Community Analysis Boosts Microplastics Research on Land Use Impact Studies

As a class of emerging pollutants, microplastics are that have received much attention in recent years owing to their persistence in the environment and potential toxic effects on organisms. They have been detected almost everywhere on Earth, including the pedosphere, hydrosphere, atmosphere, biosphere, and even cryosphere.    

Microplastics with various shapes, sizes, colors and polymer types can migrate between different media in the aqueous environment, which gives a high degree of similarity between microplastics and planktonic communities. Therefore, several researchers have proposed the concept of “microplastic community” to study the pollution characteristics and spatial variation of microplastics in the environment by applying the research methods in community ecology. However, microplastic community is mostly applied at larger spatial scales, such as basin-wide or even nationwide, and there is a lack of comparison of the effectiveness of this concept at different spatial scales and geographical areas.   

Recently, a research group led by Prof. WU Chenxi from the Institute of Hydrobiology (IHB) of the Chinese Academy of Sciences applied the methodology of the “microplastic community” study to the medium spatial scale region (Hubei Province), and demonstrated the spatial pattern and influencing factors of microplastic pollution in the region. This study was published in Science of the Total Environment.      

In this study, the researchers investigated microplastics in the surface water of 20 water bodies in Hubei Province and a total of 136 sampling sites were set up. Microplastics were detected in all samples and the average abundance of microplastics in the water bodies of 20 rivers and lakes was 1.74 items/L, which indicated that microplastic pollution is widespread in Hubei Province. Meanwhile, the negative correlation between the abundance of microplastics and the distance of sampling sites from residential areas indicated the influence of anthropogenic activity matters.   

To further understand the influence of anthropogenic activity on microplastic pollution, we extracted land use data to be used as an indicator of anthropogenic activity and used microplastic community analysis to accommodate multidimensional data for analysis. The results showed that microplastic community composition did not differ significantly between water types, but significant differences emerged when the sample sites were divided by geographical region into mountain and plain. Moreover, the researchers identified several land use types significantly associated with microplastic community composition through db-RDA and correlation analysis.   

As mentioned above, several previous studies in large spatial scales have reported the similarity of microplastic communities decreases significantly with increasing distance between sample sites. However, in this study the researchers only observed a very weak correlation. Together with the land use data, the researchers calculated “land use distance” and found a stronger correlation than geographical distance.   

The above findings suggest that at moderate spatial scales, source differences due to different land use types may have a greater impact on microplastic pollution characteristics relative to spatial distance. The concept of “microplastic community” can be a helpful complementary tool for quantitatively assessing differences in the sources of microplastics in different regions. The comparison with previous studies also revealed the importance of regional and spatial scales in the analysis of microplastic community. 

(Editor: MA Yun)