Mr. Estrella et al., BIODEGRADATION, SORPTION, AND TRANSPORT OF 2,4-DICHLOROPHENOXYACETIC ACID IN SATURATED AND UNSATURATED SOILS, Applied and environmental microbiology, 59(12), 1993, pp. 4266-4273
The fate of an organic contaminant in soil depends on many factors, in
cluding sorption, biodegradation, and transport. The herbicide 2,4-dic
hlorophenoxyacetic acid (2,4-D) was used as a model compound to illust
rate the impact of these interacting factors on the fate of an organic
contaminant. Batch and column experiments performed with a sandy loam
soil mixture under saturated and unsaturated conditions were used to
determine the effects of sorption and biodegradation on the fate and t
ransport of 2,4-D. Sorption of 2,4-D was found to have a slight but si
gnificant effect on transport of 2,4-D under saturated conditions (ret
ardation factor, 1.8) and unsaturated conditions (retardation factor,
3.4). Biodegradation of 2,4-D was extensive under both batch and colum
n conditions and was found to have a significant impact on 2,4-D trans
port in column experiments. In batch experiments, complete mineralizat
ion of 2,4-D (100 mg kg-1) occurred over a 4-day period following a 3-
day lag phase under both saturated and unsaturated conditions. The bio
degradation rate parameters calculated for batch experiments were foun
d to be significantly different from those estimated for column experi
ments.