Assessment of hydrogeochemistry and the quality of groundwater in 24-Parganas districts, West Bengal

摘要

Hydrogeochemistry of an area helps in understanding the geological processes which control the chemistry of water and play an important role in determining the suitability of groundwater for various purposes. In the present study, an attempt has been made to understand the geological processes controlling the quality of water in a part of North and South 24-Parganas districts of West Bengal. 39 representative groundwater samples were collected from the study area and physico-chemical parameters were analyzed for all the samples. Schoeller and Durov diagram were used to understand the hydro-chemical nature of water. Results obtained from water chemistry were used in the interpretation of controlling processes using different conventional graphs, and determining the quality of groundwater. Silicate weathering and ion exchange are the dominant processes controlling the chemistry of groundwater in the study area, where calcium and magnesium in the water are replaced by the sodium and potassium in the minerals from the host rock as chloro-alkaline indices are negative at most of the places. Saturation index was calculated to understand the mineralogy of the subsurface. The groundwater is oversaturated with iron containing minerals like Fe(OH)_3, goethite, and hematite, while undersaturated with anhydrite and gypsum. The groundwater suitability was determined by calculating water quality index for drinking purpose; while SAR, and residual sodium carbonate indices for the agricultural purpose. The groundwater in the study area is not suitable for drinking, but can be used for other household use and in irrigation for agriculture.