Tracing the source of marine debris on the beaches of northern New South Wales, Australia: The Bottles on Beaches program.

Identifying the source of marine plastic pollution accumulating on ocean beaches is often difficult as unidentifiable fragments of plastic usually predominate. In this study, we surveyed plastic bottles as a relatively identifiable subset of plastics on 30km of beach along a 200-km section of the north coast of New South Wales, Australia. Source and product type (contents) were determined using barcodes, inscriptions/embossing, or bottle shape and characteristics. Country of origin and product type could be determined for two-thirds of the 694 bottles found. Just over half (51%) of these were of domestic origin with the remainder dominated by bottles from China (24%) and south-east Asian countries (21%). As most of the foreign bottles lacked marine growth, and are unavailable for purchase in the region, passing ships are hypothesised as the primary source.