Lead, cadmium and arsenic bioavailability in the abandoned mine site of Cabezo Rajao (Murcia, SE Spain)

An in vitro method that simulated the physiological conditions of the digestive process was applied to samples taken from an old mining site, providing information on the levels of metals (Cd, Pb and As) that can be ingested and assimilated by humans. Samples were first characterized by determining pH, texture, mineralogical composition and total metal contents. The mean pH value was 5.4, ranging from 3.1 to 8.4. The mean total metal content for Pb was 2,632+/-59 mg kg(-1), 65+/-1.5 mg kg(-1) for Cd and 279.9+/-9.9 mg kg(-1) for As. Cadmium was the most bioavailable metal both in the stomach and intestinal phases (mean value of 47% and 27.8%, respectively), followed by lead (25.3% and 11.5%) and arsenic (4.9% and 0.5%). A Pearson correlation matrix suggested that pH and mineralogical composition were important factors controlling metal bioavailability from materials in abandoned mining sites.