Abstract
The analysis and prospection using hydrogeochemical methodologies on arsenic (As) contamination episode in region of Spain (Girona, Catalua) was investigated on the period (2000-2011), to analyze the mechanisms and characteristics of process on the solubilization of As in groundwater and effects of the episode of severe drought (2006-2007) on hydrogeochemical characteristics of the aquifer. The aquifer of study is a Mediterranean Delta; the geology of the zone has influence from sedimentary deposition of Ter River Basin and the prograde and draw back of the history coastline. The aquifer is an alluvial system where mean concentration of (As) is 30 A mu g/L in groundwater; parallel to this, the concentrations of elements iron (Fe) and manganese (Mn) exceed the guidelines of the World Health Organization (Guidelines for drinking-water quality electronic resource incorporating 1st and 2nd addenda, vol 1, Recommendations, 3rd edn, World Health Organization, Geneva, 2006) for drinking water. Range concentrations from other elements found in the groundwater were: Aluminum (Al, 4-716 A mu g/L), Barium (Ba, 48-603 A mu g/L), Cupper (Cu, 0.2-105.3 A mu g/L), Chrome (Cr, 1.1-47 A mu g/L) and Nickel (Ni, 1-51 A mu g/L). The arsenic solubilization trigger mechanism comes from desorption of oxide minerals and reduction related on neutral pH and reductive environment; the source of this kind of oxides is probably from marine sediments deposited in the process of delta's formation. During the climatic event of drought (2006-2007), the As concentration was responding to decline levels of the water volume on the aquifer, increasing their concentration and localized in a small area of the study zone, and these are effects of the reduction in groundwater flow on the aquifer.