Impacts of Reservoir Creation on the Biogeochemical Cycling of Methyl Mercury and Total Mercury in Boreal Upland Forests

Hall, Britt D.; Louis, Vincent L. St.; Rolfhus, Kristofer R.; Bodaly, R. A.; Beaty, K. G.; Paterson, Michael; Cherewyk, K.A. Peech

doi:10.1007/s10021-003-0094-3

Cited by 113 publications

(170 citation statements)

References 40 publications

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“…Furthermore, laboratory experiments on the effects of labile terrestrial organic matter on microbial production of MeHg, CO 2 , and CH 4 in sediments from Manitoba lakes and reservoirs (4) yielded results comparable to observations reported by Bodaly et al With increasing concentration of organic matter, the rates of MeHg production and bioaccumulation rose progressively, peaked at a critical point, and then declined despite a concurrent increase in CO 2 and CH 4 levels and a decrease in sediment Eh, which proved that there was no decline in overall microbial activity (4). The investigator inferred that MeHg production dropped because the rate of demethylation exceeded the rate of methylation owing to ecological succession in the microbial community (4; cf.…”

supporting

confidence: 82%

“…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%

“…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). Several of the phenomena highlighted in their article were reported and discussed at length in this literature, which includes some studies that are particularly pertinent to the FLUDEX project and related work by Bodaly and associates (5)(6)(7)(8).…”

mentioning

confidence: 99%

“…Thus, comparison of sediments from two Manitoba reservoir sites, one rich and the other poor in submerged terrestrial organic matter, and a reference lake unaffected by impoundment demonstrated that microbial de composition of the organic matter involved production of copious CO 2 , CH 4 , and methyl mercury (MeHg) accompanied by consumption of O 2 and the crea tion of reducing conditions (2). Understandably, the sediment richest in organic matter had the largest total (mainly inorganic) Hg content as well as the most intense Hg methylating activity and highest MeHg concentration (cf.…”

mentioning

confidence: 99%

“…The results showed that the Hg content of walleye (Stizostedion vitreum), a species that appears to be particularly suitable for whole-lake bioassays of MeHg production (4,14), could be predicted by means of an empirical compound variable (the "Hg methylating capability" of the sedimentary microflora multiplied by the abundance of bioavailable Hg in the sediment), which was formulated to measure the relative rate of MeHg production in samples of finegrained offshore sediments (4; cf. 2,14).…”

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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supporting

confidence: 82%

Section: Responsementioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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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Forest harvest contribution to Boreal freshwater methyl mercury load

Kronberg

Drott

Jiskra

et al. 2016

Global Biogeochemical Cycles

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Effects of Boreal forest harvest on mercury (Hg) and methyl mercury (MeHg) soil pools and export by stream runoff were quantified by comparing 10 reference watersheds (REFs) covered by >80 year old Norway spruce (Picea abies Karst.) forests with 10 similar watersheds subjected to clear-cutting (CCs). While total Hg soil storage did not change, MeHg pools increased seven times (p = 0.006) in the organic topsoil 2 years after clear-cutting. In undulating terrain, situated above the postglacial marine limit (ML) of the ancient Baltic Sea, the mass ratio between flux-weighted MeHg and dissolved organic carbon (MeHg/DOC) in stream runoff increased 1.8 times (p < 0.004) as a consequence of forest harvest. When recalculated to 100% clear-cutting of the watershed, the annual MeHg stream export increased 3.8 times (p = 0.047). Below the ML, where the terrain was flatter, neither the MeHg/DOC ratio nor the annual export of MeHg differed between REFs and CCs, likely because of the larger contribution of MeHg exported from peaty soils and small wetlands. The most robust measure, MeHg/DOC, was used to calculate MeHg loadings to Boreal headwaters. If the forest harvest effect lasts 10 years, clear-cutting increases MeHg runoff by 12-20% in Sweden and 2% in the Boreal zone as a whole. In Sweden, having intensely managed forests, 37% and 56% of MeHg are exported from peatlands and forest soils, respectively, and forest clear-cutting is adding another 6.6%. In the Boreal zone as a whole peatlands and forests soils contribute with 53% and 46%, respectively, and clearcutting is estimated to add another 1.0%. An expected rapid increase in Boreal forest harvest and disturbance urge for inclusion of land use effects in mercury biogeochemical cycling models at different scales.

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The effects of hydrologic fluctuation and sulfate regeneration on mercury cycling in an experimental peatland

et al. 2015

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A series of severe droughts during the course of a long-term, atmospheric sulfate-deposition experiment in a boreal peatland in northern Minnesota created a unique opportunity to study how methylmercury (MeHg) production responds to drying and rewetting events in peatlands under variable levels of sulfate loading. Peat oxidation during extended dry periods mobilized sulfate, MeHg, and total mercury (Hg T ) to peatland pore waters during rewetting events. Pore water sulfate concentrations were inversely related to antecedent moisture conditions and proportional to past and current levels of atmospheric sulfate deposition. Severe drying events caused oxidative release of MeHg to pore waters and resulted in increased net MeHg production likely because available sulfate stimulated the activity of sulfate-reducing bacteria, an important group of Hg-methylating bacteria in peatlands. Rewetting events led to increased MeHg concentrations across the peatland, but concentrations were highest in peat receiving elevated atmospheric sulfate deposition. Dissolved Hg T concentrations also increased in peatland pore waters following drought but were not affected by sulfate loading and did not appear to be directly controlled by dissolved organic carbon mobilization to peatland pore waters. Peatlands are often considered to be sinks for sulfate and Hg T in the landscape and sources of MeHg. Hydrologic fluctuations not only serve to release previously sequestered sulfate and Hg T from peatlands but may also increase the strength of peatlands as sources of MeHg to downstream aquatic systems, particularly in regions that have experienced elevated levels of atmospheric sulfate deposition. DROUGHT INCREASES MERCURY IN PEATLANDS 1697 PUBLICATIONS

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Impacts of Reservoir Creation on the Biogeochemical Cycling of Methyl Mercury and Total Mercury in Boreal Upland Forests

Cited by 113 publications

References 40 publications

Response | Mercury and the FLUDEX project

Response | Mercury and the FLUDEX project

Forest harvest contribution to Boreal freshwater methyl mercury load

The effects of hydrologic fluctuation and sulfate regeneration on mercury cycling in an experimental peatland

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