High accuracy analysis of microplastic sources in the terrestrial and coastal environments

2022 Fiscal Year Final Research Report

• Project/Area Number: 19K12372
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 64010:Environmental load and risk assessment-related
• Research Institution: Kumamoto University
• Principal Investigator: Nakata Haruhiko 熊本大学, 大学院先端科学研究部(理), 准教授 (60311875)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: マイクロプラスチック / 道路塵埃 / プラスチック添加剤 / 発生源解析

Outline of Final Research Achievements

In this study, we established the high-accuracy determination method of microplastic (MP) source based on specific additive profiles in MPs in road dusts as chemical tracers. More than 100 plastic products, road dust, stormwater, and river sediments were analyzed for polymer types and organic/ inorganic additives, and their composition were statistically compared.
As results, more than 150 organic and inorganic elements were identified in plastic products. PMMA, PVC, and EVA were dominant polymers in MPs in road dusts. The red-colored MPs in road dusts contained several phthalates, and similar profile were identified in red paint on the road. This implies that PMMA MPs in road dust are originated from road paint. Also, the organic additive profiles in MPs in road dusts were statistically similar to those in braille block, reflector, and road marking. This study strongly suggests that plastic additives are suitable chemical tracers of MP sources in road dust.

Free Research Field

環境化学

Academic Significance and Societal Importance of the Research Achievements

MPの環境負荷を減らすには、発生源を高精度に把握することが重要であるが、市販プラ製品は種類が多く、5 mm以下に微小化した「破片」の元の姿を予測する手がかりは無いに等しい。環境試料の微量分析が専門の研究代表者は、微小化したMPでも含有添加剤を測定可能な技術を有しており、それを活かそうと考えた。また、プラ製品は用途に応じて添加剤の種類が異なる点にも着目し、添加剤をトレーサーにしたマイクロプラスチックの起源推定手法の開発を試み、一定の成功を収めた。添加剤には有害性が懸念されるものも多く、本研究は「毒を持って毒を制する」形で展開した点に、独創性の高さと学術的意義が含まれているといえよう。