Microplastics from biodegradable mulching films affect soil physicochemical properties and earthworm reproduction, but not microarthropod communities

Applied Soil Ecology, vol. 218, pp. 106703

Abstract

Agricultural mulching films represent a major source of microplastics (MPs; defined as particles 1 μm-5 mm in size) in soils. With a projected exponential increase of the global use of agricultural mulching films, concentrations of MPs in soil are bound to increase. Short-term single species toxicity tests using mulching film-based MPs showed effects on soil invertebrates at high concentrations, up to 5 % ( w /w dry soil), as well as on soil physicochemical properties. This study aimed to provide insight into the long-term effects of mulching film-based MPs by simulating an agricultural growing season in a highly controlled mesocosm system called CLIMECS. Eight replicate constructed cores of Lufa 2.2 soil spiked with 0 % (control), 0.025 %, 0.05 %, 0.2 % or 0.8 % starch-polybutadiene adipate terephthalate MPs received a constant springtail community ( Heteromurus nitidus, Protaphorura fimata and Sinella curviseta ), two species of earthworm ( Aporrectodea caliginosa and Lumbricus rubellus ), cress ( Lepidium sativum ) as vegetation cover, and lettuce ( Lactuca sativa ) as a crop. After 13 weeks incubation, soil pH and smaller soil aggregate fractions were significantly decreased already at the lowest exposure concentration of 0.025 % MPs compared to the control ( p < 0.05 and p < 0.001, respectively). Springtail community composition did not show differences between treatments. Earthworm survival was not affected by the MPs, but total earthworm reproduction was lower at 0.2 % and 0.8 % MPs compared to the 0.05 % treatment. This study showed that MPs derived from biodegradable mulching film plastics may affect soil physicochemical properties and earthworm reproduction at environmentally relevant concentrations. • A mesocosm study was conducted to assess the effects of biodegradable microplastics. • Microplastics were successfully recovered and quantified from the soil after 13 weeks. • Starch-PBAT blend microplastics from mulching films affect soil pH and aggregation. • The tested microplastics did not affect Collembola community composition. • Earthworm survival was not affected, but total reproduction was reduced.

Authors 4

1. Sam van Loon

   Vrije Universiteit Amsterdam

   Affiliation as printed

   Section Ecology and Evolution, Amsterdam Institute for Life and Environment, Vrije Universiteit, Amsterdam, the Netherlands

2. Lotte de Jeu

   Vrije Universiteit Amsterdam

   Affiliation as printed

   Section Ecology and Evolution, Amsterdam Institute for Life and Environment, Vrije Universiteit, Amsterdam, the Netherlands

3. Salla Selonen

   Finnish Environment Institute

   Affiliation as printed

   Finnish Environment Institute, Latokartanonkaari 11, 00790, Helsinki, Finland

4. Cornelis A.M. van Gestel corresponding

   Vrije Universiteit Amsterdam

   Affiliation as printed

   Section Ecology and Evolution, Amsterdam Institute for Life and Environment, Vrije Universiteit, Amsterdam, the Netherlands