Water Quality Snapshots: Accurate Surface Water Monitoring using Optical Spectroscopy Techniques

The European Union underlines the availability and quality of water as a precondition for human, animal and plant life as well as an indispensable resource for the economy. The sustainability of aquatic ecosystems is therefore considered a priority within the EU. The Water Framework Directive (WFD) entails environmental reporting obligations to EU Commission, where each member state shall regularly report on the environmental state of the aquatic ecosystems. Any activities impacting these ecosystems are bound to monitoring requirements.

The water quality of the most important surface waters is monitored regularly by means of sampling. Monitoring frequency varies but is usually not higher than once per two weeks. Many small surface waters are not monitored at all. In order to monitor the effects of eutrophication on the water quality some parameters are measured: Algal biomass is approximated by a standard measurement of Chlorophyll-a, turbidity is measured

by Secchi-disk and the amount of cyanobacteria is determined by microscope cell-counts. If there are indications for cyanobacterial blooms then e.g. the microcystine concentration can be measured, although recent publications indicate that this is a quite unreliable measurement because of high heterogeneity. Furthermore, collecting this data is costly and time consuming. Blooms can be missed because of the low time resolution.

Therefore management of the water system is always out of phase with the actual developments.

Recent developments in portable spectroscopy enabled the development of a new instrument enabling automatic, instantaneous and continuous measurements of most of the controlling parameters relevant to authorities responsible for monitoring water quality. The lowcost, high quality and continuous information delivered by a portable (or fixed position) instrument, can play an important role in real-time warning for water quality deterioration. Because of its unique set of measured parameters, the instrument is also eminently suitable to monitor the effect of water quality improvement programs and to act as a controlling device for restorative measures such as water inlet, bubble screens (to prevent layer formation), etc.