ISSN:
1573-515X
Keywords:
Soil aluminum
;
Precambrian shield
;
organically bound aluminum
;
saturation indices
;
lichen-bedrock surfaces
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
,
Geosciences
Notes:
Abstract Solid phase controls of dissolved aluminum chemistry of soil and surface waters were investigated in several pristine, low order Precambrian shield catchments. Soil extraction and leaching experiments were conducted to quantify the various pools of solid phase soil aluminum and their relative mobility. Reactive soil aluminum (exchangeable + organic + amorphous forms), comprised 〈 20% of the total soil aluminum. Leaching soils with pH 3.0 HCl solutions indicated that Na4P2O7 extractable aluminum (largely organic complexes) was the most mobile form of reactive soil aluminum. Aluminum hydroxide from vermiculate interlayers was also mobilized from all soil horizons and its contribution to dissolved aluminum increased with soil depth. Runoff and soil waters from organic LFH and Ah soil horizons were highly undersaturated with respect to Al(OH)3 solid-phases. Several natural bedrock surfaces (metagranites) covered with moss or lichen were leached with HCl solutions. Significantly more aluminum was removed from bedrock surfaces colonized with the mossRacomitrium microcarpon compared to that of the lichen-covered surfaces. Aluminum removal increased dramatically as the acidity of the leaching solution increased to pH 3.0. Leachates solutions collected from bedrock surfaces became increasingly undersaturated with respect to Al(OH)3 minerals at lower pH values. Aluminum solubility appears to be controlled by equilibrium with organic complexation, modified by kinetically constrained dissolution of interlayer aluminum.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02182881
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