The aim of this study was to conduct geochemical analyses of mud bed sediments and the superficial waters of the Rio Quequén Grande catchment, located in the southeast section of the province of Buenos Aires. The Rio Quequén Grande outflow into the Atlantic Ocean, near the city of Necochea. The river has cut its channel into aeolian deposits (loess and reworked loess). Most of the catchment consists of a flat plain. Bed sediments and superficial water were sampled along the drainage network of the Rio Quequén Grande catchment. The mud bottom sediments were analyzed to determine the major and trace elements, using the Ray-X fluorescence (X RF) method and loss on ignition (LOI). Together with the analyzed samples, the composition of other samples of Argentinian loess and the composition of the Upper Continental Crust (UCC) were also plotted. They revealed considerable compositional variation. The sample analysis also showed compositional differences as regards grain size. The samples from the Rio Quequén Grande are of sedimentary origin, as are the majority of loess deposits in the world. The main cations and anions of the superficial water were analyzed. In some samples a remarkably high concentration of toxic elements was found. Of these, the concentration of the arsenic content is higher than 100 μg/l in the northeastern sector of the hydrographic basin, principally due to the lithological composition of the Quaternary deposits, which are locally rich in grains of volcanic origin. The integrated analysis of the geochemical results allows us to conclude that the geological setting has a strong influence on the geochemical composition of the sediment and water. The major zones with a pollution risk were identified.
Geochemical characterization of bed sediments of the Rio Quequén Grande catchment, Argentina
TERUGGI, Liliana Beatriz;MARROCCHINO, Elena;VACCARO, Carmela
2005
Abstract
The aim of this study was to conduct geochemical analyses of mud bed sediments and the superficial waters of the Rio Quequén Grande catchment, located in the southeast section of the province of Buenos Aires. The Rio Quequén Grande outflow into the Atlantic Ocean, near the city of Necochea. The river has cut its channel into aeolian deposits (loess and reworked loess). Most of the catchment consists of a flat plain. Bed sediments and superficial water were sampled along the drainage network of the Rio Quequén Grande catchment. The mud bottom sediments were analyzed to determine the major and trace elements, using the Ray-X fluorescence (X RF) method and loss on ignition (LOI). Together with the analyzed samples, the composition of other samples of Argentinian loess and the composition of the Upper Continental Crust (UCC) were also plotted. They revealed considerable compositional variation. The sample analysis also showed compositional differences as regards grain size. The samples from the Rio Quequén Grande are of sedimentary origin, as are the majority of loess deposits in the world. The main cations and anions of the superficial water were analyzed. In some samples a remarkably high concentration of toxic elements was found. Of these, the concentration of the arsenic content is higher than 100 μg/l in the northeastern sector of the hydrographic basin, principally due to the lithological composition of the Quaternary deposits, which are locally rich in grains of volcanic origin. The integrated analysis of the geochemical results allows us to conclude that the geological setting has a strong influence on the geochemical composition of the sediment and water. The major zones with a pollution risk were identified.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
