Stuart E. Taylor

Source of heavy metals in sediments of the Port Jackson estuary, Australia

The Port Jackson estuary has a highly urbanised and industrialised catchment and is central to Sydney, which with a population of approximately 4 million, comprises almost a quarter of Australias population. The estuary has a long history of contamination which has resulted in extensive areas of polluted sediments mainly associated with the most industrialised/commercialised parts of the catchment. The highest concentrations of sedimentary heavy metals occur at the headwaters of embayments and tributaries in the estuary, especially in the central city region where gradients decline rapidly away from canals. High total suspended solids, elevated concentrations of heavy metals in sediment and in particulates in canals draining large catchments are evidence that drainage from these areas is a major source of contaminants to this estuary. Another possible important point source of heavy metals is leachates from reclamation areas, whereas licenced polluters do not impact on a regional scale. Of the diffuse sources, atmospheric contributions may be substantial, but storm water drains with small catchments and sewer overflows have no observable impression on the regional distribution of heavy metals in surficial sediments. Biological effects criteria suggest that heavy metal concentrations in sediments are sufficiently high to adversely affect biota over large areas of Port Jackson. Large volumes of contaminated sediment and a continuing supply of heavy metals to the estuary will make remediation difficult.

The distribution of polycyclic aromatic hydrocarbons in surficial sediments of Sydney Harbour, Australia

Abstract Surface sediment was collected from 124 sites in Sydney Harbour and analysed for the 16 polycyclic aromatic hydrocarbons (PAHs) listed as priority pollutants by the US EPA, as well as 2-methylnaphthalene. PAH concentrations varied widely, from μ g kg−1 of total PAH. The spatial distribution of PAHs suggested that they derive predominantly from urban run-off. However, discrete point sources of PAH appear to exist at several sites. The relative abundance of individual PAH compounds was remarkably consistent throughout the harbour and indicated that high temperature combustion processes are the predominant source of PAH contamination in Sydney Harbour. Comparison with numerical effects-based sediment quality guidelines derived in the US indicated that most of the sites studied in Sydney Harbour (89%) have levels of PAH which are predicted to either occasionally or frequently result in adverse biological effects.

Distribution and possible sources of organochlorine residues in sediments of a large urban estuary, Port Jackson, Sydney

Sydney Harbour is surrounded by a large capital city of about four million people and its highly urbanised (86%) catchment supports a substantial industrial base and an extensive transport infrastructure. Large commercial and naval ports occupy the waterway and the harbour is an important recreational area. Surficial sediment in Sydney Harbour contains high concentrations of PCBs, HCB, total chlordane, total DDT, aldrin, dieldrin, heptachlor and heptachlor‐epoxide, but low concentrations of lindane. PCBs, total chlordane, and to a lesser extent dieldrin, are most elevated in sediment in creeks on the southern shores of the harbour suggesting sources within older, highly urbanised/industrialised catchments of western‐central Sydney. There are high concentrations of total DDT and HCB in sediments of the upper harbour and Homebush Bay suggesting that chemical industries on the shores of the estuary in this area are sources of these contaminants. Although no sediment quality guidelines apply in Australia, empirically derived biological effects criteria suggest that sediment over extensive areas of Sydney Harbour may have an adverse impact on biota. Especially of concern are sediments containing high concentrations of chlordane and DDT.

Historical catchment changes and temporal impact on sediment of the receiving basin, Port Jackson, New South Wales

Port Jackson (Sydney Harbour) is a major deep‐water estuary on the central New South Wales coast and is surrounded by a highly urbanised and industrialised catchment. Concentrations of trace metals and organochlorine pesticide residues are high in sediment in the upper reaches of the estuary. Historical fluxes of contaminants into the estuary were determined by radio‐isotopic dating of 12 sediment profiles in nine highly contaminated embayments. The onset of contamination in estuarine sediment was correlated with catchment‐wide urbanisation and industrialisation of Sydney. Contamination of estuarine sediment in Port Jackson first occurred ca 1860, near the present central business district and spread westward and northward. Trace‐metal contamination was initiated ∼20 years after the commencement of industry in the subcatchments, and a rapid increase in trace‐metal concentrations corresponds closely with maximum industrial activity in these catchments. Organochlorine pesticide residues occur in estuarine sediments 40–50 years after the onset of contamination by trace metals and their appearance closely corresponds with the manufacturing and application history of these compounds. The transit time of contaminants from fluvial catchment to incorporation in estuarine sediment is short (probably <2 years). Trace metals in sediment reached maximum concentrations in 1970 and a subsequent decrease in concentrations in the upper estuary reflects relocation of industry away from the estuary foreshores and tighter controls on industrial discharges. In Middle Harbour and the lower estuary, trace‐metal concentrations continue to increase, due to the comparatively recent increases in commercial and industrial growth in these areas.

Extraction of heavy metals in Sydney Harbour sediments using 1M HCl and 0.05M EDTA and implications for sediment‐quality guidelines

Sixty sediment samples with a wide range of heavy‐metal concentrations and sediment textures were collected from Sydney Harbour. The samples were extracted with 1M HCl, 0.05M EDTA and HClO4/HNO3 and analysed by flame atomic absorption spectrometry for Zn, Pb, Cu and Cd. 1M HCl extracted a large proportion of heavy metals in oxic sediments (60–100%), whereas the extractability of metals with 0.05M EDTA was generally lower (by ∼20%). Extractability was unrelated to the level of contamination or to sediment texture. The extractability of Cu in anoxic sediments was substantially lower with 1M HCl (∼20%) and 0.05M EDTA (∼10%) than with HClO4/HNO3. The extractability of Pb with 0.05M EDTA was also reduced in anoxic sediments (to ∼70%). The use of weak extractants, in particular 1M HCl, is recommended by the recently introduced ANZECC and ARMCANZ interim sediment‐quality guidelines. These extractants are believed to provide a better measure of the bioavailable metal content than strong acid extractants. In this study, anoxic, sulfidic environments had a major influence on metal extractability with weak extractants. The implication of this is that the number of samples requiring further testing, as stipulated by the guidelines, would be significantly reduced in anoxic sediments.

The use of size-normalised procedures in the analysis of organic contaminants in estuarine sediments

Sediments are being used increasingly for monitoring the aquatic environment because of their ability to integrate contaminants over time, and because they provide valuable information on source, dispersion and accumulation of toxicants. However, as the majority of contaminants are usually associated with the fine fraction of the sediment, interpretation of spatial distributions is often confounded by variable grain size. The confounding effects of variable grain size can be reduced by separating the fine fraction of the sediment and analysing the contaminant concentration of this material. This approach is commonly used in heavy metal studies, but it is rare in the analysis of organochlorine compounds because of an absence on information on possible contaminant loss to the sieve water during the separating process, and possible removal of contaminants with the coarse fraction. Results from the current study indicate such losses to be minimal and examples are presented to illustrate the superiority of size-normalised data in the identification of source and in the determination of dispersion and accumulation of contaminants.

Possible Biological Significance of Contaminated Sediments in Port Jackson, Sydney, Australia

Comprehensive investigations of estuaries incentral New South Wales has identified Port Jackson as themost contaminated waterway on the eastern seaboard ofAustralia. Extensive areas of the estuary are mantled insediment containing high concentrations of a large range ofmetallic and organic contaminants. Although extensive, thisdatabase does not provide an effective basis for determiningthe potential adverse effects of chemicals on livingresources. In the absence of any ecotoxicologicalinformation, the recently published (1999) draft Australianand New Zealand Environmental and Conservation Council(ANZECC) sediment quality guidelines have been used toassess possible adverse biological effects of thesetoxicants. The ANZECC guidelines use the lower effects range of thewidely used U. S. National Oceanic and AtmosphericAdministration (NOAA) scheme to identify potentiallycontaminated sediment and as a threshold to trigger foradditional investigative work. This guideline level has beenused in the current study to assess possible toxicity ofcontaminated sediments in Port Jackson. It is estimated thatsediments in approximately 26% of the estuary, mainly theupper parts of the harbour and much of the central harbour,have a 67% probability of being toxic. Sediments in thecentral harbour and a major tributary, the Middle Harbour,comprising about 40% of the estuary, have a 13 to 25%probability of toxicity. All sediments in the harbour,except at the mouth of the estuary, would require additionalenvironmental assessment based on the proposed draft ANZECCsediment quality guidelines.

Environmental status of sediments in the lower Hawkesbury-Nepean River, New South Wales∗

Like many other estuarine systems, the lower Hawkesbury–Nepean River is under increasing environmental pressure from continued development. Hornsby Shire Council instigated an investigation of sediment quality in this river as part of an Estuary Management Program to determine sources and the regional extent of sediment contamination, and to assist in the prioritisation of any required remedial actions. The outcomes and recommendations of this investigation have been incorporated in the Lower Hawkesbury Estuary Management Plan to be implemented progressively over a 7–10 year time frame. Sediments from 52 locations in the lower Hawkesbury–Nepean River and tributaries were analysed for trace metals, major elements, nutrients, TOC, organic contaminants and grainsize, and 16 of these locations were selected to determine concentrations of tributyltin (TBT) in the sediments. Organic booster biocides (diuron, chlorothalonil, irgarol and dichlofluanid), which augment Cu-based antifoulants since TBT was banned in 1989, were analysed in sediments from four locations near marinas, including a pristine reference location. Analysis for these compounds in sediments is rarely undertaken in Australia and this study represents the first of its kind for sediments in the lower Hawkesbury–Nepean River. Concentrations of diuron up to 40 μg/kg were detected in sediments near a marina compared with <1 μg/kg at the reference location, suggesting an impact from booster biocides used in antifoulants on sediments in areas of high boating activity. Regionally, only few heavy metals and no organic contaminants exceed ANZECC/ARMCANZ sediment quality guideline values in sediments of the lower Hawkesbury–Nepean River. However, sediments near marinas and riverside settlements in upper Berowra and Cowan Creeks contain elevated concentrations of TBT and heavy metals and may pose adverse effects on aquatic biota.

A Remarkable Recovery in the Sydney Rock Oyster (Saccostrea glomerata) Population in a Highly Urbanised Estuary (Sydney Estuary, Australia)

ABSTRACT Birch, G.F.; Apostolatos, C., and Taylor, S.E., 2013. A Remarkable Recovery in the Sydney Rock Oyster (Saccostrea glomerata) Population in a Highly Urbanised Estuary (Sydney Estuary, Australia). Surveys of the Sydney rock oyster (Saccostrea glomerata) in the Sydney estuary (Australia) in 1995 and 2005 provided evidence of a significant and widespread increase in the abundance of this bivalve over this period. Oyster abundance and density increased predominately in the upper estuary where a 300% increase in water-line length coverage occurred over the 10-year period. The timing of increased abundance and co-incidence of high-shipping activity with areas of maximum oyster increase, suggest that partial banning of tributyltin in 1989 may have played a major role in the increase of S. glomerata in this estuary.