Hydrogeochemistry and groundwater quality assessment using the water quality index and heavy-metal pollution index in the alluvial plain of Atibaia river- Campinas/SP, Brazil

• Published in: Groundwater for sustainable development 2021-11, Vol.15, p.100661, Article 100661
• Main Authors: Rupias, Osvaldo Jorge Brito, Pereira, Sueli Yoshinaga, de Abreu, Ana Elisa Silva
• Format: Article
• Language: English
• Subjects: Hand dug wells; Peri-urban area; Shallow aquifer
• ISSN: 2352-801X; 2352-801X
• DOI: 10.1016/j.gsd.2021.100661

Alluvial aquifers are highly vulnerable to contamination, especially in areas with peri-urban occupation and on-site sanitation systems. Due to the importance of the quality of groundwater in those areas, this article aims to understand hydrochemical characteristics and to evaluate groundwater quality using the Water Quality Index (WQI) and Heavy-Metal Pollution Index (HPI). Seasonal sampling campaigns of 20 samples of groundwater in hand dug wells were done during wet and dry seasons. The main hydrochemical facies determined in the Piper Diagram allowed to classify the waters as Ca–HCO3, Ca–Na–HCO3 and Na–Ca–HCO3 during the wet season, and Ca–HCO3, Na–Ca–HCO3 and Na–Ca–Cl during dry season, suggesting shallow waters and short residence time. The groundwater in the study area is mostly controlled by the incongruous weathering of silicates and the process of ionic exchange, as well as the anthropogenic sources that act as secondary contributions. The saturation index results show a state of supersaturation (SI > 0) for the following minerals: goethite, kaolinite and illite, and subsaturation (SI