Soil microorganisms in soil cleanup: How can we improve our understanding?

Successful in situ biodegradation must depend on microbial catalysis as well as physical transport. While there has been much effort directed toward understanding vadose zone transport processes, our understanding of the microbial ecology of the indigenous catalysts limits our ability to manage biodegradation processes in soil. The environmental factors commonly listed as controlling in situ biodegradation are water, oxygen, redox potential, nutrients, pH, and temperature. Simplistic statements concerning the environmental determinants of in situ biodegradation may reflect a naive understanding of microbial ecology and may in fact direct management efforts in inappropriate directions. We discuss what we need to know about soil microbial ecology to elevate in situ biodegradation to a reliable and well-understood remediation option. We need to know the following: What controls the presence of the desired metabolic capability; the distribution of degrading communities relative to contaminant source; and what controls activities of relevant communities?