PERFORMANCE OF THE IN-SITU MICROCOSM TECHNIQUE FOR MEASURING THE DEGRADATION OF ORGANIC-CHEMICALS IN AQUIFERS

An in situ microcosm (ISM) consists of a stainless steel cylinder isol ating about 2 L of the aquifer and is equipped with valves allowing fo r loading and sampling from the ground surface. During the last five y ears, this technique has been used frequently to study the degradation of organic chemicals in polluted and pristine aquifers representing d ifferent redox environments. The ISM technique has great potential for providing field-relevant degradation potentials and rate constants, b ut care must be taken in using the equipment and interpreting the resu lts. This paper provides details concerning the installation and opera tion of an ISM and presents experiences concerning data interpretation and monitoring of redox conditions.