Abstract
The effects of in situ exposure to low concentrations
(micrograms per liter) of herbicides on aerobic degradation
of herbicides in aquifers were studied by laboratory
batch experiments. Aquifer material and groundwater
were collected from a point source with known exposure
histories to the herbicides mecoprop (MCPP), dichlorprop,
BAM, bentazone, isoproturon, and DNOC. Degradation of the
phenoxy acids, mecoprop and dichlorprop, was observed
in five of six sampling points from within the plume.
Mecoprop was mineralized, and up to 70% was recovered
as 14CO2. DNOC was degraded in only two of six sampling
points from within the plume, and neither BAM, bentazone,
nor isoproturon was degraded in any sampling point. A linear
correlation (R2 g 0.83) between pre-exposure and amount
of herbicide degraded within 50 days was observed for
the phenoxy acids, mecoprop and dichlorprop. An improved
model fit was obtained from using Monod degradation
kinetics compared to zero- and first-order degradation
kinetics. An exponential correlation (R2 g 0.85) was also
found between numbers of specific phenoxy acid degrading
bacteria and pre-exposure. Combination of these results
strongly indicates that the low concentration exposure to
phenoxy acids in the aquifer resulted in the presence of
acclimated microbial communities, illustrated by the elevated
numbers of specific degraders as well as the enhanced
degradation capability. The findings support application of
natural attenuation to remediate aerobic aquifers
contaminated by phenoxy acids from point sources.
Original language | English |
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Journal | Environmental Science & Technology (Washington) |
Volume | 36 |
Issue number | 10 |
Pages (from-to) | 2205-2212 |
ISSN | 0013-936X |
DOIs | |
Publication status | Published - 2002 |
Keywords
- CHALK AQUIFER
- GROUND-WATER
- MECOPROP
- SHALLOW SANDY AQUIFER
- IN-SITU
- ACID HERBICIDES
- ATRAZINE
- ACCELERATED DEGRADATION
- CHIRAL HERBICIDE
- SOIL