J. Phys. IV France 107 (2003) 1361
DOI: 10.1051/jp4:20030554

Mercury transport through a porous medium in presence of natural organic matter

V. Wernert^{1, 2}, F.H. Frimmel² and P. Behra<sup>1, 3

1</sup>  Institut de Mécanique des Fluides et des Solides, UMR 7507 du CNRS, Université Louis Pasteur, 2 rue Boussingault, 67000 Strasbourg, France
²  Universität Karlsruhe (TH), Engler-Bunte-Institut, Engler-Bunte-Ring 1, 76131 Karlsruhe, Germany
³  École Nationale Supérieure des Ingénieurs en Arts Chimiques et Technologiques, Laboratoire de Chimie Agro-Industrielle, UMR 1010, INRA/INP-ENSIACET, 118 route de Narbonne, 31077 Toulouse cedex 4, France

Abstract
Natural organic matter (NOM), derived from degradation of living organism matter, can significantly control the fate and transport of chemical components, particularly metal ions, by forming organometallic complexes in aquatic systems. Column experiments were performed to study the mobility of humic acids (HA) and Hg. Single component (HA or Hg) and multicomponent (Hg and HA) experiments were conducted to assess transport behaviour of Hg in the presence of HA. A natural quartz sand was used as porous sorbing medium. HA breakthrough curves (BTCs) showed a first step with a sharp front followed by an important tailing over a long period of time. The tailing of HA BTCs is assumed to be due to slow sorption kinetics of HA onto the quartz sand and the non linear nature of the sorption isotherms. The time required to get steady-state concentration for organic C depended on the inlet HA concentration. HA sorption depends also on pH, the highest HA sorption being observed at due to electrostatic attractions. The Hg transport is strongly enhanced in the presence of HA and the Hg BTCs are quite similar to the HA BTCs. These results suggest strong aqueous complexation between Hg and HA and the formation of ternary surface complexes of type B.

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