POTENTIAL FOR MICROBIAL-GROWTH IN ARID SUBSURFACE SEDIMENTS

To determine if bacterial populations could be increased for bioremedi ation of contaminants, the microbial growth arising in 200 h from the solid material from the vadose zone at an arid site after addition of water and nutrients was determined. Initial bacterial populations and activities at the site were very low. Bacteria grew in the interbed sa nds and silts with the higher carbon contents (0.08-1.1%), but did not respond in the basalts and interbed material with lower carbon conten t (undetectable). In longer term studies, to 30 d, there was evidence for bacterial activity in less than 25% of either the basalts or inter bed material.