A microplastic used as infill material in artificial sport turfs reduces plant growth

Abstract

Societal Impact Statement Plastic pollution is of increasing societal concern, particularly with regard to aquatic environments, where it has received widespread news media attention. However, plastic and plastic byproducts also pollute terrestrial ecosystems, and the potential impacts on organisms are currently poorly understood. Here, we show that a microplastic type used in artificial sport turfs may have negative effects on plant growth. Given the scale of plastic pollution, urgent research is needed to determine the impact of microplastics on terrestrial organisms and their communities, as well as an exploration of alternative, biodegradable materials and measures to reduce the spread of microplastics in nature. Summary The Anthropocene is, among other factors, characterized by the accumulation of plastic in the environment. While studies on the consequences of plastic pollution for animals, particularly in aquatic environments, have increased in recent years, much less is known about potential effects of plastic pollution on plants in terrestrial environments. Ethylene propylene diene monomer (EPDM) is a microplastic used in artificial sport turfs. Here, we tested in two separate experiments the effects of different concentrations of EPDM on the performance of Plantago lanceolata and on competition between seven grassland‐plant species. At very low concentrations of the EPDM granules, growth of P. lanceolata was slightly improved, but at concentrations of 5% and higher there were strong negative effects on survival and growth. These negative effects were found under low and high nutrient conditions, and for all tested species. The EPDM granules also negatively affected the root weight ratio, which indicates that the root system was more strongly affected than the shoot. Due to the strong negative effects on plant growth, the granules also reduced the competitive interactions between plants. Our study shows that it is not only animals in aquatic environments that may be affected by plastic pollution, and that this may also be the case for wild plants in terrestrial ecosystems.

Microplastic Shape, Polymer Type, and Concentration Affect Soil Properties and Plant Biomass

“…Microplastic effects on plant performance and soil properties will not only depend on the shape, polymer type, and concentration levels, but also on the plant species identity and soil type. For instance, contrary to our results, Qi et al (2018) found that polyethylene films did not affect biomass of a wheat crop, van Kleunen et al (2019) found a negative effect of microplastics on plant biomass, while Lozano and Rillig (2020) found that PES fibers may increase biomass of some plant species while decreasing that of others in a grassland community. Likewise, contrary to our results, microfibers may rather promote soil aggregation at the plant community level ( Lozano et al, 2020 ).…”

“…Our knowledge about microplastic effects on terrestrial systems is still scarce and effects reported for plants and soil often seem contradictory, as effects may differ depending on microplastic shape, polymer structure, degradation, additives, and concentration, as well as on the target plant or soil. For instance, microplastic granules of ethylene propylene at 5% may decrease plant biomass likely linked to its polymer composition ( van Kleunen et al, 2019 ), while polyester (PES) fibers at 0.4% may have the opposite effect as microfibers can enhance soil water content and soil aeration ( de Souza Machado et al, 2019 ). PES fibers can also increase soil aggregation as they may help to entangle soil particles ( de Souza Machado et al, 2019 ; Lozano et al, 2020 ), while opposite effects are detectable for, e.g., polyamide (PA) fibers ( de Souza Machado et al, 2019 ).…”

Microplastic effects on carbon cycling processes in soils

“…In addition, key plant symbionts, such as root-colonizing mycorrhizal fungi, might be affected by MPs or their effects on soil physicochemical properties. In some cases, resulting effects of MP on plant growth have been positive [ 20 , 21 ], but there are also reports of negative effects [ 22 ]. Such differences are explained by the fact that different MPs (including their chemical additives, some of which might be toxic), soils, and plants were used in these different studies, but it is not clear how each of these factors contributed to observed effects.…”

Tire abrasion particles negatively affect plant growth even at low concentrations and alter soil biogeochemical cycling

“…Microplastics often have positive effects on plant performance (de Souza Machado et al, 2018;Lehmann et al, 2020), but also negative effects can occur (Qi et al, 2018;van Kleunen et al, 2020). Tire particles have been tested in past studies for their suitability as potting substrate for plants.…”