Quantitative study of Be(II) complexation by soil fulvic acids by molecular fluorescence spectroscopy

The interaction of the beryllium ion [Be(ll)] with one of the major constituent of soil organic matter, fulvic acids (fua), was investigated. The complexation of Be(ll) by two samples of fua (amph and gran), at a concentration of 80 mg/L, was monitored by synchronous fluorescence spectroscopy at four pH values (4, 5, 6, and 7). A self-modeling curve resolution technique (evolving factor analysis) was used in the analysis of the sets of spectra collected at increasing Be(ll):fua ratio to obtain concentration profiles that ideally correspond to one type of binding site. These profiles were adjusted to a 1:1 complexation model. Quite strong complexation of Be(ll) by fua occurs at nearly neutral pH (6-7) (logarithm of the conditional stability constant between 5.6 and 6.5), indicating that fua probably affect markedly the mobility of Be(ll) in the environment.