Investigating the impact of long-term agricultural practices on selected peri-urban aquifers in tropical Southwest India

Hydrogeochemical evaluation of groundwater resources is of paramount significance in the tropics as it aids identification of safe and sustainable water resources. Evaluation of heavy metals in water is necessary as they integrate into the food chain and pose deleterious effects on human and aquatic life. To identify the extent of heavy metal occurrence in groundwater, 40 samples were collected seasonally from dug wells located in agriculture-intensive areas and analysed for physicochemical parameters and heavy metals. Water quality and pollution indices were used to evaluate overall groundwater quality and threat to humankind. The heavy metal concentrations in groundwater were observed in the increasing sequence of Zn > Cu > Pb > Ni > Co (post-monsoon) and Zn > Pb > Cu > Ni > Co (pre-monsoon). Heavy metal pollution index (HPI) revealed that the dissolved heavy metal content was found below critical value. Correlation analysis (CA) and principal component analysis (PCA) revealed that the groundwater hydrochemistry is influenced by geogenic (rock-water interaction, precipitation, simple dissolution, and base-exchange reactions) and anthropogenic sources. The results of this study will help in developing a long-term groundwater monitoring system for metal pollution, sustainable management, and conservation of peri-urban groundwater resources to achieve water security.