Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: November 3, 1995
Publication Date: N/A
The responses of subsurface microbial communities to high concentrations of herbicides are not well understood. Biodegradation of [ring-14C] 2,4-D added at 0.1, 10 and 100 ug/g in soil and sediment samples (0 - 3.7 m depth) was measured in conjunction with microbial PLFA patterns, 2,4-D-degraders, and protozoa populations. 2,4-D was mineralized in all soil and subsurface sediments after lag periods which tended to increase with depth and 2,4-D concentration. Initial degradation rates were related to populations of 2,4-D-degrading microorganisms, which declined with depth. Degrader populations increased in subsurface sediments treated with 10 or 100 ug/g 2,4-D, but remained a small component of the total microbial population. In the deeper sediments protozoan activity appeared to limit 2,4-D degrader populations. Principal components analysis of PLFA revealed distinct microbial communities at the different depths, but there was little effect attributable to 2,4-D.