A number of soil and water samples were screened for the biological capacity to metabolize trichloroethylene. One water sample was found to contain this capacity, and a gram-negative, rod-shaped bacterium which appeared to be responsible for the metabolic activity was isolated from this sample. The isolate degraded trichloroethylene to CO2 and unidentified, nonvolatile products. Oxygen and water from the original site of isolation were required for degradation. * Corresponding author. t Gulf Breeze Research Laboratory contribution no. 572.

The distribution of KeponeO (chlordecone) in a sediment bed after various periods of continuous toxicant input to the overlying water column was determined in a laboratory system. Most of the Kepone was found to accumulate in the top 0.6 to 1.5 cm of sediment. A mathematical model was developed to predict Kepone concentrations with depth over time in the sediment. An equilibrium partition coefficient was determined from batch sorption tests and a molecular diffusion coefficient for Kepone was estimated from an empirical relationship between diffusivity and molecular weight. A computed Kepone distribution based on diffusion rates that decreased with depth and with incubation time gave the best fit to the observed data. We attribute the apparently faster rates in the upper sediment to mixing between interstitial and overlying water. Our results illustrate the value of models in conjunction with laboratory studies in defining the interactions of pollutants with sediment beds.

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The influence of lugworms (Arenicola cristata Stimpson) and seagrass (Thalussia testudinum Koenig) on Keponem (chlordecone) distribution in sediment/water systems was examined. Radiolabeled Kepone was introduced into continuous-flow sediment/water systems, and the dissolved and sorbed concentrations of Kepone were quantified. Lugworm activity decreased the Kepone concentration in the water and increased its concentration in the sediment. The presence of seagrasses did not appreciably affect the concentration of Kepone in the water. Bioturbation appeared to be the prime factor in the transport of Kepone from water to sediment.