Assessment of road pollutants in roadside retention ponds.

Road networks are a significant, yet understudied, contributor to microplastic (MP) pollution in the environment. Road runoff contains particulate matter (e.g., tyre and road wear particles (TRWPs) and paint fragments) and dissolved chemicals (e.g., leached tyre and plastic related additive chemicals) which are of emerging concern. Sustainable urban drainage systems (SuDS) such as retention ponds manage runoff and are a key pathway for pollutants from roads to the wider aquatic environment. Hence the aim of this work was to assess retention ponds as a pathway for TRWPs, MPs, and additive chemicals entering the aquatic environment. A direct injection ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method was developed and validated to analyse 25 additive chemicals in environmental samples. Method quantification limits (MQLs) ranged from 4.3 × 10-3 – 13 μg/L and 0.13 – 4.6 × 102 μg/kg in water and sediment respectively which was suitable to determine most chemicals below their predicted no effect concentration (PNEC). A low-cost 24-hour sampling device, which minimised the usage of plastic and water volume to be transported, was developed to simultaneously isolate particles in-situ and collect water samples for additive chemical analysis. TRWPs, paint fragments and additive chemicals were detected in all inlet and outlet samples (n = 8) collected from two retention pond systems in North-east Scotland during summer and winter conditions. This demonstrates their ubiquity in runoff and incomplete removal by retention ponds. Additionally, a passive sampling method for additive chemicals was developed as it is capable of longer-term (e.g., ≥ 7 days) monitoring. Its application provided further evidence of incomplete tyre chemical removal by retention ponds. However, pond sediment analysis revealed particle retainment, with concentrations in the order of ~1.0 × 106 particles/kg dry weight. Particles in sediment also indicated longer-term trends, with greater concentrations of TRWPs and paint fragments linked to slip roads and painted rumble strips in the pond catchments, respectively. More additive chemicals were present in sediment (n = 21) compared to water (n = 8). Furthermore, a greater number were present above their PNEC in sediment (n = 11) indicating this matrix provides a greater risk and required further investigation. Only HMMM (hexamethoxymethylmelamine) was present above its PNEC (PNEC = 0.017 μg/L and 0.25 μg/kg in freshwater and sediment respectively) in both matrices. Additionally, 6PPD-quinone (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine quinone) was present in 94 % of sediment samples. The presence of pollutants at potentially harmful levels highlights the need to future work to establish mitigation strategies to reduce the risk posed to the wider environment as well as best practises for management and maintenance of SuDS.

Author dc:creator

• McKenzie, Katie

Advisor dc:contributor.advisor

• B. Petrie

• Microplastics
• Tyre and road wear particles (TRWPs)
• Tyre additives
• Sustainable urban drainage systems (SuDS)
• 6PPD-quinone
• Hexamethoxymethylmelamine (HMMM)

Language dc:language

en

Identifier

oai:rgu-repository.worktribe.com:3475690
https://doi.org/10.48526/rgu-wt-3475690

OAI identifier oai:identifier

oai:rgu-repository.worktribe.com:3475690