Sources and pathways of marine litter

This background report for the BLASTIC project identifies and classifies land-based sources and pathways of macroplastic marine litter (>25 mm). It emphasizes that approximately 80% of marine litter originates from land, with a particular focus on urban areas. The document proposes a framework for municipalities to map litter sources—such as recreation, general littering, waste treatment, and industrial activities—and their corresponding pathways (human direct dumping, wind, and water) to facilitate the creation of local abatement measures.

• Land-based activities are the primary origin of marine litter, with estimates suggesting that "up to 80% of the marine litter is from land-based sources".
• In the Central Baltic Region, plastic items constitute 60% of marine litter, and more than half of those plastics are "composed of packaging waste".
• The report identifies three primary pathways through which litter reaches the sea: human activity via "direct dumping", wind transport "through air", and water transport via "drains and rivers, runoff and stormwater/floods, and sewerage".
• Sewerage systems, particularly the discharge of untreated municipal sewage and sewer overflows during heavy rains, are critical pathways for urban litter. The report notes that "Eastern Baltic countries have a large percentage of coastal outfalls" that lack preliminary treatment screens.
• The document proposes a specific classification of land-based sources for municipal mapping, including: recreation and tourism, general littering (including smoking), waste water collection and treatment, municipal waste collection/treatment (including illegal dumping), cleaning of public spaces, industry and commercial sectors (including ports), and agriculture.
• Recreational and tourism activities are highlighted as a major source of litter, often due to "inappropriate disposal of litter by the public" and a "lack of adequate infrastructure" such as insufficient waste bins.

APA

Moora, H., & Piirsalu, E. (2016). Sources and pathways of marine litter. Stockholm Environment Institute. https://www.sei.org/wp-content/uploads/2017/12/blastic-backgroundreport-final.pdf

Chicago

Moora, Harri, and Evelin Piirsalu. Sources and pathways of marine litter. Stockholm Environment Institute, 2016. https://www.sei.org/wp-content/uploads/2017/12/blastic-backgroundreport-final.pdf.

Wikipedia

{{cite report |last1=Moora |first1=Harri |last2=Piirsalu |first2=Evelin |title=Sources and pathways of marine litter |publisher=Stockholm Environment Institute |date=2016 |url=https://www.sei.org/wp-content/uploads/2017/12/blastic-backgroundreport-final.pdf |access-date=17 August 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{moora2016sources, author = {Moora, Harri and Piirsalu, Evelin}, title = {{Sources and pathways of marine litter}}, institution = {Stockholm Environment Institute}, year = {2016}, url = {https://www.sei.org/wp-content/uploads/2017/12/blastic-backgroundreport-final.pdf}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }