EXAFS Study of the Nature of Zinc Complexation Sites in Humic Substances as a Function of Zn Concentration G. Sarret, A. Manceau, J.L. Hazemann, A. Gomez and M. Mench J. Phys. IV France, 7 C2 (1997) C2-799-C2-802 DOI: 10.1051/jp4:1997239