Backwash process of marine macroplastics from a beach by nearshore currents around a submerged breakwater. Issue 2 (30th December 2015)

• Record Type: Journal Article
• Authors: Kataoka, Tomoya; Hinata, Hirofumi; Kato, Shigeru
• Is Part Of: Marine pollution bulletin. Volume 101:Issue 2(2015:Dec.)
• Page Start: 539
• Page End: 548
• Publication Date: 2015-12-30
• Subjects: Marine macroplastics -- Residence time -- Submerged breakwater -- Nearshore current -- Mark-recapture experiment; Marine pollution -- Periodicals; Marine Biology -- Periodicals; Water Pollution -- Periodicals; Mer -- Pollution -- Périodiques; Publications périodiques; Pollution des mers; Lutte antipollution; Electronic journals; 363.7394
• DOI: 10.1016/j.marpolbul.2015.10.060
• Languages: English
• ISSNs: 0025-326X

Abstract

Abstract: A key factor for determining the residence time of macroplastics on a beach is the process by which the plastics are backwashed offshore (backwash process). Here, we deduced the backwash process of plastic fishing floats on Wadahama Beach based on the analysis of two-year mark-recapture experiments as well as nearshore current structures revealed by sequential images taken by za webcam installed at the edge of a cliff behind the beach. The analysis results revealed the occurrence of a combination of offshore currents and convergence of alongshore currents in the surf zone in storm events around a submerged breakwater off the northern part of the beach, where 48% of the backwashed floats were last found. We conclude that the majority of the floats on the beach were transported alongshore and tended to concentrate in the convergence zone, from where they were backwashed offshore by the nearshore currents generated in the events. Highlights: Beached plastic float movements were revealed by two-year mark-recapture experiments. Nearshore currents around a submerged breakwater were revealed by webcam images. Plastic floats were mainly backwashed offshore from the lee of the breakwater. Nearshore currents in storm events controlled the backwash process.