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<p>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&#xa0;µg/L), dilution during monsoon (105.25&#xa0;µg/L), and partial recovery in post-monsoon (129.06&#xa0;µg/L). Spatial analysis identifies the Bagri-Rarh physiographic dualism as the fundamental control, with high-intensity contamination (&gt; 200&#xa0;µg/L in &gt; 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 &lt; 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&#xa0;µg/L yr⁻<sup>1</sup>. Vertical stratification identifies a peak arsenic window between 15 and 46&#xa0;m (mean 148&#xa0;µg/L), with concentrations declining below 46&#xa0;m (mean 74.60&#xa0;µg/L). Spearman rank correlation analysis identifies groundwater level as the dominant control on arsenic variability (ρ =  − 0.646, p &lt; 0.01), followed by total hardness (ρ = 0.593, p &lt; 0.01) and dissolved iron (ρ = 0.587, p &lt; 0.01), while bicarbonate (ρ = 0.391, p &lt; 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.</p>

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

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年7月5日

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  • Kismode Doha,
  • Syed Naushad Ahmad,
  • Md Naiyer Zaidy

摘要

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.