Kadmium i berg, jord och mineral - förekomst och påverkan på den nära omgivningen

Sammanfattning: This report covers a survey of the natural occurence of the heavy metal cadmium (Cd) in soil and bedrock in Skåne, Sweden and Europe. The main focus is on the cadmium concentrations in samples of sphalerite (ZnS) collected in quarries in Skåne during the study, and in samples of sphalerite from the rest of Sweden and locations in Spain and USA depostited by the Department of Geology, Lund University. The effects on organisms living in areas with high cadmium concentrations are also reviewed. Cadmium was found in varying concentrations in the different examined samples of sphalerite. The highest concentrations, 6350 ppm Cd, were found in a sample from Dalby quarry in Skåne. The second highest concentration, 2230 ppm Cd, was found in a sample from Pheonixville, Pennysylvania, USA. The lowest concentrations, 100 ppm Cd, were found in a sample from Åmmeberg, Sweden. The concentration of cadmium in the collected samples from Skåne varies from 200 to 1500 ppm. Linear correlations were found between cadmium- and zink-, and cadmium- and sulphide concentrations in sphalerite. The correlations were stronger in samples with generally low concentrations of cadmium than in high concentration samples. This indicates that a linear correlation is valid only to a certain limit, when samples contain both sphalerite and other minerals. For the entire range of cadmium concentrations, a logarithmic correlation is more likely to describe the relation. However, at low concentrations a linear correlation still works well. Both plants and animals can be negatively affected by high concentrations of cadmium, with decreased growth and increased mortality as consequences. There are also examples of both plants and animals developing resistance to cadmium, with an ability to store the cadmium in a way that makes it bio-unavailable.