Stormwater monitoring using on-line UV-Vis spectroscopy.

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 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 (Escherichia coli) from captured storm events showed poor correlations to nitrate and other typical on-line parameters in this study. This is possibly explained by the nature of the stormwater catchment outside of rain events, where the sources of bacteria and nutrients may be physically separated until mixed during surface runoff as a result of rainfall. In addition, the poor correlations among the microbiological data and on-line parameters could be due to the different sources of bacteria and nutrients that were transported to the stormwater drain where sampling and measurement were conducted.

Influence of drying time on nematode eggs in scats of scincid lizard Egernia stokesii.

Two pharyngodonid nematode species, Pharyngodon tiliquae and Thelandros trachysauri, infect the Australian lizard Egernia stokesii (gidgee skink) in populations from South Australia. Eggs are detected in lizard scats that are deposited in piles outside the rock crevice refuges that the lizards occupy. Eggs were isolated by salt flotation from fresh scats and from scats that had been dried in simulated field conditions for 7, 14, 21, and 28 days. Egg counts decreased with drying time for both nematode species, but T. trachysauri eggs were still detected after 28 days of drying, whereas P. tiliquae eggs were rarely detected after 14 days. These results suggest that egg counts can be used to infer host infection status only from relatively fresh scats and that eggs of the 2 species persist in a state where they can be detected by standard flotation techniques, for different times.

Evaluation of heterotrophic plate and chromogenic agar colony counting in water quality laboratories.

The enumeration of bacteria using plate-based counts is a core technique used by food and water microbiology testing laboratories. However, manual counting of bacterial colonies is both time and labour intensive, can vary between operators and also requires manual entry of results into laboratory information management systems, which can be a source of data entry error. An alternative is to use automated digital colony counters, but there is a lack of peer-reviewed validation data to allow incorporation into standards. We compared the performance of digital counting technology (ProtoCOL3) against manual counting using criteria defined in internationally recognized standard methods. Digital colony counting provided a robust, standardized system suitable for adoption in a commercial testing environment. The digital technology has several advantages:•Improved measurement of uncertainty by using a standard and consistent counting methodology with less operator error.•Efficiency for labour and time (reduced cost).•Elimination of manual entry of data onto LIMS.•Faster result reporting to customers.