  We have studied Bi-2212 microcrystals aged at ambient conditions for 40 days.
Combined x-ray absorption near edge structure and x-ray fluorescence
measurements with micrometer space resolution show both an increase of Cu$^{+}$
with respect to Cu$^{2+}$ and an enrichment in Cu vs Bi and Sr cation content
near the sample edges in the b-axis direction. A parallel study on an
electrically contacted sample has indirectly detected the O loss, observing
both a resistivity increase and an increase in sample thickness near the edges.
We conclude that the O out-diffusion along the b-axis is accompanied by Cu
cation migration in the same direction.
