1) Laboratoire de Me´canismes et Transfert en Ge´ologie (LMTG), Universite´ de Toulouse, CNRS, IRD, OMP, 14 Avenue Edouard Belin, 31400 Toulouse, France, 2) Institute of Genetics and Plant Physiology, Moldavian Academy of Science, Kishinev, Moldavia, 3) Institute of Microbiology, Russian Academy of Science, Moscow, Russia Geochimica et Cosmochimica Acta (2008), V72, pp1742–1757, doi: 10.1016/j.gca.2008.01.018 Copper isotope fractionation during its interaction with soil and aquatic microorganisms and metal oxy(hydr)oxides: Possible structural control O.S. Pokrovsky (1), J. Viers (1), E.E. Emnova (2), E.I. Kompantseva (3), R. Freydier (1) This work is aimed at quantifying the main environmental factors controlling isotope fractionation of Cu during its adsorption from aqueous solutions onto common organic (bacteria, algae) and inorganic (oxy(hydr)oxide) surfaces. Adsorption of Cu on aerobic rhizospheric (Pseudomonas aureofaciens CNMN PsB-03) and phototrophic aquatic (Rhodobacter sp. f-7bl, Gloeocapsa sp. f-6gl) bacteria, uptake of Cu by marine (Skeletonema costatum) and freshwater (Navicula minima, Achnanthidium minutissimum and Melosira varians) diatoms, and Cu adsorption onto goethite (FeOOH) and gibbsite (AlOOH) were studied using a batch reaction as a function of pH, copper concentration in solution and time of exposure. Stable isotopes of copper in selected filtrates were measured using Neptune multicollector ICP-MS.