Analysis of Cadmium and Chromium Temporal Variations in Muthurajawela Wetland: A Heavy Metal Contamination Assessment from Kerawalapitiya Waste Park

Abstract

This research investigates the temporal variations of cadmium (Cd) and chromium (Cr) contamination in Muthurajawela wetland, Sri Lanka's largest saline wetland ecosystem, resulting from leachate discharge from the adjacent Kerawalapitiya Waste Park. A comprehensive monitoring study was conducted over multiple seasonal periods from March 2024 to October 2024, analyzing heavy metal concentrations across twelve sampling points (SP01-H3SP12) within the wetland system. The study revealed significant spatial and temporal variability in both cadmium and chromium concentrations, with cadmium levels ranging from 0.00004 mg/L to 0.78 mg/L across different sampling locations and seasonal periods, while chromium concentrations varied from 0.00003 mg/L to 8.6 mg/L. Critical contamination hotspots were identified at sampling points SP01, D1SP02, and D2SP3, which consistently exhibited elevated heavy metal concentrations throughout the monitoring period. Seasonal analysis demonstrated that cadmium contamination peaked during the March 2024 period at several locations, while chromium showed maximum concentrations during August 2024 at specific monitoring sites. The proximity to the waste disposal facility emerged as a primary factor influencing contamination levels, with downstream sampling locations showing progressive dilution effects. These findings highlight the urgent need for enhanced leachate management strategies and continuous monitoring protocols to protect this internationally significant wetland ecosystem from persistent heavy metal contamination. The study contributes valuable baseline data for environmental protection measures and informs policy development for sustainable waste management practices in sensitive coastal wetland environments