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Hydrocarbons and faecal material in urban stormwater and estuarine sediments: source characterisation and quantification


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Green, G 1997 , 'Hydrocarbons and faecal material in urban stormwater and estuarine sediments: source characterisation and quantification', PhD thesis, University of Tasmania.

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Hydrocarbons from road runoff and faecal matter from sewage overflows have
previously been implicated as major contributors to urban stormwater
contamination, but little source identification or quantitative data exist. In this.
study chemical marker techniques were utilised to identify specific sources of
these contaminants in selected stormwater catchments of Hobart, Tasmania. The
mean concentration of hydrocarbons in stormwater during this study was found
to be 2.88 mg/l with an estimated total annual discharge to the Derwent Estuary
in the order of 164,000 kg/year. Assessment of the major hydrocarbon inputs to
the Derwent estuary demonstrated that stormwater is the largest single
contributor. Source elucidation of hydrocarbons demonstrated inputs to
stormwater from automotive oils, diesel fuel, and plant waxes. Analysis of
polycyclic aromatic hydrocarbon (PAH) profiles by gas chromatography-mass
spectrometry and multivariate analysis confirmed, in most cases, that
automobile sump oil, rather than unused lubricating oils were the major
component of oil in stormwater. Cluster analysis, based on PAH composition,
was used for grouping stormwater samples relative to potential source materials.
Other techniques such as the use of PAH isomer pair ratios proved useful for
determining the input of combustion derived P AH. In sheltered embayments of
the Derwent Estuary a clear link was demonstrated between urban stormwater
and the build-up of hydrocarbon contaminants in sediments. Localised extreme
hydrocarbon concentrations were found associated with stormwater discharge
and boat mooring areas. Aliphatic hydrocarbons (10,100 iJg/g) and P AHs
(27iJg/g) in sediments at Prince of Wales Bay were the highest yet recorded
levels for estuarine sediments in Australia. Stormwater in Hobart was found to be highly contaminated with faecal pollution. Sterol and bacterial analysis of
stonnwater samples showed that dog faeces is potentially the most significant
contributor to the faecal contamination. This finding was demonstrated
primarily by the similarity between sterol profiles of dog faeces and stonnwater
samples and the low levels or absence of sterol markers for other sources of
faeces. Human faecal material was detected in urban stonnwater by tracing the
faecal sterol coprostanol. During flood conditions, human faeces, attributed to
cross contamination from the sewerage system, became a major contaminant in
stonnwater. During dry weather, urban runoff contained low levels of human
faecal material possibly derived from illegal sewer connections. On an annual
basis in Hobart, stonnwater was calculated to represent an estimated 80-91 % of
faecal input to the Derwent estuary. A study of hydrocarbons and sterols in
marine and shoreline sediments undertaken at Davis Station in Antarctica has
been included in this project. This comparatively simple system, largely devoid
of external pollution influences, provided an ideal test case for the detennination
of hydrocarbon and sewage impacts from a known human population.

Item Type: Thesis - PhD
Authors/Creators:Green, G
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