ABUNDANCE OF MICROPLASTICS IN LANDFILLS AND THEIR EFFECTS ON MICROBIAL PROCESSES

Landfilled waste supports heterogeneous biotic and abiotic processes depending on temporal inputs (waste, cover soils), site management, and internal landfill conditions (temperature, pressure, moisture). These differences can affect the typical functionality of landfills. We are focusing on microplastics (MP) in landfill settings, including their abundance at various depths, observed in situ degradation, effects on biogeochemical cycling, and ability to disrupt anaerobic microbial communities, as documented in non-landfill settings. We prepared multiple landfill microcosms (experimental MP and control) in 100 ml bottles incubated in a 45°C water bath for 73 days, and a range of microplastics were added to the experimental microcosms after methanogenesis was established. Over an extended period of time, wet chemistry, microbial diversity, and gas volumes were measured to compare with the control treatment that did not receive additional microplastics. Impacts on community structure were examined through 16S rRNA sequencing. Microscopic images of the embedded microplastics were also taken before and after incubation to assess signs of degradation. In addition, a sediment-microplastic isolation (SMI) unit was built to determine the abundance of microplastic in samples from a Southeastern US landfill. Geochemical results of the first set of microcosms indicated an impact on the speciation of iron, while minimal difference was observed in sulfide concentrations. Moreover, analysis of community structure over the course of the experiment showed a shift in microbial populations. While plastic is one form of waste, it continues to be generated at an astounding rate, and understanding the impact microplastics have on landfill ecosystems (microbial processes) will help us better manage current and future landfills.