Heavy metal deposition and cycling at two Mediterranean holm oak (Quercus ilex L.) forests in northeastern Spain

Trace metal deposition in precipitation was not significantly different in two holm oak forests with contrasted exposure to pollution in the area around Barcelona (Northeastern Spain), but dry deposition was higher at the more exposed site. Rain events of European origin had higher concentrations of Cu, Pb, Zn and Cd than those from African, Atlantic Ocean and Local provenances. Estimated from the recovered quantities in artificial plates, dry deposition was, for Zn, Cu and Pb: 342, 25 and 210 g ha(-1) yr(-1), respectively at the exposed site, and 254, 13 and 15 g ha-1 yr-1 at the sheltered one. Deposition in bulk precipitation was lower than dry deposition: 221, 6.2 and 6.4 g ha(-1) yr(-1) for Zn, Cu and Pb, respectively (average of the two sites).