GEOL 1121 Lecture Notes - Lecture 13: Acid Rain, Formaldehyde, Hydrosphere
17 Mar 2018
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Document Summary
Hydrosphere = oceans + lakes + rivers + groundwater. Most rock-forming minerals are metastable at earth"s surface. These metastable minerals react with h2o, co2, o2 of the hydrosphere & atmosphere. The reaction of rocks with the atmosphere and hydrosphere is weathering . Key culprits are h2o, o2, h2co3 (carbonic acid), h2so4 (sulfuric acid) New minerals (especially clays & fe-oxides) & dissolved chemical species are products. Reactions proceed along cracks/fractures where water penetrates. Dissolution and removal of material is part of the process. Where layers layers tilted, the weathering process can highlight rock structure. Ridge formed by resistant layer, probably sandstone. Valley underlain by easily weathered rock, probably shale. Key observation: rainwater is slightly acidic due to: H2o + co2 = h2co3 (formation of carbonic acid in atmosphere) Ph = -log [h+] where [h+] is concentration of hydrogen ion; log scale; low numbers = acidic; high numbers = alkaline; ph = 7 is neutral.
