Details

Autor(en) / Beteiligte

• Holcombe, Brook L.
• Keil, Richard G.
• Devol, Allan H.

Titel

Determination of Pore-Water Dissolved Organic Carbon Fluxes from Mexican Margin Sediments

Ist Teil von

• Limnology and oceanography, 2001-03, Vol.46 (2), p.298-308

Ort / Verlag

Waco, TX: American Society of Limnology and Oceanography

Erscheinungsjahr

2001

Quelle

Wiley-Blackwell Journals

Beschreibungen/Notizen

• 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-2d-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 DO14C 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-2d-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.