Peer Reviewed: Experimenting with Hydroelectric Reservoirs

Bodaly, R. A.; Beaty, K. G.; Hendzel, Len H.; Majewski, Andrew; Paterson, Michael; Rolfhus, Kristofer R.; Penn, Alan; Louis, Vincent L. St.; Hall, Britt D.; Matthews, Cory J. D.; Cherewyk, Katharine A. CherewykK.A.; Mailman, Mariah; Hurley, James P.; Schiff, Sherry L.; Venkiteswaran, Jason J.

doi:10.1021/es040614u

Cited by 54 publications

(35 citation statements)

References 17 publications

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“…We thank Togwell Jackson for his interest in our feature article on the experimental flooding (FLUDEX) project (1). His main complaints were that our article lacked interpretation and inadequately reviewed the relevant literature.…”

Section: Responsementioning

confidence: 99%

“…Thus, although MeHg production slowed significantly in all of the FLUDEX reservoirs after the first year of flooding, it did not slow equally among the reservoirs. The quality of organic carbon may have differed among the reservoirs, especially with regard to the stimulation of Hg methylation (1,4), but because of the low levels of oxygen in the medium-carbon reservoir, redox conditions may also have played a role. Of course, redox conditions were influenced by rates of decomposition, which were also affected by organic carbon quality.…”

Section: Responsementioning

confidence: 99%

“…Bodaly et al recently outlined the re sults of the first three years of the Flooded Uplands Dynamics Ex periment (FLUDEX) but included hardly any interpretive discussion of the observed phenomena (1). It might have helped the authors to interpret their data more adequately and with greater insight if they had studied certain previously published papers concerning the effects of flooding on the bio geochemistry of mercury (Hg) in hydroelectric reservoirs of northern Manitoba, Canada (2)(3)(4).…”

mentioning

confidence: 99%

“…15, 16), and because Hg-binding agents, such as thiols and sulfides generated by anaerobic bacteria, rendered inorganic Hg(II) less available for methylation (9). Similarly, comparison of FLUDEX soils with "low", "medium", and "high" concentrations of organic matter showed that the MeHg flux was greatest in soil of medium organic content (1). This phenomenon, however, was not adequately explained or discussed.…”

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confidence: 99%

“…As Bodaly and associates themselves acknowledged earlier (21), the bioaccumulation of Hg in reservoirs is controlled by many variables, and much remains to be learned about this complex phenomenon; however, their paper on the FLUDEX project (1) gives no indication that they have advanced our knowledge of it. …”

mentioning

confidence: 99%

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Response | Mercury and the FLUDEX project

Bodaly¹,

Beaty²,

Hendzel³

et al. 2005

Environ. Sci. Technol.

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Section: Responsementioning

confidence: 99%

Section: Responsementioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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Response | Mercury and the FLUDEX project

Bodaly¹,

Beaty²,

Hendzel³

et al. 2005

Environ. Sci. Technol.

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Critical perspectives on mercury toxicity reference values for protection of fish

Fuchsman

Henning

Sorensen

et al. 2016

Enviro Toxic and Chemistry

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Environmental management decisions at mercury-contaminated sediment sites are predicated on the understanding of risks to various receptors, including fish. Toxicity reference values (TRVs) for interpreting risks to fish have been developed to assess mercury concentrations in fish or fish prey. These TRVs were systematically evaluated based on several lines of evidence. First, their conceptual basis and specific derivation were evaluated, including a close review of underlying toxicity studies. Second, case studies were reviewed to investigate whether TRVs are predictive of effects on fish populations in the field. Third, TRVs were compared with available information regarding preindustrial and present-day background concentrations of mercury in fish. The findings show that existing TRVs are highly uncertain, because they were developed using limited data from studies not designed for TRV derivation. Although field studies also entail uncertainty, several case studies indicate no evidence of adverse effects despite mercury exposures that exceed the available TRVs. Some TRVs also fall within the range of background mercury concentrations in predatory or prey fish. Lack of information on the selenium status of mercury-exposed fish is a critical confounding factor, and the form of methylmercury used in toxicity testing may also contribute to differences between TRV-based predictions and field observations of mercury effects on fish. On balance, the available information indicates that several of the TRVs reviewed are lower than necessary to protect fish populations. The 20% effect concentration from a previously published dose-response analysis appears closer to an effect threshold, based on available laboratory data. Additional research is needed to provide a stronger basis to establish dose-response relationships for mercury effects on fish.

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Impact of flow diversion by run‐of‐river dams on American dipper diet and mercury exposure

Silverthorn

Bishop

Jardine

et al. 2017

Enviro Toxic and Chemistry

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Run-of-river dams produce lower greenhouse gas emissions than large hydropower projects, but there is a paucity of research on their potential ecotoxicological impacts through disruption of natural flow regimes. We used stable isotopes (δ C, δ N, δ S) to reconstruct diet and trace methylmercury in a predatory river-resident passerine, the American dipper (Cinclus mexicanus), at 7 regulated and 6 free-flowing mountain streams in coastal British Columbia, Canada. Assimilated diets were comparable among regulated and unregulated streams, dominated by benthic macroinvertebrates and resident freshwater fish, with negligible contributions from anadromous Pacific salmon. Although invertebrates at unregulated streams were isotopically similar along their gradient, dippers and invertebrates sampled below dams on regulated streams had S-depleted tissues, suggesting increased activity of sulfate-reducing bacteria and more Hg methylation below the dams. Mercury concentrations in dipper blood (417.6 ± 74.1 standard error [SE] ng/g wet wt at regulated streams, 340.7 ± 42.7 SE ng/g wet wt at unregulated streams) and feathers (1564 .6 ± 367.2 SE ng/g dry wt regulated, 1149.0 ± 152.1 SE ng/g dry wt unregulated), however, were not significantly different between stream types. Relative to other passerines across western North America, dippers in these densely forested mountain streams experienced high mercury exposure; and one recently regulated stream supported dippers with mercury concentrations of potential toxicity concern (up to 8459.5 ng/g dry wt in feathers and 1824.6 ng/g wet wt in whole blood). Elevated mercury in dippers is likely attributable to the birds' relatively high trophic position and high regional inorganic mercury deposition; however, biogeochemical conditions in reservoirs of some regulated streams may be contributing to methylmercury production. Environ Toxicol Chem 2018;37:411-426. © 2017 SETAC.

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Peer Reviewed: Experimenting with Hydroelectric Reservoirs

Abstract: Researcherscreated reservoirs in Canada to explore the impacts of hydroelectric developments on greenhouse gas and methylmercury production. Researchers created reservoirs in Canada to explore the impacts of hydroelectric developments on greenhouse gas and methylmercury production.

Cited by 54 publications

References 17 publications

Response | Mercury and the FLUDEX project

Response | Mercury and the FLUDEX project

Critical perspectives on mercury toxicity reference values for protection of fish

Impact of flow diversion by run‐of‐river dams on American dipper diet and mercury exposure

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