Development of a model for estimating a residence time of plastics on sandy beaches

2015 Fiscal Year Final Research Report

• Project/Area Number: 25820234
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Hydraulic engineering
• Research Institution: National Institute for Land and Infrastructure Management
• Principal Investigator: Kataoka Tomoya 国土技術政策総合研究所, その他部局等, 研究官 (70553767)
• Research Collaborator: HINATA Hirofumi ; KATOU Shigeru ; KAKO Shinichiro
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: 海洋プラスチック / 滞留時間 / 線形システム解析 / 海岸清掃効果 / 海浜流 / 和田浜海岸

Outline of Final Research Achievements

Plastics in the marine environment rapidly break down due to the light-induced degradation and biodegradation on a beach, and thus would become microplastics. In this study, we have investigated a residence time of plastics on a beach and factors determining the residence time.
Plastics were backwashed offshore due to nearshore hydrodynamics, and their remnants decrease exponentially. As an application of exponential decay of plastics, we have established a method for evaluating an amount of microplastics generated on a beach based on a linear system analysis. On the other hand, remnant plastics were moved corresponding to the nearshore current pattern. This indicates that the nearshore currents would contribute to the backwash of plastic from the beach. We conclude that the horizontal scale of nearshore current structure and frequent of nearshore current occurrence are important indexes for estimating the residence time of plastics on the beach.

Free Research Field

海岸工学