Microplastics in a remote lake basin of the Tibetan Plateau: Impacts of atmospheric transport and glacial melting
Huike Dong
Abstract
Plastic\npollution is fast becoming one of the most pressing global\nissues that we currently face. Remote areas, such as the polar regions\nand the Tibetan Plateau, are now also exposed to microplastic contamination.\nHowever, with the impact of global warming, the transport of microplastics\nwithin the glacier-lake basins in such regions remains unclear. In\nthis work, the Nam Co Basin in the Tibetan Plateau was selected to\nstudy the characteristics of microplastics in the rain fallout, lake\nwater, glacial runoff, and non-glacial runoff. Fiber and films were\nthe most common microplastic morphologies in all water samples; a\nhigher proportion (37%) of light-weighing polypropylene and small-size\n(50–300 μm, ∼30%) microplastics were found in\nthe glacial runoff. Air mass trajectory analysis showed that microplastics\ncould be transported through the atmosphere over a distance of up\nto 800 km. For microplastic loading in lakes, the atmospheric fallout\nwas estimated to be 3.3 tons during the monsoon season, whereas the\ncontributions of glacial runoff (∼41 kg) and non-glacial runoff\n(∼522 kg) were relatively low. For the microplastic loading\nin glaciers, the atmospheric deposition was ∼500 kg/yr, and\nthe output caused by glacial melting only accounted 8% of the total\natmospheric input. All these results suggested that the dominant pathway\nthrough which microplastics enter remote mountainous lake basins is\natmospheric deposition, and once deposited on glaciers, microplastics\nwill be stored for a long time. This work provides quantitative evidence\nelucidating the fate of microplastics in alpine lake environments.