Abstract Soil forms an integral component of terrestrial ecosystems and regulates its well-being. Despite the abundant literature on the concentration of metals in several soil types in India, their values in the forests are mostly unreported. To address this knowledge gap, in this study, we assessed the vertical profiles of several metals including lead (Pb), potassium (K), boron (B), manganese (Mn), iron (Fe), nickel (Ni), cadmium (Cd), chromium (Cr), cobalt (Co), zinc (Zn), magnesium (Mg), mercury (Hg), silver (Ag), copper (Cu) and arsenic (As), in a pristine forest using the ICP–OES technique. Our study site is the Kaziranga National Park, a major forest in northeast India, the region with above-average forest cover in the country. For a comprehensive understanding, we have computed multiple indices, including the elemental enrichment factor (EF), geo-accumulation index (Igeo), contamination factor (Cf), pollution load index (PLI), and ecological risk. We find a significant accumulation of heavy metals in the topsoil, several times higher than the deeper layers, due to a high amount of undecomposed soil organic matter, which binds well with heavy metals. The estimated mean potential ecological risk index shows the forest floor to be highly polluted by several heavy metals. Research highlights <UnorderedList Mark="Bullet"> <ItemContent> This research explores the movement and distribution of several heavy metals across soil strata using ICP–OES measurements, the dynamics of which substantially influence the absorption of metals by plants and consequently pose risks to wildlife and human populations. </ItemContent> <ItemContent> A negative correlation is observed between the soil depth and lead concentration, suggesting that the soil organic matter in the forest acts as a sink of this metal. </ItemContent> <ItemContent> Soil depth significantly influences potassium concentration, with high variability across the soil column, suggesting the soils have undergone varying degrees of weathering, ultimately impacting the availability of this metal for plant uptake. </ItemContent> <ItemContent> Both mercury and soil organic matter concentrations are highest in the litter layers and gradually decay with depth, indicating the forest canopy has the capability to capture atmospheric mercury through stomatal and non-stomatal pathways. </ItemContent> </UnorderedList>

Elemental profiling of a subtropical forest soil: A case study from Kaziranga National Park, India

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发表日期：

2025年4月25日

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Somasree Samanta,
Pramit Kumar Deb Burman,
Nirmali Gogoi,
Dipankar Sarma,
Tanushree Gaine,
Supriyo Chakraborty,
Punarbasu Chaudhuri

摘要

Abstract

Soil forms an integral component of terrestrial ecosystems and regulates its well-being. Despite the abundant literature on the concentration of metals in several soil types in India, their values in the forests are mostly unreported. To address this knowledge gap, in this study, we assessed the vertical profiles of several metals including lead (Pb), potassium (K), boron (B), manganese (Mn), iron (Fe), nickel (Ni), cadmium (Cd), chromium (Cr), cobalt (Co), zinc (Zn), magnesium (Mg), mercury (Hg), silver (Ag), copper (Cu) and arsenic (As), in a pristine forest using the ICP–OES technique. Our study site is the Kaziranga National Park, a major forest in northeast India, the region with above-average forest cover in the country. For a comprehensive understanding, we have computed multiple indices, including the elemental enrichment factor (EF), geo-accumulation index (I_geo), contamination factor (C_f), pollution load index (PLI), and ecological risk. We find a significant accumulation of heavy metals in the topsoil, several times higher than the deeper layers, due to a high amount of undecomposed soil organic matter, which binds well with heavy metals. The estimated mean potential ecological risk index shows the forest floor to be highly polluted by several heavy metals.

Research highlights

This research explores the movement and distribution of several heavy metals across soil strata using ICP–OES measurements, the dynamics of which substantially influence the absorption of metals by plants and consequently pose risks to wildlife and human populations.

A negative correlation is observed between the soil depth and lead concentration, suggesting that the soil organic matter in the forest acts as a sink of this metal.

Soil depth significantly influences potassium concentration, with high variability across the soil column, suggesting the soils have undergone varying degrees of weathering, ultimately impacting the availability of this metal for plant uptake.

Both mercury and soil organic matter concentrations are highest in the litter layers and gradually decay with depth, indicating the forest canopy has the capability to capture atmospheric mercury through stomatal and non-stomatal pathways.