Quantification and Identification of Microplastics in Irrigation Water Systems: Ecological Risks and Mitigation Strategies
摘要
Microplastics (MPs) are an emerging pollutant in agricultural irrigation systems, particularly in densely populated regions with intensive land use. This study investigated the distribution, characteristics, and ecological risks of MPs across seven sampling sites within a rural irrigation network. MPs concentrations ranged from 3.1 to 64.3 particles/L, with the highest levels observed at sites receiving domestic runoff and urban channel inputs. Fibers (44%) and films (39%) were the dominant shapes, primarily composed of polyethylene terephthalate (PET), polypropylene (PP), and polystyrene (PS), with particle sizes ranging from 0.5 to 1 mm to > 1.5 mm. Ecological risk assessments using the Polymer Hazard Index (PHI) and Pollution Load Index (PLI) classified several sites, particularly WS3, as moderately to highly contaminated. A strong positive correlation (r = 0.89, p < 0.01) was observed between population density and MPs concentration, highlighting the influence of anthropogenic pressures. To address these risks, the study proposes mitigation strategies based on site-specific conditions, including the implementation of localized waste management improvements, reduction of single-use plastics, regular monitoring of irrigation channels, and public education initiatives. These findings offer a baseline for developing integrated environmental management frameworks and inform policymakers of the urgent need to incorporate MPs pollution control into rural water and agricultural planning.