PARTITIONING AND MINERALIZATION OF [C-14]LINDANE IN A LABORATORY SEDIMENT-WATER SYSTEM

To develop a guideline for a simulation test for aerobic degradability in surface water, the fate of [C-14]lindane (gamma-hexachlorocyclohex ane) was studied in laboratory systems using natural river water and s ediments. No sterilized controls were set up. Thus, measured data refl ect the sum of biotic and abiotic processes. Tests were carried out un der various experimental conditions to investigate which of these woul d affect the feasibility of the test, the fate of lindane, the physico chemical state, and the biological activity within the sediment-water systems. Lindane (37.7 nmol) was applied either to the water (3 L) or the sediment (0.33 L). Sediments remained nonreducing, and there was n o serious decline of nutrients nor enzymatic activities. In one experi ment up to 14.1% of the applied lindane was mineralized to (CO2)-C-14 within 50 d and in a second one up to 35.3%. At day 91 of the latter e xperiment up to 46.8% were found to have been mineralized. Among the e xperimental factors tested, the method of lindane application and temp erature predominantly affected mineralization. The type of aeration an d the semicontinuous addition of organic nutrients were of minor impor tance. Sediments and water collected at the same site hut at different times showed variation in carbon content as well as in esterase and d ehydrogenase activities. Nevertheless, these parameters could not be c orrelated with mineralization of lindane during the tests. Between 1 a nd 9% of the radioactivity volatilized during the tests. At the end, 2 3 to 66% were bound to sediments and 15 to 45% of the total activity w as neither extractable by water nor by cyclohexane.