Drought Alleviates the Negative Effects of Microplastics on Soil Micro-Food Web Complexity and Stability

Soil ecosystems are under considerable pressure due to anthropogenic factors, including microplastics (MPs) pollution and drought. However, little is known about the interactive effects of MPs and drought on soil organisms, especially soil micro-food web. We conducted a microcosm experiment with MPs pollution (including two types and two sizes of MPs) and drought to investigate their interaction effects on soil microbial, protist, and nematode communities in soil micro-food web. We found that MPs significantly decreased the complexity and stability of soil micro-food web, with greater negative effects of biodegradable and smaller-sized MPs than conventional and larger-sized MPs. Drought had negative effects on soil micro-food web in the non-MPs pollution soils while increasing the complexity and stability of soil micro-food web in the MPs pollution soils. Drought increased the proportion of negative correlations between bacteria and fungi in the biodegradable MPs soils while decreasing the proportion of negative correlations between protists and nematodes in the smaller-sized MPs soils. Our study reveals that drought may alleviate the negative effects of MPs on soil micro-food web by reducing competition among lower trophic levels in the biodegradable MPs pollution soils while reducing competition among higher trophic levels in the smaller-sized MPs pollution soils.

[Microplastics pollution in the Yellow River basin: current status and control strategy]

Microplastics pollution has attracted worldwide attention. Compared with the status quo of microplastics pollution in marine environment and other major rivers and lakes, the relevant data of the Yellow River basin is relatively inadequate. The abundance, types, and spatial distribution characteristics of microplastic pollution in the sediments and surface water of the Yellow River basin were reviewed. Meanwhile, the status of microplastic pollution in the national central city and Yellow River Delta wetland was discussed, and the corresponding prevention and control measures were put forward. The results showed that the spatial distribution of microplastics pollution in sediments and surface water of the Yellow River basin increased from upstream to downstream, especially in the Yellow River Delta wetland. There are obvious differences between the types of microplastics in sediment and surface water in the Yellow River basin, which is mainly related to the materials of microplastics. Compared with similar regions in China, the microplastics pollution levels in national key cities and national wetland parks in the Yellow River basin are in the medium to high degree, which should be taken seriously. Plastics exposure through various ways will cause serious impact on aquaculture and human health in the Yellow River beach area. To control microplastic pollution in the Yellow River basin, it is necessary to improve the relevant production standards, laws and regulations, and improve the capacity of biodegradable microplastics and the degradation capacity of plastic wastes.

Microplastics in the sediment of Lake Ulansuhai of Yellow River Basin, China

As an emerging organic pollutant, microplastics in the ocean have been the subject of much study. However, there is a lack of research on freshwater environments, notably in sediment, China. Microplastics contamination in sediment of Lake Ulansuhai has been investigated in the study, and its concentration range was from 24 ± 7 to 14 ± 3 n/kg. Further, it exhibited a difference in spatial distribution with high content in the north zone of the lake far from the entrance of the drainage canal and it has a decreasing tendency with the flow from north to south in lake. Colored plastic particles acted as the dominated pollution type, and more than 79.69% of microplastics were smaller than 2 mm in size, existed as the form of fibers. FTIR results mirrored that the main types of microplastics were polyethylene, polyethylene terephthalate, polypropylene, and polyvinyl chloride. Results obtained from SEM/EDS showed that there were cracks, holes, and irregular curls on the surface of it, and these microplastics may provide attachment sites for other pollutants. The appearance of metallic elements such as Al, Ni, and Fe showed that microplastics and other pollutants in Lake Ulansuhai have a combined effect, which may aggravate the degree of pollution in the lake. PRACTITIONER POINTS: Microplastics were found in the sediment of Lake Ulansuhai with a spatial distribution characteristic. Abundance and morphological characteristics such as shape, color, and size have been analyzed in the paper. Polyethylene, polyethylene terephthalate, polypropylene, and polyvinyl chloride were the main types of microplastics in the sediment detected by FTIR. There were metallic elements combined on the surface of microplastics increased risk of combined pollution.