Small, polar micropollutants are of particular relevance for aquatic ecosystems and human health as they can potentially reach drinking water sources. A riverbank filtration (RBF) site in the Dutch river Rhine basin used for drinking water production was investigated, where a well field was built on a transect stretching from the north bank of the river Lek for about 2 km inland. The travel time from the river to the last well was estimated to be 50 years. Samples from River Lek and RBF from 8 wells were concentrated 200 times by solid-phase extraction prior to analysis with liquid chromatography coupled to high resolution tandem mass spectrometry. Potential non-target contaminants were prioritized and tentatively identified with computational data analysis methods. Data pre-processing was performed in enviMass, then dissimilarity matrices were calculated from the resulting profiles, which were fed to a hierarchical clustering algorithm to group profiles with comparable spatial intensity trends. Distinct trends were chosen for closer inspection. For masses corresponding with 50% of the most intense profiles in these clusters, MS and MS/MS peak lists were extracted with RMassBank. MetFrag was used to perform <i>in silico</i> fragmentation of candidate structures retrieved from ChemSpider and PubChem, including spectral similarity calculations using the Mass Bank of North America. Results were filtered by candidate score and checked for chromatographic quality with MZmine. Elemental composition of precursors and fragments was assessed with GenForm and identification confidence was classified. Several non-target peaks were tentatively annotated as pesticides, transformation products, pharmaceuticals or industrial chemicals, most of which had not been previously detected at the site. Confirmation with reference standards is underway. These results provide valuable information to monitor the migration of these pollutants through the river bank and into the aquifer, as well as to assess their removal by both RBF and drinking water treatment.

Detecting polar micropollutants in a river-riverbank filtrate using non-target screening

255th National Meeting (2018)

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