Time-Resolved Investigation of the Priming Effect of Biodegradable Plastics on Soil Organic Matter Using Radiocarbon Analysis

초록

As biodegradable plastics become integrated into the modern economy, soil contamination by biodegradable microplastics (MPs) has raised concerns owing to their potential to alter soil organic matter (SOM), an important carbon reservoir, through priming effects. Priming effects refer to the acceleration (positive) or suppression (negative) of SOM decomposition following an external carbon input. Previous studies have relied on carbon-13 isotope analysis, which lacks the resolution required for precise carbon tracing, to study the priming effects of biodegradable MPs. Herein we present a novel approach combining accelerator mass spectrometry-based radiocarbon (carbon-14) analysis with a closed-jar incubation system to quantify the priming effects of two fossil-based biodegradable MPs, poly(epsilon-caprolactone) (PCL) and poly(butylene adipate-co-terephthalate) (PBAT). This method enables high-resolution time-resolved partitioning of biogenic and fossil-derived carbon sources. Both biodegradable MPs show a net negative priming effect (up to - 35.4 & micro;g C g- 1 soil for PCL after 9 d, and - 9.6 & micro;g C g- 1 soil for PBAT after 24 d), with transient positive priming observed at certain time points. This study provides a robust approach for accurate assessment of the priming effects of biodegradable plastics on SOM and offers a potential analytical framework to devise end-of-life management strategies for biodegradable plastics in agroecosystems.

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