Physics
Scientific paper
May 1994
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1994gecoa..58.2325d&link_type=abstract
Geochimica et Cosmochimica Acta, vol. 58, Issue 10, pp.2325-2332
Physics
37
Scientific paper
Land plants and their associated microbiota directly affect silicate mineral weathering in several ways: by generation of chelating ligands, by modifying pH through production of CO 2 or organic acids, and by altering the physical properties of a soil, particularly the exposed surface areas of minerals and the residence time of water. In laboratory experiments far from equilibrium, 1 mM oxalate (a strong chelator of Al) has a negligible effect on the dissolution rate of alkali feldspars, but some effect on calcic feldspars and olivine. By analogy to oxalate, the overall effect of organic ligands on the weathering rate of silicate minerals in nature is likely to be small, except perhaps in microenvironments adjacent to roots and fungal hyphae. The effect of pH on silicate mineral dissolution rate depends on pH: below pH 4-5, the rate increases with decreasing pH, in the circumneutral region the rate is pH-independent, and at pH values above around 8 the rate increases with increasing pH. Vegetation should thus cause an increase in weathering rate through the pH effect only where the pH is below 4-5. As an overall generalization, the effect of plants on weathering rate through changes in soil-solution chemistry is probably small for granitic rocks; it may be greater for more mafic rocks. It is the release of Ca and Mg from mafic rocks that has the greatest influence on the global CO 2 budget. The effect of changes in soil physical properties on weathering rate can be major. By binding fine particles, plants can greatly increase weathering rates in areas of high physical erosion. Where erosion rates are lower, the effect of plants is less clear. On long timescales plants may decrease chemical weathering by binding secondary products and isolating unweathered minerals from meteoric water. A major unknown in estimating the effect of the advent of land plants on weathering rates is the nature (thickness, particle size distribution, permeability) of the regolith on the pre-Silurian continents. The indirect effect of vegetation through changing the regional distribution of precipitation may be as important as the direct effects.
No associations
LandOfFree
The effect of land plants on weathering rates of silicate minerals does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The effect of land plants on weathering rates of silicate minerals, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The effect of land plants on weathering rates of silicate minerals will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-886210