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
