Biogenic methane in coastal unconsolidated sediment systems: A review

Duan, Xiaoyong; Yin, Ping; Tsona, Narcisse T.; Cao, Ke; Xie, Yongqing; He, Xianqiang; Chen, Bin; Chen, Junbing; Gao, Fei; Yang, Liu; Lv, Shenghua

doi:10.1016/j.envres.2023.115803

Cited by 4 publications

(2 citation statements)

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“…Based on two boreholes with a depth of ~60 m, the second interface has been found. In the second interface, the content of methane decreases rapidly with the increase of depth, while the content of sulfate increases rapidly with the increase of depth (Duan et al, 2023). The existence of a second interface was reasonable, but more evidence was needed to reveal its controlling mechanism.…”

Section: Introductionmentioning

confidence: 98%

“…There were 1.1~3.0 × 10 6 Pg biogenic CH 4 in global marine sediments (Lee et al, 2022). The emission of shallow gas from sedimentary deposits can cause harmful impacts on offshore infrastructures, marine ecosystems, and even global climate change (Sultan et al, 2020;Duan et al, 2023). Shallow gas in marine sediments was closely linked to the carbon cycle, making it a significant concern for scientific community (Holgerson and Raymond, 2016).…”

Section: Introductionmentioning

confidence: 99%

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The relationships between vertical variations of shallow gas and pore water geochemical characteristics in boreholes from the inner shelf of the East China Sea

Li,

Duan,

et al. 2024

Front. Mar. Sci.

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Shallow gas was widely recognized in the coastal region, especially in the estuarine delta areas with high organic matter (OM) burial flux. In this study, the vertical variations of shallow gas and the related geochemical indicators from two boreholes in the coastal region of the East China Sea (ECS) were investigated. Two gas-bearing layers were identified in the sediments from the Holocene and late Pleistocene series. Both boreholes exhibit a “typical” and an “inverse” Sulfate Methane Transition Zone (SMTZ). The “typical” SMTZs (SMTZ1 and SMTZ3) were in the upper part of the gas-bearing layers, where sulfate levels decrease and methane levels increase with depth. Conversely, the “inverse” SMTZs (SMTZ2 and SMTZ4) were in the lower part of the gas-bearing layers, exhibiting an increase in sulfate levels and a decrease in methane levels with depth, a phenomenon rarely documented in previous research. The downward variations of pore water geochemical characteristics indicates that these ions were related to Anaerobic Oxidation of Methane (AOM) processes. The increase in Ca2+ and Ba2+ concentrations and the gradual decrease in sulfate at the SMTZ reflect a series of biogeochemical processes resulting from the dissolution of carbonate and other minerals by AOM. The research indicates that sulfate in AOM may originate from multiple sources. Through analyzing the vertical distribution of shallow gas and the geochemical properties of pore water, this study elucidates the shallow gas formation mechanism and the features of the SMTZ, laying the groundwork for further investigations.

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Section: Introductionmentioning

confidence: 98%