S. McCready

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.

Catchment condition as a major control on the quality of receiving basin sediments (Sydney Harbour, Australia).

The current work aimed to compile existing information to better understand the source, fate and effects of metallic contaminants in one catchment-receiving basin system (Iron Cove) in Sydney Harbour (Australia). Copper, Pb and Zn concentrations of potential source materials, i.e. soils (mean 62, 410 and 340 microg g(-1), respectively) and road dust (mean 160, 490 and 520 microg g(-1), respectively) and in materials being transported to the estuary, i.e. in gully pots (mean 110, 200 and 260 microg g(-1) for Cu, Pb, and Zn, respectively), in bedload (mean 210, 880 and 1700 microg g(-1), respectively) and particulates in canals draining the catchment (mean 325, 290 and 1865 microg g(-1), respectively) were highly enriched. Estuarine sediments in the receiving basin are enriched 20 times over pre-anthropogenic concentrations and are toxic to benthic animals at the canal mouths. Stormwater remediation is required to reduce metal loads to the adjacent estuary.

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.

Toxicity of surficial sediments from Sydney Harbour and vicinity, Australia.

The toxicological responses of three species to 103 surficial saltwater sediment samples from Sydney Harbour, and coastal lakes and estuaries on the south-east coast of New South Wales, Australia, were tested in a battery of four to six laboratory toxicity tests. This is the first large-scale toxicological study of sediments in Australia, the objective of which is to assess the protective and predictive abilities of North American biological effects-based sediment quality guidelines, recently adopted in Australia. Amphipods were exposed to whole sediments in survival and reburial tests, sea urchin fertilisation and larval development tests were conducted on porewaters, and bacterial bioluminescence (Microtox®) tests were conducted on organic solvent extracts and porewaters. Local indigenous species were used for the amphipod and sea urchin tests (Corophium sp. and Heliocidaris tuberculata, respectively). A wide range of responses, from ≤25 to 100% of negative controls were observed in all tests. Mean control-adjusted responses ranged from 46 to 96% for all tests. The percentages of highly toxic samples ranged from 11 to 83% in the various tests. The order of test sensitivity was: amphipod survival ≤ Microtox® test of porewaters ≤ amphipod reburial ≤ sea urchin larval development ≤ sea urchin fertilisation ≤ Microtox® test of solvent extracts. Concordance between toxicity tests in classifying samples as highly toxic or not, ranged from 47 to 79%, indicating some similarities between test results, but not complete equivalence. Combined toxicity test results showed that the incidence of highly toxic responses occurring in the majority of tests (75–100% of tests) was low (5% of samples), but a large percentage of samples had highly toxic results in at least one test (76% of samples). Toxicity was more pervasive in the Sydney region than in coastal lakes and estuaries south of Sydney. The current study demonstrated the utility of indigenous invertebrate species and the Microtox® bacterium in a sediment toxicity test battery for Australian saltwater sediments.

Sensitivity of an indigenous amphipod (Corophium colo) to chemical contaminants in laboratory toxicity tests conducted with sediments from Sydney Harbor, Australia, and vicinity

Laboratory survival tests were conducted with an indigenous infaunal amphipod, Corophium colo, on 103 sediment samples from Sydney Harbor (NSW, Australia) and vicinity, containing a wide range of chemicals and concentrations. The present study describes the sensitivity of C. colo to the sediments and compares the results to data for North American amphipods (Rhepoxynius abronius and Ampelisca abdita) previously used to establish and validate sediment-quality guidelines (SQGs). The incidence of toxicity increased with increasing contamination, as indicated by increasing numbers of SQGs exceeded and increasing mean SQG quotients. The incidence of highly toxic results (p < 0.05 and mean amphipod survival of < 80% that of controls) for highly contaminated samples was approximately half (28-40%) that of a large U.S. database (74%). The incidence of highly toxic responses for samples with intermediate levels of contamination also was lower in the present study (5-13%) compared to the results in large U.S. studies (approximately 30-50%). Corophium colo reburial tests showed greater sensitivity compared to survival tests, with a maximum incidence of statistically significant responses in moderately contaminated sediments of 70%. The present study showed that adult Corophium organisms are suitable for testing lethal responses in highly contaminated sediments (i.e., with mean effects range-median quotients of >1.5). Reburial results provide additional sensitivity.

Complex relationships between shallow muddy benthic assemblages, sediment chemistry and toxicity in estuaries in southern New South Wales, Australia

Synoptic sediment quality triad (contaminants, benthic assemblages, toxicity testing) data were collected for sites in Sydney estuary, adjacent Cooks River and five less-modified southern estuaries. Matching data tested relationships between contaminants and benthic assemblages, correlations with specific contaminants, and the ability of sediment quality guidelines to predict the risk of adverse effects. Significant but weak relationships occurred in complex patterns between assemblages, contaminant concentrations and environmental variables. Maximum benthos abundance occurred where sediment contamination was high and was dominated by polychaetes. Spionidae (polychaete) and Galeommatidae (mollusc) abundances were strongly correlated with site environmental characteristics and with varying mixtures of metals and organic contaminants. The risk of adverse effects on benthic assemblage structure increased with increasing sediment toxicity except for areas of very high contamination and for non-bioavailable anthropogenic chemicals. The overall weight-of-evidence scores differentiated the highly modified sites from less-contaminated southern estuaries, where toxicity scores were higher than predicted.