Assessing the performance of measurement devices for continuously monitoring of organic matter and nutrient in river water

Abstract

The evaluation of the metrological performance parameters of 27 water quality monitoring devices for continuously measuring nutrients and organic matter in river waters was conducted both under controlled conditions in the laboratory and under field conditions during a 3-month field trial. It consisted of (i) designing protocols to assess metrological performance parameters under controlled and field conditions of monitoring devices (ii) selecting a site to conduct a field trial (iii) selecting monitoring devices and (iv) conducting the testing. The results obtained for the devices measuring nitrate, total nitrogen and organic carbon are presented in this paper. The performances evaluated under controlled conditions were very acceptable with the vast majority of the monitoring devices being characterized by a repeatability below 5 %, a bias below 10 %, a linearity deviation below 10 % and a combined expanded uncertainty below 15 %. Moreover, the monitoring devices tested were found to have quantification limits suitable with regard to the concentration levels measured in the Oise River between October 2015 and February 2016. Finally, from the results obtained as well as the feedback on testing a great variety of monitoring devices, it was possible to draw some recommendations for improving the measurements using the devices tested.