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Thursday, April 30, 2009
Sadrivaan A and B (The Hilton Istanbul Hotel )
Objectives. To evaluate the pollution trends, effects of environmental variables and management.
Materials and Methods. The public data of monitoring of monthly (1993-2007) E-coli counts on 47 stations in the Town of Acton, MA water bodies were used; gathering samples and conducting tests were made according to the standard methods. In 2002 a new sewage treatment plant began functioning. Due to non-normality of data distributions and 15% of data being left and right censored, the 0.5 quantile/median was chosen as the object of statistical analysis based on non-parametric tests, regressions, and spectra.
Analysis. For the whole period, station medians were in low range of (1-55) CFU/100ml with just two natural outliers. Distinct seasonal median variability with maximum for summer and minimum for winter was observed: (50-84) and (5-12) CFU/100ml respectively. The spectra of seasonal medians revealed statistically significant peak on the period of one year reflecting the power of seasonal phenomenon. Overlapping non-parametric confidence intervals for seasonal medians showed no significant difference between their levels for times before and after the treatment plant began working. Supporting that, seasonal Mann-Kendall (M-K) statistics found out no significant (95%CI) temporal trend for Acton area despite on increase in population of people, wild animals and road traffic during 15 years. At the same time, more detailed analysis revealed statistically significant downtrend for spring and combined spring/summer M-K statistics and regressions just for period of time after a plant began functioning and adjacent to it watershed. Temporal E-coli medians were positively correlated with the water temperature in streams and negatively with the recharge rates of those that were associated with the natural processes of E-coli reproduction and turbulent diffusion/dilution there.
Conclusion. Functioning of sewage treatment plant improved the environmental situation in observed period, locally - during spring-summer seasons and in neighboring watershed only.
Materials and Methods. The public data of monitoring of monthly (1993-2007) E-coli counts on 47 stations in the Town of Acton, MA water bodies were used; gathering samples and conducting tests were made according to the standard methods. In 2002 a new sewage treatment plant began functioning. Due to non-normality of data distributions and 15% of data being left and right censored, the 0.5 quantile/median was chosen as the object of statistical analysis based on non-parametric tests, regressions, and spectra.
Analysis. For the whole period, station medians were in low range of (1-55) CFU/100ml with just two natural outliers. Distinct seasonal median variability with maximum for summer and minimum for winter was observed: (50-84) and (5-12) CFU/100ml respectively. The spectra of seasonal medians revealed statistically significant peak on the period of one year reflecting the power of seasonal phenomenon. Overlapping non-parametric confidence intervals for seasonal medians showed no significant difference between their levels for times before and after the treatment plant began working. Supporting that, seasonal Mann-Kendall (M-K) statistics found out no significant (95%CI) temporal trend for Acton area despite on increase in population of people, wild animals and road traffic during 15 years. At the same time, more detailed analysis revealed statistically significant downtrend for spring and combined spring/summer M-K statistics and regressions just for period of time after a plant began functioning and adjacent to it watershed. Temporal E-coli medians were positively correlated with the water temperature in streams and negatively with the recharge rates of those that were associated with the natural processes of E-coli reproduction and turbulent diffusion/dilution there.
Conclusion. Functioning of sewage treatment plant improved the environmental situation in observed period, locally - during spring-summer seasons and in neighboring watershed only.
Learning Objectives: Demonstrate the assessment of the local pollution trends as a result of the environmental management on the basis of the fecal bacteria monitoring and advanced statistical analysis.
Sub-Theme: Environmental and Occupational Health
See more of: Poster: Environmental and Occupational Health
See more of: Public Health Practices Around the Globe
See more of: Public Health Practices Around the Globe