Stormwater Monitoring Using On-line UV-Vis Spectroscopy for Surrogate Measurements of Chemical Contaminants and Compared With Microbiological Data

Abstract Stormwater runoff contains a myriad of pollutants, including faecal microbes, and can pose a threat to urban water supplies, impacting both economic development and public health. Therefore, it is a necessity to implement a real-time hazard detection system that can collect a substantial amount of data, assisting water authorities to develop preventive strategies to ensure the control of hazards entering drinking water sources. An on-line UV-Vis spectrophotometer was applied in the field to collect real-time continuous data for various water quality parameters (nitrate, DOC, turbidity and total suspended solids) during three storm events in Mannum, Adelaide, Australia. This study demonstrated that the trends for on-line and comparative laboratory analysed samples were complimentary through the events. Nitrate and DOC showed a negative correlation with water level while turbidity and total suspended solids indicated a positive correlation with water level during the high rainfall intensity. The correlations among nitrate, DOC, turbidity, total suspended solids, and water level are the opposite during the low rainfall intensity. Nitrate, one of the main pollutants in stormwater, was investigated and used as a surrogate parameter for microbial detection. However, the microbiological data (E.coli) from captured storm events showed poor correlations to nitrate and other typical on-line parameters in this study, possibly explained by the nature of the stormwater catchment outside of rain events, where the sources of bacteria and nutrients may be physically separate until mixed during surface runoff as a result of rainfall. In addition, the poor correlations among the microbiological data and on-line parameters can be due to the different sources of bacteria and nutrients that end up into the stormwater drain.