Separation and Identification of Conventional Microplastics from Farmland Soils

Area of Science:

• Environmental Science
• Analytical Chemistry
• Soil Science

Background:

• Microplastic (MP) pollution in terrestrial ecosystems is a growing concern, with numerous studies investigating MP presence and effects on soil and crop health.
• Current research faces challenges due to diverse extraction and analytical methods, hindering result comparability and reliable evidence generation for policy and industry.

Purpose of the Study:

• To present a standardized, low-cost protocol for sampling, separating, and chemically identifying conventional MPs in soil.
• To enhance the feasibility, applicability, and cost-effectiveness of soil MP analysis for widespread adoption.

Main Methods:

• Soil samples (0-30 cm) collected using plastic-free tools.
• Simulated soil types with polyethylene (PE)-MPs for quantification.
• Density separation using saturated sodium chloride (NaCl) solution and organic digestion with sodium hydroxide (NaOH).
• Quantification via Nile Red staining and fluorescent microscopy.
• Polymer identification using micro-Fourier-Transform Infrared Spectroscopy (μ-FTIR) or Laser-Direct Infrared (LDIR) spectroscopy.

Main Results:

• Achieved MP recovery rates between 83% and 90% across different simulated soil media.
• The protocol is designed for operational ease, utilizing readily available materials.

Conclusions:

• The developed protocol offers an efficient, cost-effective, and feasible method for soil MP analysis.
• Standardizing soil MP analysis methods will improve data comparability and support scientific research and policy decisions.
• An accompanying video provides step-by-step guidance for virtual learning and application.