Response of soil biochemical properties and ecosystem function to microplastics pollution

Area of Science:

• Environmental Science
• Soil Science
• Ecotoxicology

Background:

• Microplastic contamination is a growing concern in terrestrial ecosystems.
• Understanding microplastic impacts on soil nutrient cycling and microbial activity is crucial for soil health assessment.

Purpose of the Study:

• To investigate the effects of polyethylene microplastics (PE MPs) of different sizes and concentrations on soil biochemical properties and ecosystem function.
• To identify key indicators of soil ecosystem function affected by microplastic pollution.

Main Methods:

• Exposure of soil to PE MPs (13 μm and 130 μm) at varying concentrations (0-10% w/w).
• Measurement of soil respiration rate, enzyme activities (urease, β-glucosidase, catalase), pH, and nutrient content (available phosphorus, dissolved reactive phosphorus, dissolved organic carbon, available potassium, total dissolved nitrogen).

Main Results:

• 13 μm MPs reduced soil respiration, β-glucosidase, and catalase activity, while increasing urease activity and decreasing pH, available phosphorus, dissolved reactive phosphorus, dissolved organic carbon, and available potassium.
• 130 μm MPs had minimal effects on dissolved organic carbon and dissolved reactive phosphorus but reduced pH, total dissolved nitrogen, available phosphorus, and available potassium at high concentrations, while increasing soil respiration.
• Soil ecosystem function was significantly reduced by MPs, with respiration rate, available phosphorus, dissolved reactive phosphorus, and β-glucosidase activity being key predictors.

Conclusions:

• Microplastic pollution poses a significant risk to soil ecosystem function, altering nutrient cycling and microbial activity.
• The impact of microplastics on soil health is dependent on both particle size and concentration (dose-dependent and size-dependent).
• Further research is needed to understand the long-term behavior and consequences of microplastics in agroecosystems.