『Abstract
Concentrations of major, minor and trace elements were determined
in soil solutions from the island of Pantelleria, Sicily Channel,
to evaluate the weathering extent of soils evolved on trachytic
and pantelleritic rocks and the aqueous transport of elements
by their soil solutions. The chemical index of alteration (CIA)
indicates a low-to-moderate degree of weathering; consistently,
the mineralogical and geochemical imprints of the parent rocks
are generally preserved. The chemical weathering appears to be
incongruent, owing to primary minerals and glass dissolving to
a variable degree while secondary minerals have formed. Based
on the calculated saturation state of primary and secondary minerals
with respect to the soil solutions and on mineralogical observations,
olivine and pyroxene are unstable and dissolving whereas magnetite
and hematite are stable. The main weathering products are amorphous
phases, such as ferrihydrite, amorphous aluminium hydroxide and
silica. Clay mineral formation appears to be incipient and mainly
limited to kaolinite and smectite, although for some soil profiles
a hydrothermal origin is suggested for these minerals. Chemical
characteristics of soil solutions and elemental mobility are controlled
by the element source and water-rock interaction.
Keywords: Volcanic soils; Soil solutions; Eater-rock interaction;
Solute mobility; Pantelleria』
1. Introduction
2. Geology, hydrology and climate of the study area
2.1. Geological setting
2.2. Hydrothermal activity
2.3. Hydrogeological and geomorphological features
2.4. Climate
3. Methods
3.1. Soil profile sampling
3.2. Soil profile analysis
3.3. Soil solution sampling
3.4. Soil solution analysis
3.5. Aqueous speciation
4. Results
4.1. Soil mineralogy and chemistry
4.2. Soil solutions
5. Source of dissolved solids
6. Soil profile development, weathering extent and solute mobility
7. Chemical weathering and reactions
8. Conclusions
Acknowledgments
References