Date of Submission
Environmental and Urban Studies
Project Advisor 1
Disinfection byproducts (DBPs) are formed when chlorine, or any other disinfectant, is added to drinking water and reacts to a small fraction of natural organic matter (NOM) present in the water supply. DBPs may be carcinogenic when exposed to for a long term at high concentrations. However, the usage of chlorine or other disinfectants on the water supply must not be compromised. The precursors of DBPs are studied in the Saw Kill by acquiring data from 2017 to 2019 from the Saw Kill Monitoring Program. This includes colored dissolved organic matter (CDOM), chlorophyll a, and turbidity, which are indicative of NOM behavior in the river. Three figures of each parameter are created in relation to land usage (forested, developed, and MCA) and seasonality, while distribution plots and natural log-transformed plots are created to test for normality via the Shapiro-Wilks test. Correlations between the parameters are plotted and tested via Kendall Tau and Spearman Rho’s test. In addition, stream inflows to the reservoirs of Neversink and Cannonsville are studied by evaluating its grab samples for temperature fluorescence quenching of CDOM and sample degradation via two Handheld AquaFluor Fluorometers (of the same model, but different calibration methods), and microbial activity via an ATP (adenine triphosphate) assay. The CDOM data is corrected for temperature effects by using the equation provided by Watras et al. (2011), CDOMr = CDOMm/[1 + ρ(Tm – Tr)], and then correlated with dissolved organic carbon (DOC). Results from the Saw Kill plots indicate that parameters are not normally distributed, and there is a weak correlation between them. From the limited dataset (n=2), there is no indication of seasonality or land usage affecting the concentration of the investigated parameters. Furthermore, preliminary results from the laboratory experiments of Neversink and Cannonsville samples reveal that CDOM fluorescence emission intensity decreases by ~1% per temperature (°C) increase. The corrected CDOM values are highly correlated with DOC (r2=0.97). From the results of the limited ATP assays, Cannonsville has greater microbial activity. Samples with 72 and 58 holding days have a sample degradation of ~2 RFU and may be considered negligible in comparison to RFU changes between samples of different months. Saw Kill data suggest that DBP formation potential associated with CDOM and turbidity are highest in the fall of 2018 and associated with chlorophyll a is highest in the spring and summer of 2019. Meanwhile, Neversink and Cannonsville data suggest that CDOM temperature correction varies based on sample collection in regard to river hydrology. Corrected CDOM data is indicative of a strong indicator for DOC; however, further research is needed. Despite the fluorometers having different calibration methods, there are negligible differences in the data analysis. Ultimately, the following are recommendations provided for the Saw Kill Monitoring Program: the Bard fluorometer should be calibrated using quinine sulfate, and CDOM values should be corrected by using the equation provided by Watras et al. (2011). From the equation, the temperature coefficient, ρ, should be determined by conducting temperature quenching experiments and taking account of influences such as storms and river hydrology.
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Choy, Victoria, "Exploring the Precursors of Disinfection Byproducts and CDOM Fluorescence Monitoring" (2020). Senior Projects Spring 2020. 104.
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