『Abstract
Chemical weathering of rocks or sediments is extremely important
for the generation of soils, for the evolution of landscape, and
as a main source of inorganic nutrients for plant growth and therefore
for life. Temporal trends in weathering mechanisms, plant succession
and nutrients availability in cold environments can be successfully
studied in soil chronosequences along a glacier forefield. In
the present paper, this was carried out in the pro-glacial area
of Morteratsch. Different forms of phosphorus in the soil, stream
and spring water chemistry were investigated. Apatite constitutes
the main source of P, but it occurs only as a minor accessory
mineral phase in the granitic/gneiss parent material. The identification
of apatite was performed using SEM-EDX and cathodoluminescence.
Water chemistry data indicated some calcite dissolution at the
earliest phase of exposure, pyrite and - on older surfaces increasingly
- feldspar weathering. Apatite also seemed to contribute to Ca
which is leached from the soils. The concentrations of dissolved
P in the stream and spring waters were, however, extremely low
(only a few μg P/l). In the topsoil, the total stocks of P showed
a slight decrease with time. Losses were rather difficult to detect
even though the water fluxes through the soils and discharges
are relatively high. Soil organic P is almost identical to the
EDTA-extractable fraction. In an 11.5 ky-old soil outside the
glacier forefield the concentration and proportions of organic
P, EDTA-extractable P and inorganic P forms did not differ that
much from the oldest soils (max. 150 years) of the glacier forefield.
In the bulk soil, about 78％ of total P was transformed into an
organic form (40％ already after 150 years) and, in the fine earth,
about 81％ (40-70％ after about 150 years of soil evolution). Thus
the P transformation reactions are shown to be very rapid, occur
predominantly in the early phase of soil formation, and could
be best described by an exponential decay model.
Keywords: Phosphorus; Glacier forefield; Weathering; Apatite;
Initial soils』
1.Introduction
2. Investigation area
3. Materials and methods
3.1. Soil and water sampling
3.2. Chemical, physical and mineralogical analyses
3.3. Statistics
4. Results
4.1. Soils
4.2. Water analyses
4.3. Hydrology
5. Discussion
6. Conclusions
Acknowledgements
References