Insights from monitoring abundances and characteristics of plastic leakage in city waterways and tourist beaches of Cambodia

• Citizen science for sustainable and affordable environmental monitoring. • Detection, identification, characterization and quantification of plastic waste. • Overview and awareness of solid leakage plastics in municipalities of Cambodia. • Showcasing remote sensing in tracking and detecting leakage waste. Plastic leakage from mismanaged or illegal dumping of waste especially in developing countries is a global environmental wicked problem. Significant efforts have been dedicated to monitoring, reducing, recycling and improving circularity of mismanaged plastics to support progress towards achieving globally acceptable environmental standards (e.g., UN SDG 6, 12, 14). We present findings from citizen science-based field surveys conducted in preselected sites, paired with clean-ups (i.e., 15 main and 173 sub-zones) in municipalities across Cambodia. The surveys involved the characterization (e.g., colour, form, polymer type, brand) and quantification of various plastic items found in solid waste. Visual inspection and captured photographs confirmed that vegetation in the waterways acts as a sink for plastic waste by entrapment of items that created localized hotspots. The evidence-based results are discussed in the broader context of their potential socio-economic implications. Additionally, remote sensing technologies are highlighted as an evolving complementary tool with the capability to monitor, locate hotspots, and track plastic leakage. Thematic maps from satellite imagery were also used to demonstrate the potential to derive qualitative and quantitative indicators from both datasets-of-opportunity and dedicated drone observations. The current study provides valuable insights into the management of solid waste and the consumption and production patterns of plastics in the studied municipalities of Cambodia. It emphasizes the importance of employing a synergy of monitoring strategies, as a step ahead in developing sustainable and cost-effective data sources. The presented approaches can play a crucial role in fostering scientific evidence-based policymaking and informed roadmap planning for improved environmental management.