Microplastic, a possible trigger of landfill sulfate reduction process.

The environmental impact of microplastics (MPs) formed from landfill has not been gained enough attention. This research investigated the characteristics of the MPs occurrence in landfills through field sampling. It shows that the MPs abundance in the landfill surface soil and non-landfill areas can reach 3573 items·g and 3041 items·g, respectively. The vertical abundance of MPs increases significantly with depth, ranging from 387 to 11,599 items·g with small size (≤10 μm, 65.61 %) and flake or wedge shape (38.48 %). The leachate movement in a longitudinal direction enables MPs to accumulate more easily in the landfill bottom layer with high moisture abundance. The abundance of MPs are significantly correlated with SO and S content, the two typical metabolic substrate and product of sulfate reduction process. In such heterogeneous environment, this significant correlation is not a random phenomenon in terms of the MPs have known substantial impact on biogeochemical processes. Microplastic is a possible trigger of landfill odor emission related with sulfate reduction. This research could serve as a reference for MPs and odor pollution management in landfills.