The presence of microplastic and/or cadmium govern the carbon, nitrogen, and phosphorus cycles in sediments

The accumulations of microplastics (MPs) and cadmium (Cd) are ubiquitous in sediments. However, the impact of MPs or Cd on element cycles in sediments, particularly on greenhouse gas (GHG) emissions, has not been systematically reported. Herein, a microcosm experiment was conducted to investigate the responses of sedimentary carbon, nitrogen and phosphorus transformation processes, GHG emissions and microbial communities to MPs, Cd and MPs+Cd . The results indicate the processes such as methanogenesis, methanotrophy, organic carbon degradation, nitration, and denitrification in sediments were significantly affected under MPs or Cd exposure. Consequently, polyethylene and polystyrene MPs significantly increased GHG emissions and global warming potential (GWP). Although Cd significantly impacted GHG emissions, it resulted in no obvious effect on GWP. Notably, the coexistence of MPs and Cd could impact microbial communities in MPs biofilms and promote the expression of gene nosZ, which may ultimately antagonize N2O emissions.