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J Water Health 03 (2005) 349-358

Spatial and rainfall related patterns of bacterial contamination in Sydney Harbour estuary
Grant C. Hose, Brad R. Murray, Geoff Gordon, Fiona E. McCullough and Nicholas Pulver

Institute for Water and Environmental Resource Management, University of Technology, Sydney, PO Box 123, Broadway, NSW 2007, Australia, Tel.: +61 2 9514 4087, Fax: +61 2 9514 4095, grant.hose@uts.edu.au

Institute for Water and Environmental Resource Management, University of Technology, Sydney, PO Box 123, Broadway, NSW 2007, Australia, Tel.: +61 2 9514 4087, Fax: +61 2 9514 4095, grant.hose@uts.edu.au

Ecotoxicology and Water Science Section, New South Wales Department of Environment and Conservation, PO Box A290, Sydney South, NSW 1232, Australia

Environmental Protection and Operations Division, New South Wales Department of Environment and Conservation, PO Box 668, Parramatta, NSW 2124, Australia

Beachwatch Programs Section, New South Wales Department of Environment and Conservation, PO Box A290, Sydney South, NSW 1232, Australia

ABSTRACT
Water quality in recreational areas in Sydney Harbour, Australia, was analysed first to identify spatial patterns in faecal coliform and enterococci densities, and then to determine the relationship between bacterial densities and catchment rainfall. Non-metric multidimensional scaling separated sites closest to the mouth of the harbour from those further up the harbour's west and north-west arms. Sites closest to the harbour mouth generally had lower frequencies of high bacterial densities that exceeded median water quality guideline values. We attribute this to greater tidal flushing at sites closer to the harbour mouth. Eight site groups were identified within the harbour. Within each group, multiple regression analyses indicated rainfall accounted for between 15 and 66% of the variability in the bacterial densities. Variation in bacterial densities explained by rainfall was lower for sites closer to the harbour mouth where tidal flushing is greatest. Thus, our findings indicate that simple rainfall-based regression models are appropriate for predicting bacterial concentrations when flushing at a site is limited. More complex models incorporating a suite of environmental variables may improve the ability to predict bacterial concentrations at well-flushed sites, but even then, their predictive ability may be low.




J Water Health 03 (2005) 381-392

A review of technologies for rapid detection of bacteria in recreational waters
Rachel T. Noble and Stephen B. Weisberg

University of North Carolina at Chapel Hill, Institute of Marine Sciences, 3431 Arendell St, Morehead City,NC, 28557,USA, rtnoble@email.unc.edu

Southern California Coastal Water Research Project, 7171 Fenwick Lane, Westminster,CA, 92683,USA, stevew@sccwrp.org

ABSTRACT
Monitoring of recreational beaches for fecal indicator bacteria is currently performed using culture-based technology that can require more than a day for laboratory analysis, during which time swimmers are at risk. Here we review new methods that have the potential to reduce the measurement period to less than an hour. These methods generally involve two steps. The first is target capture, in which the microbial group of interest (or some molecular/chemical/or biochemical signature of the group) is removed, tagged or amplified to differentiate it from the remaining material in the sample. We discuss three classes of capture methods: 1) Surface and whole-cell recognition methods, including immunoassay techniques and molecule-specific probes; 2) Nucleic acid methods, including polymerase chain reaction (PCR), quantitative PCR (Q-PCR), nucleic acid sequence based amplification (NASBA) and microarrays; and 3) Enzyme/substrate methods utilizing chromogenic or fluorogenic substrates. The second step is detection, in which optical, electrochemical or piezoelectric technologies are used to quantify the captured, tagged or amplified material. The biggest technological hurdle for all of these methods is sensitivity, as EPA's recommended bathing water standard is less than one cell per ml and most detection technologies measure sample volumes less than 1 ml. This challenge is being overcome through addition of preconcentration or enrichment steps, which have the potential to boost sensitivity without the need to develop new detector technology. The second hurdle is demonstrating a relationship to health risk, since most new methods are based on measuring cell structure without assessing viability and may not relate to current water quality standards that were developed in epidemiology studies using culture-based methods. Enzyme/substrate methods may be the first rapid methods adopted because they are based on the same capture technology as currently-approved EPA methods and their relationship to health risk can be established by demonstrating equivalency to existing procedures. Demonstration of equivalency may also be possible for some surface and whole-cell recognition methods that capture bacteria in a potentially viable state. Nucleic acid technologies are the most versatile, but measure nonviable structure and will require inclusion in epidemiological studies to link their measurement with health risk.




J Water Health 03 (2005) 453-468

Quantifying the impact of runoff events on microbiological contaminant concentrations entering surface drinking source waters
R. S. Signor, D. J. Roser, N. J. Ashbolt and J. E. Ball

School of Civil and Environmental Engineering, The University of New South Wales, Sydney, NSW 2052,Australia, Tel: +61(2) 9385 5064, Fax: +61(2) 9385 6139, ryan.signor@student.unsw.edu.au

School of Civil and Environmental Engineering, The University of New South Wales, Sydney, NSW 2052,Australia, Tel: +61(2) 9385 5064, Fax: +61(2) 9385 6139, ryan.signor@student.unsw.edu.au

School of Civil and Environmental Engineering, The University of New South Wales, Sydney, NSW 2052,Australia, Tel: +61(2) 9385 5064, Fax: +61(2) 9385 6139, ryan.signor@student.unsw.edu.au

School of Civil and Environmental Engineering, The University of New South Wales, Sydney, NSW 2052,Australia, Tel: +61(2) 9385 5064, Fax: +61(2) 9385 6139, ryan.signor@student.unsw.edu.au

ABSTRACT
Concentrations of microbiological contaminants in streams increase during rainfall-induced higher flow !.event!/ periods as compared to !.baseflow!/ conditions. If the stream feeds a drinking water reservoir, such periods of heightened pathogen loads may pose a challenge to the water treatment plant and subsequently a health concern to water consumers downstream. In order to manage this risk, it is desirable to first quantify the differences in surface water quality between baseflow and event conditions. The Event Mean Concentration (EMC) is a flow-weighted average concentration of a contaminant over the duration of a single event, proposed here as a standard parameter for quantifying the net effect of events on microbial water quality. Application of the EMC concept was assessed using flow and quality data for several events from an urbanised catchment. Expected mean EMCs were significantly larger than expected mean baseflow concentrations (p-value!B0.012) for three microbial agents - Escherichia coli (13,000 [n = 7] v. 610 [n = 16] mpn/100 ml), Cryptosporidium (234 [n = 6] v. 51 [n = 16] oocysts/10 litres) and Campylobacter (48 [n = 5] v. 2.1 [n = 16] mpn/100 ml). These parameter estimates were complemented by estimating data variability and uncertainty in the form of second-order random variables. As such the results are in a format appropriate for potential use as components in probabilistic risk assessments evaluating the effect runoff events have on drinking water quality.



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