Overview of available methods to monitor marine plastic litter Incl. method for riverine litter monitoring developed within BLASTIC.

Abstract

This document is prepared within the BLASTIC project (Plastic waste pathways into the Baltic Sea). The project was supported by EU Interreg Central Baltic (2016-2018). The overall aim is, by mapping and monitoring marine plastic litter, to facilitate the reduction of the inflows of plastic litter and of hazardous substances into the Baltic Sea. The results of the project included a compiled list of sources and pathways of marine plastic littering, and recommendations/action plants to reduce plastic marine litter in the Baltic Sea.1 A methodology suited for riverine litter monitoring of litter was also developed, and described in this document. The present document is one of the outputs of Work Package 3: Monitoring of plastic litter. The document compiles existing methods for monitoring plastic litter in rivers and the coastal waters/areas of the Baltic Sea in general, and the method for monitoring plastic litter developed within Blastic in particular. The focus in the document is on beach litter, floating litter and seafloor litter, and also on monitoring plastic macro-litter (>2.5 cm), although some methods/principles could be used for monitoring litter other than plastic and of smaller sizes. The target group for the document is municipalities with the main objective to give an overview of available methods to facilitate the choice of monitoring method, provide basic information on monitoring methodology, resources required and illustrate with examples. For each section we provide a short description of strengths and weaknesses related to each specific monitoring method. The information presented for each method is based on literature, and has not been tested in practice. The only exception is the method for monitoring plastic litter in rivers, which was developed and tested in Blastic project.