A STUDY OF OXIC ANOXIC EFFECTS ON DEGRADATION OF STEROLS AT THE SIMULATED SEDIMENT-WATER INTERFACE OF COASTAL SEDIMENTS/

Laboratory incubation experiments were conducted to determine the beha vior of sterols at the sediment-water interface in oxic and anoxic sed iments. Both plankton and 4-C-14-cholesterol were used as tracers. Cho lesterol was rapidly degraded at the sediment-water interface: 55% of C-14-cholesterol was lost from sediments under anoxic conditions and 7 8% under oxic conditions over three and one-half months. About 3% of i nitially-added free radiolabel was incorporated into a bound pool that was released only by saponification of solvent-extracted sediment. Le ss than 1% of initially-added radiolabel remained in pore waters after three and one-half months. Rate constants for degradation of choleste rol in oxic and anoxic surficial sediments were estimated by tracking variations in radioactivity and sterol concentration as a function of time. We discuss our results in terms of factors affecting sterol degr adation in coastal marine sediments, including molecular structure, se diment matrix effect, and redox conditions; (C) 1998 Elsevier Science Ltd. All rights reserved.