Mercury (Hg) transfer as a descriptor of the hydrological functioning (water course - watertable exchange) of the upper Rhine flood plain : impact of river canalizations

Mercury (Hg) levels in 4 aquatic moss-species (Bryophytes) from the hydrographical system of the Alsatian floodplain (canalized Rhine, its main tributary, the 111 river with a functional floodplain, groundwater-fed stream network) were analyzed (Fig. 1.). The moss-species Fontinalis antipyretica Hedw., Cinclidotus danubicus Schiffn. & Baumg., Cinclidotus nigricans (Brid.) Wijk & Marg. and Amblystegium riparium Hedw. were found at various sites according to the characteristics of the river. The choice of the sampling sites was based on results obtained in former studies (Carbiener & Herrscher 1989, Carbiener & Tremolieres 1990, Tremolieres et al. 1991, Eglin & Robach 1992) using different methods of water quality investigation and river-aquifer interaction (hydrological tracer : Cl"; physico-chemical parameters : (NO(3) -, PO(4)(3-), NH(4)(+)); phytosociological bioindication scale using river macrophyte communities).