The Port Jackson estuary has a highly urbanised and industrialised catchmen
t and is central to Sydney, which with a population of approximately 4 mill
ion, comprises almost a quarter of Australia's population. The estuary has
a long history of contamination which has resulted in extensive areas of po
lluted sediments mainly associated with the most industrialised/commerciali
sed parts of the catchment. The highest concentrations of sedimentary heavy
metals occur at the headwaters of embayments and tributaries in the estuar
y, especially in the central city region where gradients decline rapidly aw
ay from canals. High total suspended solids, elevated concentrations of hea
vy metals in sediment and in particulates in canals draining large catchmen
ts are evidence that drainage from these areas is a major source of contami
nants to this estuary. Another possible important point source of heavy met
als is leachates from reclamation areas, whereas licenced polluters do not
impact on a regional scale. Of the diffuse sources, atmospheric contributio
ns may be substantial, but storm water drains with small catchments and sew
er overflows have no observable impression on the regional distribution of
heavy metals in surficial sediments. Biological effects criteria suggest th
at heavy metal concentrations in sediments are sufficiently high to adverse
ly affect biota over large areas of Port Jackson. Large volumes of contamin
ated sediment and a continuing supply of heavy metals to the estuary will m
ake remediation difficult. (C) 1999 Elsevier Science B.V. All rights reserv
ed.