Investigation of beach litter accumulation in selected sites along the coastal belt of Colombo district, Sri Lanka

Plastics are major component in beach litter in the coastal zone of the Colombo district that greatly effect on the cleanliness of beaches. Thus, an in-depth study has been conducted to determine the clean state of selected sites. Abundance of each type of plastic-waste and their distribution in both tidal and transition zones were investigated. In addition, their sources based on the category of the beach, such as commercial, fisheries, residential, tourism and recreational and riverine were verified. The study was conducted for six weekends continuously from the 25 th of January 2025 to the 23 rd of March 2025 using Clean Coast Index (CCI) method and the observations were then analyzed quantitatively by statistical methods and qualitatively by performing Qualitative Data Analysis (QDA). Findings confirmed a strong spatial variation in plastic pollution levels across the study areas, emphasizing the urgent need of target-based waste management interventions, particularly in Ratmalana, where plastic accumulation was significantly higher than in all other locations. As per the CCI values, Ratmalana was mostly depicted with ‘dirty’ and ‘extremely dirty.’ And based on the results, plastic types belong to Other- type 7 was 28% (459), which is followed by Polypropylene- type 5 was 21% (352), Polystyrene- type 6 was 15% (252), HDPE- type 2 was 14% (232), PET - type 1 was 11% (192), LDPE- type 2 was 10% (159), and PVC- type 3 was 1% (11). Findings of the present study suggests the implementation of wide range of mitigation measures are necessary including source-level waste control strategies at vulnerable locations, where the coastal population is concentrated.