Design and application of a new 24-h water sampler for monitoring particulate and dissolved road pollutants

Road pollution is a threat to aquatic ecosystems globally. Road runoff contains a mixture of particulate (e.g. tyre and road wear particles (TRWPs), road lining paint fragments and microplastics) and 'dissolved' pollutants (e.g. leached tyre and plastic additive chemicals). There is a lack of sampling approaches, however, for collection of particulate and dissolved pollutants which avoids transport of large volumes of water needed for particulate analysis and minimises sample contact with plastic materials. Therefore, the aim was to develop a new stainless-steel 24-h portable sampler for in situ isolation of particulates from a large sample volume (> 10 L) and simultaneous collection of water for additive chemical analysis. This was achieved using readily available materials (battery powered peristaltic pump, stainless-steel refuse vessel, sieves etc.) and at < 50% of the cost of commercially available plastic bodied composite samplers. The newly designed sampler was applied in the field to monitor pollutants entering a retention pond from a road drainage system. Particle concentrations > 50 µm in length were 25.5, 13.7 and 2.0 particles/L for TRWPs, paints and microplastics, respectively, with most (89%) in the 50-99-µm size range. Five additive chemicals were also determined in the collected water (1H-benzotriazole, 5-methylbenzotriazole, hexamethoxymethylmelamine, 1,3-diphenylguanidine and 1-cyclohexyl-3-phenylurea) at concentrations up to 0.18 µg/L. This new sampler has demonstrated to be effective for the simultaneous monitoring of particulate and dissolved road pollutants in water. Its ease of construction, limited plastic usage and low cost make it an attractive alternative to existing sampling methods for monitoring road pollution.