Preliminary Data on Dissolved Organic Carbon and Sugar in Interstitial Water from the Mississippi Fan and Orca and Pigmy Basins, Deep Sea Drilling Project Leg 96

Abstract

Preliminary data on dissolved organic carbon (DOC) and dissolved sugars in interstitial water samples collected at Sites 618, 619, and 623 of Deep Sea Drilling Project Leg 96 are presented.At Site 618 in Orca Basin, the DOC content of the interstitial water peaks in the hypersaline sulfate reduction zone. The sugar content reaches a maximum and the DOC content begins to decrease at the depth of methane gas generation. Below that depth, the sugar and DOC contents are about constant.At Site 619 in Pigmy Basin, the DOC content increases slightly with depth in the sulfate reduction and the methane fermentation zones. The sugar content is lower in the sulfate reduction zone than in the methane fermentation zone; sugar concentration increases and fluctuates with methane gas percentages within the methane fermentation zone.At Site 623 in the lower fan region of the Mississippi Fan, there is no sulfate reduction zone. The DOC and sugar contents of the interstitial water are almost constant with depth.

The Diagenetic Factors Controlling the Dissolved Organic Carbon (DOC) in Pore Water from Deep Sea Sediments (ODP Leg 113|Weddell Sea)

“…Previous studies of coastal (Starikova, 1970;Nissenbaum et al, 1971;Krom and Sholkovitz, 1977) and hemipelagic sedi ments (Michaelis et al, 1982;Ishizuka et al, 1986b) have dem onstrated that the bulk of dissolved organic carbon in marine pore waters is made up of complex HMW compounds. Nissen- (1971) and Krom and Sholkovitz (1977) argued that the HMW compounds are formed by condensation of LMW compounds released during biological degradation of sedimen tary organic carbon.…”

“…They found that free carbohydrates and amino acids constituted less than 20% of DOC and that the relative proportion of these compounds de creased with depth in the core. At ODP Sites 618, 619, and 623, Ishizuka et al (1986b) reported concentrations of DOC between 23 and 225 mg C/L. They observed roughly parallel concentra tion profiles of sugars and DOC.…”

“…To our knowledge the only studies of dissolved organic car bon in pore waters of marine sediments buried deeper than 40 m below seafloor (mbsf) are those reported by Michaelis et al (1982) and Ishizuka et al (1986b). Analyzing pore water from DSDP Sites 474 and 479 (see Table 1 for information on the in dividual sites), Michaelis et al (1982) reported concentrations of dissolved organic carbon between 31 and 204 mg C/L.…”

Amino acids in interstitial waters from ODP Sites 689 and 690 on the Maud Rise, Antarctic Ocean.

“…No systematic depth trends were observed in this cases. Ishizuka et al (1986b) reported DOC concentrations between 23 and 225 mgC L -1 at ODP Sites 618, 619 and 623 on the Mississippi Fan and Orcha and Pigmy Basins. On the other hand, DOC concentrations at Sites 689 and 690 were one to two orders of magnitude lower than those at above sites (1.82-6.91 mgC L -1 ).…”

“…Since DFAA was a major fraction of THAA, low molecular weight (LMW, molecular weight less than 1000) fractions were small contributor for the DOC. Previous studies of coastal (Krom and Sholkovitz, 1977) and hemipelagic sediments (Michaelis et al, 1982;Ishizuka et al, 1986b) have demonstrated that the bulk of DOC in marine interstitial waters is made up of complex high molecular weight (HMW, molecular weight greater than 1000) fractions. Krom and Sholkovitz (1977) argued that the HMW compounds are formed by condensation of LMW compounds released during biological degradation of sedimentary organic carbon.…”