Investigation of the amount coastal plastic debris and their reduction

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K18755
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 22:Civil engineering and related fields
• Research Institution: Kochi University of Technology
• Principal Investigator: SATO Shinji 高知工科大学, システム工学群, 教授 (90170753)
• Project Period (FY): 2021-07-09 – 2024-03-31
• Keywords: 海岸・海洋ごみ / プラスチックごみ / 海岸ごみ回収

Outline of Final Research Achievements

A field study was conducted for marine plastic waste drifted on sand-gravel beach on Kochi Coast by using a 10-band multi-spectral camera mounted on a RTK-UAV. Opaque plastic debris were identified by pixel-based analysis of three parameters, standard deviation σ of 10-band spectra, Normalized Difference Vegetation Index and correlation between spectrum and wavelength of multi-bands. Distribution of debris was changed by storm waves due to a typhoon. Many micro-plastic debris, with diameter smaller than 5 mm, were found below wood debris. The presence of resin pellets, the primary microplastics, appears to indicate the progress of marine plastic pollution even on relatively clean Kochi Coast.
The reduction of the coastal debris was found to be efficient by removing the debris in accumulation areas alone.

Free Research Field

海岸工学

Academic Significance and Societal Importance of the Research Achievements

海洋プラスチックごみについては，G20サミットなどにおいて国際合意がなされ，削減に向けた取組を進める必要がある．特に，粒径5mm以下のマイクロプラスチックは生態系への影響が懸念されている．海洋漂流物は，波浪の作用により海岸に漂着・集積するため，海岸での賦存量を把握することは，汚染の深刻度を推定し回収対策を計画するうえで重要な基礎資料となる．プラスチックごみの検出手法に関する研究が行われてきたものの，調査のコストや解像度などに課題が多い．本研究では，マルチスペクトルカメラを搭載したUAVによる海岸漂着プラスチックごみの量・質の検出・分析を，海浜表面のスペクトル特性を利用し行うことを目的とした．