Modelling nutrient loads to Sydney estuary (Australia)

Sydney estuary (Australia) catchment is substantially urbanised (80%) and small (480 km²) with a large population (2.5 million) and is therefore highly sensitive to anthropogenic influence. The Model for Urban Stormwater Improvement Conceptualisation used to model nutrient export to the estuary determined an average annual load of 475 t total nitrogen, 63.5 t total phosphorus and 343,000 t total suspended solids. Model verification included intense, short-term water sampling and analysis undertaken in the current project and use of published data spanning 10 years. Under high-rainfall conditions (>50 mm day^???1), the estuary becomes stratified and nutrients are either removed from the estuary directly in a plume or indirectly by advective/dispersive remobilisation. The majority of the nutrient load is delivered during moderate rainfall (5–50 mm day^???1) conditions and accumulates close to discharge points and remains in the estuary. To significantly reduce nutrient load, management strategies should aim to minimise low and moderate rainfall pollutant loads.     

The use of sedimentary metal data in predictive modelling of estuarine contamination,assessment of environmental condition and pollutant source identification (Narrabeen Lagoon,Sydney, Australia)

Environmental Science and Pollution Research - Narrabeen Lagoon is recognized as an Intermittently Closed and Open Lake or Lagoon (ICOLL) and is the largest coastal lagoon (2.2 km2) in the...     

The effect of zeolite on the toxicity of lead to fungi

In order to determine whether clinoptilolite, a naturally occurring zeolite, had any ameliorative effect on lead (Pb) toxicity to fungi, a series of growth experiments were performed. Three fungi, Aspergillus niger, Botrytis cinerea, and Fusarium culmorum, were grown on appropriately amended solid agar media, and their linear extension rates determined. B. cinerea was 25% inhibited, as compared to a control, at 100 mg dm(-3) Pb, and completely inhibited at 1000 mg dm(-3) Pb. F. culmorum was completely inhibited, and A. niger 97% inhibited at 1000 mg dm(-3) Pb. The addition of 3% clinoptilolite partially removed this inhibition in the case of A. niger and B. cinerea and almost completely removed it for F. culmorum. At a constant 500 mg dm(-3) Pb, increasing concentrations of clinoptilolite increased the linear extension rate of F. culmorum and B. cinerea, close to the rates achieved by the untreated controls. A. niger was not inhibited markedly at this Pb concentration. The evidence suggests that the Pb is adsorbed by the clinoptilolite which reduces the availability, and hence toxicity, of the metal to the fungi.     

Trace metals and organochlorines in sediments near a major ocean outfall on a high energy continental margin (Sydney, Australia)

Sewage effluent from a large ocean outfall south of Sydney, southeastern Australia, is efficiently dispersed on this high energy continental margin. An enrichment of Ag, Cu, Pb and Zn is only detectable in the fine fraction (<62.5 microm) of sediment. Ag, Co, Cu, Ni, Pb and Zn in the bulk sample correlate strongly with the mud content of surficial sediment, making an identification of the anthropogenic trace metal source difficult using total sediment analyses. The concentrations of HCB and DDE in the total sediment are also slightly elevated near the outfall. In the vicinity of the outfall, the estimated sewage component in the fine fraction of sediment, using Ag, Cu and Zn in a conservative, two-endmember physical mixing model, is <5% and is <0.25% of the total sediment. A greater anthropogenic Pb component in the fine fraction (mean: 24.8%) of surficial sediment compared to Ag, Cu and Zn may suggest a source other than sewage to Sydney continental margin sediments.     

Application of Sediment Quality Guidelines in the Assessment and Management of Contaminated Surficial Sediments in Port Jackson (Sydney Harbour), Australia

Sediments in the Port Jackson estuary are polluted by a wide range of toxicants and concentrations are among the highest reported for any major harbor in the world. Sediment quality guidelines (SQGs), developed by the National Oceanographic and Atmospheric Administration (NOAA) in the United States are used to estimate possible adverse biological effects of sedimentary contaminants in Port Jackson to benthic animals. The NOAA guidelines indicate that Pb, Zn, DDD, and DDE are the most likely contaminants to cause adverse biological effects in Port Jackson. On an individual chemical basis, the detrimental effects due to these toxicants may occur over extensive areas of the harbor, i.e., about 40%, 30%, 15% and 50%, respectively. The NOAA SQGs can also be used to estimate the probability of sediment toxicity for contaminant mixtures by determining the number of contaminants exceeding an upper guideline value (effects range medium, or ERM), which predicts probable adverse biological effects. The exceedence approach is used in the current study to estimate the probability of sediment toxicity and to prioritize the harbour in terms of possible adverse effects on sediment-dwelling animals. Approximately 1% of the harbor is mantled with sediment containing more than ten contaminants exceeding their respective ERM concentrations and, based on NOAA data, these sediments have an 80% probability of being toxic. Sediment with six to ten contaminants exceeding their respective ERM guidelines extend over approximately 4% of the harbor and have a 57% probability of toxicity. These areas are located in the landward reaches of embayments in the upper and central harbor in proximity to the most industrialised and urbanized part of the catchment. Sediment in a further 17% of the harbor has between one and five exceedences and has a 32% probability of being toxic. The application of SQGs developed by NOAA has not been tested outside North America, and the validity of using them in Port Jackson has yet to be demonstrated. The screening approach adopted here is to use SQGs to identify contaminants of concern and to determine areas of environmental risk. The practical application and management implications of the results of this investigation are discussed.     

A novel method using sedimentary metals and GIS for measuring anthropogenic change in coastal lake environments

Background, aim and scope  

A new method using sedimentary metals and geographic information system as indicators for assessing temporal and spatial anthropogenic change in estuaries has been applied to a large coastal lake (Lake Macquarie) in New South Wales, Australia.     

Comparison of two carbon analysis methods for monitoring diesel particulate levels in mines

Two carbon analysis methods are currently being applied to the occupational monitoring of diesel particulate matter. Both methods are based on thermal techniques for the determination of organic and elemental carbon. In Germany, method ZH 1/120.44 has been published. This method, or a variation of it, is being used for compliance measurements in several European countries, and a Comité Européen de Normalization Working Group was formed recently to address the establishment of a European measurement standard. In the USA, a 'thermal-optical' method has been published as Method 5040 by the National Institute for Occupational Safety and Health. As with ZH 1/120.44, organic and elemental carbon are determined through temperature and atmosphere control, but different instrumentation and analysis conditions are used. Although the two methods are similar in principle, they gave statistically different results in a previous interlaboratory comparison. Because different instruments and operating conditions are used, between-method differences can be expected in some cases. Reasonable agreement is expected when the sample contains no other (i.e., non-diesel) sources of carbonaceous particulate and the organic fraction is essentially removed below about 500 degrees C. Airborne particulate samples from some mines may meet these criteria. Comparison data on samples from mines are important because the methods are being applied in this workplace for occupational monitoring and epidemiological studies. In this paper, results of a recent comparison on samples collected in a Canadian mine are reported. As seen in a previous comparison, there was good agreement between the total carbon results found by the two methods, with ZH 1/120.44 giving about 6% less carbon than Method 5040. Differences in the organic and elemental carbon results were again seen, but they were much smaller than those obtained in the previous comparison. The relatively small differences in the split between organic and elemental carbon are attributed to the different thermal programs used.     

Evaluation of the SKC DPM cassette for monitoring diesel particulate matter in coal mines

In a previous study, the efficacy of commercial and prototype impactors for sampling diesel particulate matter (DPM) in coal mines was investigated. Laboratory and field samples were collected on quartz-fiber filters and analyzed for organic and elemental carbon. Coal dust contributed a minimal amount of elemental carbon when commercial cascade impactors and prototype impactors, designed by the University of Minnesota (UMN) and the US Bureau of Mines (BOM), were used to collect submicrometer dust fractions. Other impactors were not as effective at excluding coal dust. The impactors evaluated in that study were either not commercially available or were multi-stage, expensive, and difficult to use for personal measurements. A commercial version of the BOM impactor, called the DPM Cassette, was recently introduced by SKC. Tests were conducted to evaluate the performance of the DPM Cassette for measuring diesel-source elemental carbon in the presence of coal dust. Bituminous coals from three mines in two different coal provinces were examined. The dust particle diameters were small and the coal dust contained a high percentage of carbon, thereby giving a worst-case condition for non-anthracite coal mines. Results for the DPM Cassette were essentially identical to those obtained by the BOM impactors in a previous study. At a respirable coal dust concentration of 5.46 mg m(-3), which is 3.8 times the regulatory limit, the DPM Cassette collected only 34 microg m(-3) of coal-source elemental carbon.