Study of trace elements in organs and tissues of striped dolphins (Stenella coeruleoalba) found dead along the Ligurian coasts (Italy)

Concentrations of copper, iron, manganese, zinc, selenium and mercury (tota l and organic) were measured in muscle tissue, brain, heart, lung, kidney, spleen, and liver of 18 dead striped dolphins (Stenella coeruleoalba) found stranded on the beaches of the Ligurian Sea. Distribution of the trace ele ments among the tissues and bioaccumulation are discussed. High levels of m ercury were observed in all tissues analysed, with concentrations reaching 260 mug g(-1) dry weight (dry wt.) in the muscle, 448 mug g(-1) dry wt. in the lung, 1316 mug g(-1) dry wt. in the spleen, and 2993 mug g(-1) dry wt. in the liver. Mercury present in the organic form was, on average, approxim ately 30% of the total for all tissues with the exception of the heart, whi ch showed higher values (mean 63%), and liver, where organic mercury was ve ry low (mean 12%). In muscle tissue the organic mercury fraction decreased with increasing total mercury concentration. The liver accumulated trace el ements to a greater extent than the other organs studied, with the exceptio n of iron. Principal component analysis (PCA) revealed a grouping of the sp ecimens on the basis of their estimated age. A strong positive correlation between the concentration of inorganic mercury and selenium was found for a ll the tissues analysed. In the liver the selenium to inorganic mercury mol ar ratio was very close to 1, confirming results of previous authors. (C) 2 000 Elsevier Science Ltd. All rights reserved.