Year: 2025
Type: article
Abstract: Microplastic contamination of freshwater river systems represents a rapidly growing environmental concern, yet the mechanisms governing the spatial transport and temporal fate of these particles from upstream to downstream river reaches remain poorly resolved. This research presents a quantitative analysis of microplastic abundance, polymer composition, and morphological character at three sites (upstream, midstream, downstream) along a 94 km reach of a river in Shaanxi Province, China, sampled seasonally from March 2022 to December 2023 at Silk Road University, Xi'an, and Yellow Mountain College of Sciences, Hefei. Surface water samples were collected using 330 μm stainless steel trawl nets and analysed by stereomicroscopy and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). Microplastic concentrations ranged from 196.4 items/m³ at the upstream site to 558.8 items/m³ at the downstream site, a 2.85-fold longitudinal increase. Polyethylene terephthalate (PET), polyethylene (PE), and polypropylene (PP) were the three most abundant polymer types, collectively comprising 64.8% of all identified particles. Fibres were the most prevalent morphological type (53.4%), consistent with textile-derived inputs. Seasonal variation showed peak microplastic concentrations in summer (June-August), attributed to increased agricultural irrigation return flows and higher recreational human activity in riparian zones. A multi-parameter radar analysis confirmed that all assessed microplastic characteristics intensified from upstream to downstream, with downstream microplastics also showing higher surface adsorption indices, raising concerns about co-transport of adsorbed hydrophobic organic contaminants.Microplastic contamination of freshwater river systems represents a rapidly growing environmental concern, yet the mechanisms governing the spatial transport and temporal fate of these particles from upstream to downstream river reaches remain poorly resolved. This research presents a quantitative analysis of microplastic abundance, polymer composition, and morphological character at three sites (upstream, midstream, downstream) along a 94 km reach of a river in Shaanxi Province, China, sampled seasonally from March 2022 to December 2023 at Silk Road University, Xi'an, and Yellow Mountain College of Sciences, Hefei. Surface water samples were collected using 330 μm stainless steel trawl nets and analysed by stereomicroscopy and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). Microplastic concentrations ranged from 196.4 items/m³ at the upstream site to 558.8 items/m³ at the downstream site, a 2.85-fold longitudinal increase. Polyethylene terephthalate (PET), polyethylene (PE), and polypropylene (PP) were the three most abundant polymer types, collectively comprising 64.8% of all identified particles. Fibres were the most prevalent morphological type (53.4%), consistent with textile-derived inputs. Seasonal variation showed peak microplastic concentrations in summer (June-August), attributed to increased agricultural irrigation return flows and higher recreational human activity in riparian zones. A multi-parameter radar analysis confirmed that all assessed microplastic characteristics intensified from upstream to downstream, with downstream microplastics also showing higher surface adsorption indices, raising concerns about co-transport of adsorbed hydrophobic organic contaminants.
Authors: Feng Yang, Hao Wang, Hui Deng, Xia Liu
Language: English
Subfield: Pollution
Field: Environmental Science
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W7154337307