Phytoliths dissolution

Alexandre et al. (1997) found that the biogenic sihca input into the biogeochemical silica cycle from the dissolution of phytoliths is twice as large as silica input from primary silicate mineral weathering in the tropical Congo rainforest. Biogenic (opaline) silica dissolves faster than sihcate minerals. While most of the phytoliths dissolve rapidly with a mean residence time of 6 months (Alexandre et al., 1994), and the sihca is recycled by the forest, a small part (7.5%) does not dissolve and is preserved in the soil. 

Contaminants. Fe and A1 ions can become chemically adsorbed onto surfaces of particulate silica and inhibit dissolution (Jones and Handreck, 1967) occluded carbonaceous matter also has been suggested as possibly having an inhibitory effect on the dissolution of phytoliths (Wilding and Drees, 1974). 

The rate of dissolution of quartz, also in the presence of Al(iii), was studied in [192]. The rate of dissolution of quartz at 25°C and higher temperatures as a function of pH is reported in [188]. The dissolution rate of silica at pH 10 increases as the Na concentration in solution (as chloride or sulfate) increases [193]. The dissolution kinetics of silica as the function of pH and ionic strength was studied in [194]. The kinetics of dissolution of silica at low pH was studied in [195]. The rate of dissolution of bamboo phytoliths, which are composed chiefly of silica, is reported in [196]. 

Fraysse, F. et al.. Surface properties, solubility and dissolution kinetics of bamboo phytoliths, Geochim. Cosmochim. Acta, 70, 1939, 2006. 

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