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Abstract

Stormwater quality in the City of Hobart has been examined by past local
studies. However, heavy metals were not critically examined in those studies. This
research was undertaken to determine the levels of heavy metals discharged by three
major rivulets namely, Sandy Bay Rivulet, Hobart Rivulet and New Town Rivulet
into the Derwent Estuary.
Nine stormwater samples were collected through grab sampling during the
first-flush period at three rivulet sites, including street runoff and stormwater in the
suburbs. The sampling period took place from October 2001 till February 2002.
Levels of pH and total suspended solids (TSS) concentrations were measured. Levels
of heavy metals such as Al, Cd, Cr, Co, Cu, Fe, Mn, Ni, Pn and Zn were determined
using Inductively Coupled Plasma Atomic Emission Spectrometry (ICP) in the
laboratory. Total metals concentrations, sediment and dissolved heavy metals were
calculated and compared against international and national standards. In addition,
studies from past stormwater studies, including local studies were used as a
benchmark in this study.
Results show metals like Cu, Ni and Zn were found mainly in dissolved form
while Pb, Al and Fe were mainly in particulate matter. High levels of dissolved Cu
and Zn are found in Hobart and New Town Rivulets. Distribution and levels of heavy
metals are found to be highly dependent on landuse across the three rivulets'
catchments. High levels of Al and Fe were found to their abundance in the Earth's
crust. High levels of Mn in Sandy Bay Rivulet were due to geologic makeup of Sandy
Bay region. Other metals, excluding Cu, Pb and Zn are found to be within guidelines.
Non-point sources such as residential areas and point sources have been
identified as potential sources of metals. Zn concentrations are significantly higher
than Pb and Cu. Heavy metals in street runoff sample reveal higher levels of Cu, Ni
and Zn than Atlanta streets. Comparison with local studies reveal an increase in TSS
in Sandy Bay Rivulet, increass in Zn levels in Hobart Rivulet and an overall higher level of heavy metals in stormwater sediment as compared to sediments in the
Derwent Estuary.
It is recommended reduction measures like efficient sediment traps should be
installed at three rivulets, as well as source reduction programs to be adopted by the
state government or local councils to curb the level of sedimentation, as well as the
amount of heavy metals contaminated sediment from entering the Derwent Estuary.

Item Type:	Thesis - Research Master
Authors/Creators:	Lee Wan Aik, D
Keywords:	Urban hydrology, Urban runoff, Water quality, Heavy metals
Copyright Holders:	The Author
Copyright Information:	Copyright 2002 the Author - The University is continuing to endeavour to trace the copyright owner(s) and in the meantime this item has been reproduced here in good faith. We would be pleased to hear from the copyright owner(s).
Additional Information:	Thesis (M.Env.Mgt.)--University of Tasmania, 2002. Includes bibliographical references
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