There are many sites in New Zealand, and overseas, where soils are contaminated by past industrial practices. Contaminated soils may be hazardous to the environment and to human health. Contaminated soils may be remediated by expensive, and potentially destructive, chemical and physical means. As an alternative to chemical and physical remediation, methods are being developed that rely on enhancement of natural soil bioremediation processes. Soil bioremediation usually relies on the stimulation of soil microbes. Bioremediation is relatively inexpensive and environmentally sound. However there are limitations to the success of bioremediation.

Limitations include the distribution and numbers of microbes and the availability of oxygen. One new method that is being used in the treatment of contaminated soils is earthworm assisted bioremediation. Vermiculture has been shown to be successful in the remediation of drilling mud contaminated with drilling fluids.

I am undertaking research, in conjunction with Perry Environmental Ltd, on the viability of applying earthworm assisted bioremediation to a contaminated soil. The goal is to develop a working vermiculture system for soil remediation. Laboratory work will be undertaken to investigate the mechanisms of the earthworm effects on the soil contaminants. A field experiment is being undertaken to test earthworm survival, and remediation effectiveness, for a range of soil and compost mixes.