Quantifying arsenic post-depositional mobility in lake sediments impacted by gold ore roasting in sub-arctic Canada using inverse diagenetic modelling

Leclerc, Émilie; Venkiteswaran, Jason J.; Jasiak, Izabela; Telford, James V.; Schultz, Mackenzie D.J.; Wolfe, Brent B.; Hall, Roland I.; Couture, Raoul-Marie

doi:10.1016/j.envpol.2021.117723

Cited by 12 publications

(6 citation statements)

References 57 publications

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“…Trapping of As in the oxic zone leads to As accumulation in the iron oxide layer (up to 0.3 μmol As g −1 ) near the SWI ( Figure 2B ). Other studies have reported similar concentrations of particulate As in the top layer of coastal sediments (Mucci et al, 2000 ; Chaillou et al, 2003 ), higher concentrations are generally found in contaminated marine (0.4–0.7 μmol As g −1 ; Chaillou et al, 2003 ) and lake sediments (up to 15 μmol As g −1 ; Barrett et al, 2019 ; Leclerc et al, 2021 ).…”

Section: Resultsmentioning

confidence: 60%

“…However, the dAs concentrations observed here are about four times lower than previously found in North-Sea sediments, where e-SOx was the dominant process (van de Velde et al, 2017 ). They are also lower than in deltaic sediments that sustain an active iron cycle (Sullivan and Aller, 1996 ) and contaminated lake sediments (Barrett et al, 2019 ; Leclerc et al, 2021 ), where pore water dAs can reach up to 2 μM (and sometimes up to 10 μM). Just below the zone of As release, the pore water showed a zone with strong dAs consumption, which corresponded to the interface between the ferruginous and the sulphidic pore water.…”

Section: Resultsmentioning

confidence: 95%

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Cable Bacteria Activity Modulates Arsenic Release From Sediments in a Seasonally Hypoxic Marine Basin

et al. 2022

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Eutrophication and global change are increasing the occurrence of seasonal hypoxia (bottom-water oxygen concentration <63 μM) in coastal systems worldwide. In extreme cases, the bottom water can become completely anoxic, allowing sulfide to escape from the sediments and leading to the development of bottom-water euxinia. In seasonally hypoxic coastal basins, electrogenic sulfur oxidation by long, filamentous cable bacteria has been shown to stimulate the formation of an iron oxide layer near the sediment-water interface, while the bottom waters are oxygenated. Upon the development of bottom-water anoxia, this iron oxide “firewall” prevents the sedimentary release of sulfide. Iron oxides also act as an adsorption trap for elements such as arsenic. Arsenic is a toxic trace metal, and its release from sediments can have a negative impact on marine ecosystems. Yet, it is currently unknown how electrogenic sulfur oxidation impacts arsenic cycling in seasonally hypoxic basins. In this study, we presented results from a seasonal field study of an uncontaminated marine lake, complemented with a long-term sediment core incubation experiment, which reveals that cable bacteria have a strong impact on the arsenic cycle in a seasonally hypoxic system. Electrogenic sulfur oxidation significantly modulates the arsenic fluxes over a seasonal time scale by enriching arsenic in the iron oxide layer near the sediment-water interface in the oxic period and pulse-releasing arsenic during the anoxic period. Fluxes as large as 20 μmol m−2 day−1 were measured, which are comparable to As fluxes reported from highly contaminated sediments. Since cable bacteria are recognized as active components of the microbial community in seasonally hypoxic systems worldwide, this seasonal amplification of arsenic fluxes is likely a widespread phenomenon.

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Section: Resultsmentioning

confidence: 60%

Section: Resultsmentioning

confidence: 95%

Cable Bacteria Activity Modulates Arsenic Release From Sediments in a Seasonally Hypoxic Marine Basin

et al. 2022

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“…Inverse diagenetic modelling was used to objectively constrain uxes of solutes across the sediment-water interface. 65,66 Porewater proles were modelled assuming the absence of signicant advective ux and at steady state (i.e., d C /dt ¼ 0). The onedimensional mass conservation equation provided by Boudreau 1997 67 at steady state was solved using the computer code PROFILE 68 using sediment porosity and the elements' diffusion coefficients as inputs, to yield uxes of La, P, and Fe across the sediment-water interface (SWI) at the three sampling sites.…”

Section: Flux Calculations Across the Sediment-water Interfacementioning

confidence: 99%

Response of sediment phosphorus partitioning to lanthanum-modified clay amendment and porewater chemistry in a small eutrophic lake

Neweshy

Planas²,

Tellier³

et al. 2022

Environ. Sci.: Processes Impacts

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“…Inverse diagenetic modelling was used to objectively constrain fluxes of solutes across the sediment-water interface 65,66 . Porewater profiles were modelled assuming the absence of significant advective flux and at steady state (i.e., δC/δt = 0).…”

Section: Flux Calculations Across the Sediment-water Interfacementioning

confidence: 99%

Response of sediment phosphorus partitioning to lanthanum-modified clay amendment and porewater chemistry in a small eutrophic lake.

Neweshy

Planas

Tellier³

et al. 2022

Preprint

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Sustained eutrophication of the aquatic environment by the remobilization of legacy phosphorus (P) stored in soils and sediments is a prevailing issue worldwide. Fluxes of P from the sediments to the water column, referred to as internal P loading, often delays the recovery of water quality following a reduction in external P loads. Here, we report on the vertical distribution and geochemistry of P, lanthanum (La), iron (Fe) and carbon (C) in the culturally eutrophied Lake Bromont. This lake underwent remediation treatment using La- modified bentonite (LMB) commercially available as PhoslockTM. We investigated the effectiveness of LMB in decreasing soluble reactive phosphorus (SRP) availability in sediments and in reducing dissolved fluxes of P across the sediment-water interface. Sediment cores were retrieved before and after LMB treatment at three sites representing bottom sediment, sediment influenced by lakeside housing and finally littoral sediment influenced by the lake inflow. Sequential extractions were used to assess changes in P speciation. Depth profiles of dissolved porewater concentrations were obtained after LMB treatment at each site. Results indicate that SRP extracted from the sediments decreased at all sites, while total extracted P (PTOT) bound to redox-sensitive metal oxides increased. 31P NMR data on P extract reveals that 20-43% of total solid-phase P is in the form of organic P (Porg) susceptible to be released via microbial degradation. Geochemical modelling of porewater data provides evidence that LaPO4(s) mineral phases, such as rhabdophane and/or monazite, are likely forming. However, results also suggest that La3+ binding by dissolved organic carbon (DOC) hinders La-phosphate precipitation. We rely on thermodynamic modelling to suggest that high Fe2+ would bind to DOC instead of La3+, therefore promoting P sequestrations by LMB under anoxic conditions.

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Quantifying arsenic post-depositional mobility in lake sediments impacted by gold ore roasting in sub-arctic Canada using inverse diagenetic modelling

Cited by 12 publications

References 57 publications

Cable Bacteria Activity Modulates Arsenic Release From Sediments in a Seasonally Hypoxic Marine Basin

Cable Bacteria Activity Modulates Arsenic Release From Sediments in a Seasonally Hypoxic Marine Basin

Response of sediment phosphorus partitioning to lanthanum-modified clay amendment and porewater chemistry in a small eutrophic lake

Response of sediment phosphorus partitioning to lanthanum-modified clay amendment and porewater chemistry in a small eutrophic lake.

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