Cycling of manganese and iron in Lake Mendota, Wisconsin

Stauffer, Robert E.

doi:10.1021/es00147a002

Cited by 32 publications

(12 citation statements)

References 27 publications

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“…While this peak was not detected in October, this could be due to insufficient sampling resolution, since the profile from September suggests that particulate Mn is localized to a thin band in the water column (Figure S2). Together, these data suggest localized reduction, just below the oxic–anoxic interface, of settling Mn oxides that were produced by the downward migration of the thermocline, as previously shown to occur in Lake Mendota and other lakes. , This indicates that Mn reduction could be an important TEAP near the oxic/anoxic interface during late anoxia …”

Section: Results and Discussionsupporting

confidence: 75%

“…Dissolved iron (Fe) transiently accumulated (5 μM) in the hypolimnion immediately following anoxia but was quickly precipitated out by sulfide and was unlikely to serve as an electron acceptor in the water column (Figure S1). 75 Manganese (Mn) also accumulated shortly after anoxia developed and remained in the hypolimnion throughout the anoxic period, ranging from 4 to 6 μM. In June and August, the near-bottom hypolimnetic accumulation of Mn and linear profile suggests that Mn was being reduced in the surficial sediments and diffusing into the hypolimnion.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Mercury Methylation Genes Identified across Diverse Anaerobic Microbial Guilds in a Eutrophic Sulfate-Enriched Lake

Peterson

McDaniel

Schmidt

et al. 2020

Environ. Sci. Technol.

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Mercury (Hg) methylation is a microbially mediated process that converts inorganic Hg into bioaccumulative, neurotoxic methylmercury (MeHg). The metabolic activity of methylating organisms is highly dependent on biogeochemical conditions, which subsequently influences MeHg production. However, our understanding of the ecophysiology of methylators in natural ecosystems is still limited. Here, we identified potential locations of MeHg production in the anoxic, sulfidic hypolimnion of a freshwater lake. At these sites, we used shotgun metagenomics to characterize microorganisms with the Hg-methylation gene hgcA. Putative methylators were dominated by hgcA sequences divergent from those in well-studied, confirmed methylators. Using genome-resolved metagenomics, we identified organisms with hgcA (hgcA+) within the Bacteroidetes and the recently described Kiritimatiellaeota phyla. We identified hgcA+ genomes derived from sulfate-reducing bacteria, but these accounted for only 22% of hgcA+ genome coverage. The most abundant hgcA+ genomes were from fermenters, accounting for over half of the hgcA gene coverage. Many of these organisms also mediate hydrolysis of polysaccharides, likely from cyanobacterial blooms. This work highlights the distribution of the Hg-methylation genes across microbial metabolic guilds and indicate that primary degradation of polysaccharides and fermentation may play an important but unrecognized role in MeHg production in the anoxic hypolimnion of freshwater lakes.

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Section: Results and Discussionsupporting

confidence: 75%

Section: ■ Results and Discussionmentioning

confidence: 99%

Mercury Methylation Genes Identified across Diverse Anaerobic Microbial Guilds in a Eutrophic Sulfate-Enriched Lake

Peterson

McDaniel

Schmidt

et al. 2020

Environ. Sci. Technol.

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“…Insoluble Mn(II) in the form of Mn304, MnCO3, Mn(II) adsorbed onto Mn(IV) or Fe(III) oxides or other minerals, and various forms of MnS may constitute a significant portion of the Mn(II) generated from Mn(IV) reduction (26,29,30,78,153,217,228,232,261,263,312,326). Thus, measurements of the accumulation of dissolved Fe(II) and Mn(II) in interstitial waters of sediments or the water overlying sediment can provide a useful indication of Fe(III) and Mn(IV) reduction (109,122,144,156,158,159,167,173,220,276,290,315,326) but cannot be used to calculate the contribution of Fe(III) or Mn(IV) reduction to the overall organic-matter decomposition in the sediments.…”

Section: Decomposition Of Organic Matter In Modernmentioning

confidence: 99%

Dissimilatory Fe(III) and Mn(IV) reduction.

Lovley

1991

Microbiological Reviews

1,200

719

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“…Some temperate lakes contain small peaks of manganese in the oxic portion of the water column, which cannot be adequately explained by chemical equilibria (36,49). The depth profiles of metals that adsorb to manganese oxides, including cobalt and lead, covary with profiles for soluble manganese in some freshwater sediments and water columns (13,27,33,36).…”

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confidence: 99%

Manganese Reduction by Microbes from Oxic Regions of the Lake Vanda (Antarctica) Water Column

Bratina

Stevenson

Green

et al. 1998

Appl Environ Microbiol

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Depth profiles of metals in Lake Vanda, a permanently ice-covered, stratified Antarctic lake, suggest the importance of particulate manganese oxides in the scavenging, transport, and release of metals. Since manganese oxides can be solubilized by manganese-reducing bacteria, microbially mediated manganese reduction was investigated in Lake Vanda. Microbes concentrated from oxic regions of the water column, encompassing a peak of soluble manganese [Mn(II)], reduced synthetic manganese oxides (MnO2) when incubated aerobically. Pure cultures of manganese-reducing bacteria were readily isolated from waters collected near the oxic Mn(II) peak. Based on phylogenetic analysis of the 16S rRNA gene sequence, most of the isolated manganese reducers belong to the genusCarnobacterium. Cultures of a phylogenetically representative strain of Carnobacterium reduced synthetic MnO2 in the presence of sodium azide, as was seen in field assays. Unlike anaerobes that utilize manganese oxides as terminal electron acceptors in respiration, isolates of the genusCarnobacterium reduced Mn(IV) via a diffusible compound under oxic conditions. The release of adsorbed trace metals accompanying the solubilization of manganese oxides may provide populations of Carnobacterium with a source of nutrients in this extremely oligotrophic environment.

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Cycling of manganese and iron in Lake Mendota, Wisconsin

Cited by 32 publications

References 27 publications

Mercury Methylation Genes Identified across Diverse Anaerobic Microbial Guilds in a Eutrophic Sulfate-Enriched Lake

Mercury Methylation Genes Identified across Diverse Anaerobic Microbial Guilds in a Eutrophic Sulfate-Enriched Lake

Dissimilatory Fe(III) and Mn(IV) reduction.

Manganese Reduction by Microbes from Oxic Regions of the Lake Vanda (Antarctica) Water Column

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