2:35 PM - 3:00 PM
[O03-03] What amount of plastic litter is generated annually by beach users in Japan?
★Invited Papers
Keywords:plastic, beach, beach users
Coastal areas, including beaches, are valuable tourism resources that constitute a major source of marine microplastics. The accumulation of plastic litter on beaches is believed to have a significant impact on the future amount of microplastics in the marine environment. While prior studies have predominantly focused on the quantification of plastic litter on beaches, including both beach-based and beached litter, there are still significant knowledge gaps concerning daily litter generation by beach users and litter generation rates (in g/person/h or pieces/person/h). The research team employed a novel methodology to estimate these rates and the volume of litter on beaches nationwide in Japan. We conducted surveys at four popular beaches during the summer and fall/winter of 2021-2023. The plastic litter from beach users was collected, counted, and weighed. We also estimated the litter generation rate by measuring the number of beach users on the day of the survey, based on image processing. The results indicated that the generation rate during the summer (fall and winter) ranged from 0.178 (0.128) to 1.10 (0.453) g/person/h, which is approximately equivalent to one person discarding one cigarette butt per hour. In number, the rate ranged from 0.064 (0.042) to 0.196 (0.122) pieces/person/h. Using cell phone big data, we pioneered a novel method for estimating the amount of plastic waste generated by beach users. This method involved examining the number of person-hours spent on 770 beaches nationwide in Japan and multiplying it by the generation rate obtained from the survey. The calculation yielded an estimated average weight of 12.50 t/y (2.8 million pieces/y), with a margin of error that ranged from 6.54 to 18.40 t/y (1.7 to 3.89 million pieces/y). These findings contribute to the evaluation of beach cleanup effects.