Using Compensated Fluorescence Probes Data for Proactive Water Treatment Management

Abstract

In this study we investigated and quantified the effects of a number of environmental conditions on the readings of fluorescent dissolved organic matter (fDOM) and total algae probes. These currently monitor fDOM, chlorophyll-a and phycocyanin for the full depth profile of different reservoirs in South-East Queensland (Australia), but interferences and quenching affecting these parameters have led to uncertainty in the reliability of the readings. Additionally, in the case of the total algae probe, obtaining reliable estimates of algal biovolume or cell counts is challenging since the pigments content varies with species and several other environmental variables influence estimates. With regards to the fDOM, a number of experiments were performed which enabled the development of a sequential compensation model accounting for the main trivial quenching. In addition, the compensated readings were compared to other experiments' outputs to check for correlations between readings and character/molecular weight of DOM to develop an accurate real-time model that may be useful in assisting DOM removal by coagulation. Preliminary work with the algae probe also showed potential to derive more specific information on species/abundance for better cyanobacteria management.

Monitoring Approaches for Faecal Indicator Bacteria in Water: Visioning a Remote Real-Time Sensor for E. coli and Enterococci

“…As expressed by de Oliveira et al [119], this shows that accurate and reliable corrections are possible for raw fDOM readings from turbidity interferences. Their model outperformed other linear and non-linear multivariate regression models; however, they recommended further work to develop a more generalised compensation model following site-specific development data [119,124], as site-specific particle size distributions and other features can cause different degrees of interference.…”

“…There is potential to gain higher accuracy and improved data from fluorescence tools by developing salinity compensation models [124,133]. Salinity can be determined using salinity meters and electrical conductivity meters [76].…”

“…De Oliveira et al [119] tested the effects of high salinity (due to its increase when concentrating DOM) on fDOM readings and found that no variations in readings were noticed. Bertone et al [124] pointed out that based on previous research studies, salinity alters the intramolecular reaction, interferes with fDOM readings, and can cause quenching on fDOM measurements; however, in terms of potential quenching when testing freshwater systems, salinity levels should be negligible. In marine waters, conversely, Carstea et al [73] found several fluorophores overlapping in the peak-T region, and it is difficult to pinpoint a specific compound.…”