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July 7, 2026Open Access

Spatiotemporal dynamics and controlling factors of groundwater arsenic contamination in Murshidabad district of West Bengal

KDKismode DohaAligarh Muslim University SASyed Naushad AhmadAligarh Muslim University MZMd Naiyer ZaidyAligarh Muslim University

Key Points

This study aims to understand the spatiotemporal dynamics and controlling factors of groundwater arsenic contamination in Murshidabad.
Integrated a comprehensive secondary dataset of 15,035 records with seasonal primary field data.
Conducted Mann-Kendall trend analysis to identify annual changes in arsenic concentrations.
Performed spatial analysis and vertical stratification assessments to determine contamination patterns.
Identified arsenic levels peaking at 149.20 µg/L in pre-monsoon, with significant decreases during monsoon and slight recovery post-monsoon.
Notable annual increases in arsenic concentrations were observed (p < 0.05) in six blocks, with Sen’s slopes varying from + 0.271 to + 1.208 µg/L yr⁻ 1.
Groundwater level was found to be the dominant control on arsenic variability, significantly correlated with levels at ρ = − 0.646, p < 0.01.

Abstract

Abstract Groundwater arsenic contamination remains a critical public health threat across the Bengal Basin, yet its block-level dynamics in Murshidabad remain insufficiently understood. This study integrates a comprehensive secondary dataset of 15,035 records with seasonal primary field data to assess spatial, depth, river, and hydrogeochemical patterns. The results show a clear seasonal variation follows a consistent pattern of higher concentrations in pre-monsoon (149.20 µg/L), dilution during monsoon (105.25 µg/L), and partial recovery in post-monsoon (129.06 µg/L). Spatial analysis identifies the Bagri-Rarh physiographic dualism as the fundamental control, with high-intensity contamination (> 200 µg/L in > 20% of wells) concentrated in the eastern Holocene floodplain, declining westward and markedly lower in the western Rarh upland. Mann–Kendall trend analysis identifies statistically significant annual increases (p < 0.05) in six blocks, particularly within the Padma corridor and the central Bhagirathi doab, with Sen’s slopes ranging from + 0.271 to + 1.208 µg/L yr⁻ 1 . Vertical stratification identifies a peak arsenic window between 15 and 46 m (mean 148 µg/L), with concentrations declining below 46 m (mean 74.60 µg/L). Spearman rank correlation analysis identifies groundwater level as the dominant control on arsenic variability (ρ = − 0.646, p < 0.01), followed by total hardness (ρ = 0.593, p < 0.01) and dissolved iron (ρ = 0.587, p < 0.01), while bicarbonate (ρ = 0.391, p < 0.05) and electrical conductivity exhibit significantly weaker or non-significant associations. Arsenic exhibits a near-monotonic decline with distance from the Padma River, whereas the Bhagirathi corridor displays a non-linear pattern linked to paleochannel heterogeneity. These findings underscore the need for seasonally informed groundwater monitoring and site-specific hydrogeological assessment across all blocks.

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