Microplastics in soil are stunting growth of earthworms, key players in healthy soil and ecosystems

Oceans aren't the only ecosystem facing the threat of microplastic pollution. In a first-of-its-kind study of the impact of microplastics on endogeic worms that live in topsoil, researchers have found tiny particles of plastic akin to those bags and bottles are made of in topsoil, and it appears to be causing earthworms to grow abnormally.The report, published in Environmental Science and Technology, found that these effects on earthworms have serious implications for the health of soil itself.The study found that earthworms living in an environment with high-density polyethylene (HDPE), the polymer used widely in plastic bottles and bags, lost about 3.1 percent of their body weight on average. Earthworms living in topsoil without microplastics, on the other hand, grew 5.1 percent heavier in the same period of time. Soil with a high concentration of microplastics also had lower soil pH (i.e, the soil was more acidic). While researchers have association this weight loss with microplastics, they're yet to understand the specific reasons for it.[caption id="attachment_4452689" align="alignnone" width="1280"]

Earthworms consume and convert organic material into fertilizer in a process called vermiculture. Reuters[/caption]"It may be that the response mechanisms to microplastics may be comparable in earthworms to that of the aquatic lugworms, which have been previously studied. These effects include the obstruction and irritation of the digestive tract, limiting the absorption of nutrients and reducing growth," lead author of the study, Bas Boots from the Anglia Ruskin University, said in a statement. Earthworms, often referred to as the "engineers of the ecosystem", improve soil structure by burrowing, and help drain nutrients and water from the surface. This could impact the ecosystem in a big way, according to one of the study's researchers."It’s therefore highly likely that any pollution that impacts the health of soil fauna, such as earthworms, may have cascading effects on other aspects of the soil ecosystem, such as plant growth," Boots said.