Singh Jaswant, Yadav Brijesh Kumar
Department of Hydrology, Indian Institute of Technology Roorkee, Roorkee, 247667, Uttarakhand, India.
Environ Monit Assess. 2025 Jul 24;197(8):947. doi: 10.1007/s10661-025-14416-5.
Microplastic (MP) contamination is an emerging environmental concern due to its potential impacts on soil health, hydrological processes, and aquatic ecosystems, yet its transport mechanisms across different land use types under seasonal variability remain insufficiently understood. This study systematically investigates the vertical transport, seasonal variability, and environmental risks of MPs across five land use types: riverbanks, dumpsites, agricultural, residential, and woodlands. Field sampling was conducted during pre-monsoon and post-monsoon seasons, with soil and sediment collected from five depth intervals (0-20, 20-40, 40-60, 60-80, and 80-100 cm). MP concentrations varied significantly across land uses, with dumpsites exhibiting the highest in the surface layer (39,113 ± 4750 particles/kg pre-monsoon, 35,920 ± 6294 particles/kg post-monsoon), while woodlands retained the lowest (530 ± 101 particles/kg pre-monsoon, 703 ± 199 particles/kg post-monsoon). Smaller MPs (< 0.3 mm) showed greater vertical transport, especially post-monsoon. Fragments dominated all land uses (45% in deeper riverbank soils), with fibers enriched at the surface (up to 30%). Transparent and white MPs were the most common (up to 34%) with color heterogeneity (black, blue, red) peaking in dumpsites. Low-density polymers such as polyethylene (PE) and polypropylene (PP) dominated deeper layers (up to 60% in woodland), while high-density polymers remained surface bound. Risk indices identified dumpsites as critical hotspots: Pollution load index (PLI) rose from 30.7 to 33.7, and potential ecological risk index (PERI) exceeded 4400 in both seasons. These findings underscore the critical role of land use and seasonal hydrological variability in MP transport, highlighting potential threats to ecosystems.
微塑料（MP）污染因其对土壤健康、水文过程和水生生态系统的潜在影响，正成为一个新出现的环境问题，然而，在季节变化下其在不同土地利用类型间的传输机制仍未得到充分了解。本研究系统调查了微塑料在河岸、垃圾场、农业用地、住宅用地和林地这五种土地利用类型中的垂直传输、季节变化及环境风险。在季风来临前和季风过后季节进行了实地采样，从五个深度区间（0 - 20厘米、20 - 40厘米、40 - 60厘米、60 - 80厘米和80 - 100厘米）采集土壤和沉积物。微塑料浓度在不同土地利用类型间差异显著，垃圾场表层微塑料浓度最高（季风来临前为39,113 ± 4750颗粒/千克，季风过后为35,920 ± 6294颗粒/千克），而林地微塑料浓度最低（季风来临前为530 ± 101颗粒/千克，季风过后为703 ± 199颗粒/千克）。较小的微塑料（< 0.3毫米）显示出更大的垂直传输，尤其是在季风过后。碎片在所有土地利用类型中占主导（在较深的河岸土壤中占45%），纤维在表层富集（高达30%）。透明和白色微塑料最为常见（高达34%），颜色异质性（黑色、蓝色、红色）在垃圾场达到峰值。低密度聚合物如聚乙烯（PE）和聚丙烯（PP）在较深层占主导（在林地中高达60%），而高密度聚合物则集中在表层。风险指数将垃圾场确定为关键热点：污染负荷指数（PLI）从30.7升至33.7，潜在生态风险指数（PERI）在两个季节均超过4400。这些发现强调了土地利用和季节性水文变化在微塑料传输中的关键作用，突出了对生态系统的潜在威胁。
