The Recycling of Biogenic Material at the Sea Floor

Martin, William R.; Sayles, F.L.

doi:10.1016/b978-0-08-095975-7.00702-6

Cited by 5 publications

(1 citation statement)

References 126 publications

(171 reference statements)

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“…In sediments, where age increases with sediment burial, organic matter reactivity generally decreases with depth because more labile organic matter is preferentially remineralized near the sediment surface, leaving behind less reactive organic matter for subsequent decomposition with burial. Organic matter remineralization rates are therefore generally highest near the sediment‐water interface and decrease in a near‐continuous fashion with depth [e.g., Soetaert et al ., ; Martin and Sayles , ; Jørgensen and Parkes , ]. In some marine sediments, however, profiles of pore water solutes such as O 2 , nitrate, and sulfate suggest the occurrence of this type of depth attenuation of remineralization processes in surface sediments, along with the existence of a deeper reaction zone.…”

Section: Introductionmentioning

confidence: 99%

Using ammonium pore water profiles to assess stoichiometry of deep remineralization processes in methanogenic continental margin sediments

Burdige

Komada

2013

Geochem Geophys Geosyst

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[1] In many continental margin sediments, a deep reaction zone exists which is separated from remineralization processes near the sediment surface. Here, methane diffuses upward to a depth where it is oxidized by downwardly diffusing sulfate. However, the methane sources that drive this anaerobic oxidation of methane (AOM) in the sulfate-methane transition zone (SMT) may vary among sites. In particular, these sources can be thought of as either (i) "internal" sources from in situ methanogenesis (regardless of where it occurs in the sediment column) that are ultimately coupled to organic matter deposition and burial, or (ii) "external" sources such as hydrocarbon reservoirs derived from ancient source rocks, or deeply buried gas hydrates, both of which are decoupled from contemporaneous organic carbon deposition at the sediment surface. Using a modeling approach, we examine the relationship between different methane sources and pore water sulfate, methane, dissolved inorganic carbon (DIC), and ammonium profiles. We show that pore water ammonium profiles through the SMT represent an independent "tracer" of remineralization processes occurring in deep sediments that complement information obtained from profiles of solutes directly associated with AOM and carbonate precipitation, i.e., DIC, methane, and sulfate. Pore water DIC profiles also show an inflection point in the SMT based on the type of deep methane source and the presence/absence of accompanying upward DIC fluxes. With these results, we present a conceptual framework which illustrates how shallow pore water profiles from continental margin settings can be used to obtain important information about remineralization processes and methane sources in deep sediments.

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Section: Introductionmentioning

confidence: 99%