Seasonal variations in nickel and vanadium in Mont Blanc snow and ice dated from the 1960s and 1990s.

Ni and V have been determined in snow and ice collected at a high altitude location (Col du Doˆme) near the summit of Mont Blanc on the French–Italian border; dated from the 1960s and 1990s. Ni and V were simultaneously determined by inductively coupled plasma sector field mass spectrometry. Measured concentrations range from 6 to 700 pg g21 and 4 to 1100 pg g21 for Ni and V, respectively. The results show pronounced seasonal variations in the concentrations of both metals, with high concentration values in summer layers and much lower values for winter layers. These seasonal variations are linked especially with the existence of inversion layers during winter months. Ni and V concentrations in excess of the contributions from rock and soil dust (Niexcess, Vexcess) appear to be mainly associated with anthropogenic inputs, with pronounced seasonal variations. Large variations in the Vexcess/ Niexcess ratio are observed, with a higher ratio in summer than in winter. This shows differences in anthropogenic inputs at Col du Doˆme during the different parts of the year. The above ratio was compared with the corresponding ratios for oil combustion from stationary sources and the exhaust from gasoline and diesel engines. It appears that Ni and V concentrations at Col du Doˆme are probably the result of changing combinations of contributions from oil combustion for power generation, industrial and residential uses, on one side, and automobile and truck traffic, on the other side, with possibly a significant contribution from Ni smelters in Russia during winter months.