Hydrocarbons from superficial sediments

Review papers on the subject of marine organic geochemistry have recently been published (Farrington and Meyers, 1975 Morris and Culkin, 1975 Yen, 1977 and Simoneit, 1978). In this section the sediment thickness considered will be limited to approximately 50 cm. 

Concentrations of extractable organic material vary from 10 to about 500—700 /xg per gram of dry sediment. Total hydrocarbons are in the range 1—100 ng g of dry sediment. Higher concentrations are reported for inshore areas (Clark and Blumer, 1967) or polluted zones, for example the New York Bight (Farrington and Tripp, 1977). 

The presence of n-Cu or n-Ci7 hydrocarbons, which indicate a msirine contribution by algae, has been documented for near-shore sediments (Clark and Blumer, 1967), but the residence time of lighter n-alkanes is certainly too short to allow their deposition without any significant loss during the slow sedimentation process from the water column to deep sediments. 

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