The NMR spectra were measured in solution, for a series of compounds m
odelling the interaction of lead(II) with the humic substances of the
soil. From the results it appears that the metal binding site is predo
minantly the carboxylate group. The Pb-207 chemical shift is as a sens
itive probe of the complexing ability of the various ligands and can b
e used as an analitycal tool in the study of the interaction of this m
etal with the soil organic matter.