Biogeochemical cycling in an organic-rich coastal marine basin: 11. The sedimentary cycling of dissolved, free amino acids
- Univ. of North Carolina, Chapel Hill (USA)
In the anoxic sediments of Cape Lookout Bight, NC, concentrations of total dissolved free amino acids (TDFAAs) are highest near the sediment-water interface, and decrease to non-zero, asymptotic concentrations at depths greater than 20 cm. TDFAAs in the overlying waters are <1 {mu}M. Dissolved free amino acid (DFAA) profiles often show a secondary subsurface maximum in the region between the 1 and 5 mM sulfate isopleths. This phenomenon appears to be related to the transition in the sediments of this region from sulfate reduction to methanogenesis. A steady-state diagenetic model which quantifies the processes affecting DFAAs in these sediments yields rates of DFAA production and consumption that agree reasonably well with independent estimates of these quantities in Cape Lookout Bight and other anoxic marine sediments. The combined results of modelling pore water DFAA and sedimentary amino acid profiles indicate that significant exchange of amino acids occurs between the sediments and pore waters. These results demonstrate that the biogeochemistry of dissolved free amino acids in the pore waters of Cape Lookout Bight sediments is dominated by internal transformations (i.e. production from sedimentary amino acids, microbial remineralization, and reincorporation back into the sediments). There is some uncertainty in the magnitude of the flux of DFAAs across the sediment-water interface, although it appears to be of secondary importance when compared to the other sedimentary processes affecting DFAAs.
- OSTI ID:
- 6161843
- Journal Information:
- Geochimica et Cosmochimica Acta; (USA), Vol. 54:11; ISSN 0016-7037
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
AMINO ACIDS
MINERAL CYCLING
INTERSTITIAL WATER
BIOGEOCHEMISTRY
SEDIMENT-WATER INTERFACES
ATLANTIC OCEAN
CHEMICAL COMPOSITION
DIAGENESIS
DISSOLUTION
GEOLOGIC MODELS
NORTH CAROLINA
PRECIPITATION
CARBOXYLIC ACIDS
CHEMISTRY
FEDERAL REGION IV
GEOCHEMISTRY
GROUND WATER
HYDROGEN COMPOUNDS
INTERFACES
NORTH AMERICA
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
SEAS
SEPARATION PROCESSES
SURFACE WATERS
USA
WATER
580000* - Geosciences