Statistical Analysis of Urban Non-Point Source Pollution and Nitrate Contamination in the Groundwater at Thuckalay, Kanyakumari District, South India

Abstract

A statistical analysis of nitrate contamination in the groundwater at the Thuckalay area of Padmanabhapuram town, South India, is conducted using data collected from 2000 to 2019 that includes rainfall, groundwater level, and groundwater quality. The findings indicate that there was a rise in nitrate contamination in the groundwater between 2001 and 2011. This increase can be attributed directly to the 6.69% increase in population and the corresponding increase of 108.79 hectares in residential areas, which accounts for the 17% expansion. The elevated concentrations of EC (1830 µS/cm), Cl (511 mg/L), Na (210 mg/L), NO 3 (150 mg/L), TH (420 mg/L), and precipitation (1,184) in 2011 may have an impact on the non-point source contamination in the subject area, which is caused by flowing water bodies. An investigation was conducted into the sources and regulating factors of elevated nitrate levels through the utilisation of cross plots and fitted line plots of NO 3 in conjunction with other chosen hydrochemical parameters. Nitrate contamination of the groundwater is indicated by a positive Pearson correlation coefficient between NO 3 and Ca, Cl, EC, Na, SAR, SO 4 , TH, TA, and WL. Furthermore, a nitrate pollution index greater than three signifies a higher degree of pollution during the years 2005, 2010, 2011, 2013 and 2014. The primary sources of nitrate contamination in the vicinity of the study area were human and animal refuse that was disposed of in open areas. This may be the result of increased fertiliser application on agricultural land. Restoring groundwater quality in the studied area is possible through periodic monitoring, regulation of polluting sources, and implementation of a natural, cost-effective redevelopment technique.