Investigating the Temporal Variations in Leachate Contamination Risk Assessment at Kerawalapitiya Waste Park within Muthurajawela Wetland, Sri Lanka: An LPI-Based Investigation

Abstract

This research examines temporal fluctuations in leachate contamination potential at Kerawalapitiya Waste Park, Sri Lanka's largest open waste disposal facility situated within the ecologically significant Muthurajawela wetland ecosystem. Using the Leachate Pollution Index methodology across three distinct seasonal periods over a comprehensive three-year monitoring campaign from 2022 to 2024, the study assessed multiple physicochemical parameters encompassing organic pollutants, inorganic components, heavy metals, major ions, and nutrient indicators to determine environmental contamination threats to the adjacent wetland system. Results revealed substantial seasonal and annual variability in contamination potential, with total LPI values fluctuating around 10.0 during the 2023 wet season and 37.2 during the 2024 dry season. Organic matter emerged as the primary pollution contributor, peaking at 80.0 during the 2024 intermediate season, while heavy metal contamination exhibited erratic behavior with maximum levels of 43.8 recorded during the 2024 dry season. The year 2024 represented the most environmentally hazardous period, with all measured components demonstrating elevated contamination levels. Seasonal analysis throughout the monitoring period revealed irregular patterns, suggesting that conventional seasonal management approaches are inadequate for addressing the complex interactions between climatic factors, waste composition, and leachate generation processes. These findings underscore the urgent need for enhanced monitoring protocols and adaptive pollution management strategies that can respond to temporal variations in contamination composition, while contributing valuable insights into leachate contamination dynamics in tropical wetland environments and informing targeted environmental protection measures for sensitive coastal ecosystems.