Fate of microplastic fibers in agricultural soils with sewage sludge application

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K04758
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 22060:Environmental systems for civil engineering-related
• Research Institution: Tokyo University of Technology
• Principal Investigator: Urase Taro 東京工科大学, 応用生物学部, 教授 (60272366)
• Co-Investigator(Kenkyū-buntansha): 松井 徹 東京工科大学, 応用生物学部, 教授 (90372812)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: マイクロプラスチック / 水環境 / 下水汚泥 / 路面堆積物 / 農地 / タイヤ片

Outline of Final Research Achievements

Microplastics (MPs) including PET-fibers from clothes and tire particles from roadside deposits are of concern in utilizing sewage sludge for agricultural purposes. This study aimed to clarify the fate of MPs in urban water systems with reliable measurement methods for MPs in soil matters by pyrolysis gas chromatograph-mass spectrometry (GC/MS). The pyrolysis-products were determined for several materials including HDPE, PP, PET, PA6 and so on. Two-year observation showed no obvious degradation of several plastic materials either in agricultural soil matters or in compost fertilizer made from sewer sludge. Benzothiazole contained in the roadside deposits could be used as an indicator for tire particles because its concentration was not decreased during heated environment. Tire particles were shown to be easily transported from roadside to water environment on rain events judging from the analysis of benzothiazole.

Free Research Field

土木環境システム

Academic Significance and Societal Importance of the Research Achievements

マイクロプラスチックの問題は国民の関心の高い環境問題の一つであり，レジ袋からストローまでさまざまな形で生活に関連している。また，多くの研究者が精力的に研究している学術的課題である。しかし，この問題については海での研究が多く，陸域での問題は十分に解明されていない。下水汚泥の農業での有効利用は，リン資源のほとんどを輸入に頼るわが国では重要な課題である。本研究は下水汚泥に含まれるマイクロプラスチックの分析法や陸域での分解挙動に関して知見を深めることで，下水汚泥の有効利用を阻害する要因を緩和し，マイクロプラスチックの陸域での挙動の一端をあきらかにしており，社会的あるいは学術的な意義が十分大きい。