Geochemical estimation of copper contamination in the healing mud from Makirina Bay, central Adriatic.

The coastal sediment from Makirina Bay in the central Adriatic represents an important source of healing mud (peloid) of high quality organoleptic properties that could in future be used for medical treatment. In this study, we estimated the contamination of the sediment with copper which can cause some undesirable health effects. Concentrations of Cu vary from 12 to 63 mg/kg in surface sediment and are higher in the central part of the Bay where the mud fraction prevails. Different normalizing methods were used, i.e. surface/background ratio, index of geoaccumulation, reference metal normalization, enrichment factor (EF) and grain size normalization, to compensate for the influence of the natural variability in sediment mineralogy and granulometry, and to assess whether the concentrations observed in surface sediment represent background or contaminated levels. Results show that Cu concentrations in the surface sediment are twice as high as local background values but in the same range as many clay materials used for medical treatment in Italy. The results also show that more detailed studies on Cu mobility are necessary prior to actual use of peloid in medical treatment.