title: A sensitive and robust method for automated on-line monitoring of enzymatic activities in water and water resources.
abstract: The realisation of a novel concept for automated on-line monitoring of enzymatic activities in water was successfully demonstrated by long-term field testing at two remote Austrian ground water resources. The β-D-glucuronidase (GLUC) activity was selected as a representative enzymatic model parameter for the on-line determination. But the device can be adapted for any enzymatic reaction with diagnostic relevance for microbial water quality monitoring, as demonstrated for the β-D-galactosidase activity. Automated filtration of volumes up to 5 litres supports sensitive quantification of enzymatic activities. Internet-based data transfer, using internal control parameters for verification and a dynamic determination of the limit of quantification, enabled robust enzymatic on-line monitoring during a 2-year period. A proportion of 5,313 out of 5,506 GLUC activity measurements (96.5%) could be positively verified. Hydrological (discharge, gauge, turbidity, temperature, pH, electric conductivity, spectral absorbance coefficient at 254 nm) as well as microbiological parameters (Escherichia coli, coliforms) were concurrently determined to characterise the investigated ground water resources. The enzymatic on-line measurements closely reflected the different hydrological conditions and contamination patterns of the test sites. Contrary to expectations, GLUC did not qualify as a proxy-parameter for the occurrence of cultivation-based E. coli contamination and warrants further detailed investigations on its indication capacity as a rapid means for microbial faecal pollution detection in such aquatic habitats. Microbial on-line monitoring is likely to become more important in the future, complementing existing surveillance strategies for water safety management. Further perspectives on the application of such analytical on-line technologies, such as their connection with event-triggered sampling and standardised diagnostics, are discussed.
authors.affiliation: Institute of Chemical Engineering, Research Group Environmental Microbiology and Molecular Ecology, Vienna University of Technology, Gumpendorferstraße 1A/166-5-2, A-1060 Vienna, Austria E-mail: a.farnleitner@aon.at.
authors.forename: G
authors.initials: G
authors.lastname: Ryzinska-Paier
authors.affiliation: mbOnline GmbH, Daniel Gran Straße 48, 3100 St. Pölten, Austria and WSB Labor-GmbH, Steiner Landstraße 27a, 3500 Krems, Austria.
authors.forename: T
authors.initials: T
authors.lastname: Lendenfeld
authors.affiliation: mbOnline GmbH, Daniel Gran Straße 48, 3100 St. Pölten, Austria and WSB Labor-GmbH, Steiner Landstraße 27a, 3500 Krems, Austria.
authors.forename: K
authors.initials: K
authors.lastname: Correa
authors.affiliation: Centre for Water Resource Systems (CWRS), Vienna University of Technology, Karlsplatz 13, A-1040 Vienna, Austria.
authors.forename: P
authors.initials: P
authors.lastname: Stadler
authors.affiliation: Vienna University of Technology, Interuniversity Cooperation Centre for Water and Health, Gumpendorferstraße 1a, 1060 Vienna, Austria.
authors.forename: A P
authors.initials: AP
authors.lastname: Blaschke
authors.affiliation: Institute of Chemical Engineering, Research Group Environmental Microbiology and Molecular Ecology, Vienna University of Technology, Gumpendorferstraße 1A/166-5-2, A-1060 Vienna, Austria E-mail: a.farnleitner@aon.at.
authors.forename: R L
authors.initials: RL
authors.lastname: Mach
authors.affiliation: Department for Water Resources Management, Institute for Water, Energy and Sustainability, Joanneum Research, Elisabethstraße 16/II, A-8010 Graz, Austria.
authors.forename: H
authors.initials: H
authors.lastname: Stadler
authors.affiliation: Division Water Hygiene, Institute for Hygiene and Applied Immunology, Medical University of Vienna, Kinderspitalgasse 15, A-1090 Vienna, Austria.
authors.forename: A K T
authors.initials: AK
authors.lastname: Kirschner
authors.affiliation: Institute of Chemical Engineering, Research Group Environmental Microbiology and Molecular Ecology, Vienna University of Technology, Gumpendorferstraße 1A/166-5-2, A-1060 Vienna, Austria E-mail: a.farnleitner@aon.at; Vienna University of Technology, Interuniversity Cooperation Centre for Water and Health, Gumpendorferstraße 1a, 1060 Vienna, Austria.
authors.forename: A H
authors.initials: AH
authors.lastname: Farnleitner
mesh_terms: D004784:Environmental Monitoring / Q000295:instrumentation*; D005966:Glucuronidase / Q000032:analysis*; D060587:Groundwater / Q000032:analysis*; D014871:Water Microbiology; D060753:Water Quality; D014881:Water Supply / Q000032:analysis*
chemical_list: D005966:Glucuronidase