The partitioning of organic carbon fluxes and sedimentary organic matter decomposition rates in the ocean

• Published in: Marine chemistry 1983-01, Vol.13 (2), p.141-168
• Main Authors: Reimers, Clare E, Suess, Erwin
• Format: Article
• Language: English
• Subjects: Earth sciences; Earth, ocean, space; Exact sciences and technology; Isotope geochemistry; Isotope geochemistry. Geochronology; Marine; Marine geology; oceans
• ISSN: 0304-4203; 1872-7581
• DOI: 10.1016/0304-4203(83)90022-1

The partitioning of annual organic carbon fluxes from five stations located in the vicinity of the Pacific-Antarctic Ridge and the Peru continental margin suggests that 35–85% of the total near-bottom organic carbon flux is utilized at or near the sediment-water interface. These estimates have large uncertainties, but illustrate that assessments of organic carbon utilization can be made by several stepwise approaches which are generally applicable to a wide spectrum of marine environments. In one approach, the mineralization of organic carbon from the sediments was predicted from both sedimentary organic carbon and pore water nutrient profiles with comparable results. Neglecting sediment mixing, the rate constants of the anoxic sediments off Peru range from 0.1 × 10 −3 to 4 × 10 −3 y −1, and rate constants derived for oxic SW Pacific sediments range from 3 × 10 −4 to 7 × 10 −4 y −1. As with other values reported for sulfate reducing sediments by Toth and Lerman (1977) and for oxic central Pacific sediments by Müller and Mangini (1980), log-log plots of rate constants vs. sedimentation rate define two parallel linear relationships for oxic and anoxic sediments, respectively. The apparently enhanced rates for oxic environments may result from large benthic organisms which redistribute a portion of the available detritus and in doing so convert it into more easily accessible and metabolizable organic matter. In low-oxygen environments, bottom feeders and infauna are less abundant and more likely to irrigate rapidly accumulating sediments.