Variation in soil surface area in a chronosequence of soils from Glen Feshie, Scotland and its implications for mineral weathering rate calculations

• Published in: Geoderma Vol. 85; no. 1; pp. 1 - 18
• Main Authors: Hodson, Mark E., Langan, Simon J., Kennedy, Fiona M., Bain, Derek C.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.07.1998; Elsevier
• Subjects: chronosequence; Earth sciences; Earth, ocean, space; Exact sciences and technology; Geochemistry; mineral soils; particle size; Soil and rock geochemistry; Soils; surface area; Surficial geology; United Kingdom; Scotland; Great Britain; Western Europe; surface area; particle size; chronosequence; mineral soils; particulate matters; minerals; oxalates; oxides; Europe; dissolution; alkali feldspar; SEM data; soil horizons; feldspar; weathering; organic minerals; plagioclase; grain size; oxihydroxides; depth; soil profiles; prediction; silicates; framework silicates; soils
• ISSN: 0016-7061; 1872-6259
• DOI: 10.1016/S0016-7061(98)00013-5

The inorganic component of soil horizons from a chronosequence of six soils, developed in Glen Feshie, Scotland shows an increase in surface area with soil age and a decrease in surface area with increasing depth in the soil profiles. Surface area increases due to the development of discontinuous porous coatings on mineral grains, the preferential dissolution of specific areas of individual minerals resulting in complex, highly irregular grain shapes and a general reduction in grain size due to dissolution. The discontinuous coatings consist, predominantly, of oxalate extractable Al–Si oxyhydroxides and account for between 61 and 94% of the total inorganic surface area. Failure to take into account the increase of mineral surface area with time can lead to predictions of decreasing mineral dissolution rate with soil age in contrast to laboratory studies which assume that mineral dissolution can reach a steady state. The difference between total and reactive mineral surface area may help to explain the frequently reported result that laboratory measured mineral dissolution rates are up to several orders of magnitude greater than those measured in the field.