Micro-PIXE studies of Cd distribution in the nephridia of the earthworm Eisenia fetida (Oligochaeta)

The distribution and accumulation of Cd in the nephridia of earthworms of t he species Eisenia fetida (Oligochaeta) was studied using the NAC nuclear m icroprobe. Worms were exposed to CdSO4 in a cattle manure substrate. Elemen tal maps were obtained using the true elemental imaging system (dynamic ana lysis). It was found that at a substrate concentration of 300 mg kg(-1) CdS O4, Cd did accumulate in the nephridia, showing clear patterns in its distr ibution within this organ. It accumulated to the greatest extent in the reg ion between the nephridiopore and first loop, and the urinary vasiculus, re aching values of 890 +/- 40 mg kg(-1) and 570 +/- 20 mg kg(-1) in these reg ions, respectively. This is in contrast to the lower concentrations in the body wall (76 +/- 15 mg kg(-1)) of the worm. (C) 1999 Elsevier Science B.V. All rights reserved.