Abstract
While much is known about microplastics in aquatic environments, only few studies have focused on how microplastics interact with terrestrial organisms. The objective of our study was to investigate the interactions of earthworms with microplastics in a natural environment with environmentally realistic plastic concentrations. We investigated whether earthworms would ingest microplastics and incorporate them into their bodies and cast, and whether microplastics would alter the intestinal and soil microbiome. Lumbricus terrestris was exposed to two types of microplastics, biodegradable polybutylene adipate terephthalate (PBAT) and low-density polyethylene (LDPE) in mesocosoms filled with natural soil. Microplastics were mixed with poplar leaves, and earthworms were allowed to forage for food for 20 days. Surface and bulk soil, earthworm’s cast, and earthworms themselves were sampled and analyzed for plastic content and microbial communities. Earthworms did not show macroscopic health deterioration (weight loss, vitality). We observed microplastics particles in earthworm casts and guts. Raman spectroscopy indicated that PBAT in guts and cast had degraded to some extent; however, LDPE remained unchanged among the different samples. Microbial analysis showed that soil and casts has similar microbial communities; however, they were significantly different from the gut samples. Microplastic treatments did not result in a statistically significant change in bacterial richness, diversity, or community composition for soil, casts, or guts compared to controls. Taken together, our results suggest that, at environmentally realistic concentrations and short exposure times, PBAT and LDPE microplastics do not have adverse effects on Lumbricus terrestris earthworms.
| Original language | English |
|---|---|
| Pages (from-to) | 340-349 |
| Number of pages | 10 |
| Journal | ACS Agricultural Science and Technology |
| Volume | 3 |
| Issue number | 4 |
| DOIs | |
| State | Published - Apr 17 2023 |
| Externally published | Yes |
Funding
This work was supported by Bioenergy Energy, Natural Resources, and Environment grant 2020-67019-31167/1022800 from the USDA National Institute of Food and Agriculture. Funding was further provided by USDA/NIFA through Hatch project 1014527 and W4188 Multi-State Project. A portion of this research was performed on a project award (10.46936/expl.proj.2020.51632/60000231) from the Environmental Molecular Sciences Laboratory, a DOE Office of Science User Facility sponsored by the Biological and Environmental Research program under Contract No. DE-AC05-76RL01830. The authors thank Patrick El-Khoury for access to his facility to perform a portion of the Raman measurements. The authors thank the WSU Franceschi Microscopy and Imaging Center for access to their facility and Valerie Lynch-Holm for help with the use of the electron microscope.
Keywords
- Lumbricus terrestris
- biodegradable plastics
- earthworms
- microbial communities
- microplastics
- polyethylene