The Great Mica Belt of Jharkhand, India, is an intensively disturbed mining region due to long-term mica extraction, which increases anthropogenic pressures on environmental components. Despite the environmental fragility of this region, systematic baseline information on rainwater chemistry and trace metal deposition has been lacking, particularly in comparison to other mining-impacted regions where such studies are more extensively documented. Addressing this gap is crucial for understanding atmospheric deposition processes in mining-dominated landscapes of eastern India. Unlike previous studies that predominantly focus on coal-mining, urban, or industrial regions, this study specifically investigates a mica-mining dominated environment, which has distinct mineralogical composition and emission characteristics influencing rainwater chemistry. This study aims to evaluate the chemical composition and trace metal concentrations of monsoonal rainwater collected at Koderma and Tisri within the Great Mica Belt. A total of 60 rain water samples were analyzed for physicochemical parameters (pH, EC, TDS), major and minor ions (i.e., Ca2⁺, Mg2⁺, Na⁺, K⁺, Cl⁻, HCO₃⁻, SO₄2⁻, NO₃⁻, NH₄⁺ and F⁻), and metals. Source contributions were evaluated using enrichment factor (EF), non-sea-salt fraction (nssf), and neutralization factor analyses. Rainwater pH ranged from 5.38 to 7.26, indicating acidic to alkaline conditions, with 9% of samples at Koderma and 14% at Tisri falling below the acid rain threshold (pH 5.6). Sulphate and nitrate were the dominant acidic species, reflecting strong anthropogenic influences from mining activities, vehicular emissions, and biomass burning. EF and nssf results highlight significant non-marine contributions of major and minor ions. Alkaline constituents such as Ca2⁺, Mg2⁺, and NH₄⁺ partially neutralized rainwater acidity, with non-sea-salt Ca2⁺ and NH₄⁺ identified as the principal neutralizing agents. The (NO₃⁻ + SO₄2⁻)/(Ca2⁺ + Mg2⁺) ratios suggest moderate acidity, especially at Tisri. Trace metal analysis revealed elevated concentrations of Zn as the dominant metal at both sites, along with significant levels of Ba and Sr, indicating contributions from mining activities, industrial sources, and crustal inputs. Moderate concentrations of Al and Fe further suggest the influence of transported dust on rainwater chemistry. The study provides the comprehensive assessment of rainwater chemistry and trace metal deposition in the Great Mica Belt of Jharkhand, thereby establishing a critical baseline for a previously underexplored mica-mining region. The findings also demonstrate the combined influence of acidic pollutants and crustal inputs on atmospheric composition and contribute to a broader understanding of atmospheric deposition processes in mica mining environments which highlight the distinct role of mica extraction activities in influencing rainwater chemistry.

Physico-Chemical Characteristics and Quality Assessment of Rainwater in the Great Mica Belt, Jharkhand, India

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发表日期：

2026年5月1日

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Mukesh Kumar Mahato,
Soma Giri,
Ashwani Kumar Tiwari,
Abhay Kumar Singh,
Pankaj Kumar

摘要

The Great Mica Belt of Jharkhand, India, is an intensively disturbed mining region due to long-term mica extraction, which increases anthropogenic pressures on environmental components. Despite the environmental fragility of this region, systematic baseline information on rainwater chemistry and trace metal deposition has been lacking, particularly in comparison to other mining-impacted regions where such studies are more extensively documented. Addressing this gap is crucial for understanding atmospheric deposition processes in mining-dominated landscapes of eastern India. Unlike previous studies that predominantly focus on coal-mining, urban, or industrial regions, this study specifically investigates a mica-mining dominated environment, which has distinct mineralogical composition and emission characteristics influencing rainwater chemistry. This study aims to evaluate the chemical composition and trace metal concentrations of monsoonal rainwater collected at Koderma and Tisri within the Great Mica Belt. A total of 60 rain water samples were analyzed for physicochemical parameters (pH, EC, TDS), major and minor ions (i.e., Ca²⁺, Mg²⁺, Na⁺, K⁺, Cl⁻, HCO₃⁻, SO₄²⁻, NO₃⁻, NH₄⁺ and F⁻), and metals. Source contributions were evaluated using enrichment factor (EF), non-sea-salt fraction (nssf), and neutralization factor analyses. Rainwater pH ranged from 5.38 to 7.26, indicating acidic to alkaline conditions, with 9% of samples at Koderma and 14% at Tisri falling below the acid rain threshold (pH 5.6). Sulphate and nitrate were the dominant acidic species, reflecting strong anthropogenic influences from mining activities, vehicular emissions, and biomass burning. EF and nssf results highlight significant non-marine contributions of major and minor ions. Alkaline constituents such as Ca²⁺, Mg²⁺, and NH₄⁺ partially neutralized rainwater acidity, with non-sea-salt Ca²⁺ and NH₄⁺ identified as the principal neutralizing agents. The (NO₃⁻ + SO₄²⁻)/(Ca²⁺ + Mg²⁺) ratios suggest moderate acidity, especially at Tisri. Trace metal analysis revealed elevated concentrations of Zn as the dominant metal at both sites, along with significant levels of Ba and Sr, indicating contributions from mining activities, industrial sources, and crustal inputs. Moderate concentrations of Al and Fe further suggest the influence of transported dust on rainwater chemistry. The study provides the comprehensive assessment of rainwater chemistry and trace metal deposition in the Great Mica Belt of Jharkhand, thereby establishing a critical baseline for a previously underexplored mica-mining region. The findings also demonstrate the combined influence of acidic pollutants and crustal inputs on atmospheric composition and contribute to a broader understanding of atmospheric deposition processes in mica mining environments which highlight the distinct role of mica extraction activities in influencing rainwater chemistry.