Nitrogen cycling in deeply oxygenated sediments: Results in Lake Superior and implications for marine sediments

Li, Jiying; Katsev, Sergei

doi:10.4319/lo.2014.59.2.0465

Cited by 25 publications

(32 citation statements)

References 48 publications

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“…At the Eastern Basin locations investigated here, oxygen penetrates 10-12 cm into the sediment (Li et al 2012), and in low-sedimentation offshore areas exceeds 6-12 cm (Li et al 2012;Li and Katsev 2014). Nitrate is found to penetrate even deeper (Carlton et al 1989;Li and Katsev 2014). The overlap of the geochemical profiles of nitrate and ferrous iron provides evidence for the coupling of iron oxidation to nitrate reduction (Li and Katsev 2014), a phenomenon known from previous studies (Kasten et al 2003;Wilson et al 1985;Berger 1983;Froelich et al 1979).…”

Section: Introductionmentioning

confidence: 70%

“…Nitrate is found to penetrate even deeper (Carlton et al 1989;Li and Katsev 2014). The overlap of the geochemical profiles of nitrate and ferrous iron provides evidence for the coupling of iron oxidation to nitrate reduction (Li and Katsev 2014), a phenomenon known from previous studies (Kasten et al 2003;Wilson et al 1985;Berger 1983;Froelich et al 1979).…”

Section: Introductionmentioning

confidence: 87%

“…This may be due to different nutrient concentration in the pore water at the two sites: the concentrations of ammonium and phosphate were considerably higher at EM (Li and Katsev 2014;Li 2014). Higher levels of oxygen and organic matter both allow increased cellular respiration and can support bacterial communities at greater densities.…”

Section: Microbial Communities In Sediments Of Lake Superiormentioning

confidence: 94%

“…Welldefined Mn and Fe layers in the oxidized upper sediment have been reported at multiple locations (Sly and Thomas 1974;Li et al 2012). Though typically located near the depth of oxygen penetration or nitrogen penetration (Li and Katsev 2014), these layers are also sometimes found in the presently anoxic or in the presently oxic zones (Richardson and Nealson 1998). The organic carbon mineralization in Lake Superior is dominated by aerobic respiration: At the offshore low-sedimentation locations, more than 95 % of carbon is mineralized using oxygen as electron acceptor (Carlton et al 1989;Li et al 2012), denitrification accounts for less than 2 % (Li and Katsev 2014), while metal reduction and sulfate reduction account for even smaller fractions (Li and Katsev 2014;Li 2014).…”

Section: Introductionmentioning

confidence: 98%

“…The organic carbon mineralization in Lake Superior is dominated by aerobic respiration: At the offshore low-sedimentation locations, more than 95 % of carbon is mineralized using oxygen as electron acceptor (Carlton et al 1989;Li et al 2012), denitrification accounts for less than 2 % (Li and Katsev 2014), while metal reduction and sulfate reduction account for even smaller fractions (Li and Katsev 2014;Li 2014). At the Eastern Basin locations investigated here, oxygen penetrates 10-12 cm into the sediment (Li et al 2012), and in low-sedimentation offshore areas exceeds 6-12 cm (Li et al 2012;Li and Katsev 2014). Nitrate is found to penetrate even deeper (Carlton et al 1989;Li and Katsev 2014).…”

Section: Introductionmentioning

confidence: 99%

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Geomicrobiology of Iron Layers in the Sediment of Lake Superior

et al. 2015

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Previous studies of deeply oxygenated (8-12 cm) sediments in Lake Superior revealed prominent iron (Fe)-rich layers, up to 2 cm thick. Whereas metal enrichments are common near the oxic-anoxic boundary in aquatic sediments, several geomicrobiological aspects of their formation remain unknown. In this study, we analyzed geochemical and microbiological signatures associated with the Fe-rich layer in Lake Superior at two locations (230 and 310-m water depth) in the Eastern Basin of the lake. We measured oxygen and metal contents in the sediment solid phase and imaged the Fe-rich layer with transmission and scanning electron microscope (TEM and SEM). Bacterial communities were characterized using tag-encoded FLX small subunit ribosomal gene amplicon pyrosequencing. The SEM images reveal filamentous structures encrusted with spheres of ca. 20 nm in diameter. TEM and energy dispersive X-ray spectroscopy observations of thin sections indicate that bacteria cells served as nucleation surfaces for Fe-oxide formation. The Fe-rich layers, in contrast to the layers directly above them, were dominated by members of the NC10 phylum, known for anaerobic methane oxidation, and also harbored a high proportion of Nitrospira species that were most similar to members of a Fe-rich seep. Taken together the results suggests that microorganisms, whose cell surfaces are serving as templates for iron oxide precipitates that might also be mediating the iron oxidation, support formation of the Fe-rich layers.

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Section: Introductionmentioning

confidence: 70%

Section: Introductionmentioning

confidence: 87%

Section: Microbial Communities In Sediments Of Lake Superiormentioning

confidence: 94%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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Geomicrobiology of Iron Layers in the Sediment of Lake Superior

et al. 2015

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Phosphorus recycling in deeply oxygenated sediments in Lake Superior controlled by organic matter mineralization

Zhang

Katsev

2018

Limnology & Oceanography

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Remobilization of phosphorus from aquatic sediments has been extensively investigated in systems prone to anoxia, while studies in well‐oxygenated systems have been rare. The recycling efficiency of P in the offshore sediments in the Great Lakes, in particular, is still poorly known. We investigated phosphorus cycling at 13 locations (26–318 m water depth) in oligotrophic Lake Superior where oxygen penetrates into sediments by 2–12 cm. Vertical distributions of iron and phosphorus were measured in porewater and solid fractions, and transformation rates and vertical fluxes were calculated. Whereas a significant fraction of P is bound to ferric Fe in surface sediments, P effluxes into the water column (2.5–7.0 μmol m−2 d−1) are only weakly affected by iron reduction, because Fe : P ratios in surface sediment are high (∼ 40–80 mol : mol), and P sorption capacity is far from its limit. In contrast to organic rich systems where P effluxes are sensitive to redox conditions, phosphate effluxes in organic‐poor well‐oxygenated Lake Superior are controlled by the rates of organic phosphorus mineralization, similar to marine sediments. The efficiency of P recycling in Lake Superior sediments, however, is substantially lower than in marine sediments due to different P biogeochemistry. Only ∼ 12% of deposited P is returned to the water column. While burial into sediments is the dominant sink for P in the lake, sediments still contribute up to 40% of total water column P inputs. Similar behavior should be expected in other well‐oxygenated freshwater systems, such as other large oligotrophic lakes.

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Organic sulfur from source to sink in low‐sulfate Lake Superior

Phillips,

Ulloa,

Hyde

et al. 2023

Limnology & Oceanography

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Organic sulfur plays a crucial role in the biogeochemistry of aquatic sediments, especially in low sulfate (< 500 μM) environments like freshwater lakes and the Earth's early oceans. To better understand organic sulfur cycling in these systems, we followed organic sulfur in the sulfate‐poor (< 40 μM) iron‐rich (30–80 μM) sediments of Lake Superior from source to sink. We identified microbial populations with shotgun metagenomic sequencing and characterized geochemical species in porewater and solid phases. In anoxic sediments, we found an active sulfur cycle fueled primarily by oxidized organic sulfur. Sediment incubations indicated a microbial capacity to hydrolyze sulfonates, sulfate esters, and sulfonic acids to sulfate. Gene abundances for dissimilatory sulfate reduction (dsrAB) increased with depth and coincided with sulfide maxima. Despite these indicators of sulfide formation, sulfide concentrations remain low (< 40 nM) due to both pyritization and organic matter sulfurization. Immediately below the oxycline, pyrite accounted for 13% of total sedimentary sulfur. Both free and intact lipids in this same interval accumulated disulfides, indicating rapid sulfurization even at low concentrations of sulfide. Our investigation revealed a new model of sulfur cycling in a low‐sulfate environment that likely extends to other modern lakes and possibly the ancient ocean, with organic sulfur both fueling sulfate reduction and consuming the resultant sulfide.

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Nitrogen cycling in deeply oxygenated sediments: Results in Lake Superior and implications for marine sediments

Cited by 25 publications

References 48 publications

Geomicrobiology of Iron Layers in the Sediment of Lake Superior

Geomicrobiology of Iron Layers in the Sediment of Lake Superior

Phosphorus recycling in deeply oxygenated sediments in Lake Superior controlled by organic matter mineralization

Organic sulfur from source to sink in low‐sulfate Lake Superior

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