RESUMO
Use of natural geological materials for arsenic (As) removal is an emerging solution at a household level for poor people in remote rural settlements, especially when the materials are locally available and can be collected by the local population. Their low or zero cost makes these materials very attractive compared with synthetic or commercial materials. Sometimes, this may be the only option to provide safe water to very poor settlements. Their suitability for As removal from water is mainly due to adsorption, co-precipitation and ion exchange processes involving Fe- and Al-rich minerals and clay minerals present in the soils or sediments. In the present study, various clay-rich soils from the Santiago del Estero province (SDE, NW Argentina) and, for comparison, a laterite from the Misiones province have been tested as adsorbents for As in shallow naturally contaminated groundwaters of the Río Dulce alluvial aquifer in SDE. Batch adsorption experiments showed higher As(V) removal for the Misiones laterite sample (99 %) as compared with the soils from SDE (40-53 %), which can be related to lower contents of water-soluble and oxalate extractable Al and Fe in the last samples. These results suggest the application of the Misiones laterite soil as an alternative for As removal. However, high transportation costs from Misiones to SDE can be an economical restriction for the low-income population of SDE.
Assuntos
Arsênio/química , Água Subterrânea/química , Metais/química , Solo/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Adsorção , Alumínio/química , Argentina , Arsênio/isolamento & purificação , Ferro/química , Manganês/química , Poluentes Químicos da Água/isolamento & purificaçãoRESUMO
Factors controlling arsenic (As) mobilization in the aquifers of the Río Dulce alluvial cone were investigated. Groundwater analyses show severe As contamination (average concentration of 743 mug/L) from geogenic sources, but spatial variability of As concentration is considerable. Sequential leaching of sediment samples from unsaturated zone using de-ionised water, bicarbonate, acetate, and oxalate extracted As to different extents. Sediment oxalate extraction showed that Al and Mn oxide and hydroxides are more abundant than Fe oxides and hydroxides, in spite of similar total Fe, Mn, and Al concentrations in the sediment. Speciation calculations performed for saturated zone samples indicated that Fe and Al oxides and hydroxides are stable in groundwater, suggesting that As adsorption processes may be to some extent controlled by the presence of Fe and Al mineral phases. Principal Component Analysis (PCA) showed that As is related to F, V, Mo, B, Si, most likely due to their common origin in volcanic ash. This suggests the volcanic ash as the probable source of groundwater As. Locally, elevated pH values linked to carbonate dissolution, cation exchange, and dissolution of silicates promote release of adsorbed As. Another factor contributing to the release of As locally may be the input of organic matter from excessive irrigation. The conceptual model of As release includes: i) As influx from dissolution of volcanic glass in volcanic ash, ii) adsorption of As on the surface of Fe and Al mineral phases in relatively low pH zones, and iii) high mobility of As in high pH zones. Future work should be focused on the determination of mineralogical forms of As in volcanic ash and on detailed investigation on factors controlling As mobility.
RESUMO
En esta publicación se presentan los trabajos que integran las memorias del XVIII Congreso Nacional del Agua, celebrado en la ciudad de Termas de Rio Hondo, provincia de Santiago del Estero Argentina, del 12 al 16 de junio del año 2000. En el cuerpo principal del libro se publican los resúmenes extendidos y en el CD-ROM anexo los textos completos de las 210 contribuciones aceptadas pra el presente Congreso. Se presentan los trabajos agrupados en cada una de las diez temáticas del Congreso, a saber: 1. Hidrologia de superficie; 2. Hidrologia subterrránea; 3. Riego y Drenaje; 4. Aprovechamientos, Presas, Embalses y Obras menores; 5. Hidráulica; 6. Medio ambiente y calidad de aguas; 7. Legislación y administración del agua; 8. Planeamiento y gestión de los recursos hídricos; 9. Geomorfología, erosión y sedimentación; 10. Temas especiales: Hidrología urbana, hidroinformática, modelación y técnicas experimentales
Assuntos
Irrigação Agrícola , Drenagem Sanitária , Barragens , Lagos Artificiais , Hidráulica , Meio Ambiente , Qualidade da Água , Legislação , Planejamento Hídrico , Erosão , SedimentaçãoRESUMO
En esta publicación se presentan los trabajos que integran las memorias del XVIII Congreso Nacional del Agua, celebrado en la ciudad de Termas de Rio Hondo, provincia de Santiago del Estero Argentina, del 12 al 16 de junio del año 2000. En el cuerpo principal del libro se publican los resúmenes extendidos y en el CD-ROM anexo los textos completos de las 210 contribuciones aceptadas pra el presente Congreso. Se presentan los trabajos agrupados en cada una de las diez temáticas del Congreso, a saber: 1. Hidrologia de superficie; 2. Hidrologia subterrránea; 3. Riego y Drenaje; 4. Aprovechamientos, Presas, Embalses y Obras menores; 5. Hidráulica; 6. Medio ambiente y calidad de aguas; 7. Legislación y administración del agua; 8. Planeamiento y gestión de los recursos hídricos; 9. Geomorfología, erosión y sedimentación; 10. Temas especiales: Hidrología urbana, hidroinformática, modelación y técnicas experimentales
Assuntos
Barragens , Drenagem Sanitária , Erosão , Hidráulica , Irrigação Agrícola , Lagos Artificiais , Legislação , Meio Ambiente , Planejamento Hídrico , Qualidade da Água , SedimentaçãoRESUMO
El presente trabajo de investigacion constituye un paso en el diseño y construccion de las perforaciones que se ubicaran en el abanico aluvial del Rio Dulce en las ciudades de Santiago del Estero y La Banda, Argentina. El metodo propuesto permite predecir y diseñar con buena precision los parametros hidraulicos del pozo antes de su fase constructiva, focalizando errores de apreciacion en cuanto al diseño, para saber el orden de rendimientro esperable del pozo, o mejorarlo
Assuntos
Argentina , Perfuração de Poços , Poços de Água , Hidrogeologia , Hidráulica , Água Subterrânea , Água Subterrânea , Indústria da ConstruçãoRESUMO
La compañia de agua de Santiago del Estero decidio expepandir los limites de la red de distribucion de agua potable, la cual es extraida del subsuelo ubicados en pozos perifericos a las ciudades de Santiago del Estero y La Banda. Por esta razon, se realizo una investigacion sobre los acuiferos ubicados en el abanico aluvial del Rio Dulce, y sus posibilidades de explotacion