Quantitative analysis of metal distribution along the Ganga (Hooghly) estuary: Towards establishing the inter-relation between surface water, groundwater and estuarine water

Jangid, Narayan (2022) Quantitative analysis of metal distribution along the Ganga (Hooghly) estuary: Towards establishing the inter-relation between surface water, groundwater and estuarine water. Masters thesis, Indian Institute of Science Education and Research Kolkata.

Text (MS dissertation of Narayan Jangid (17MS144)) 17MS144_Thesis_file.pdf - Submitted Version Restricted to Repository staff only Download (9MB)

Abstract

Estuaries are characterized by their various biological, physical and chemical processes like estuarine flocculation and coagulation, solute particle interaction, porewater advection, trace-metal cycling, groundwater-surface water interaction. Hooghly estuary having a high amount of biodiversity possesses a constant threat from the heavy metal contamination. To quantify the risk of these heavy metals on the estuarine ecosystem, here I tried to investigate the heavy metal contamination in the estuarine compartments like groundwater, sediment, soil and surface water. The surface water and groundwater contamination of heavy metals are compared with the WHO permissible limits for drinking purposes and the risk of these contaminants is evaluated with respect to these permissible limits. The study suggests As contamination in the surface water and groundwater and Mn contamination in groundwater to be higher than the permissible limits (0.01 mg/L for As and 0.05 mg/L for Mn). Similarly to study the heavy metal contamination of the soil of the estuarine region, the assessment of heavy metal contamination in the soil samples collected from the estuary region was carried out and was compared with the standard permissible limit of these contaminants in the soil. For sediments, the toxicity of heavy metals and ecological risk assessment was carried out by following sediment quality guidelines (SQG). Here, various evaluation methods like geoaccumulation index, potential ecological risk index and toxic risk index were used to assess the risk of heavy metal contamination on the sediment-dwelling organisms. Estuaries, where process like surface water-groundwater interaction happens, it is important to evaluate the relationship of this interaction since this not only influence the water quantity in the region but also affect the water quality. The effect of groundwater contamination of heavy metal on the surface water contamination and vice-versa becomes an important factor to have a clear understanding of estuarine ecosystem. So, here I tried to investigate the inter-relation between the surface water and groundwater contamination of heavy metals. Althogh there exist some correlation between the concentration of contaminants in the estuary but to have a proper understanding about the reason behind that correlation requires further analysis.

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