Analyses of gravitational soil solutions in an alpine podzol showed that a
significant amount of C, Si, Al and Fe are leached in the colloidal form. T
he nature of colloids depends on the season of the water collection and on
the pedological horizon. Chemical analyses, analytical electron microscopy
and thermodynamic calculations showed that imogolite and protoimogolite all
ophane form in gravitational water running across the E-horizon during the
snowmelt. (C) 2000 Academie des sciences / Editions scientifiques et medica
les Elsevier SAS.