Reaction rate-surface area relationships during the early stages of weathering—I. Initial observations

摘要: It has commonly been assumed that the weathering rates of feldspars are proportional to their exposed surface areas. However, does not affect whole a grain uniformily; preferential dissolution occurs at highly localized sites, which determined by location crystalline defects. To examine importance reactions these sites relative those occurring on bulk surfaces, we compared 5 different size fractions an alkali feldspar, whose specific areas (m2/g) spanned range factor twenty. At any given pH value, (moles/g/h) for five varied less than two. The results suggest defects dominate processes during early stages dissolution. Furthermore, exposure is simply or easily related total area. These findings strongly care must be taken distinguish between reaction controlled mechanism and area model frequently—and incorrectly—assumed equivalent. data presented here consistent with former but dispute latter.