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 the species Eisenia fetida (Oligochaeta) was studied using the NAC nuclear microprobe. Worms were exposed to CdSO4 in a cattle manure substrate. Elemental maps were obtained using the true elemental imaging system (dynamic analysis). It was found that at a substrate concentration of 300 mg kg(-1) CdSO4, Cd did accumulate in the nephridia, showing clear patterns in its distribution within this organ. It accumulated to the greatest extent in the region between the nephridiopore and first loop, and the urinary vasiculus, reaching values of 890 +/- 40 mg kg(-1) and 570 +/- 20 mg kg(-1) in these regions, 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.