The arsenic (As) and fluoride (F⁻) concentration in groundwater and potential adverse human health risk was investigated in the Central-West Region of the Chaco Province, northern Argentina. The mean concentration of As in shallow groundwater was 95 μg/L, where 76% of samples exceeded the World Health Organization (WHO) guideline value of 10 μg/L, while in deep groundwater it was 90 μg/L, where 63% samples exceeded 10 μg/L. For As health risk assessment, the average daily dose, hazard quotient (HQ), and cancer risk were calculated. The values of HQ were found to be >1 in 77% of samples. This level of contamination is considered to constitute a high chronic risk compared with U.S. Environmental Protection Agency (EPA) guidelines. Further, a significant portion of the population has lifetime carcinogenic risk >10⁻⁴ and may suffer from cancer. A positive correlation was observed between As and F⁻ in groundwater. The Código Alimentario Argentino (CAA) suggested a limit of F⁻ in drinking water as low as 0.8 mg/L under tropical environmental conditions; however, in shallow (39%) and deep groundwater (32%), samples exceeded these values. Exposure to F⁻ was calculated and compared with the adequate intake of minimal safe level exposure dose of 0.05 mg/kg/d and it was noted that 42% of population may be at high risk of fluorosis. Chronic exposure to high As and F⁻ levels in this population represents a concern due to possible adverse health effects attributed to these elements.

The occurrence and distribution of arsenic and 23 other trace elements have been investigated in groundwater from Comandante Fernández Department in the Central region of Chaco Province, Northern Argentine. The arsenic concentrations samples ranged between 0.7 to 1990 g L −1 ; 91% ( = 45) exceeds the 10 g L −1 World Health Organization (WHO) provisional standard limits for drinking water. Fluorine was detected in 31% of groundwater samples. Furthermore, there was found a significant correlation between As and F ( 2 = 0.50), indicating an association in the prevalence of both elements. In addition, about 78%, 31%, 16%, 13%, and 4.5% of groundwater samples had, respectively, B, Fe, Al, Mn, and Sb exceeding Código Alimentario Argentino (CAA) guideline values. In contrast of the previously values descript, the corresponding to Cr, Be, Ni, Pb, Ag, Se, and Zn were found below the quantification limit. The presence of As and trace elements in groundwater represents an important issue because it can cause a public health problem.

RESUMENEn el presente trabajo se describe una experiencia realizada con alumnos de la cátedra de Química Analítica I de la Universidad Nacional del Chaco Austral (UNCAUS), y se aplicó la estrategia con los Alumnos del tercer año de la Carrera de Profesorado en Ciencias Químicas y del Ambiente, en la que se utilizaron clases tradicionales, con trabajos colaborativos y el uso de nuevas tecnologías, las WebQuest. La incorporación de WebQuest tiene por objeto optimizar el proceso de enseñanza-aprendizaje y la información , además de servir de apoyo a las clases presenciales, promoviendo el aprendizaje autónomo. También se analizan las ventajas de este recurso didáctico y que el equipo docente enfrentó para el desarrollo de la misma. Se muestran algunos de los resultados alcanzados con la experiencia basados en un enfoque constructivista y de aprendizaje colaborativo. PALABRAS CLAVE:WebQuest, Formación docente, Química Analítica. ABSTRACTIn this paper an experiment carried out with students from the Chair of Analytical Chemistry I of the National University of the Chaco Austral (UNCAUS) is described, and the strategy was applied to the third year students of the School of Teaching in Chemistry and environment in which traditional classes were used, collaborative work and the use of new technologies, the WebQuest. Incorporating WebQuest aims to optimize the teachingPágina 1 / 10

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