Dose Effect of Polyethylene Microplastics Derived from Commercial Resins on Soil Properties, Bacterial Communities, and Enzymatic Activity

Lesbia Gicel Cruz ¹, Fo-Ting Shen ^2,3, Chiou-Pin Chen ⁴

⁰International Master Program in Agriculture, National Chung Hsing University, Taichung 40227, Taiwan.

Microorganisms +

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September 28, 2024

View abstract on PubMed

Summary

Even low concentrations of polyethylene microplastics (MPs) alter soil chemistry and microbial communities. High MP concentrations significantly impact soil pH and phosphate availability, affecting functional soil microbes.

Area Of Science

Environmental Science
Soil Science
Microbiology

Background

Soils act as the largest terrestrial reservoir for microplastics (MPs).
The long persistence of MPs in soils amplifies their potential environmental effects.
Understanding MP impacts on soil health is crucial for ecosystem management.

Purpose Of The Study

To investigate the effects of varying polyethylene (PE) microplastic concentrations on soil chemical properties, enzyme activities, and bacterial communities.
To assess the dose-dependent responses of soil ecosystems to PE microplastic contamination over a 70-day incubation period.

Main Methods

Addition of different concentrations (0%, 1%, 7%, 14%) of polyethylene microplastics to soil samples.
Monitoring of soil chemical properties (pH, exchangeable ions, phosphate availability) over 70 days.
Assay of soil enzyme activities, including fluorescein diacetate (FDA), acid phosphatase (ACP), and N-acetyl-β-d-glucosaminidase (NAG).
Analysis of bacterial community structure at phylum and family levels using molecular techniques.

Main Results

Low PE MP concentrations altered exchangeable calcium (Ca) and magnesium (Mg) levels.
High PE MP concentrations significantly affected soil pH and phosphate ion availability.
Enzyme activities (FDA, ACP, NAG) showed a dose-related response, with significant impacts on FDA and ACP at the highest concentration (MP_14).
Microbial communities exhibited changes at both phylum and family levels across all PE MP treatments.

Conclusions

Even low doses of polyethylene microplastics can impact soil functional microbial communities.
Higher microplastic concentrations lead to more pronounced changes in soil chemistry and enzyme activity.
Soil microbes adapted to resource-limited, polluted environments may be more affected by microplastic contamination.

Keywords:

dose–response effect plastic mulch plastics soil contaminant soil environment soil enzyme soil microbe soil microbial diversity soil microbial ecology soil pollutant