Sulfate reduction and anaerobic methane oxidation in Black Sea sediments

Jørgensen, Bo Barker; Weber, Andreas; Zopfi, Jakob

doi:10.1016/s0967-0637(01)00007-3

Cited by 239 publications

(177 citation statements)

References 45 publications

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“…While AOM is thus generally coupled to SO 4 2À reduction (SDMO) in marine waters and sediments (e.g. Iversen and Jørgensen, 1985;Boetius et al, 2000;Jørgensen et al, 2001), other electron acceptors of AOM have been much less frequently studied in freshwater systems. Due to low the SO 4 2À concentrations usually observed in freshwaters environments, AOM is often considered to be negligible compared to aerobic CH 4 oxidation (Rudd et al, 1974).…”

Section: Introductionmentioning

confidence: 99%

Emission and oxidation of methane in a meromictic, eutrophic and temperate lake (Dendre, Belgium)

et al. 2017

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h i g h l i g h t sThe studied lake was meromictic and characterized by high methane, nutrients and sulfate concentrations in the water column. High aerobic and anaerobic methane oxidation rates were observed in the water column, and were dependent on the season. Anaerobic methane oxidation was linked to sulfate reduction, and potentially to nitrate reduction. Despite high methane oxidation rates, methane fluxes to the atmosphere were high. a r t i c l e i n f o a b s t r a c tWe sampled the water column of the Dendre stone pit lake (Belgium) in spring, summer, autumn and winter. Depth profiles of several physico-chemical variables, nutrients, dissolved gases (CO 2 , CH 4 , N 2 O), sulfate, sulfide, iron and manganese concentrations and d 13 C-CH4 were determined. We performed incubation experiments to quantify CH 4 oxidation rates, with a focus on anaerobic CH 4 oxidation (AOM), without and with an inhibitor of sulfate reduction (molybdate). The evolution of nitrate and sulfate concentrations during the incubations was monitored. The water column was anoxic below 20 m throughout the year, and was thermally stratified in summer and autumn. High partial pressure of CO 2 and CH 4 and high concentrations of ammonium and phosphate were observed in anoxic waters. Important nitrous oxide and nitrate concentration maxima were also observed (up to 440 nmol L À1 and 80 mmol L À1 , respectively). Vertical profiles of d 13 C-CH 4 unambiguously showed the occurrence of AOM. Important AOM rates (up to 14 mmol L À1 d À1 ) were observed and often co-occurred with nitrate consumption peaks, suggesting the occurrence of AOM coupled with nitrate reduction. AOM coupled with sulfate reduction also occurred, since AOM rates tended to be lower when molybdate was added. CH 4 oxidation was mostly aerobic (~80% of total oxidation) in spring and winter, and almost exclusively anaerobic in summer and autumn. Despite important CH 4 oxidation rates, the estimated CH 4 fluxes from the water surface to the atmosphere were high (mean of 732 mmol m À2 d À1 in spring, summer and autumn, and up to 12,482 mmol m À2 d À1 in winter).

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Section: Introductionmentioning

confidence: 99%

Emission and oxidation of methane in a meromictic, eutrophic and temperate lake (Dendre, Belgium)

et al. 2017

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“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14]). Concentration and oxidation rate measurements of CH 4 dissolved in the water column and sediments [1][2][3][4][5][6] have been used to assemble CH 4 geochemical budgets for the entire Black Sea [1] and the north-western shelf [5]. These studies indicate that the Black Sea is the largest surface water reservoir of dissolved CH 4 (96 Tg) of which 0.066 Tg yr − 1 are emitted into the atmosphere [1].…”

Section: Introductionmentioning

confidence: 99%

“…However, they determined the flux of CH 4 from the shelf core to be 0.2 mol m − 2 yr − 1 leaving 86.7% of the balancing source flux not quantified [1]. Subsequent measurements of CH 4 concentration profiles in sediment cores [5,6] indicate that the diffusive flux of CH 4 from sediments to the water [47]. By convention [47], all radiocarbon results are normalized to 13 C. Samples were collected in the (○) central Black Sea water column in July 1988 [1,50] and (▴) western Black Sea water column in May 2001.…”

Section: Introductionmentioning

confidence: 99%

Basin-wide estimates of the input of methane from seeps and clathrates to the Black Sea

Kessler

Reeburgh

Southon

et al. 2006

Earth and Planetary Science Letters

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Numerous methane-emitting bottom features, such as seeps, methane clathrate hydrates (clathrates), and mud volcanoes, have been identified recently in the Black Sea. The fluxes of methane from these sources averaged over large spatial scales are unknown. Here we take advantage of the fact that the Black Sea is a semi-enclosed basin with restricted deep water circulation to establish firstorder estimates of basin-wide fluxes of methane from these sources to the water column and atmosphere. First, we measured the natural radiocarbon content of methane ( 14 C-CH 4 ) dissolved in the water column and emitted from seeps. The 14 C-CH 4 results showed that the dominant source of methane to the water column is emitted from seeps and a smaller source is diagenetically produced in relatively modern sediments. The 14 C-CH 4 results were then used to partition a basin-wide total methane budget; this analysis estimated the basin-wide flux of methane from seeps and clathrates to the water column to be 3.60 to 4.28 Tg yr − 1 . Second, a geochemical box model was used to calculate possible distributions of methane inputs from seeps and clathrates as well as provide additional estimates of the basin-wide flux of methane from seeps and clathrates to the water column (4.95 to 5.65 Tg yr − 1 ).

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“…However, even showing high slope in sulfate profile in this depth, the geochemical data showed high concentration of methane (around 20,000 ppm) and gas hydrate formation (PC51).The methane profile is crossing the SMI, which suggests that the AOM does not consume all the available methane migrating through the zone of major AOM activity (Knab et al 2009, Reeburgh et al 1991, Jørgensen et al 2001, Hensen et al2003. AOM of this type, having such methane-tailing profiles, is referred as "sluggish" and it is generally associated with variable methane flux rates (Jørgensen et al2001).…”

Section: Discussionmentioning

confidence: 92%

“…It remains unclear why the microorganisms cannot bring down the substrate concentrations further and shorten the lifetime of coexisting methane and sulfate. Little is known about their limiting the efficiency of the anaerobic methane oxidizing microorganisms (Jørgensen et al 2001). Since the gradients have not significantly smoothed, the event at PC51 and PC53 has probably occurred very recently like a magnitude of the mass (re-)movements, for example.…”

Section: Discussionmentioning

confidence: 99%

The influence of methane fluxes on the sulfate/methane interface in sediments from the Rio Grande Cone Gas Hydrate Province, southern Brazil

et al. 2017

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Much research has been published regarding the relation between major gas hydrate accumulations and the global carbon cycle. In this context, the determination of the sulfate/methane interface (SMI) depth is of primary importance in order to understand the dynamics of methane flux in the shallow section. This paper identifies the depth of the SMI in sediments based on sulfate and methane concentration profiles in cores recovered in the Rio Grande Cone Gas Hydrate Province, Pelotas Basin, southern Brazil. The shape of methane and sulfate concentration profiles in the sediments can be linked to the local methane flux rate as follows: (i) near linear, high upward-diffusing methane flux coupled with high sulfate diffusion from seawater; (ii) irregular, variable methane flux rates; and (iii) kink-type profile, which is indicative of variable rather than strictly high upward methane flux. The areas in which a high methane flux was identified are spatially associated with gas chimneys in sediments within pockmarks, whereas profiles with low methane flux are present in adjacent areas. These chimneys appear as acoustic blankings in seismic records and can therefore be mapped in subsurface. The wavy-like seismic reflection following the SMI coincides with the occurrence of authigenic carbonate nodules and concretions. In addition, high methane fluxes and the occurrence of concretions and nodules carbonates were correlated by stratigraphic position of the concretions bearing intervals and sulfate profiles. KEYWORDS: gas hydrate; methane flux; Rio Grande Cone; Brazil. RESUMO: Muitas pesquisas têm sido publicadas relacionando elevadas acumulações de hidrato de gás e o ciclo global do carbono. Nesse contexto, a determinação da profundidade da interface sulfato/metano (SMI) é importante para entender a dinâmica do fluxo de metano em locais rasos. Este artigo científico identifica a profundidade da SMI em sedimentos com base em perfis de concentração de sulfato e metano em testemunhos recuperados na Província do Hidrato de Gás do

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Sulfate reduction and anaerobic methane oxidation in Black Sea sediments

Cited by 239 publications

References 45 publications

Emission and oxidation of methane in a meromictic, eutrophic and temperate lake (Dendre, Belgium)

Emission and oxidation of methane in a meromictic, eutrophic and temperate lake (Dendre, Belgium)

Basin-wide estimates of the input of methane from seeps and clathrates to the Black Sea

The influence of methane fluxes on the sulfate/methane interface in sediments from the Rio Grande Cone Gas Hydrate Province, southern Brazil

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