Evaluating the natural attenuation of synthetic organic chemicals in a chalk aquifer

Hampson, Karen (2013) Evaluating the natural attenuation of synthetic organic chemicals in a chalk aquifer. Doctoral thesis, University of East Anglia.

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Hydrocarbon contaminants regularly leach into groundwater because of human
activities and accidental chemical spills. Here, the contaminants pose a threat to the
environment and valuable drinking water resources. Many subsurface environments
are able to purify the groundwater of such contaminants, thus lowering the cost of
remediation. This has sparked an interest in the use of naturally occurring processes
to degrade contaminants in the subsurface and has opened up an area of research
focusing on „natural attenuation‟.
For the successful application of natural attenuation and in order to obtain regulatory
approval a reliable assessment of the mechanisms responsible for the removal of
contaminants in an aquifer is essential. This thesis presents evidence to support the
natural attenuation of isoproturon (IPU) and sulphanilamide (SULPH) in a chalk
aquifer and assesses in-situ biodegradation by: (a) analysing historical monitoring
data to identify and support biodegradation processes at the contaminated field site;
(b) the development of in-situ microcosm approaches, (c) determining the catabolic
activity present across the site using ex-situ microcosm studies that replicate in-situ
aquifer conditions and, (d) identifying and quantifying biodegradation in the aquifer
(of SULPH) using compound specific isotope analysis.
Based on the historical data and ex-situ microcosms IPU biodegradation was found
to be occurring at the site; albeit at very low levels (2 %). It is suggested that the
high concentrations of other contaminants at the site (up to 650 mg L-1), compared to
the low IPU concentrations (9 μg L-1) may have impeded IPU biodegradation.
However, even these low levels of IPU biodegradation may be important in aquifers
exhibiting long residence times. The historical data and ex-situ microcosms further
indicated the biodegradation of around 50% of the SULPH present at the site.
The development of novel compound specific isotope analysis indicates 56 % of the
SULPH has undergone biodegradation at the site. These three approaches; historical
data, ex-situ microcosms and compound specific isotope analysis, provide strong
evidence to support the occurrence of natural attenuation at the site. Of particular
originality, is the identification of natural attenuation of SULPH in a chalk aquifer
and the quantification of its biodegradation using compound specific isotope

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Environmental Sciences
Depositing User: Users 2259 not found.
Date Deposited: 05 Mar 2014 11:09
Last Modified: 31 May 2019 00:38
URI: https://ueaeprints.uea.ac.uk/id/eprint/47908

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