THE EFFECT OF CRYSTALLINITY ON DISSOLUTION RATES AND CO2 CONSUMPTION CAPACITY OF SILICATES

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dc.contributor.author Wolff-Boenisch D.
dc.contributor.author Gislason S.R.
dc.contributor.author Oelkers E.H.
dc.date.accessioned 2024-05-11T04:45:01Z
dc.date.available 2024-05-11T04:45:01Z
dc.date.issued 2006
dc.identifier https://elibrary.ru/item.asp?id=12091916
dc.identifier.citation Geochimica et Cosmochimica Acta, 2006, 70, 4, 858-870
dc.identifier.issn 0016-7037
dc.identifier.uri https://repository.geologyscience.ru/handle/123456789/43885
dc.description.abstract Comparison of measured far-from-equilibrium dissolution rates of natural glasses and silicate minerals at 25 °C and pH 4 reveals the systematic effects of crystallinity and elemental composition on these rates. Rates for both minerals and glasses decrease with increasing Si:O ratio, but glass dissolution rates are faster than corresponding mineral rates. The difference between glass and mineral dissolution rates increases with increasing Si:O ratio; ultra-mafic glasses (Si:O ? 0.28) dissolve at similar rates as correspondingly compositioned minerals, but Si-rich glasses such as rhyolite (Si:O ? 0.40) dissolve ?1.6 orders of magnitude faster than corresponding minerals. This behaviour is interpreted to stem from the effect of Si-O polymerisation on silicate dissolution rates. The rate controlling step of dissolution for silicate minerals and glasses for which Si:O > 0.28 is the breaking of Si-O bonds. Owing to rapid quenching, natural glasses will exhibit less polymerisation and less ordering of Si-O bonds than minerals, making them less resistant to dissolution. Dissolution rates summarized in this study are used to determine the Ca release rates of natural rocks at far-from-equilibrium conditions, which in turn are used to estimate their CO2 consumption capacity. Results indicate that Ca release rates for glasses are faster than those of corresponding rocks. This difference is, however, significantly less than the corresponding difference between glass and mineral bulk dissolution rates. This is due to the presence of Ca in relatively reactive minerals. In both cases, Ca release rates increase by ?two orders of magnitude from high to low Si:O ratios (e.g., from granite to gabbro or from rhyolitic to basaltic glass), illustrating the important role of Si-poor silicates in the long-term global CO2 cycle. ? 2005 Elsevier Inc. All rights reserved.
dc.subject CARBON DIOXIDE
dc.subject CRYSTALLINITY
dc.subject DISSOLUTION
dc.subject REACTION RATE
dc.title THE EFFECT OF CRYSTALLINITY ON DISSOLUTION RATES AND CO2 CONSUMPTION CAPACITY OF SILICATES
dc.type Статья
dc.identifier.doi 10.1016/j.gca.2005.10.016


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