Dissolution kinetics of carbonate rocks: 1. Effects of lithology on dissolution rate

Abstract

Laboratory dissolution of Middle Ordovician rock samples from central Pennsylvania was studied at 23°C and 1 atm carbon dioxide pressure. Carbonate dissolution rates were compared at 22% bicarbonate saturation with respect to both calcite and dolomite. The results show that carbonate lithology exerts a strong influence on the dissolution rate and hence on the degree of cavity development in karst aquifers. The dissolution rate is most significantly affected by dolomite and impurity content. The rate decreases as percentages of dolomite and disseminated insolubles increase. Maximum dissolution rates occur for carbonate rocks with 1.0–2.5% MgO content and having abundant silty streaks. The sparite content is inversely related to cave development but is independent of dissolution rates measured under the laboratory conditions adopted in this study.

Dinâmica Do Sistema Hidrogeológico Cárstico Na Área De Tranqueira - Região Metropolitana De Curitiba

“…Com relação aos dolomitos, a solubilidade é considerada 20 vezes menor do que a dos calcários (Castany, 1971). Em trabalho experimental posterior, Rauch & White (1977) encontraram taxas de dissolução máxima quando o teor de MgO da rocha carbonática está entre 1,0 e 2,5%, sendo que essas taxas decrescem à medida que as porcentagens de dolomita e insolúveis disseminados aumentam ( fig. 3.1 A e B).…”

“…C. Taxa de dissolução carbonática a 22 % de saturação comparada com a textura petrográfica de rochas carbonáticas. Modificado de Rauch & White (1977). menos solúveis se o tamanho dos grãos e o empacotamento forem uniformes.…”

“…O desenvolvimento das cavidades e as taxas de dissolução são máximos quando a rocha apresenta um baixo conteúdo de dolomita, teor de magnésio baixo (mas não zero), pouco material insolúvel disseminado, e textura cristalina fina (micrito, especialmente biomicrito) (Rauch & White, 1977).…”

Evaluation of Neutralization Potential Determinations for Metal Mine Waste and a Proposed Alternative

“…Reactions 3 and 5 are dominant above approximately pH 6.3, while reactions 4 and 6 are dominant below this pH. The rate of magnesium carbonate dissolution is reported to be slower than that of calcium carbonate (Rauch and White 1977). Iron carbonates will provide no net neutralization of acid.…”

William B. White and Elizabeth L. White (USA): their contributions to karst hydrogeology discussed in an interview

“…William White found a first answer to this question: Water in contact with limestone rapidly reaches a saturation level of about 80%, but after that point, the dissolution rate drops dramatically and finally becomes very slow. Therefore, slightly undersaturated water can actually enter deep into the limestone and cause initial karstification, and thus create initial groundwater flowpaths (White 1977;Rauch and White 1977). Later, other researchers continued to work on this problem and developed sophisticated models to simulate the process of speleogenesis and groundwater flow through evolving conduit networks.…”