Resumen de Assesment of trace elements and mobility of arsenic and manganese in lagoon sediments of the salars of huasco and coposa, chilean altiplano
Venecia Herrera Apablaza, Ida de Gregori, Hugo Pinochet
Total concentration of Fe, Mn, Zn, Cu, Cr, Cd, As, Sb and Se in lagoon sediments found in the Salars of Huasco and Coposa, Chilean Altiplano and the mobility of As and Mn by means of a simple extractions methodology was studied. The optimum digestión was made with HC1:HNO3 3:1, and the detection of elements, by means of FAAS, ET-AAS, HG-AAS and HG-AFS techniques. Sediments contain a high concentration of As, which ranges from 43 to 268 mg Kg-1 but low concentration in the majority of other elements with different proportions depending on the date of sampling. Huasco presented the greater enriched condition and the concentration of Mn was approximately nine times higher. The greater mobility of As species, was obtained in the metalloid's higher accumulation season. The extracting solutions of: 0.11M HOAc; acetate buffer in the ratio of 1 to 50; and, double-phase extraction in the ratio of 1 to 25, presented the same efficiency. Because of the high concentration of As, it is not possible to obtain the same mobility, when a acetate buffer in the ratio of 1 to 25 is employed. The 100% quantitative extraction was achieved by using 0.43M HOAc and a solution of 0.25M H2SO4 Salue. The removal of As, using oxalate buffer, depends the origin and, the content of Fe and Mn in the sample. When the oxalate buffer is employed Huasco presented a higher mobility (61 and 67%) than Coposa (37%). Sediments do not present any soluble salts of Mn in water. The percentage of Mn extracted with 0.11M HOAc, and any of the other three extractors, are much higher in Huasco. However, when using 0.25M H2SO4 Salue, this tendency becomes inverted exhibiting less mobility in Huasco (45 - 88%) than in Coposa (63 - 99%).
