Uptake and biodegradation kinetics of 2,4-Dichlorophenoxyacetic Acid (2,4-D) from South Saskatchewan River water by an indigenous microbial community
Date
1999
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Degree Level
Masters
Abstract
The research project entitled "Uptake and Biodegradation Kinetics of 2,4-
Dichlorophenoxyacetic Acid (2,4-D) from South Saskatchewan River Water by an Indigneous
Microbial Community" was designed to provide insight regarding the persistence of the well-used
herbicide, 2,4-D, in Prairie surface water supplies. By examination of the microbial
response to the presence of 2,4-D and other water quality conditions, such as pH adjustments
and humic acid amendments, in a natural water sample, it was determined that 2,4-D is not
likely to be persistent in Saskatchewan surface water.
The addition of an acid or base and/or aqueous humic acid to water samples did not
significantly affect the uptake and biodegradation kinetics of the indigenous 2,4-D-degrading
microbial community. Biodegradation of the 2,4-D parent material was credited to a strain of
bacteria minimally identified as Pseudomonas cepacia via microbial isolation techniques,
including a known resistance to the anti-biotic, chloramphenicol. It is not presumed that this
microbial population was solely responsible for the biodegradation of 2,4-D. This population
was merely chosen as the representative, identifiable population in the water samples.
Complete mineralisation of the parent compound was confirmed through bi-weekly analyses of
dissolved and total organic carbon components and weekly analyses of pH changes in the water
samples. The total organic carbon content decreased as carbon dioxide was released from
solution indicating complete degradation of the 2,4-D molecule. pH also gradually declined
indicating the release of carbon dioxide in the 2,4-D mineralisation process.
On average, given the specific conditions examined in these experiments, not more than 40
hours was required to completely mineralize 2,4-D concentrations ranging between 6.5 and
12.5 mg/L.
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Degree
Master of Science (M.Sc.)
Department
Environmental Engineering
Program
Environmental Engineering