Sublethal effects of microplastics sourced from polypropylene agricultural plastics on four soil invertebrate species

The increasing use of agricultural plastics (APs) and resulting accumulation of microplastics (MPs) in soils potentially affects soil organisms. This study assessed the effects of polypropylene MPs derived from commonly used black ribbon and white fleece mulching fabrics on four soil invertebrates. Animals were exposed to MP concentrations of 0.005 % - 5 % in Lufa 2.2 soil to assess effects on survival, reproduction (Enchytraeus crypticus, Folsomia candida) and behavior (Eisenia andrei, Porcellio scaber). Both MP types dose-relatedly decreased soil bulk density, and increased soil water holding capacity at high concentrations. The MPs from white fleece mulching fabric also increased soil pH at all concentrations tested. Reproduction was affected more by MPs from black ribbon fabric than from white fleece mulching fabric, significantly affecting enchytraeids at 1 % and 5 %, and at 5 %, respectively, and springtails only at 5 % for the black ribbon fabric MPs. Earthworms avoided soil at 5 % of the first or 0.5 % and 5 % of the second MP type. Isopods seemed attracted, but also showed different walking behavior at 5 % of black ribbon fabric MPs. MPs derived from commonly used APs were shown to affect soil properties at low concentrations and the reproduction and behavior of soil invertebrates.