Microplastic characteristic in the soil across the Tibetan Plateau.

Microplastics are widely detected in terrestrial environments. However, microplastic features in the soil of remote areas are still sparse. In this study, microplastic pollution in soil across the Tibetan Plateau was systematically investigated. The results revealed that microplastic was ubiquitous in the soil of the Tibetan Plateau with an average abundance of 47.12 items/kg-dry weight (range: 5-340 items/kg). Compared with the published data of soil microplastic pollution in other regions, the microplastic pollution in the Tibetan Plateau was relatively low. Fibers represented 43.54% of microplastic particles detected, followed by fragments (32.20%) and films (23.78%). They mainly consisted of polyvinyl chloride, polyethylene, polypropylene, and polystyrene. Transparent and white microplastics were prevalent, and small microplastics (50-500 µm) occupied approximately 66% of all microplastics. High values of microplastics were found near Lhasa, Naqu, and Linzhi. Furthermore, microplastic pollution was found to be negatively related to the distance to the nearest city (p < 0.01), wind velocity (p = 0.014), altitude (p = 0.181), yet positively related to precipitation (p = 0.024). This work presents new insights into the magnitude of microplastics contamination in the soil across the Tibetan Plateau and supplies valuable data for future research on ecotoxicology, ecosystem impacts, and earth system feedback of microplastics on terrestrial ecosystems.

Research progresses of microplastic pollution in freshwater systems.

Microplastics (MPs) have received widespread attention as an emerging environmental pollutant. They are ubiquitous in the freshwater system, causing a global environmental issue. The current features and perspectives of MPs in the freshwater systems can provide the concerns of their ecological effects, which has not been addressed widely. Therefore, in this study, we reviewed the characteristics of MPs in freshwater environments and discussed their sources and potential impacts. The abundance of MPs in freshwater system ranged from approximately 3-6 orders of magnitude in different regions. There colors were mainly white and transparent, with polypropylene (PP) and polyethylene (PE) as the major polymers. The main shape of these MPs was fibers with dominant size of less than 1 mm. Analysis indicated MPs in freshwater system mostly originated from human activities such as sewage discharge in highly contaminated areas, while atmospheric long-distance transport and precipitation deposition played an important role in remote areas. Freshwater MPs pollutants also affected drinking water and aquatic organisms. Because the abundance of MPs in organisms was relatively balanced, the pollution level of biological MP pollution cannot accurately characterize the pollution status in the watershed currently. Future research should focus and strengthen on periodic monitoring to characterize the temporal and spatial changes of MPs, and enhance toxicological research to explore MPs pollution impact on biota and humans.