G. Birch et al., The source of anthropogenic heavy metals in fluvial sediments of a rural catchment: Coxs River, Australia, WATER A S P, 126(1-2), 2001, pp. 13-35
A serious health scare involving the supply of drinking water to Sydney, Au
stralia has recently focussed attention on the environmental status of rive
r catchments of the main reservoir, Lake Burragorang. Although the Coxs Riv
er - a major catchment of Lake Burragorang - comprises mainly forests and g
razing land, it supports a moderate sized town, power stations and coal min
es. The heavy metal content of stream-bed sediments characterises environme
ntal impact in this rural catchment and sources of contamination. Sediment
in a creek flowing through a country town (population 12 000) is markedly e
nriched in Cr, Pb and Zn (3x, 18x and 52x, respectively) over background, p
robably due to a long history of metal-based industry. The highest Cu, Pb a
nd Zn concentrations (204, 332 and 2460 mug g(-1), respectively) in fluvial
sediment in the town are, however associated with discharges from a sewage
treatment plant. Two coal-based power stations in the catchment contribute
considerable Cu and Ni (maximum concentrations 562 and 157 mug g(-1), resp
ectively) to ambient fluvial sediments, possibly from cooling towers and co
al storage areas. The highest Co and Cr concentrations (113 and 490 mug g(-
1)) in fluvial sediments of this catchment are associated with coal-mining
activities. Selective extraction indicates that about 50% of the anthropoge
nic fraction may be bioavailable, whereas sequential extraction procedures
suggest that < 25% is associated with the easily exchangeable/adsorbed phas
e. Two dams restrict the migration of heavy metals down the Coxs River and
sediment discharging into Lake Burragorang is low in metals.