Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6335045 | Applied Geochemistry | 2015 | 12 Pages |
Abstract
The dissolution of silicate minerals by CO2-rich fluids and the subsequent precipitation of CO2 as carbonate minerals represent a means of permanently storing anthropogenic CO2 waste products in a solid and secure form. Modelling the progression of these reactions is hindered by our poor understanding of the rates of mineral dissolution-precipitation reactions and mineral surface properties in natural systems. This study evaluates the chemical evolution of groundwater flowing through a basalt aquifer, which forms part of the leaking CO2-charged system of the Blackfoot Volcanic Field in south-eastern Idaho, USA. Reaction progress is modelled using changes in groundwater chemistry by inverse mass balance techniques. The CO2-promoted fluid-mineral reactions include the dissolution of primary plagioclase, orthoclase, pyroxene and gypsum which is balanced by the precipitation of secondary albite, calcite, zeolite, kaolinite and silica. Mineral mole transfers and groundwater flow rates estimated from hydraulic head data are used to determine the kinetics of plagioclase and orthoclase feldspar dissolution. Plagioclase surface area measurements were determined using the evolution of the U-series isotope ratios in the groundwater and are compared to published surface area measurements. Calculated rates of dissolution for plagioclase range from 2.4Â ÃÂ 10â12 to 4.6Â ÃÂ 10â16Â mol/m2/s and orthoclase from 2.0Â ÃÂ 10â13 to 6.8Â ÃÂ 10â16Â mol/m2/s respectively. These feldspar reaction rates, correlate with the degree of mineral-fluid disequilibrium and are similar to the dissolution rates for these mineral measured in other natural CO2-charged groundwater systems.
Related Topics
Physical Sciences and Engineering
Earth and Planetary Sciences
Geochemistry and Petrology
Authors
Alexandra Maskell, Niko Kampman, Hazel Chapman, Daniel J. Condon, Mike Bickle,