Direct measurement of the combined effects of lichen,rainfall, and temperature onsilicate weathering |
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| Institution: | 1. U.S. Environmental Protection Agency, Office of Research and Development, National Center for Environmental Assessment, Cincinnati, OH, USA;2. Tetra Tech, 10711 Red Run Blvd., Suite 105, Owings Mills, MD 21117, USA;3. U.S. Environmental Protection Agency, Office of Water, Office of Science and Technology, Health and Ecological Criteria Division, Washington, DC 20460, USA;1. Università degli Studi di Cagliari, via Trentino 51, 09127 Cagliari, Italy;2. U.S. Geological Survey, MS 964d Denver Federal Center, Denver, CO 80225, USA;1. Mechanical Engineering Department, Thapar University, Patiala, Punjab Pin 147004, India;2. Chemical Engineering Department, Thapar University, Patiala, Punjab Pin 147004, India |
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| Abstract: | A key uncertainty in models of the global carbonate–silicate cycle and long-term climate is the way that silicates weather under different climatologic conditions, and in the presence or absence of organic activity. Digital imaging of basalts in Hawaii resolves the coupling between temperature, rainfall, and weathering in the presence and absence of lichens. Activation energies for abiotic dissolution of plagioclase (23.1 ± 2.5 kcal/mol) and olivine (21.3 ± 2.7 kcal/mol) are similar to those measured in the laboratory, and are roughly double those measured from samples taken underneath lichen. Abiotic weathering rates appear to be proportional to rainfall. Dissolution of plagioclase and olivine underneath lichen is far more sensitive to rainfall. |
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