2021

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The paleolimnological record of diatoms and climate, spanning the last 2800 years, was investigated in a small subarctic lake (Pocket Lake) that from AD 1948 to 2004 was contaminated by gold smelting waste. An age-depth model was constructed using a combination of 210Pb, 14C, and tephra to determine a 2800 year history of lake ontogeny (natural aging), biological diversity, and regional climate variability. Diatoms form six strong paleoecological assemblages over time in response to changes in local hydrological and sedimentological conditions (including metals). Selected environmental variables explained 28.8% of the variance in the diatom assemblages, with Fe, Ca, and sediment end member distribution being important indicators. The diatom assemblages correlated to the Iron Age Cold Epoch (2800–2300 cal BP), Roman Warm Period (2250–1610 cal BP), Dark Age Cold Period (1500–1050 cal BP), Medieval Climate Anomaly (ca. 1100–800 cal BP), and the Little Ice Age (800–200 cal BP). The disappearance of Staurosira venter highlights the change from the Iron Age Cold Epoch to the Roman Warm Period. After deposition of the White River Ash (833–850 CE; 1117–1100 cal BP), transition to circumneutral conditions was followed in tandem by a transition to planktic influenced communities. Ten discrete peaks of Cu, Pb, and Zn were observed and attributed to soluble mobility from catchment soils through enhanced seepage and spring snowmelt. The prominent metal spikes were aligned with increases in Brachysira neoexilis. Downward mobilization of arsenic and antimony from contaminated surficial sediments highlight the problem of post depositional industrial contamination of paleosediments. Results demonstrate that paleoclimatic changes in the region, modulated by solar radiation, impacted temperature and precipitation in the lake catchment, influencing temporal shifts in diatom ecology. Changes in diatom taxa richness provided valuable information on the relative influence of water quality (planktic taxa) and sediment input (benthic taxa). The diatom assemblage succession also provides evidence that natural aging over time has played a role in the ecological evolution of the lake.

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Section: Anthropogenic Impactsmentioning

confidence: 99%

Late-Holocene diatom community response to climate driven chemical changes in a small, subarctic lake, Northwest Territories, Canada

et al. 2021

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“…As have typically been attributed to natural sources associated with As enrichment in underlying bedrock geology (Cheney et al, 2020;GNWT, 2003). Additional approaches to differentiate between geogenic and industrial sources of As are required in the Yellowknife area and would be relevant to other regions impacted by point sources of pollution.…”

Section: Mining Pollution Landscape Recovery and Research Justificationmentioning

confidence: 99%

“…The widespread distribution of As2O3 resulted in environmental impacts to soils (Hocking et al, 1978;Hutchinson et al, 1982;Jamieson et al, 2017), lake waters (Houben et al, 2016;Palmer et al, 2015), and lake sediments (Galloway et al 2017;Cheney et al 2020;Palmer et al 2020) across the region. Several studies since the 1970's have reported concentrations of As and antimony (Sb) (another roaster associated element) in near-surface soils in the Yellowknife region (Bromstad et al, 2017;Hocking et al, 1978;Hutchinson et al, 1982;Jamieson et al, 2017;St.…”

Section: Mining History and Previous Work On Soils In The Regionmentioning

confidence: 99%

“…Data within 5 km of Giant Mine were not included in background estimates for granitoid (5 -10 mg kg -1 ) and volcanic lithologies (10 -30 mg kg -1 ), but no information is included on the methodology used to calculate geochemical background (Kerr 2006). Recent work has indicated that the impact of stack emissions in soils and lake sediments extends beyond 20 km from Yellowknife (Jamieson et al, 2017;Pelletier et al, 2020) and perhaps as far as 40 km (Cheney et al, 2020). Considering this information, an estimation of geochemical background should acknowledge these regional impacts and likely exclude soils near historical point sources of emissions, unless mineralogical evidence suggests that high As in soils near emissions point sources is associated with natural enrichment.…”

Section: Mining History and Previous Work On Soils In The Regionmentioning

confidence: 99%

“…Previous estimates of geochemical background in soils in the Yellowknife region suggest As concentrations in soils are elevated relative to other jurisdictions due to natural processes associated with mineralization and bedrock enrichment (ESG, 2001;GNWT, 2003). Recent work has highlighted the persistence and widespread dispersion of As from historical mining and roasting emissions and suggests that elevated As in soils and lake sediments may be the result of widespread dispersion of As from past mining emissions rather than natural processes (Bromstad et al 2017;Galloway et al 2017;Jamieson et al 2017;Van Den Berghe et al 2018;Cheney et al 2020;Palmer et al 2020;Sivarajah et al 2020).…”

Section: Introductionmentioning

confidence: 99%

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Environmental processes that control the chemical recovery of arsenic impacted northern landscapes

Palmer¹

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Arsenic (As) is a contaminant of global concern because of its toxic and carcinogenic properties.Waste streams associated with gold mining activities have resulted in extensive As pollution of landscapes worldwide. The Yellowknife area in the Northwest Territories, Canada was contaminated by more than half a century of As-bearing atmospheric mining emissions from the roasting of arsenopyrite ore during historical gold ore processing . The environmental footprint from legacy mining emissions persists on the landscape and questions remain about the distribution and fate of As in the local environment. The principal objective of this thesis was to improve our understanding of the environmental processes that control the chemical recovery of As impacted landscapes. Individual field studies were designed to address: a) the distribution, source, and solid-phase speciation of As in Yellowknife area soils; b) the seasonal variation of As in surface waters of shallow lakes; c) the influence of contrasting winter hydrology on the geochemical cycling of As in a shallow lake; and d) the seasonal contributions of terrestrial and aquatic fluxes of As in a contaminated watershed. The combination of mineralogical, geospatial, and statistical tools provided a novel method for determination of geochemical background in soils for areas impacted by legacy mining emissions, including recent unambiguous identification of anthropogenically impacted soils. Year-round investigations of surface waters, sediments, and sediment porewaters provided new insights into seasonal and under-ice processes that influence the mobility and geochemical cycling of As. The evaluation of terrestrial and aquatic As fluxes across a contaminated watershed revealed continued transport of legacy arsenic from catchment soils to lakes, and hydrology mediated within-lake processing and export of arsenic. Thus, climate and hydrology were found to play a fundamental role in the chemical recovery of As impacted lakes.

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Regional changes in Cladocera (Branchiopoda, Crustacea) assemblages in subarctic (Yellowknife, Northwest Territories, Canada) lakes impacted by historic gold mining activities

et al. 2021

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Determining the effects of past gold mining using a sediment palaeotoxicity model

Cited by 24 publications

References 56 publications

Late-Holocene diatom community response to climate driven chemical changes in a small, subarctic lake, Northwest Territories, Canada

Late-Holocene diatom community response to climate driven chemical changes in a small, subarctic lake, Northwest Territories, Canada

Environmental processes that control the chemical recovery of arsenic impacted northern landscapes

Regional changes in Cladocera (Branchiopoda, Crustacea) assemblages in subarctic (Yellowknife, Northwest Territories, Canada) lakes impacted by historic gold mining activities

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