Hydrogen ion exchange on amorphous silica in seawater |
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Authors: | CH Culberson RM Pytkowicz EL Atlas |
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Institution: | School of Oceanography, Oregon State University, Corvallis, Oreg. U.S.A. |
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Abstract: | The amount of hydrogen ion exchange on the surface of amorphous silica in seawater was measured as a function of pH at 2 and 25°C. Hydrogen ion exchange with the cations present in seawater is pH dependent and at 25°C the fraction of the surface in the cation form increases from 9% at pH 7 to 22% at pH 8. The exchange is temperature dependent and at 2°C and pH 8, 14% of the exchange sites are occupied by cations, as opposed to 22% of the exchange sites at 25°C. These results were used to calculate the buffer capacity of a model sediment consisting of pore water and amorphous silica. For a sediment of 70% porosity, pH 7.7, and 25°C, the buffer capacity of sediment plus pore water is 67 times the buffer capacity of pure seawater. |
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