title: Hydrogeochemistry and statistical analysis applied to understand fluoride provenance in the Guarani Aquifer System, Southern Brazil.
abstract: High fluoride concentrations (up to 11 mg/L) have been reported in the groundwater of the Guarani Aquifer System (Santa Maria Formation) in the central region of the state of Rio Grande do Sul, Southern Brazil. In this area, dental fluorosis is an endemic disease. This paper presents the geochemical data and the combination of statistical analysis (Principal components and cluster analyses) and geochemical modeling to achieve the hydrogeochemistry of the groundwater and discusses the possible fluoride origin. The groundwater from the Santa Maria Formation is comprised of four different geochemical groups. The first group corresponds to a sodium chloride groundwater which evolves to sodium bicarbonate, the second one, both containing fluoride anomalies. The third group is represented by calcium bicarbonate groundwater, and in the fourth, magnesium is the distinctive parameter. The statistical and geochemical analyses supported by isotopic measurements indicated that groundwater may have originated from mixtures of deeper aquifers and the fluoride concentrations could be derived from rock/water interactions (e.g., desorption from clay minerals).
authors.affiliation: Departamento de Geologia, Instituto de Geociências, Universidade Federal do Rio Grande do Sul, Avenida Bento Gonçalves, 9500, Porto Alegre, RS, CEP 91501-970, Brazil.
authors.forename: Maria Paula C
authors.initials: MP
authors.lastname: Marimon
authors.forename: Ari
authors.initials: A
authors.lastname: Roisenberg
authors.forename: Alexandra V
authors.initials: AV
authors.lastname: Suhogusoff
authors.forename: Antonio Pedro
authors.initials: AP
authors.lastname: Viero
mesh_terms: D001938:Brazil; D016000:Cluster Analysis; D004781:Environmental Exposure / Q000009:adverse effects; D004784:Environmental Monitoring / Q000379:methods*; D005459:Fluorides / Q000032:analysis* / Q000302:isolation & purification; D009050:Fluorosis, Dental / Q000453:epidemiology; D060587:Groundwater / Q000032:analysis* / Q000737:chemistry; D006801:Humans; D025341:Principal Component Analysis
chemical_list: D005459:Fluorides