The diagenesis of phosphorus in a nearshore marine sediment

Chemical analyses have been made for total inorganic phosphorus, total organic phosphorus, and organic carbon in plankton and in anoxic sediments from Long Island Sound, U.S.A. When combined with laboratory experiments, the measurements of other studies on the same sediments, and mathematical modelling, the results indicate that: 1. (1) A large proportion of dissolved phosphate in the upper ~10 cm of sediment (zone of bioturbation) is provided by the release of adsorbed phosphate during the reduction of ferric oxyhydroxides; 2. (2) Below the zone of bioturbation phosphate is liberated to solution solely via organic matter decomposition and the release is stoichiometrically coupled to bacterial sulfate reduction and ammonia formation, 3. (3) A steady state diagenetic model can be used to predict the profile of organic phosphorus from that of dissolved phosphate at depths below the zone of bioturbation; 4. (4) The flux of dissolved phosphate out of the sediment must arise largely from phosphate liberation occurring very close (< 1 cm) to the sediment-water interface; 5. (5) There is a large preferential loss of phosphorus relative to carbon from organic matter at the time of or prior to burial, whereas after burial phosphorus is not lost preferentially at this location.