Exploration of Source-Specific Markers for Secondary Microplastics Derived from Polyolefin-Coated Fertilizers

Area of Science:

• Environmental Science
• Polymer Chemistry
• Agricultural Science

Background:

• Polyolefin-coated fertilizers are prevalent in Japanese agriculture.
• Secondary microplastics pose environmental risks.
• Source identification of microplastics is crucial for mitigation.

Purpose of the Study:

• To identify characteristic additives in polyolefin-coated fertilizers as source-specific markers.
• To develop a framework for attributing microplastics to fertilizer origins.
• To assess the prevalence of fertilizer-derived microplastics in agricultural soil.

Main Methods:

• Analysis of polyolefin-based fertilizer samples using thermal desorption gas chromatography-mass spectrometry.
• Identification of plasticizers, fatty acids, and levoglucosan.
• Development and application of a stepwise identification framework.
• Analysis of secondary microplastics from agricultural soil.

Main Results:

• Polyethylene was the main polymer, with poly(vinyl acetate), starch, and clay as minor components.
• Characteristic fatty acids and levoglucosan were identified as potential markers.
• These markers were detected in commercial products, environmental samples, and degraded materials.
• The developed framework successfully attributed 14 out of 15 soil microplastic samples to polyolefin-coated fertilizers.

Conclusions:

• Characteristic additives in polyolefin-coated fertilizers serve as reliable markers for secondary microplastics.
• The proposed identification framework is practical for source attribution in agroecosystems.
• This research provides a method to understand microplastic pollution from agricultural inputs.