High-resolution multi-parameter monitoring of microbial water quality and particles at two alpine karst springs as a basis for an early-warning system

Abstract

Karst aquifers are important resources for drinking water supply and are very vulnerable to contamination. Microbial concentrations at karst springs, in particular, often vary quickly over a short period of time. In this study, the response of microbial water quality and particle-size distribution of two alpine karst springs to rainfall events was investigated to test and validate parameters that can be used as early-warning systems for fecal contamination. At both investigated karst springs, total organic carbon, particle-size distribution (especially small particle fractions), and particle load show a good correlation to the fecal indicator bacteria E. coli and can therefore be used as a real-time indicator of fecal contamination at the investigated springs. In addition to conventional bacterial determination methods, the β-D-glucuronidase activity, which can be measured in near real-time, was used as a novel indicator parameter for fecal contamination. At the event scale, the β-D-glucuronidase (GLUC) activity shows a good correlation to E. coli and can be used as an additional real-time indicator of fecal contamination. For the studied springs, when they show two peaks in turbidity and small particles, these two parameters are suitable for an early warning system because the bacterial contamination occurs during the secondary peak of these parameters. These results highlight the vulnerability of karst aquifers and demonstrate the applicability of advanced measurement techniques in detecting fecal contamination in real-time, which is especially important given the time-consuming nature of conventional bacterial detection methods.

Microbial drinking water monitoring now and in the future

“…As a result, a fluorescent signal is generated and measured by laser detection. Coliminder has recently been applied to assess quality of the intake water for drinking water production, as the β‐D‐glucuronidase shows a good correlation to the E. coli and can thus be used as a real‐time faecal indicator (Frank et al., 2022 ; Hachad et al., 2024 ). Because these methods are often not sensitive enough to detect the low concentration of unwanted bacteria in the drinking water that they have been applied to the source water.…”

Evaluation of Water Quality from the Zimny Sztok Spring (Southern Poland)—Preliminary Results

“…Drinking water is water that is of acceptable quality (according to the WHO's guidelines or national standards for drinking water quality) in terms of physical, chemical and microbiological properties, which can therefore be used safely [29]. Due to the fact that maintaining the appropriate quality of drinking water is necessary for ensuring human health, it is essential to supervise this quality by monitoring this water through constant control using sensors.…”