Fluoride characterization by principal component analysis in the hydrochemical facies of Serra Geral Aquifer System in Southern Brazil

Abstract

Principal component analysis is applied to 309 groundwater chemical data information from wells in the Serra Geral Aquifer System. Correlations among seven hydrochemical parameters are statistically examined. A four-component model is suggested and explains 81% of total variance. Component 1 represents calcium-magnesium bicarbonated groundwaters with long time of residence. Component 2 represents sulfated and chlorinated calcium and sodium groundwaters; Component 3 represents sodium bicarbonated groundwaters; and Component 4 is characterized by sodium sulfated with high fluoride facies. The components' spatial distribution shows high fluoride concentration along analyzed tectonic fault system and aligned on northeast direction in other areas, suggesting other hydrogeological fault systems. High fluoride concentration increases according to groundwater pumping depth. The Principal Component Analysis reveals features of the groundwater mixture and individualizes water facies. In this scenery, it can be determined hydrogeological blocks associated with tectonic fault system here introduced.

Multivariate statistical analysis for fluoride occurrence in groundwater in the Northern region of Ghana

“…Due to its favorable dissolution properties, fluorite seems to be the main mineral that predominantly controls aqueous fluoride geochemistry in most environments (Apambire et al, 1997;Mamatha and Rao, 2010;Weinstein and Davison, 2004). Fluoride contamination of groundwater can also result from anthropogenic sources/industrial activities such as application of phosphatic fertilizers, processing of phosphatic raw materials, use of clays in ceramic industries, electroplating, aluminum smelting operations and burning of coal (Brunt et al, 2004;Chen et al, 2010;Frencken, 1992;Kundu et al, 2001;Naani et al, 2008).…”

Caracterizacao hidrogeologica e hidroquimica do aquifero livre localizado no manto de alteração da Formação Serra Geral, na bacia hidrográfica Taquari-Antas, regiao nordeste do estado do Rio Grande do Sul

“…No entanto, quando presente, as concentrações variaram entre 0,1 e 0,25 mg/L. O fluoreto é mais facilmente encontrado nas águas subterrâneas que circulam pelos aquíferos fraturados, sendo sua origem, segundo Nanni et al (2008), condicionada por estruturas tectônicas que promovem a conexão entre os sistemas aquíferos Serra Geral e Guaraní.…”

Semiautomatic and Automatic Cooperative Inversion of Seismic and Magnetotelluric Data

“…For the two reference drill holes located at the Nevada site, we have used geostatistical methods to divide the rock into classes based on a suite of geochemistry elements. For the geochemical data, PCA and k-means clustering techniques have been used to reduce the data dimension to highlight a limited number of geochemically similar rock types (Alférez et al 2015;Grunsky and Smee 2003;Jolliffe 2002;Nanni et al 2008;Roden et al 2015). The purpose of the analysis was to check the consistency of geochemical groupings with seismic boundaries, prior model conductivity distributions and the final conductivity distribution from semiautomatic and automatic cooperative inversion strategies.…”

“…9. We should reiterate that only large subvolumes are used to create the prior conductivity model after which full 3D MT inversion is applied to recover detailed conductivity distribution and associated fitting error statistics for comparison with other strategies Note that we broadly follow the methodologies expressed in Roden et al (2015), with the main difference being that Roden et al (2015) used self-organising maps (SOM) for clustering, while we use the k-means method (Alférez et al 2015;Nanni et al 2008). The .…”