Total dissolved carbohydrates (DCHOs) in the interstitial waters of marine sediments have been determined in a limited number of coastal and continental margin sediments, with concentrations that generally range from ~10 to 400 µM C (see Burdige, 2002, for a review). In most cases DCHO concentrations increase with depth in shallow sediments (uppermost ~20–30 cm) and represent ~10%–40% of the total dissolved organic carbon (DOC). Relative DCHO concentrations also generally decrease with sediment depth, although the magnitude of these changes varies among the few sites that have been examined to date (see discussions in Burdige et al., 2000, for further details).
Concentrations of dissolved carbohydrates in sediment pore waters are apparently uncoupled from particulate (sediment) carbohydrate concentrations, and DCHO concentrations appear to be more strongly controlled by sediment remineralization processes (Burdige et al., 2000). Evidence to date also suggests that DCHOs may be preferentially found in the high molecular weight (HMW) interstitial water DOC pool, and therefore they likely represent some of the initial HMW intermediates produced and consumed during sediment organic matter remineralization (Arnosti and Holmer, 1999; Burdige et al., 2000).
During Leg 201, samples were collected for analysis of dissolved carbohydrates in the interstitial waters of these sediments. In one sense, studies of DCHOs in these sediments builds on past studies of dissolved carbohydrates in the pore waters of shallow-marine and estuarine sediments (e.g., Burdige et al., 2000). However, more importantly from the standpoint of the goals of Leg 201, this work will further the understanding of biogeochemical processes occurring in the deep marine biosphere.