A sensitive and robust method for automated on-line monitoring of enzymatic activities in water and water resources

G. Ryzinska-Paier, T. Lendenfeld, K. Correa, P. Stadler, A. P. Blaschke, R. L. Mach, H. Stadler, A. K.T. Kirschner, A. H. Farnleitner*

*Corresponding author for this work

Research output: Journal article (peer-reviewed)Journal article

36 Citations (Scopus)


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.

Original languageEnglish
Pages (from-to)1349-1358
Number of pages10
JournalWater Science and Technology
Issue number6
Publication statusPublished - 2014
Externally publishedYes


  • Beta-galactosidase
  • Beta-glucuronidase
  • E. coli
  • Enzymatic on-line monitoring
  • Faecal pollution
  • Water safety plan

ASJC Scopus subject areas

  • Environmental Engineering
  • Water Science and Technology


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