[Application of Various Methods to Extract Microplastic from Typical Soils in China]

Area of Science:

• Environmental Science
• Analytical Chemistry
• Soil Science

Background:

• Microplastic pollution is a global environmental concern affecting various ecosystems, including soils.
• Standardized methods for microplastic extraction from diverse soil types are lacking, hindering accurate assessment.
• Understanding microplastic contamination in typical Chinese soils is crucial for effective environmental management.

Purpose of the Study:

• To identify optimal extraction and component identification methods for microplastics in typical Chinese soils.
• To evaluate the efficacy of different treatments (water+oil, saturated NaCl solution+oil, saturated NaCl solution) for microplastic detection.
• To assess the performance of Attenuated Total Reflectance Fourier-Transform Infrared Spectroscopy (ATR-FTIR) for polymer identification.

Main Methods:

• Four microplastic types (PET, PP, PS, PE) were analyzed in four soil types (loess, black soil, red soil, purple soil).
• Three extraction treatments were tested: T1 (water+oil), T2 (saturated NaCl solution+oil), and T3 (saturated NaCl solution).
• Microplastic identification and component analysis were performed using ATR-FTIR.

Main Results:

• Treatments T1 and T2 yielded high extraction rates (86.67%-100%) for PP, PE, and PS in loess, black, and purple soils, but residual oil interfered with FTIR analysis.
• Treatment T3 showed lower extraction rates, particularly for denser microplastics like PET (0%-13.30%), indicating potential loss.
• Red soil presented challenges, with varying extraction efficiencies for different plastic types and treatments, necessitating further investigation.

Conclusions:

• Combined water+oil (T1) or saturated NaCl solution+oil (T2) treatments are effective for extracting most microplastics from loess, black, and purple soils, provided post-extraction cleaning is employed.
• The saturated NaCl solution (T3) treatment is less effective for denser microplastics and may lead to significant sample loss.
• Specific extraction protocols require further development for complex soil matrices like red soil to ensure comprehensive microplastic detection and characterization.