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The contamination of groundwater in the aquifer of the La Llagosta basin (Besòs river basin) due to waste disposal in quarries formerly used for the extraction of dry raw materials has led to the cessation of groundwater extraction for public water supply. The mobilization of pollutants was largely caused by fluctuations in piezometric levels, which led to the washing of buried waste. The hydrogeochemical processes associated with uncontrolled waste disposal in these landfilled areas of the La Llagosta basin aquifer were studied along a flow path that crosses the contaminated area. The PHREEQC code was used to establish the reactions associated with the different mineral phases through inverse modeling. This transport code, ionic exchange phenomena, surface reactions and balance (mineral phase) reactions were used to simulate the dilution phenomenon associated with the pollution after the potential removal of the sources of contamination. One-dimensional advective–dispersive modeling indicates a substantial reduction in Ca, Mg, Na and SO within one year and stabilization within four years. [ABSTRACT FROM AUTHOR]

Field and laboratory-column studies were undertaken in order to investigate soil contamination derived from past mining activity in the Sierra Almagrera (SA) district in southeast Spain. The tailings, soil and sediment samples that were collected showed high concentrations of Ag, As, Ba, Cu, Pb, Sb and Zn when analyzed. The mean concentrations of these elements in the tailings were 29.8, 285.4, 54000, 57.7, 2687.5, 179.0 and 2269.0 ppm, respectively. In the soil samples these decreased to 14.3, 96.9, 24700, 37.5, 1859.1, 168.5 and 815.7 ppm, respectively. Geochemical analyses demonstrated high levels of As, Pb and Zn which were above the intervention values set forth in the Andalusian Regulations for Contaminated Soils for As (>50 ppm), Pb (>500 ppm) and Zn (>2000 ppm). Column experiments and mineralogical studies suggest that the dissolution of sulfates and other secondary phases, accumulated in soils and waste-sites during the dry season, acts to control the mobility of metals. The elution curves obtained from column experiments showed a mobilization of Ba, Cu, Pb and Zn, while a low mobility was seen for Ag, As and Sb.