SOIL-MICROORGANISMS IN SOIL CLEANUP - HOW CAN WE IMPROVE OUR UNDERSTANDING

Successful in situ biodegradation must depend on microbial catalysis a s well as physical transport. While there has been much effort directe d toward understanding vadose zone transport processes, our understand ing of the microbial ecology of the indigenous catalysts limits our ab ility to manage biodegradation processes in soil. The environmental fa ctors commonly listed as controlling in situ biodegradation are water, oxygen, redox potential, nutrients, pH, and temperature. Simplistic s tatements concerning the environmental determinants of in situ biodegr adation may reflect a naive understanding of microbial ecology and may in fact direct management efforts in inappropriate directions. We dis cuss what we need to know about soil microbial ecology to elevate in s itu biodegradation to a reliable and well-understood remediation optio n. We need to know the following: What controls the presence of the de sired metabolic capability; the distribution of degrading communities relative to contaminant source; and what controls activities of releva nt communities?