Comparison of Multiple Point and Composite Sampling for Monitoring Bathing Water Quality

Kinzelman, Julie; Dufour, Alfred; Wymer, Larry; Rees, G. Wyn; Pond, Katherine; Bagley, Robert C.

doi:10.1080/07438140609353887

Cited by 20 publications

(18 citation statements)

References 16 publications

(13 reference statements)

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“…Most research has involved selecting the most representative indicator microorganism as representative for the presence of pathogens (Shah et al, 2011;Love et al, 2014), health risk (Wade et al, 2010;Colford et al, 2012), the type of the assay used for testing (Haugland et al, 2005;Lavender and Kinzelman, 2009;Noble et al, 2010;Shanks et al, 2011;Raith et al, 2014), the location of sampling sites (Kinzelman et al, 2006), or the frequency of sampling events (Whitman and Nevers, 2004;Boehm and Weisberg, 2005;Converse et al, 2012). An issue that is often overlooked is the day of sampling that is most representative for human exposure.…”

Section: Discussionmentioning

confidence: 99%

New Recreational Water Quality Criteria and Their Impact on Beach Advisories in Coastal Georgia

Aslan

Benevente

2016

JGPHA

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Background: To monitor pollution of marine beaches in Georgia, enterococci have been used as indicators of fecal contamination. For the 1986 Recreational Water Quality Criteria (RWQC), the beach action value (BAV) was 104 colonyforming units (CFU)/100 ml; the new RWQC, instituted in 2012, is 70 CFU/mL, a 32.6% decrease. When the beach action value is reached, authorities are to issue a beach advisory for protection of swimmer health. The present study investigated changes in compliance with the 2012 RWQC at five high-use beaches in Georgia. Methods:In the summer of 2015, samples of water were collected from five beaches at Tybee Island. Enterococci concentrations were enumerated by USEPA-approved methods. Samples exceeding the 1986 and 2012 RWQC beach action values were compared with times that advisories were posted at these beaches.Results: At these beaches, advisories were posted four times during the summer. Since, in 2015, the previous RWQC was in use, these decisions were based on the guideline value of 104 colon-forming units (CFU)/100 ml. When the new beach action value (70 CFU/100 ml) was applied, retrospectively, for samples collected at these sites, we found that the number of advisories would have been doubled if this value had been in place at that time. Conclusions:Staring from January 2016, Georgia has adopted new water quality criteria to monitor beaches. Decreasing the beach action value to 70 CFU/100 ml strengthens beach monitoring programs because it allows for better prevention from waterborne diseases, thus protecting the health of swimmers.

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Section: Discussionmentioning

confidence: 99%

New Recreational Water Quality Criteria and Their Impact on Beach Advisories in Coastal Georgia

Aslan

Benevente

2016

JGPHA

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“…A single analysis is performed on the composite, which is used to represent each of the original individual samples (Patil 2002). Composite sampling is appropriate when individual samples can be adequately homogenized without affecting their integrity or introducing bias (Kinzleman et al 2006). In effect, the composite sample represents the average conditions in that sampled body of water or other material (Lock 1998).…”

Section: Regulatory Frameworkmentioning

confidence: 99%

“…Because of this variability, data were log-transformed (log 10 ) to more normally distribute the data (Bertke 2007;Kinzleman et al 2006). Statistical analysis consisted of evaluating the relationships between individual sample averages (arithmetic and geometric) and the composite sample result using the Pearson product-moment correlation coefficient (Bertke 2007).…”

Section: Statistical Summary and Analysismentioning

confidence: 99%

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Monitoring bathing beach water quality using composite sampling

Reicherts¹,

Emerson

2009

Environ Monit Assess

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Michigan water quality standards for public bathing beaches require local health departments to collect and analyze a minimum of three water samples for Escherichia coli during each sampling event. The geometric mean number of E. coli colonies is then compared to the 300 colonies per 100 ml standard to determine compliance. This article compares the results of the currently mandated procedure to a composite sampling method, whereby the three samples are mixed in equal volumes and analyzed once. This effectively replaces the geometric mean of the individual sample results with an arithmetic mean. Although arithmetic means are more affected by outliers, this sensitivity to high concentrations is more health conservative than the geometric mean. During the 2007 sampling season, nine bathing beaches were monitored once each week. Three individual point samples and a composite sample were analyzed for each sampling event. No statistically significant differences in bacteria concentrations were found between composite sample analysis and the arithmetic mean of individual point sample analyses. No violations were detected in the 2007 sampling season, so using historical data, a retrospective analysis was performed on samples gathered at nine bathing beaches in Kalamazoo County, Michigan during the years 2001-2007. The arithmetic mean of the three samples taken at each site served as a surrogate composite sample. The benefits of compositing the three samples were investigated assuming a 2/3 reduction in analytical costs. In the traditional sampling method, three individual samples were obtained and analyzed once in every 3-week period during the summer season, whereas compositing was simulated by taking the arithmetic mean of each week's results. The results of this retrospective cost analysis indicates that ten to 14 violations would have been missed using the less frequent traditional sampling and analysis methodology. Composite sampling is a cost-saving alternative to traditional sampling techniques that can be more protective of public health, particularly when the savings are applied to increased numbers of samples in time or space.

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“…Compositing involves mixing equal volumes of spatially discrete samples and analyzing the homogenate. In enumeration of FIB by culture-based methods in water samples, results from composite samples have been shown to be significantly correlated to the arithmetic means of single-sample results and to yield similar beach closure decisions (1,6,10). Moreover, analysis of a single composite sample has been estimated to be nearly 40% less expensive than multiple single-sample culture analyses (10).…”

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Comparison of the Multiple-Sample Means with Composite Sample Results for Fecal Indicator Bacteria by Quantitative PCR and Culture

Converse

Wymer

Dufour

et al. 2012

Appl Environ Microbiol

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cFew studies have addressed the efficacy of composite sampling for measuring indicator bacteria by quantitative PCR (qPCR). We compared results from composited samples with multiple-sample means for culture-and qPCR-based water quality monitoring. Results from composited samples for both methods were similarly correlated to multiple-sample means and predicted criteria exceedances equally. Because concentrations of fecal indicator bacteria (FIB) can be variable within a beach area, several water samples from a beach may be required to sufficiently characterize water quality (18). The development of rapid measurement methods, such as quantitative PCR (qPCR), has resulted in the ability to provide much faster water quality assessments, but these methods are valuable only insofar as a sampling scheme can accurately and efficiently characterize a water body in one or a few samples. Due to the cost of the analysis of multiple samples, analyzing composited samples may be a reasonable and less-expensive alternative (11). Compositing involves mixing equal volumes of spatially discrete samples and analyzing the homogenate. In enumeration of FIB by culture-based methods in water samples, results from composite samples have been shown to be significantly correlated to the arithmetic means of single-sample results and to yield similar beach closure decisions (1, 6, 10). Moreover, analysis of a single composite sample has been estimated to be nearly 40% less expensive than multiple single-sample culture analyses (10). Recent studies have indicated that qPCR-based measurements of FIB are statistically associated with gastrointestinal illness among swimmers (15,16,17), and composite sampling could generate significant savings for water quality monitoring programs using qPCR. Because the relationships between culture and qPCR results can vary within a beach on small temporal and spatial scales (3, 13), it is unclear whether composite sampling is as efficacious when using qPCR as when using culture methods. The purpose of this study was to determine whether composite sampling gave results statistically similar to those of multiple-point sampling when qPCR is used to measure bacterial water quality and whether the two sampling strategies are likely to produce the same beach closure decisions based on current proposed U.S. Environmental Protection Agency (EPA) guideline values for recreational water quality (14).Water samples were collected three times daily (at 0800, 1100, and 1500) from Surfside Beach, Surfside, South Carolina, on weekends and holidays between 6 June and 7 September 2009 (n ϭ 84). Three transects perpendicular to the beach were established to represent areas frequented by beachgoers. Transects were approximately 70 m apart. Duplicate water samples were collected along each transect at shin depth (0.3 m) and waist depth (1 m) in sterile polypropylene bottles. One of the duplicate water samples was used for single-sample analyses, and the other was used to create composites. Composites were made by combining 300-ml...

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Comparison of Multiple Point and Composite Sampling for Monitoring Bathing Water Quality

Cited by 20 publications

References 16 publications

New Recreational Water Quality Criteria and Their Impact on Beach Advisories in Coastal Georgia

New Recreational Water Quality Criteria and Their Impact on Beach Advisories in Coastal Georgia

Monitoring bathing beach water quality using composite sampling

Comparison of the Multiple-Sample Means with Composite Sample Results for Fecal Indicator Bacteria by Quantitative PCR and Culture

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