Abstract
Microplastics are a diverse and ubiquitous contaminant, a global change driver with potential to alter ecosystem properties and processes. Microplastic-induced effects in soils are manifold as microplastics differ in a variety of properties among which the shape is of special interest. Our knowledge is limited regarding the impact of various microplastic shapes on soil processes. Therefore, we conducted this two-part research comprising a meta-analysis on published literature and a lab experiment focusing on microplastic shapes- and polymer-induced effects on soil aggregation and organic matter decomposition. We here focus on fibers, films, foams and particles as microplastic shapes.In the meta-analysis, we found a strong research focus on fibrous and particulate microplastic materials, with films and foams neglected.Our experiment showed that microplastic shapes are important modulators of responses in soil aggregation and organic matter decomposition. Fibers, irrespective of their chemistry, negatively affected the formation of aggregates. However, for other shapes like foams and particles, the polymer identity is an important factor co-modulating the soil responses.Further research is needed to generate a data-driven foundation to permit a better mechanistic understanding of the importance and consequences of microplastics added to soils.
Highlights
Microplastics are proposed as a new global change driver with increasingly realized impacts on marine, aquatic and terrestrial systems [1,2,3,4,5]
Meta-analysis Our meta-analysis provides a quantitative summary of the impact of microplastic soil contamination on the ecosystem processes soil aggregate formation, stabilization and organic matter loss (Fig. 2)
Our meta-analysis revealed that polyester microfibers are the most often tested plastic materials in experiments focusing on soil responses to microplastic contamination
Summary
Microplastics are proposed as a new global change driver with increasingly realized impacts on marine, aquatic and terrestrial systems [1,2,3,4,5]. Microplasticinduced effects on ecosystem functions and processes are starting to be revealed, as research shifts from a more ecotoxicological focus to more fully embrace an ecosystem perspective [5, 6]. Microplastics are not a monolithic issue and neither are the effects they induce. Microplastics are a group of synthetic polymers encompassing a wide diversity in sizes, shapes, chemical composition and additives [7, 8]. They are either produced as primary microplastics or secondarily via degradation in the environment to fragments < 5 mm. Plastic particles are exposed to weathering and degradation in the environment causing further fragmentation and leaching of additives [9,10,11]
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