Faculty of Fisheries, Kagoshima University, Kagoshima, Kagoshima 890-0056, Japan
Foamed plastic fragments are major beach litters in the world. This paper investigates the occurrence of grounded and buried fragments on the coast of Kagoshima prefecture, Japan. Sand samples were collected for gathering the grounded and buried debris at 77 strand lines on 68 beaches from July 30, 1998 to November 26, 2000. After the sand was stirred in water, floating materials were scooped up with a testing sieve (0.3mm openings). Floating man-made debris (e.g. foamed plastic fragments, plastic fragments, plastic resin pellets, etc.) were sorted, dried and divided into three size groups with testing sieves (4.0mm and 10.0mm openings) and their numbers were counted. The grounded and buried foamed plastic fragments were verified at 74 strand lines on 65 beaches. Collected beach litter had a total of 80,655 pieces. Plastics accounted for 99.9% of the total number. Foamed plastic fragments accounted for 92.6% of the total, and the size range 0.3-4.0mm represented 91.0% of foamed plastic fragments. The highest density was observed on the east coast of Kagoshima Bay, and the average density was 290.4 pieces per liter. Although fragments also existed on the coast of the Amami archipelago in Kagoshima prefecture, the percentage (63.9%) was lower than on the other coast. It was presumed that the origins of the foamed plastic were the fenders of fishing boats and floats of aquaculture pens which had been washed up onto the beaches and weathered into small fragments.