CADMIUM AND CHROMIUM LEVELS IN SURROUNDING BRICK KILNS SOIL OF LALPUR, NATORE (BSc. Thesis)- Degree Awarded

CADMIUM AND CHROMIUM LEVELS IN SURROUNDING BRICK KILNS SOIL OF LALPUR, NATORE, BSc. Thesis (Degree Awarded) 

Abstract

Currently Bangladesh has over 12,000 operational brick kilns in order to fulfil the increasing need for construction materials in the country. Hazardous heavy metals such as chromium (Cr), cadmium (Cd) and lead (Pb) accumulate in the soils around the kiln areas from various sources, i.e., coal, wood, and furnace oil burning, use of tires and rubber for initial firing in the brick kiln areas. A total of 22 samples were collected from neighboring areas of three selected brick kilns, with sampling conducted from top-soil at four directions (north, south, east, and west) at distances of 100 meters and 200 meters from the kilns. The majority of the sampling areas were agricultural fields. The concentrations of heavy metals were digested and analyzed by Atomic Absorption Spectrophotometer (AAS). Chromium and lead concentrations were detected in all samples, with the concentration ranges for chromium at 100 meters and 200 meters being 25.85–41.02 mg/kg and 27.39–33.61 mg/kg, respectively. For lead, the concentration ranges at 100 meters and 200 meters were 39.45–41.21 mg/kg and 39.30–40.42 mg/kg, respectively. In all cases, the concentrations of both metals exceeded the permissible limits set by the World Health Organization (WHO) for agricultural activities. Although cadmium concentrations were below the detection limit for the majority of sampling points, one sample recorded a concentration of 2.3543 mg/kg, which is concerning. Spatial distribution analysis revealed that the higher concentrations observed to the north, south, and west at both 100 meters and 200 meters were primarily caused by the predominant wind flow, which influenced the directional spread of the heavy metals. This study's analysis using the Geo-Accumulation Index, Contamination Factor, and Pollution Load Index indicates moderate contamination of chromium, lead, and cadmium, with most sites showing significant pollution due to brick kilns emission. Ecological risk assessments reveal generally low environmental risks, with a localized probable considerable risk due to elevated cadmium concentrations at one sampling point. Hence, the study found that continuous brick production over time has degraded topsoil conditions, which could potentially reduce agricultural productivity.

Keywords: Brick kiln, heavy metals, spatial analysis, soil pollution, windrose

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