Monitoring the causes of pollution using groundwater quality and chemistry before and after the monsoon

• Published in: Physics and chemistry of the earth. Parts A/B/C Vol. 128; p. 103228
• Main Authors: Subba Rao, N., Sunitha, B., Das, Rashmirekha, Anil Kumar, B.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.12.2022
• Subjects: Anthropogenic sources; Contamination; Groundwater quality; Index wells; Land use; Monsoon recharge; Groundwater quality; Monsoon recharge; Anthropogenic sources; Index wells; Contamination; Land use
• ISSN: 1474-7065; 1873-5193
• DOI: 10.1016/j.pce.2022.103228

The present study aims to assess the causes of pollution in groundwater before and after the monsoon in relation to water types, chemical elements, and their statistical variation in a rural region of Wanaparthy district, Telangana, India. Groundwater samples collected in both seasons were analyzed. Results indicated that pH, TDS, Ca2+, Mg2+, K+, Cl-, SO42−, and NO3− values were higher after the monsoon. The Overall Water Quality Index indicated that moderate (53.86%) and very low (20.18%) groundwater quality zones increased spatially during post-monsoon compared to pre-monsoon (35.22% and 4.77%, respctively). Piper's diagram showed that the transition from freshwater to mixed water type (70%) predominates in post-monsoon. Gibbs diagrams indicated 93.33% and 80% of groundwater samples had lithological influence before and after the monsoon, respectively. Genetic water quality classification revealed that 53% and 87% of groundwater samples showed Cl−−HCO3− type before and after the monsoon, respectively. The ionic ratios indicated the dominance of mineral weathering and dissolution, ion exchange, and evaporation in pre-monsoon, but they also indicated that anthropogenic pollution activities prevailed in post-monsoon, as confirmed by the high correlations between Cl-, SO42−, and NO3− ions and supported by land use practice. Principal component (PC) analysis captured three and four PCs with 80.795% and 78.532% of the total variance and eigenvalue greater than one (1.020–5.748) before and after the monsoon, respectively, which also supported human induced contamination in post-monsoon groundwater. PC scores (>1) identified index-wells for regularly monitoring groundwater quality and also assessed pollution causes for proper management planning to reduce cost and protect the aquifer system. [Display omitted] •OWQI indicated an increase in moderate and very poor water quality zones after the monsoon .•In post-monsoon, the geogenic sources of groundwater becomes brackish .•Ionic ratios and PCA supported anthropogenic input during the monsoon.•PC scores (>1) identified index wells for regular monitoring of groundwater quality.