Localisation and mobility of trace metal in silver fir needles

Trace metals (TM: Co, Ni, Cu, Zn, Cd, and Pb) as well as Al, Mn, and Fe content was measured in needles of a remote silver fir stand in the south of France. TM localisation and behaviour in needles was evaluated by measuring total and internal content of needles of different ages. Measured concentrations fell within background values. Al, Fe, Co, and Pb were trapped in wax following atmospheric particulate deposition. Contrasting accumulation and migration behaviours of the different elements studied were observed. The wax contained less than 10% Mn, Al, Ni, Co, and Zn and 15–45% Fe, Cu, and Cd in the young needles. Lead was mostly located in the wax (50–80%), and this proportion decreased with needle age. Only the internal content of Pb and Fe increased significantly with needle age. Finally, due to atmospheric deposition accumulation, higher input fluxes of Fe, Cu, Cd, and Pb can be expected in forest soil.

► No translocation of TM during senescence is observed.
► Contrasted localizations (intern and wax) are observed for the different TM.
► Low accumulation of Mn, Al, Ni, Co and Zn in the wax (<10%).
► Moderate accumulation of Fe, Cu and Cd (15–45%) and high (50–80%) of Pb.
► TM accumulation in needles wax might increase atmospheric fluxes on forest soils.