『Abstract
In silty material, 80% of the particles range from 2 to 50μm.
Particle-size fractionation within this size range allows determination
of the main mineral bearers o natural trace elements (TE) in silty
soil. Three silty soils were studied: at Chateau(最初のaの頭に^)-Thierry
in the Paris Basin, at Muret in the Aquitaine Basin, and at Thann
in the Alsace plain. These soils mainly consist of quartz, alkaline
feldspars, plagioclase, micas and chlorite, the quantities of
which vary with particle-size as shown by XRD and chemical analyses
of major elements. Quartz content increases with increasing particle
size, whereas feldspars, micas and chlorites occur mainly in the
2-10, 0.2-2 and <0.2μm particle-size fractions, respectively.
Cu, Co, Cr, Ni, Zn, Pb and major-element contents were measured;
TE values showed a negative correlation with Si and a positive
one with Al, related to the absence of TE in quartz. Negative
correlations of TE with Na and Ca are interpreted as the absence
of TE in alkaline feldspars and plagioclase. TE values correlate
with Mg, suggesting that they are present in chlorite and trioctahedral
micas. Correlations of TE with K are more complex, K-bearing minerals
being K-feldspar and micas. In the <2μm fractions, K is lost while
TE contents increase. Micas were thus considered to be one of
the main TE bearers. As correlation does not pass through zero,
other K-bearing minerals such as K-feldspar were considered as
TE free. Generally speaking, TE contents increases as particle-size
decreases.』
1. Introduction
2. Materials and methods
2.1. Soils
2.2. Physical fractionation and analysis
3. Results
3.1. Mineralogical composition
3.2. Distribution of major elements within the particle-size
fractions
3.3. TE distribution in the particle-size fractions
3.4. Relations among elements
4. discussion
4.1. Determination of TE-bearing primary minerals
4.2. Evolution of minerals through pedogenesis
5. Conclusions
Acknowledgements
References