Distribution of trace and toxic element monitoring in soil samples from the lesser Himalayan region of India, pollution indices and source identification

Abstract Monitoring toxic and trace elements in soil is vital for environmental protection, agricultural productivity, and regulatory compliance, yet tailored methodologies for comprehensive soil analysis are limited, particularly in ecologically sensitive regions like Uttarakhand’s Lesser Himalayas. This study aimed to optimize XRF-based methods for analyzing 22 elements in soil samples from 35 locations in Uttarakhand, categorized as trace (Ni, Pb, Cu, As, Sc, Co, Br, Cs, U), minor (Zn, Ba, Mn, Zr, Rb, Ce, Sr, Cr, V), and major (Al, Fe, K, Mg). XRF parameters, including operating voltage, tube current, counting time, and sample environment, were systematically adjusted using one primary filter (W) and four secondary targets (Si, Ti, Zr, Ge). Pollution indices such as the contamination factor, geoaccumulation index, and pollution load index revealed varying degrees of contamination linked to anthropogenic activities, including industrial emissions, agriculture, and traffic. Principal component analysis (PCA) attributed these elemental variations to both natural soil composition and human influences. The study not only provided optimized analytical methods for soil analysis but also highlighted significant pollution concerns, emphasizing the need for sustained monitoring and mitigation strategies to safeguard soil health in the region. Graphical Abstract