Transect Approach for Assessing Major and Trace Elemental Contamination in Agricultural Soils of the Palamaner Division, Chittoor District, Andhra Pradesh, India

Abstract

Three soil transects were utilized in the granitic terrains of Palamaner mandal, Andhra Pradesh, India, to evaluate the pollution levels of primary and secondary metals (Si, Al, Fe, Ca, Mg, Na, K, Fe, Cu, Mn, P, and Zn) and determine the extent of soil pollution in agricultural landscapes. The soils along the transects ranged from slightly acidic to neutral, with significant variations with landscape position (F = 8.07). These soils are categorized as having low levels of organic carbon with moderate variability in A horizons (CV of 33.56%). The two-way ANOVA results indicated significant differences in cation exchange capacity (F = 4.34 for landscape; F = 4.65 for horizons) and organic carbon (F = 5.26 for landscape and 38.86 for horizons). Under semiarid conditions, the high SiO₂ content played a role in limiting the dissolution of quartz. This led to the remobilization of Fe₂O₃ in the argillic B horizons, indicating that Fe migrated along with clay. Two-way ANOVA showed a significant difference in the total zinc content between horizons and landscape positions. Interestingly, Si, Al, and Cu exhibited slight enrichment and negative geoaccumulation indices in all the soil profiles, suggesting that they were not polluted. The pollution indices formed three clusters, with significant differences in the contamination factors for SiO₂ and Cu between the clusters. A total of five principal components were identified, accounting for 76% of the overall variance. These components primarily originate from geogenic sources and fall within acceptable limits.