Distribution of Cd, Zn, Cu and Fe among selected tissues of the earthworm (Allolobophora caliginosa) and Eurasian woodcock (Scolopax rusticola)

We have measured the concentrations of heavy metals in soils, earthworms and tissues of woodcocks in Quaderna Valley, northern Italy. The soil concentration of metals analysed in this research is consistent with data reported by other authors for uncontaminated or slightly contaminated soils. In earthworms, metals were mostly accumulated in the encapsulating chloragogenous tissue; the positive correlation between Cu concentration in the soil and in earthworms is noteworthy. Heavy metal distribution in the tissues of woodcock showed that Cd accumulation in the kidney was linked to the diet. Cu and Fe were preferentially concentrated in the liver and Zn in the testis. Kidney Cd and Zn concentrations were higher in adults than in juveniles. In addition, a main kidney metallothionein isoform, containing Cd and Zn, was isolated. In the kidney, Cd levels were linearly correlated with the concentration of metallothionein. Of the investigated metals, Cd raises the greatest concern, due to the increasing soil contamination by human activities.