Title: Distribution and pool sizes of microbially available carbon in sediment measured by a microbiological assay
Abstract: A microbiological assay technique with Pseudomonas aeruginosa was used to measure the concentrations (pool sizes) of microbially available carbon in the pore water and in aqueous extracts of sediments from a salt marsh pan and from the salt marsh flat. Total organic carbon in the pan sediment increased with depth due to compaction, but available carbon was greatest in the pan sediment at the sediment/water interface and decreased rapidly with depth. In the sediment from the flat the available carbon was relatively constant in the top 0–3 cm encompassing the root zone, and only decreased below this depth. Available carbon varied from 0.5–1.0% of total organic carbon in the surface 0–3 cm of sediment, to <0.2% at depths greater than 10 cm.