Multiple sulfur isotope constraints on sulfate-driven anaerobic oxidation of methane: Evidence from authigenic pyrite in seepage areas of the South China Sea

Lin, Zhiyong; Sun, Xiaoming; Strauß, Harald; Lu, Yang; Gong, Junli; Xu, Li; Lu, Hongfeng; Teichert, Barbara M.A.; Peckmann, Jörn

doi:10.1016/j.gca.2017.05.015

Cited by 80 publications

(62 citation statements)

References 135 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Subhedral to euhedral pyrite crystals homogeneously distributed in the sediments showing the octahedral shape with a size of 5-45 µm (Figure 3b,d,f). In fact, the sectional shapes of both the pyrite band and sunflower-shaped framboid may configure a three-dimensional pyrite tube just as revealed by the previous report [49]. Several pyrite tubes are found in units A and C. Most of the tubes vary from 200 µm to 600 µm in length and from 85 µm to 140 µm in diameter; they consist of clustered pyrite framboids (Figure 3c,i).…”

Section: Sediment Texturessupporting

confidence: 59%

Petrographical and Geochemical Signatures Linked to Fe/Mn Reduction in Subsurface Marine Sediments from the Hydrate-Bearing Area, Dongsha, the South China Sea

Xiao

Zhou

et al. 2019

Minerals

View full text Add to dashboard Cite

Fe and Mn oxides and (oxy)-hydroxides are the most abundant solid-phase electron acceptors in marine sediments, and dissimilatory Fe/Mn reduction usually links with the anaerobic oxidation of methane (AOM) and organic matter oxidation (OMO) in sediments. In this study, we report the results from subsurface marine sediments in the Dongsha hydrate-bearing area in the South China Sea. The petrological and geochemical signatures show that the Fe/Mn reduction mediated by AOM and OMO might occur in sediments above the sulfate-methane transition zone. X-ray diffraction and scanning electron microscopy analyses of sediments indicate that Fe(III)/Mn(IV)-oxides and authigenic carbonate minerals coexisted in the Fe/Mn reduction zone. The lower δ13C values of dissolved inorganic carbon, coupled with an evident increase in total inorganic carbon contents and a decrease in Ca2+ and Mg2+ concentrations indicate the onset of AOM in this zone, and the greater variation of PO43− and NH4+ concentrations in pore water suggests the higher OMO rates in subsurface sediments. Geochemical and mineralogical analyses suggest that the previously buried Fe(III)/Mn(IV) oxides might be activated and lead to the onset of Fe/Mn reduction induced by AOM and OMO. These findings may extend our understanding of the biogeochemical processes involved in Fe/Mn reduction in continental shelves with abundant methane, organic matter, and terrigenous metal oxides.

show abstract

Section: Sediment Texturessupporting

confidence: 59%

Petrographical and Geochemical Signatures Linked to Fe/Mn Reduction in Subsurface Marine Sediments from the Hydrate-Bearing Area, Dongsha, the South China Sea

Xiao

Zhou

et al. 2019

Minerals

View full text Add to dashboard Cite

show abstract

“…As an example, 34 ε was found to be >20‰ in the water column of a low-sulfate lake, even at sulfate concentrations of ≤6 μM (Crowe et al, 2014). Furthermore, pyrite grains highly enriched in 34 S form at the SMT of sediments from the South China Sea (Lin et al, 2017). This must be the result of a high 34 ε sustained even at the low sulfate concentrations found in the SMT.…”

Section: Stable Sulfur Isotopesmentioning

confidence: 99%

“…MSI have been measured in a variety of modern marine sediments, for example the Baltic Sea (Strauss et al, 2012), Mangrove Lake (Pellerin et al, 2015b), Alfonso Basin (Masterson et al, 2018), and South China Sea (Lin et al, 2017, 2018). In a sapropel sediment of Mangrove Lake, Bermuda, the Δ 33 S of pore water sulfate was inconsistent with only sulfate reduction.…”

Section: Stable Sulfur Isotopesmentioning

confidence: 99%

The Biogeochemical Sulfur Cycle of Marine Sediments

2019

View full text Add to dashboard Cite

Microbial dissimilatory sulfate reduction to sulfide is a predominant terminal pathway of organic matter mineralization in the anoxic seabed. Chemical or microbial oxidation of the produced sulfide establishes a complex network of pathways in the sulfur cycle, leading to intermediate sulfur species and partly back to sulfate. The intermediates include elemental sulfur, polysulfides, thiosulfate, and sulfite, which are all substrates for further microbial oxidation, reduction or disproportionation. New microbiological discoveries, such as long-distance electron transfer through sulfide oxidizing cable bacteria, add to the complexity. Isotope exchange reactions play an important role for the stable isotope geochemistry and for the experimental study of sulfur transformations using radiotracers. Microbially catalyzed processes are partly reversible whereby the back-reaction affects our interpretation of radiotracer experiments and provides a mechanism for isotope fractionation. We here review the progress and current status in our understanding of the sulfur cycle in the seabed with respect to its microbial ecology, biogeochemistry, and isotope geochemistry.

show abstract

“…Due to unforeseen circumstances pore water was not extracted upon core recovery, but was delayed by several months 5 following the cruise, compromising the available pore water methane and sulfate profiles . Fortunately, pore water sulfate and methane concentrations are relatively well constrained from proximal sites (Lin et al, 2017b;Lu et al, 2012;Ye et al, 2016). The pore water chemistry of these nearby sites displays consistently shallow SMTZs, found between 700 and 880 cm depth, fueled by a high methane flux released from underlying gas hydrates (Sha et al, 2015).…”

Section: Methodsmentioning

confidence: 99%

Vivianite formation in methane-rich deep-sea sediments from the South China Sea

Liu¹,

Wang²,

Izon³

et al. 2018

Preprint

View full text Add to dashboard Cite

Phosphorus is often invoked as the ultimate limiting nutrient, modulating primary productivity on geological timescales. Consequently, along with nitrogen, phosphorus bioavailability exerts a fundamental control on organic carbon production, linking all the biogeochemical cycles across the Earth system. Unlike nitrogen that can be microbially fixed from 15 an essentially infinite atmospheric reservoir, phosphorus availability is dictated by the interplay between its sources and sinks.While authigenic apatite formation has received considerable attention as the dominant sedimentary phosphorus sink, the quantitative importance of reduced iron-phosphate minerals, such as vivianite, has only recently been acknowledged and their importance remains under-explored. Combining microscopic and spectroscopic analyses of handpicked mineral aggregates with sediment geochemical profiles we characterize the distribution and mineralogy of iron-phosphate minerals present in 20 methane-rich sediments recovered from the northern South China Sea. Here, we demonstrate that vivianite authigenesis is pervasive in the iron oxide-rich sediments below the sulfate-methane transition zone (SMTZ). We hypothesize that the downward migration of the SMTZ concentrated vivianite formation below the current SMTZ. Our observations support recent findings from non-steady state post-glacial coastal sedimentary successions, suggesting that iron reduction below the SMTZ, probably driven by iron-mediated anaerobic oxidation of methane (Fe-AOM), is coupled to phosphorus cycling on a much 25 greater spatial scale than previously assumed. Calculations reveal that vivianite acts as an important burial phase for both iron and phosphorus below the SMTZ, sequestering approximately half of the total reactive iron pool. By extension, sedimentary vivianite formation could serve as a mineralogical marker of Fe-AOM, signalling a low-sulfate availability against methanogenic and ferruginous backdrop. Given that similar conditions were likely present throughout vast swaths of Earth history, it is possible that Fe-AOM may have modulated phosphorus and methane availability on the early Earth. 30Biogeosciences Discuss., https://doi.

show abstract

Multiple sulfur isotope constraints on sulfate-driven anaerobic oxidation of methane: Evidence from authigenic pyrite in seepage areas of the South China Sea

Cited by 80 publications

References 135 publications

Petrographical and Geochemical Signatures Linked to Fe/Mn Reduction in Subsurface Marine Sediments from the Hydrate-Bearing Area, Dongsha, the South China Sea

Petrographical and Geochemical Signatures Linked to Fe/Mn Reduction in Subsurface Marine Sediments from the Hydrate-Bearing Area, Dongsha, the South China Sea

The Biogeochemical Sulfur Cycle of Marine Sediments

Vivianite formation in methane-rich deep-sea sediments from the South China Sea

Contact Info

Product

Resources

About