Polystyrene size-dependent impacts on microbial decomposers and nutrient cycling in streams

Area of Science:

• Environmental Science
• Ecotoxicology
• Microbiology

Background:

• Plastic particle size is a key factor in ecotoxicity.
• The impact of polystyrene (PS) particle size on microbial decomposers and nutrient cycling in streams remains unclear.

Purpose of the Study:

• To assess the influence of three PS sizes (50 nm, 1 μm, and 20 μm) on leaf litter decomposition and nutrient cycling in streams using microcosm experiments.
• To investigate the effects of acute and chronic PS exposure on microbial communities and decomposition processes.

Main Methods:

• Microcosm experiments were conducted to evaluate the effects of different polystyrene particle sizes (50 nm, 1 μm, 20 μm) on leaf litter decomposition.
• Measurements included fungal and microbial biomass, enzyme activity, fungal diversity, and nutrient regeneration (phosphorus).

Main Results:

• Acute exposure to 1 μm and 20 μm PS decreased fungal biomass but increased overall microbial biomass.
• Chronic exposure to 50 nm and 1 μm PS reduced leaf decomposition rates by 19.27% and 15.22%, respectively.
• Reduced microbial enzyme activity, fungal diversity, and dominance of Anguillospora were observed, leading to depressed nutrient regeneration, particularly phosphorus.

Conclusions:

• Nanoscale polystyrene particles have a more significant impact on microbial activity and freshwater ecosystem functioning, specifically leaf litter decomposition and nutrient cycling.
• These findings support the risk assessment of plastic pollution in freshwater systems and highlight the potential impact on primary productivity.