Sediment Diagenesis – Biologically Controlled
The biological processes that modify unconsolidated sediment after initial deposition and burial.
Throughout the sediment column, up to the temperature threshold of life, microbial activity plays an integral role in diagenesis . It is widely recognized that through their various chemoheterotrophic pathways, microorganisms are ultimately responsible for the conversion of organic carbon to CO2 and CH4 at temperatures <100oC. Some aerobic bacteria use hydrolytic enzymes to break down complex molecules into simple monomers such as sugars, amino acids, and fatty acids that they can then utilize, while most anaerobes are restricted to simple organic compounds (e.g., acetate, lactate, H2) that are the by-products of fermentation (Lovley and Chapelle, 1995). Typically, the more labile materials (e.g., proteins, carbohydrates) are degraded in near-surface sediments on time scales of days to years, and more refractory materials (e.g., lipids) are broken down deeper in the...
KeywordsPore Water Particulate Organic Carbon Sulfate Reduction Rate Anaerobic Methane Oxidation Nitrate Pore
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