An experimental study of crystalline basalt dissolution from 2 ≤ pH ≤ 11 and temperatures from 5 to 75 ºC
MetadataShow full item record
Steady-state element release rates from crystalline basalt dissolution at far-from-equilibrium were measured at pH from 2 to 11 and temperatures from 5 to 75 °C in mixed-flow reactors. Steady-state Si and Ca release rates exhibit a U-shaped variation with pH where rates decrease with increasing pH at acid condition but increase with increasing pH at alkaline conditions. Silicon release rates from crystalline basalt are comparable to Si release rates from basaltic glass of the same chemical composition at low pH and temperatures ≥ 25 °C but slower at alkaline pH and temperatures ≥ 50 °C. In contrast, Mg and Fe release rates decrease continuously with increasing pH at all temperatures. This behaviour is interpreted to stem from the contrasting dissolution behaviours of the three major minerals comprising the basalt: plagioclase, pyroxene, and olivine. Calcium is primarily present in plagioclase, which exhibits a U-shaped dissolution rate dependence on pH. In contrast, Mg and Fe are contained in pyroxene and olivine, minerals whose dissolution rates decrease monotonically with pH. As a result, crystalline basalt preferentially releases Mg and Fe relative to Ca at acidic conditions. The injection of acidic CO2-charged fluids into crystalline basaltic terrain may, therefore, favour the formation of Mg and Fe carbonates rather than calcite. Element release rates estimated from the sum of the volume fraction normalized dissolution rates of plagioclase, pyroxene, and olivine are within one order of magnitude of those measured in this study.
Showing items related by title, author, creator and subject.
Dissolution of basalts and peridotite in seawater, in the presence of ligands, and CO2: Implications for mineral sequestration of carbon dioxideWolff-Boenisch, Domenik; Wenau, S.; Gislason, S.; Oelkers, E. (2011)Steady-state silica release rates (rSi) from basaltic glass and crystalline basalt of similar chemical composition as well as dunitic peridotite have been determined in far-from-equilibrium dissolution experiments at 25 ...
Olsson-Francis, K.; Simpson, A.; Wolff-Boenisch, Domenik; Cockell, C. (2012)The weathering of volcanic rocks contributes significantly to the global silicate weathering budget, effecting carbon dioxide drawdown and long-term climate control. The rate of chemical weathering is influenced by the ...
Influence of pH and temperature on alunite dissolution: Rates, products and insights on mechanisms from atomistic simulationAcero, P.; Hudson-Edwards, K.; Gale, Julian (2015)The processes, rates, controlling factors and products of alunite (KAl3(SO4)2(OH)6) dissolution were assessed using batch dissolution experiments at pHs of c. 3, 4, 4.6, 7 and 8, and temperatures of c. 280, 293 and 313K. ...