Contribution of vertical methane flux to shallow sediment carbon pools across Porangahau Ridge, New Zealand

dc.contributor.authorCoffin, Richard B.
dc.contributor.authorHamdan, Leila J.
dc.contributor.authorSmith, Joseph P.
dc.contributor.authorRose, Paula S.
dc.contributor.authorPlummer, Rebecca E.
dc.contributor.authorYoza, Brandon
dc.contributor.authorPecher, Ingo
dc.contributor.authorMontgomery, Michael T.
dc.date.accessioned2021-10-28T19:18:33Z
dc.date.available2021-10-28T19:18:33Z
dc.date.issued2014-08-18
dc.description.abstractModerate elevated vertical methane (CH4) flux is associated with sediment accretion and raised fluid expulsion at the Hikurangi subduction margin, located along the northeast coast of New Zealand. This focused CH4 flux contributes to the cycling of inorganic and organic carbon in solid phase sediment and pore water. Along a 7 km offshore transect across the Porangahau Ridge, vertical CH4 flux rates range from 11.4 mmol·m−2·a−1 off the ridge to 82.6 mmol·m−2·a−1 at the ridge base. Stable carbon isotope ratios (δ13C) in pore water and sediment were variable across the ridge suggesting close proximity of heterogeneous carbon sources. Methane stable carbon isotope ratios ranging from −107.9‰ to −60.5‰ and a C1:C2 of 3000 indicate a microbial, or biogenic, source. Near ridge, average δ13C for pore water and sediment inorganic carbon were 13C-depleted (−28.7‰ and −7.9‰, respectively) relative to all core subsamples (−19.9‰ and −2.4‰, respectively) suggesting localized anaerobic CH4 oxidation and precipitation of authigenic carbonates. Through the transect there was low contribution from anaerobic oxidation of CH4 to organic carbon pools; for all cores δ13C values of pore water dissolved organic carbon and sediment organic carbon averaged −24.4‰ and −22.1‰, respectively. Anaerobic oxidation of CH4 contributed to pore water and sediment organic carbon near the ridge as evidenced by carbon isotope values as low as to −42.8‰ and −24.7‰, respectively. Carbon concentration and isotope analyses distinguished contributions from CH4 and phytodetrital carbon sources across the ridge and show a low methane contribution to organic carbon.en_US
dc.identifier.citationCoffin, R.B., Hamdan, L.J., Smith, J.P., Rose, P.S., Plummer, R.E., Yoza, B., Pecher, I. and Montgomery, M.T., 2014. Contribution of vertical methane flux to shallow sediment carbon pools across Porangahau Ridge, New Zealand. Energies, 7(8), pp.5332-5356.en_US
dc.identifier.doihttps://doi.org/10.3390/en7085332
dc.identifier.urihttps://hdl.handle.net/1969.6/89925
dc.language.isoen_USen_US
dc.publisherMDPIen_US
dc.rightsAttribution 4.0 International*
dc.rights.urihttp://creativecommons.org/licenses/by/4.0/*
dc.subjectcoastal sedimentsen_US
dc.subjectcarbon cyclingen_US
dc.subjectmethaneen_US
dc.subjectphytodetritusen_US
dc.subjectconvergence forcingen_US
dc.subjectstable isotopesen_US
dc.titleContribution of vertical methane flux to shallow sediment carbon pools across Porangahau Ridge, New Zealanden_US
dc.typeArticleen_US

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