漂着プラスチツクごみ由来の重金属にょる海岸汚染の定量評価?長崎県五島市大串海岸における研究

摘要

The potential risk of toxic metals that could leach into a beach environment from plastic litter washed ashore on Ookushi beach, Goto Islands, Japan was estimated by balloon aerial photography, in-situ beach surveys, and leaching experiments in conjunction with a Fickian diffusion model analysis. Chromium (Cr), cadmium (Cd), tin (Sn), antimony (Sb) and lead (Pb) were detected in plastic litter collected during the beach surveys. Polyvinyl chloride (PVC) fishing floats contained the highest quantity of Pb. Balloon aerial photography in conjunction with a beach survey gave an estimated mass of Pb derived from plastic litter of 313±247 g. Lead leaching experiments on collected PVC floats showed that Pb in the plastic litter could leach into surrounding water on the actual beach, and that plastic litter may act as a "transport vector" of toxic metals to the beach environment. Using the experimental data, the total mass of Pb that could leach from PVC plastic litter over a year onto Ookushi beach was estimated as 0.6±0.6 g/year, suggesting that toxic metals derived from plastic beach litter are a potential "pathway" to contamination of the beach environment due to their accumulation in beach soil.