The inorganic geochemistry of a Mediterranean Ridge mud breccia

Wakefield, S. J.; O'Sullivan, Gerard M.

doi:10.1016/0025-3227(95)00161-1

Cited by 5 publications

(5 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Such 13 C-depleted biomarker values can arise during methylotrophic methanogenesis utilizing organic substrates (34), but that would require extensive methane oxidation by either bacteria or other archaea to provide substrate carbon. (Exogenous organic carbon inputs appear to be small [36] and are not a likely source of substrate carbon.) Multiple lines of evidence indicate that aerobic methanotrophy by bacteria does not provide substrates for methanogenesis.…”

Section: Resultsmentioning

confidence: 99%

Biomarker Evidence for Widespread Anaerobic Methane Oxidation in Mediterranean Sediments by a Consortium of Methanogenic Archaea and Bacteria

Pancost

Damsté

Lint

et al. 2000

Appl Environ Microbiol

365

236

View full text Add to dashboard Cite

Although abundant geochemical data indicate that anaerobic methane oxidation occurs in marine sediments, the linkage to specific microorganisms remains unclear. In order to examine processes of methane consumption and oxidation, sediment samples from mud volcanoes at two distinct sites on the Mediterranean Ridge were collected via the submersible Nautile. Geochemical data strongly indicate that methane is oxidized under anaerobic conditions, and compound-specific carbon isotope analyses indicate that this reaction is facilitated by a consortium of archaea and bacteria. Specifically, these methane-rich sediments contain high abundances of methanogen-specific biomarkers that are significantly depleted in 13 C (␦ 13 C values are as low as ؊95‰). Biomarkers inferred to derive from sulfate-reducing bacteria and other heterotrophic bacteria are similarly depleted. Consistent with previous work, such depletion can be explained by consumption of 13 Cdepleted methane by methanogens operating in reverse and as part a consortium of organisms in which sulfate serves as the terminal electron acceptor. Moreover, our results indicate that this process is widespread in Mediterranean mud volcanoes and in some localized settings is the predominant microbiological process.Methane can have a stronger greenhouse effect than CO 2 , and recent work has highlighted its potential climatic impact on glacial timescales (24) and in relation to major geologic events (8,12). Consequently, controls on methane production and consumption are important concerns in the evaluation of past and future climate change. In marine sediments, anaerobic methane oxidation could be the dominant pathway for methane consumption (2,4,6,15,25,26), but the organisms involved have not been isolated and the mechanism remains controversial. Methanogenic archaea operating in reverse (9,11,14) or novel, previously uncharacterized archaea (13) have been proposed to play a vital role, but current evidence remains ambiguous.Methane tends to be highly depleted in 13 C, and organisms that consume methane either directly or indirectly via heterotrophic consumption of methanotroph biomass will be similarly depleted in 13 C. For this study, we determined distributions and carbon isotope abundances of organic components in methane-rich mud volcano sediments of the Eastern Mediterranean Ridge. In particular, we examined the ␦ 13 C values of compounds derived from specific organisms (i.e., biomarkers) presumed to play a major role in methane oxidation, including methanogens, aerobic methanotrophs, sulfate-reducing bacteria, and anaerobic heterotrophic bacteria. From these results, we evaluate the controls on and microorganisms responsible for methane oxidation in these sediments and the conditions under which methane oxidation occurs. MATERIALS AND METHODSSamples. Using a bordeaux core, samples were collected from surface sediments (upper 30 cm) of several mud volcano flows (mud breccias) in the Olimpi (Milano and Napoli mud volcanoes) and Anaximander (Amsterdam mud volcano) fi...

show abstract

Section: Resultsmentioning

confidence: 99%

Biomarker Evidence for Widespread Anaerobic Methane Oxidation in Mediterranean Sediments by a Consortium of Methanogenic Archaea and Bacteria

Pancost

Damsté

Lint

et al. 2000

Appl Environ Microbiol

365

236

View full text Add to dashboard Cite

show abstract

“…The effect of bariumbearing mud used during drilling operations of oil wells is prominent at Shuqeir city, the case that is also noticed by Holmes (1982) in the Gulf of Mex-ico, where barium is enriched in sediments due to its high content in drilling mud. Other sources of barium could be neglected; these are barium enrichment by organic matter (Mauchline & Templeton, 1966;Wakefield &O'Sullivan, 1996 andRutten et al, 1999 and barium contributed by hydrothermal solutions (Eriksson et al, 1997;Souissi et al, 1997 andCronan &Hodkinson, 1997) since the first is very low to explain for the high barium concentrations in sediments of the area of study and secondly the areas of known hydrothermal activities are too far and deep to contribute high barium concentrations to the beach sediments of the study area.…”

Section: Resultsmentioning

confidence: 99%

Discrimination of Sources of Barium in Beach Sediments, Marsa Alam-Shuqeir, Red Sea Coast, Egypt

El-Mamoney¹,

Rifaat²

2001

mar

View full text Add to dashboard Cite

The concentration of barium in beach sediments between Marsa Alam and Shuqeir, along the Egyptian Red Sea coast was investigated. There is a southward increasing trend in the concentrations of carbonate, barium and strontium. The grain size of the studied sediments follows a converse trend where sediments tend to be finer from north to south. On the other hand, trend analysis showed that barium of unnatural source increases from south to north. The data analysed reveal that the main sources of barium are: 1) The carbonate source, which is clearly confirmed by the close relation of carbonate, barium and strontium and 2) Abnormal increase in the oil exploration industry, which may be responsible for the higher barium concentrations in the northern part of the studied area.

show abstract

“…Molar ratio of total N : total P in sediments from the major sedimentary provenances across the eastern Mediterranean (Eijsink et al 2000 * Value for Total P is not given. The concentration used was that for BC03 (Eijsink et al 2000), which is a location south of Crete close to that given in Wakefield and O'Sullivan (1996). † Burial flux of N calculated from the C org accumulation rate (g m Ϫ2 yr Ϫ1 ), divided by the C org : N org ratio given in Nijenhuis et al (2001).…”

Section: Nutrient Flux Through the Straits Of Sicily-mentioning

confidence: 99%

“…Wakefield and O'Sullivan (1996) presented total N values for a station on the Mediterranean ridge south of Crete very close to Sta. BC03 measured in Eijsink et al (2000).…”

Section: Determination Of the Burial Flux Of N And P In Sediments-mentioning

confidence: 99%

“…There are few values for total N available for the deeper basins of the eastern Mediterranean and none where total N and P were measured on the same samples. Wakefield and O'Sullivan (1996) presented total N values for a station on the Mediterranean ridge south of Crete very close to Sta. BC03 measured in Eijsink et al (2000).…”

Section: Determination Of the Burial Flux Of N And P In Sediments-mentioning

confidence: 99%

See 1 more Smart Citation

Nutrient budget for the Eastern Mediterranean: Implications for phosphorus limitation

Krom

Herut

Mantoura

2004

Limnology & Oceanography

271

181

View full text Add to dashboard Cite

The eastern Mediterranean has a high nitrate to phosphate (N : P) ratio (ϳ28 : 1) in the deep water and a highly unusual P limitation of the primary productivity. We present a detailed nutrient budget of inputs to the basin, which shows that there is a high N : P ratio (Ͼ16 : 1) in all the input sources, particularly from the atmospheric source, where the N : P ratio was 117 : 1. The high N : P ratio is retained within the system because there is no significant denitrification in either the sediments or intermediate water. This is because of the extreme oligotrophic nature of the system, which is caused by the unusual anti-estuarine flow at the Straits of Sicily. Support for this conclusion is provided by the observation that the only area of the eastern Mediterranean where the N : P ratio in deeper water is ϳ16 : 1 is the northern Adriatic, which is also the only area with significant denitrification. The N budget (total input to basin vs. net output at the straits of Sicily) balances closely. This N balance suggests that N fixation is an insignificant process in this P-limited system. The unusually light 15 N values in the deep water nitrate and particulate organic nitrogen can be explained by processes other than nitrogen fixation. These processes include a lack of significant denitrification in the basin and by particulate organic matter exported from surface waters during the Plimited winter plankton bloom.

show abstract

The inorganic geochemistry of a Mediterranean Ridge mud breccia

Cited by 5 publications

References 12 publications

Biomarker Evidence for Widespread Anaerobic Methane Oxidation in Mediterranean Sediments by a Consortium of Methanogenic Archaea and Bacteria

Biomarker Evidence for Widespread Anaerobic Methane Oxidation in Mediterranean Sediments by a Consortium of Methanogenic Archaea and Bacteria

Discrimination of Sources of Barium in Beach Sediments, Marsa Alam-Shuqeir, Red Sea Coast, Egypt

Nutrient budget for the Eastern Mediterranean: Implications for phosphorus limitation

Contact Info

Product

Resources

About