Distribution and Assessment of Debris Accumulation on Sandy Beaches with Negligible Tides

• Published in: ENVIRONMENTAL SCIENCE Vol. 25; no. 6; pp. 432 - 441
• Main Authors: OKANO, Tamon, ANDOU, Shigeki, TUKUDA, Tetsuya, YASUMOTO, Motoki, MIYAZAKI, Yoshihiro
• Format: Journal Article
• Language: Japanese
• Published: SOCIETY OF ENVIRONMENTAL SCIENCE, JAPAN 30.11.2012
• Subjects: Anthropogenic beach litter; debris assessment; debris strip; floating marine litter; micro-plastic debris
• ISSN: 0915-0048; 1884-5029
• DOI: 10.11353/sesj.25.432

To establish simple monitoring methods for assessing debris accumulation on sandy beaches with negligible tides, debris items were counted and weighed in 198 surveys conducted in Tottori, Japan.Although wide beaches had somewhat greater debris number and weight than narrow beaches, the densities were lower for wide beaches. Therefore, these values should be expressed per unit-length of shoreline. Survey data do not represent the cumulative quantities of washed up debris due to differences in wave and wind phenomena among beaches, as well as cleaning. On wide beaches with negligible tides, debris generally accumulates in broadened strips and sometimes is deposited in multiple strips. On average, 65% of the pieces (135 pcs/m) and 72% of the weight (340 g/m) were accumulated within two major debris strips of 5-m width.This simplification is applicable to the monitoring of beach litter, including micro-plastic debris. Regular-shaped litter items and ropes with diameter ≥ 6 mm but not bags were few in number (6.8 pcs/m) but comprised most of the weight (293 g/m). The correlation coefficient between the above values and values for the entire beach was 0.71 for number and 0.89 for weight. This simplified method is suitable for estimating the weight of debris.