ABSTRACT
The increasing demand for sand and gravel in the construction industry has led to heightened pressure on natural deposits, resulting in substantial environmental degradation. Sand mining has been associated with adverse impacts on soil properties, including reduced fertility, contamination with heavy metals, and alteration of physical and chemical characteristics. The study assessed the environmental impact of sand mining on soils, focusing on contamination levels, pollution indices, and potential ecological risks. Soil samples were collected from active mining areas, non-mining zones, and control sites at varying depths. Soil samples were analyzed for heavy metal concentrations using an Atomic Absorption Spectrophotometer (AAS). Standard pH and conductivity meters assessed soil acidity and salinity, while the Walkley-Black method was used to determine the organic matter content. The spatial distribution of contaminants was mapped using GIS tools. Contamination Factor (CF), Pollution Load Index (PLI), Geoaccumulation Index (Igeo), and Enrichment Factor (EF) were calculated to quantify pollution severity. Principal Component Analysis (PCA) and Pearson correlation were employed to evaluate heavy metal interactions and sources. Heavy metal concentrations varied across sample locations, with manganese (Mn), iron (Fe), and copper (Cu) exhibiting moderate fluctuations, while zinc (Zn), nickel (Ni), lead (Pb), and chromium (Cr) remained relatively stable. Copper (21.8 mg/kg) exceeded the Dutch guideline of 20 mg/kg, suggesting slight contamination, while cadmium (0.73 mg/kg) was close to the 1 mg/kg threshold, indicating a potential ecological concern. The Contamination Factor (CF) classified all elements as low contamination, except Cu, which showed moderate enrichment. Pollution Load Index (PLI) values remained below 1, signifying no severe pollution. Geoaccumulation Index (Igeo) values were negative for all metals, confirming an uncontaminated environment. Principal Component Analysis (PCA) revealed distinct groupings of elements, suggesting varied pollution sources, including industrial emissions, vehicular activities, and natural geogenic processes. The Potential Ecological Risk Index (RI = 28.35) categorized the study area as low risk. The study highlighted the impact of sand mining on soil quality, with heavy metal concentrations largely within safe limits. However, there is need to monitor Cu and Cd due to their enrichment potential.
