Seasonality-driven soil and water contamination from landfill leachate in Amin Bazar, Dhaka, Bangladesh

In developing countries like Bangladesh, waste management faces significant challenges. Despite concerns about soil and water contamination from poorly managed landfills, there is a lack of studies investigating seasonal contamination at Amin Bazar. This study aims to fill this gap by examining potential soil and water contamination near the disposal site. During dry and monsoon seasons, inland surface water bodies and nearby river water exhibited critically low dissolved oxygen (DO) levels in the range of 0.14-2.13 mg/L and 2.52-3.06 mg/L; 0.20 mg/L and 6.40 mg/L, respectively, posing risks to aquatic life. Soil data within 450 m of the disposal site showed significantly higher organic content (3.37%-16.23%) and elevated heavy metal concentrations, surpassing USEPA guidelines, with the highest value of lead (Pb) found in surface water (0.096 mg/L-0.056 mg/L), groundwater (0.015 mg/L-0.04 mg/L), and soil samples (21.0 mg/kg-172.7 mg/kg). Treated leachate efficiency was in the range of 20%-60% (Cr), 98.8%-98.7% (BOD 5 ) and 55.6%-8.5% (Zn) in dry and monsoon seasons, respectively, that met Solid Waste Management (SWM) Rule 2021 standards. Inland surface water on the south side revealed heightened levels of contaminants, with Leachate Pollution Index (LPI) of 12.44, attributed to open dumping practices. Despite groundwater parameters complying with standard limits except for Pb, elevated Health Risk Index (HRI) values for As (HQ=2.71 88 ) in groundwater samples indicated potential health risks. These findings reveal clear seasonal variability and localized landfill-induced contamination, emphasizing the urgent need for improved leachate management, systematic monitoring, and sustainable waste management strategies to safeguard environmental and public health.