Aquatic and terrestrial fulvic acids are environmentally important because they affect the bioavailability and transport of metal ions. Prior studies demonstrated that Cd(lI) binds to the oxygen containing functional groups of fulvic acids. The complexation of Cd(lI) is further investigated in this study using 113Cd NMR relaxation measurements. Spin-lattice (T1), and spin- spin (Tz) relaxation times are measured over a range of Cd(II):FA ratios. The results clearly indicate two types of Cd(lI) binding sites for the Suwannee River FA (SRFA). A series of model ligands were also examined to gain further understanding of the two types of binding motifs present in the fulvic acid. The results for a model compound containing four carboxylate functionalities in near proximity, correspond very closely to the results obtained for the strong binding sites of the Cd(II)-SRF A complexes.
Revised: November 10, 2005 |
Published: December 15, 2001
Citation
Otto W., S.D. Burton, W.R. Carper, and C.K. Larive. 2001.Examination of Cadmium(II) Complexation by the Suwannee River Fulvic Acid Using 113Cd NMR Relaxation Measurements.Environmental Science & Technology 35, no. 24:4900-4904.PNNL-SA-38962.