Use of transplanted mosses and autochthonous liverworts to monitor trace metals in acidic and non-acidic headwater streams (Vosges mountains, France)

Thirteen headwater streams situated in the Vosges Mountains (northeastern France) have been studied for trace metal contamination (Al, Mn, Pb, Cd) in relation to acidification. Assessment of metal concentrations has been performed using water analyses and metal content in transplanted aquatic bryophytes. The streams studied ranged from acidic to circumneutral. Aluminium, Mn and Pb concentrations in water increased significantly with decreasing pH, whereas no relationship was observed between aqueous Cd concentrations and pH. The relation between metal contents in the moss and in the water varied markedly between metals. Aluminium and Pb levels in mosses reflect well the increasing concentrations of metals in water related to the pH whereas Mn in mosses does not. The metal content of the autochthonous liverworts was different from those of the transplanted mosses which implies different conclusions about the contamination level of the water. Adaptation to different pH conditions leading to physiological and structural specificities could explain the different ability of these two species to accumulate metals in acid surroundings.