First evidence of microplastics in the Quilca-Vítor-Chili river basin, Arequipa region, Peru.

The Chili, Vitor and Quilca rivers and their tributaries in Peru serve as a vital water resource for both irrigation and domestic use in the surrounding communities and agricultural areas. The purpose of this study was to establish, for the first time, the presence, abundance, distribution and chemical identity of polymer microparticles in aqueous samples from these river basins. The results showed that, on average, filaments were the most dominant (71.4 %), followed by fragments (17.2 %) and film (6.74 %). Identification of the polymer types revealed that the most abundant type of MPs is polyethylene (40.8 %), followed by polypropylene (23.8 %), synthetic fibres (15.8 %), and other synthetic polymers. All samples showed the occurrence of microplastics, with a mean concentration of 35.34 MPs/m³, a maximum value of 172.70 MPs/m³ and a minimum value of 3.59 MPs/m³. The results reported in this study establish a baseline for the study area for the first time; in addition, the areas were established with a Pollution Indicator, and the Pollutant Load Index (PLI) was calculated, which reinforced the proposed identification, alerting the need to control clandestine urban and rural landfills, as well as the indiscriminate use of PE big bags in the agricultural catchment.