Nutrient chemistry and seasonal variation in the groundwater quality of a Riverine Island on the west coast of Kerala, India

Abstract

This study attempted to evaluate the groundwater quality, with a special emphasis on nutrients, of a riverine coastal island near Kodungallur, Kerala. Water quality parameters were analyzed in the collected samples over pre- and post-monsoon seasons. A considerable variation in groundwater chemistry was observed in the two periods. During pre-monsoon season, many wells were contaminated with TDS, Cl, Fe, Ca and Mg in certain locations. Whereas, post-monsoon water was relatively fresh, indicating the dilution process as well as aquifer recharge by the monsoon rain and consequent regression of saline water. A higher concentration of Fe was observed in the pre-monsoon season (41%) than in the post-monsoon season (24%). Nitrate and phosphates were analyzed to assess the nutrients and the observed concentration was below their corresponding permissible limits. Results show that overexploitation of the aquifer as well as the decreased flow of the River Periyar during the pre-monsoon period increased the threat from seawater intrusion and groundwater contamination. An interesting groundwater recharge mechanism locally known as backwashing—the diversion of rainwater from rooftops to dug wells—is being practiced in the study area and has been found to be effective in raising water levels and improving water quality.

Heavy metal concentrations in drinking water in the region north-east of Jhunjhunu, Rajasthan, India

“…In the drinking water supply, the iron salts are unstable and precipitated as insoluble iron(III) hydroxide, which settles out as a rust-coloured silt. The aeration of iron-containing layers in the soil can affect the quality of both groundwater and surface water if the groundwater table is lowered or nitrate leaching occurs [23][24][25]. In the study area, the iron content in the groundwater exhibits a spatial distribution ranging from 0.44 to 1.22 mg/L.…”

Assessment of Salt Water Intrusion from Ponnani to Tavanur along the Banks of River Bharathapuzha in Kerala

“…In India, groundwater utilization is increasing as surface water availability is decreasing (Suhag, 2016). Common quality issues in the coastal belt of Kerala include low pH, high iron content, high hardness, high TDS (Total Dissolved Solids), and salinity (Kumar et al, 2020;Nazimuddin and Basak, 1998).…”