Microplastic pollution in mountain terrains and foothills: A review on source, extraction, and distribution of microplastics in remote areas

Microplastic (MP) pollution is a critical environmental concern that exists within different mountain ecosystem compartments. This review paper highlights the source, sampling, distribution, and behavior of MPs in mountain terrains and foothills. Atmospheric transport and tourism are major sources of MP pollution in mountain ecosystems. Snow samples provide the maximum concentration of MPs compared to that of stream or ice core samples. Precipitation events considerably influence MP deposition and fallout in mountains and glaciers. PE, PP, PS, polyester, and PVC are common plastic polymers with diverse shapes, such as fibers, fragments, films, and pellets. Ecological concerns and stress due to MP accumulated in natural ecosystems have also been discussed, with considerable focus on MP transport and distribution dynamics at higher altitudes as prospects for future research. A remarkable knowledge gap was observed regarding the MP pathways in the mountainous ecosystems and the assessment of microplastic-associated additives, such as heavy metals and other toxic chemicals, including the evidence of nano-sized plastics. Furthermore, studies on the ecological and biological risks posed by MPs on remote mountains is severely limited with respect to global climate change, biodiversity loss, and influence on ecosystem services.