<p>The shallow soils of a former orchard area in Point Pelee National Park, near
Leamington, Ontario, Canada have elevated concentrations of chlorinated pesticides
above the regulatory limits. Previous studies in this area have shown that the DDT, DOE
and ODD are highly persistent with an estimated half-life of DDT in the range of 15-30
years. In 2002 a pilot-scale field remediation experiment involving the application of
cyclodextrin was conducted. This experiment resulted in substantial decrease of DDT,
DDE and DDD concentrations in the upper soil layer within the remediation grid. Soil
samples were collected within the treatment plots a year after the cyclodextrin application
was completed to assess any further changes in concentrations of DDT, DDE and DDD.
Groundwater samples were collected in the vicinity of the soil remediation grid which
provided DDT, DDE and DDD concentrations in groundwater to assess the vertical
mobilization of the compounds. Mass balance of the "soil - groundwater" system was
calculated in order to estimate the degradation rate of DDT within the remediation zone.
The 2-D unsaturated/saturated flow and solute transport numerical model
"HYDRUS 2-D" was used to gain a better estimation of DDT, DDE and DDD mass and
distribution in groundwater. The effectiveness of cyclodextrin application for remediation
of DDT contaminated soils was assessed. After remediation treatments had stopped, there
was no indication of further degradation of DDT and its metabolites in the upper layer of
soil. The groundwater concentration of DDT, DDE and DDD near the remediation grid
was 10-100 times higher than background value. This increase in groundwater
concentration is a direct indication of DDT, DDE and DDD mobilization by cyclodextrin.
The estimates of total mass of DDT in groundwater are less than 1% of mass leached
from the soil. It was concluded that the application of cyclodextrin promoted enhanced
co-metabolic biodegradation of DDT and it metabolites DDE and DDD. The estimated
half-life for the displaced DDT was less than 2 months. This work demonstrates that
cyclodextrin can be a highly effective agent for remediation of DDT contaminated soils.<p> / Thesis / Master of Science (MSc)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/16750 |
| Date | 09 1900 |
| Creators | Mironov, Marina |
| Contributors | Smith, James E., Environmental Science |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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