Synthetic microfibers and tyre wear particles pollution in aquatic systems: Relevance and mitigation strategies

Evidence shows that the majority of aquatic field microplastics (MPs) could be microfibers (MFs) which can be originated directly from massive sources such as textile production and shedding from garments, agricultural textiles and clothes washing. In addition, wear and tear of tyres (TRWPs) emerges as a stealthy major source of micro and nanoplastics, commonly under-sampled/detected in the field. In order to compile the current knowledge in regards to these two major MPs sources, concentrations of concern in aquatic environments, their distribution, bulk emission rates and water mitigation strategies were systematically reviewed. Most of the aquatic field studies presented MFs values above 50%. MPs concentrations varied from 0.3 to 8925 particles m^-3 in lakes, from 0.69 to 8.7 × 10⁶ particles m^-3 in streams and rivers, from 0.16 to 192000 particles m^-3 estuaries, and from 0 to 4600 particles m^-3 in the ocean. Textiles at every stage of production, use and disposal are the major source of synthetic MFs to water. Laundry estimates showed an averaged release up to 279972 tons year^-1 (high washing frequency) from which 123000 tons would annually flow through untreated effluents to rivers, streams, lakes or directly to the ocean. TRWPs in the aquatic environments showed concentrations up to 179 mg L^-1 (SPM) in runoff river sediments and up to 480 mg g^-1 in highway runoff sediments. Even though average TRWR emission is of 0.95 kg year^-1 per capita (10 nm- 500 μm) there is a general scarcity of information about their aquatic environmental levels probably due to no-availability or inadequate methods of detection. The revision of strategies to mitigate the delivering of MFs and TRWP into water streams illustrated the importance of domestic laundry retention devices, Waste Water Treatment Plants (WWTP) with at least a secondary treatment and stormwater and road-runoff collectors quality improvement devices.