Measurement and characterisation of microplastics in English river catchment waters and sediments - WT15135 [Final report and appendices]

The objective of the project was to carry out a pilot study developing sampling and analytical protocols to determine the quantities, loads and types of microplastics (MP), in surface waters and sediments. Approaches to sampling surface waters and sediments would be reviewed and a selected approach tested on catchments agreed in consultation with the Environment Agency. From this, a provisional standard operating procedure (SOP) guideline is presented that may be used for sampling, processing and analysis of microplastics in river waters and sediments. In addition, it was investigated whether sediment samples collected in this manner could be analysed for the presence of vehicle tyre wear, through quantitative analysis of a common additive of tyre rubber, N-(1,3-Dimethylbutyl)-N’-phenyl-p-phenylenediamine (6PPD). This compound has been identified as a Priority 2 substance for freshwaters and groundwaters (high risk, low certainty) under the Environment Agency’s Prioritisation and Early Warning System (PEWS), flagging it for further consideration in sediments as it meets the toxicity criterion according to available ecotoxicity data and is not currently monitored (Environment Agency, 2023). The method is believed to be the first to be published to quantify this chemical marker in sediments using Gas Chromatography Mass Spectrometry.