A systems approach to understand microplastic occurrence and variability in Dutch riverine surface waters

Svenja Mintenig*, M. Kooi, M.W. Erich, S. Primpke, P.E. Redondo Hasselerharm, S.C. Dekker, A.A. Koelmans, A.P. van Wezel

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

107 Citations (Scopus)


Assessment methods on data quality and environmental variability are lacking for microplastics (MP). Here we assess occurrence and variability of MP number concentrations in two Dutch rivers. Strict QA/QC procedures were applied to identify MP using Fourier-transform infrared (FTIR) microscopy followed by state of the art automated image analysis. For a series of randomly selected, yet ever smaller subareas of filters, we assessed how accurately MP numbers and polymer types are represented during partial filter analysis. Levels of uncertainty were acceptable when analysing 50% of a filter during chemical mapping, and when identifying at least a subset of 50 individual particles with attenuated total reflection (ATR)-FTIR. Applying these guidelines, MP number concentrations between 67 and 11532 MP m−3 were detected in Dutch riverine surface waters. Spatial differences caused MP number concentrations to vary by two orders of magnitude. Temporal differences were lower and induced a maximum variation of one order of magnitude. In total, 26 polymer types were identified, the most common were polyethylene (23%), polypropylene (19.7%) and ethylene propylene diene monomer rubber (18.3%). The highest diversity of polymer types was found for small MPs, whereas MP larger than 1 mm was scarce and almost exclusively made of polyethylene or polypropylene. Virtually all sampling locations revealed MP number concentrations that are considerably below known effect thresholds for anticipated adverse ecological effects.
Original languageEnglish
Article number115723
JournalWater Research
Early online date16 Mar 2020
Publication statusPublished - 1 Jun 2020


  • Automated image analysis
  • Freshwater
  • FTIR microscopy
  • Microplastics
  • Spatial and temporal variability
  • Water quality


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