Patterns in riverine carbon, nutrient and suspended solids export to the Eastern James Bay: links to climate, hydrology and landscape

Melo, Michaela Ladeira de; Gérardin, Marie-Laure; Fink‐Mercier, Caroline; Giorgio, Paul A. del

doi:10.1007/s10533-022-00983-z

Cited by 7 publications

(2 citation statements)

References 83 publications

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“…The mixed catchment had analyte yields and yield ratios falling in between the wetland‐influenced Churchill and the more sediment‐laden Old Crow and Mackenzie rivers (Emmerton et al., 2013; Kirk & St. Louis, 2009; Staniszewska et al., 2022), which aligns with mixed‐landscape contributions from peatlands, mountains, and uplands. Both the peatland and mixed catchments had lower analyte yields than the Eastern James Bay rivers of variable size (Chinusaw and Nottaway rivers), likely explained by a much wetter regional climate than the dry Interior Plains (de Melo et al., 2022; Fink‐Mercier, Lapierre, et al., 2022). The most dramatic yields of THg and MeHg were observed downstream of retrogressive thaw slumps in the Peel Plateau, related to steep relief, high ice content within the widespread permafrost, and erodible Pleistocene tills (St. Pierre et al., 2018; Tank et al., 2020).…”

Section: Discussionmentioning

confidence: 99%

Concentrations and Yields of Mercury, Methylmercury, and Dissolved Organic Carbon From Contrasting Catchments in the Discontinuous Permafrost Region, Western Canada

Thompson,

Low,

Shewan

et al. 2023

Water Resources Research

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Climate change and permafrost thaw may impact the mobilization of terrestrial dissolved organic carbon (DOC), mercury (Hg), and neurotoxic methylmercury (MeHg) into aquatic ecosystems; thus, understanding processes that control analyte export in northern catchments is needed. We monitored water chemistry for 3 years (2019–2021) at a peatland catchment (Scotty Creek) and a mixed catchment (Smith Creek) in the Dehcho (Northwest Territories), within the discontinuous permafrost zone of boreal western Canada. The peatland catchment had higher DOC and dissolved MeHg, but lower total Hg concentrations (mean ± standard deviation; 19 ± 2.6 mg DOC L−1; 0.08 ± 0.04 ng DMeHg L−1; 1.1 ± 0.3 ng THg L−1) than the mixed catchment (12 ± 4.4 mg DOC L−1; 0.05 ± 0.01 ng DMeHg L−1; 3.1 ± 2.2 ng THg L−1). Analyte concentrations increased with discharge at the mixed catchment, suggesting transport limitation and the flushing of near‐surface, organic‐rich flow paths during wet periods. In contrast, analyte concentrations in the peatland catchment were not primarily associated with discharge. MeHg concentrations, MeHg:THg, and MeHg:DOC increased with water temperature, suggesting enhanced Hg methylation during warmer periods. Mean open water season DOC and total MeHg yields were greater and more variable from the peatland than the mixed catchment (1.1–6.6 vs. 1.4–2.4 g DOC m−2; 5.2–36 vs. 6.1–10 ng MeHg m−2). Crucial storage thresholds controlling runoff generation likely drove greater inter‐annual variability in analyte yields from the peatland catchment. Our results suggest climate change may influence the production and transport of MeHg from boreal‐Arctic catchments as temperatures increase, peatlands thaw, and runoff generation is altered.

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Section: Discussionmentioning

confidence: 99%

Concentrations and Yields of Mercury, Methylmercury, and Dissolved Organic Carbon From Contrasting Catchments in the Discontinuous Permafrost Region, Western Canada

Thompson,

Low,

Shewan

et al. 2023

Water Resources Research

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“…Based on temporally varying Hg:DOC and MeHg:DOC ratios, we estimated the potential bias in calculation of the export of both forms of Hg from these northern rivers using DOC as a proxy, as is commonly done in broad‐scale studies (Liu et al., 2021), then compared these estimations to measured exports in the same rivers (Fink‐Mercier, Lapierre, et al., 2022). Estimated dissolved total Hg and dissolved MeHg concentrations from DOC were highly variable (0.03–0.22 ng MeHg and 0.85–5.64 ng Hg), and the modeled export, measured by multiplying by annual discharge (DeMelo et al., 2022) and expressed in kg y −1 , diverged from true exports by 22% and 19% on average (in no consistent direction) for MeHg and Hg respectively for individual rivers. This highlights that the use of an average Hg:DOC and MeHg:DOC ratio to model exports might lead to potentially significant biases locally.…”

Section: Discussionmentioning

confidence: 99%

Hydrology and Seasonality Shape the Coupling of Dissolved Hg and Methyl‐Hg With DOC in Boreal Rivers in Northern Québec

Fink‐Mercier

Giorgio

Amyot

et al. 2022

Water Resources Research

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Co‐loading of mercury (Hg) with dissolved organic carbon (DOC) is a key driver of the observed spatial and temporal Hg patterns among aquatic ecosystems. Their strong biogeochemical coupling has spurred the use of DOC as a predictor of Hg concentrations and exports in boreal regions where sampling logistics for Hg are costly and complex. Yet relationships between Hg and methylmercury (MeHg) with DOC have recently been shown to be highly variable in terms of slope and strength, suggesting that mechanisms other than co‐transport along the land‐water continuum may drive the relationship between Hg and DOC across landscapes. In this study, we explore the relationship between Hg and MeHg with DOC across 18 boreal rivers collectively draining over 350,000 km2 of the eastern James Bay territory (Québec), comprising watersheds with a wide range of vegetation, water residence time and riverine DOC concentrations and optical properties. Our results show that although a large portion of the variation in Hg and MeHg is explained by concentrations of DOC, Hg‐DOC and MeHg‐DOC relationships and ratios vary greatly both spatially and temporally. We show that ratios and strength of the coupling can be predicted from system hydrology, with declines in Hg:DOC and increase in MeHg:DOC ratios and stronger coupling during the seasonal progression to warmer temperatures, higher water evaporation, and longer residence time. Our study highlights the role of seasonal hydrology and biogeochemical processing in governing Hg, MeHg and DOC patterns in boreal rivers.

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A review on modeling nutrient dynamics and loadings in forest-dominated watersheds under cold climate conditions

Liu,

Shrestha,

Fong

et al. 2024

Model. Earth Syst. Environ.

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This review summarized the past and current studies on forest nutrient export and existing watershed water quality models that are capable of predicting nutrient loadings from forest-dominated watersheds. Emphasis was given to the watershed models used under cold climate conditions and their capacities and limitations in assessing the impacts of forest best management practices (BMPs) and climate change scenarios on nutrient loadings at a watershed scale. The nutrient export rates in forest-dominated watersheds were found to vary significantly controlled by local climate and landscape conditions. Some watershed water quality models can estimate nutrient loadings from forests either with a simplified forest growth function or without a forest growth component. No existing watershed water quality models have explicit representation forest BMP functions. Combining or coupling with a forest growth model is required for a realistic simulation of nutrient dynamics and assessing the impact of forest BMPs in a forest-dominated watershed. The review also considered the suitability of models for exploring the potential effects of climate change on hydrologic and nutrient processes relevant to forest management. Discussions on the challenges and limitations of forested watershed water quality models and recommendations for future development were made following the review. The findings of this study can provide valuable references for water quality modeling studies in forest-dominated watersheds under cold climate conditions.

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Patterns in riverine carbon, nutrient and suspended solids export to the Eastern James Bay: links to climate, hydrology and landscape

Cited by 7 publications

References 83 publications

Concentrations and Yields of Mercury, Methylmercury, and Dissolved Organic Carbon From Contrasting Catchments in the Discontinuous Permafrost Region, Western Canada

Concentrations and Yields of Mercury, Methylmercury, and Dissolved Organic Carbon From Contrasting Catchments in the Discontinuous Permafrost Region, Western Canada

Hydrology and Seasonality Shape the Coupling of Dissolved Hg and Methyl‐Hg With DOC in Boreal Rivers in Northern Québec

A review on modeling nutrient dynamics and loadings in forest-dominated watersheds under cold climate conditions

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