Karaca, Deniz, Schleicher, Tina, Hensen, Christian , Linke, Peter and Wallmann, Klaus (2014) Quantification of methane emission from bacterial mat sites at Quepos Slide offshore Costa Rica. International Journal of Earth Sciences, 103 (7). pp. 1817-1829. DOI 10.1007/s00531-012-0839-3.

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Abstract

Seafloormethane emission from the Quepos Slide
on the submarine segment of the Costa Rica fore-arc margin
was estimated by extrapolating flux measurements from individual
seeps to the total area covered by bacterial mats. This
approach is based on the combination of detailed mapping to
determine the abundance of seeps and the application of a
numerical model to estimate the amount of benthic methane
fluxes. Model results suggest that the majority of the studied
seeps transport rather limited amount of methane (on average:
*177 lmol cm-2 a-1) into the water column due to moderate
upward advection, allowing for intense anaerobic oxidation
of methane (AOM; on average: 53 % of the methane flux is
consumed). Depth-integrated AOM rates (56–1,538 lmol
CH4 cm-2 a-1) are comparable with values reported from
other active seep sites. The overall amount of dissolved
methane released into the water column from the entire area
covered by bacterial mats on the Quepos Slide is estimated to
be about 0.28 9 106 mol a-1. This conservative estimate
which relies on rather accurate determinations of seafloor
methane fluxes emphasizes the potential importance of submarine
slides as sites of natural methane seepage; however, at
present the global extent of methane seepage from submarine
slides is largely unknown.

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