Publication Date:
2017-01-19
Description:
Recent developments in the quantitativemodeling of methane dynamics and anaerobic oxidation of methane
(AOM) in marine sediments are critically reviewed. The first part of the review begins with a comparison of
alternative kinetic models for AOM. The roles of bioenergetic limitations, intermediate compounds and
biomass growth are highlighted. Next, the key transport mechanisms in multi-phase sedimentary
environments affecting AOM and methane fluxes are briefly treated, while attention is also given to
additional controls on methane and sulfate turnover, including organic matter mineralization, sulfur cycling
and methane phase transitions. In the second part of the review, the structure, forcing functions and
parameterization of published models of AOM in sediments are analyzed. The six-orders-of-magnitude range
in rate constants reported for the widely used bimolecular rate law for AOM emphasizes the limited
transferability of this simple kinetic model and, hence, the need for more comprehensive descriptions of the
AOM reaction system. The derivation and implementation of more complete reaction models, however, are
limited by the availability of observational data. In this context, we attempt to rank the relative benefits of
potential experimental measurements that should help to better constrain AOM models. The last part of the
review presents a compilation of reported depth-integrated AOM rates (ΣAOM). These rates reveal the
extreme variability of ΣAOM in marine sediments. The model results are further used to derive quantitative
relationships between ΣAOM and the magnitude of externally impressed fluid flow, as well as between ΣAOM
and the depth of the sulfate–methane transition zone (SMTZ). This review contributes to an improved
understanding of the global significance of the AOM process, and helps identify outstanding questions and
future directions in the modeling of methane cycling and AOM in marine sediments.
Type:
Article
,
PeerReviewed
Format:
text
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