Premium
Determination of pore‐water dissolved organic carbon fluxes from Mexican margin sediments
Author(s) -
Holcombe Brook L.,
Keil Richard G.,
Devol Allan H.
Publication year - 2001
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.2001.46.2.0298
Subject(s) - total organic carbon , benthic zone , flux (metallurgy) , dissolved organic carbon , sediment , sediment–water interface , sediment trap , carbon fibers , pore water pressure , geology , oxygen minimum zone , water column , carbon cycle , sedimentary rock , environmental chemistry , environmental science , oceanography , mineralogy , chemistry , geomorphology , geochemistry , ecology , materials science , geotechnical engineering , organic chemistry , ecosystem , composite number , upwelling , composite material , biology
Sediment dissolved organic carbon (DOC) fluxes were determined in the oxygen minimum zone along the north‐western Mexican margin using five different methods: in situ benthic chambers, on‐deck incubations, slicing, dialysis sampling (peepers), and sipping. For each of the five methods, replicates (n = 6–12) were made. Directly determined fluxes (whole‐core incubations and benthic chambers) and calculated fluxes (sliced and dialysis‐sampled cores) agree well (0.41 ± 0.09, 0.36 ± 0.04, 0.25 ± 0.05, and 0.25 ± 0.05 mmol C m −2 d −1 , respectively). On the Mexican margin, the DOC flux was 8% of the sedimentary carbon input, suggesting that it is a significant component to the local carbon budget. Extrapolations of this flux to the total global margin suggest that shelf and slope sediments contribute 96 Tg C yr −1 . The residence time of oceanic DOC based on this flux is consistent with measurements of the deep‐water DO 14 C age. Profiles were also constructed from sip‐isolated pore waters and yield consistently lower DOC profile gradients and DOC fluxes (0.06 ± 0.02 mmol C m −2 d −1 ). We propose that the consistently observed discrepancy between sip‐isolated profiles and other isolation techniques is a result of sampling different reservoirs of pore water present in the heterogeneous sediment matrix.