Technical note: High-frequency, multi-elemental stream water monitoring – experiences, feedbacks and suggestions from 7 years of running three French field laboratories (Riverlabs)

High-frequency and multi-elemental stream water monitoring are acknowledged as necessary to address data limitation in the fields of catchment sciences and freshwater biogeochemistry. In recent years, the development of stream bank analyzers and on-site field laboratories to measure various solutes and/or isotopes at sub-hourly measurement intervals has been in progress at an increasing number of sites. This trend should likely persist in the future as the technologies are still improving. Here we share our experiences of running three innovative lab-in-the-field prototypes, called Riverlabs, which consist of a field deployment involving continuous sampling and filtration of stream water and its analysis using laboratory instruments such as ion chromatographs. This note gives an overview of the technical and organizational points that we identify as critical because we claim that such practical considerations are generally missing in the literature in order to provide guidelines for the successful implementation of future projects running such or similar field-laboratory setups. We share the main stages in the deployment of this tool in the field, the difficulties encountered and the proposed solutions. Our two main conclusions for a successful, long-term functioning of these types of field laboratories are, first, the necessity to adapt several central components of the field laboratory to the local conditions (climate, river geometry, topography, physico-chemical characteristics of water, power supply) and, second, the need of diverse and in-depth technical skills within the engineering team. The critical aspects discussed here relate to (1) supply of the field laboratory – basic functioning of the pumping, filtration and analytical systems; (2) data quality control and assurance via maintenance services and operations; (3) data harmonization and coordination of the laboratory components; and (4) team structure, skills and organization. We believe that sharing these experiences, combined with providing some practical suggestions, might be useful for colleagues who are starting to deploy such or similar field laboratories. These considerations will save time, improve performance and ensure continuous field monitoring.