Characteristics of microplastics in tributaries of the upper Brahmaputra River along the Himalayan foothills, India

Abstract

Microplastic (MP) pollution is a global concern, yet its presence in riverine environments has received limited research attention. This study aimed to evaluate MP levels and identify their potential sources in river surface water and nearby soil samples from two rural and remote rivers near the Jaldapara National Park in the foothills of Eastern Himalaya of India. The average MP levels in water and soil samples were 0.14±0.11 pieces/m3 and 633.33±124.72 pieces/kg d.w. respectively. The primary types of microplastics detected were fibres, followed by fragments, and films. MP sizes in water was larger than in soil samples. Blue, black, and red MPs were most abundant. Micro-Raman analysis revealed polyethylene was the dominant polymer type, followed by nylon, and polypropylene. Comparatively, pollution levels in the study area were relatively low when compared to other rivers worldwide. Understanding the sources and characteristics of microplastics is vital in formulating effective mitigation strategies and promoting responsible waste management practices. These findings provide valuable insights for policymakers, environmentalists, and local communities to implement measures that curb plastic waste and safeguard vulnerable riverine ecosystems from the adverse impacts of MP pollution.