Chemical weathering rate laws and global geochemical cycles

Lasaga, Antonio C.; Soler, Josep M.; Ganor, Jiwchar; Burch, T.E.; Nagy, Kathryn L.

doi:10.1016/0016-7037(94)90016-7

Cited by 663 publications

(359 citation statements)

References 83 publications

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“…However, weathering and dissolution rates are generally negligible over experimental periods of hours to days [Murphy, 1993]. This assumption is probably valid for most minerals, including very soluble ones such as calcite, for which the approximate dissolution time (of a hypothetical 1-mm-diameter calcite sphere in a dilute solution at pH 5) is 0.1 year [Lasaga et al, 1994].…”

Section: Paper Number 1999wr900194mentioning

confidence: 99%

Impact of intermittent rainwater and wastewater flow on coated and uncoated fractures in chalk

Weisbrod¹,

Nativ²,

Adar³

et al. 1999

Water Resources Research

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Abstract.Two coated and two uncoated slices from the fracture surface of an unsaturated chalk were exposed to short flow events (24, 8, and 9 hours) of industrial wastewater and/or synthetic rainwater, followed by long drying periods (weeks). The topography of the fracture surface was shown to be unstable due to the detachment of colloidal and large-sized particles during the first 3-7 hours of flow. Following rainwater flow, erosion was more pronounced on the coated than on the uncoated surface (mean erosion of 0.313 and 0.134 mm, respectively). Interaction with industrial wastewater generated a skin of organic matter and gypsum that collapsed following contact with rainwater, leading to a deeper erosion of the uncoated surface (1.238 mm) than of the coated one (0.549 mm). Erosion was measured using a laser-scanning system and was calculated from high-resolution topographical maps (elevation z -< _+ 0.01 mm) generated by Geographic Information System (GIS, ARCInfo) prior to and following the flow experiments. The mean thickness of the erosion was found to be strongly correlated with the thickness of a layer calculated from the total accumulated mass of particles and soluble salts released from the fracture surface. This relationship can be used to evaluate fracture surface erosion in large field and laboratory experiments. IntroductionThe important role of fracture surface coating on solute and colloid transport through unsaturated fractures has recently gained a great deal of attention. Flow in fractured, porous aquifers takes place both in the rock matrix and in the fractures intersecting the matrix. In low-permeability rocks the large contrast between the hydraulic conductivities of the fractures and the rock matrix results in flow channeling into the frac-

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Section: Paper Number 1999wr900194mentioning

confidence: 99%

Impact of intermittent rainwater and wastewater flow on coated and uncoated fractures in chalk

Weisbrod¹,

Nativ²,

Adar³

et al. 1999

Water Resources Research

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“…In the feldspar-water system, the slow kinetics of secondary mineral precipitation results in close inter-dependence of the dissolution and precipitation reaction rates Lasaga et al, 1994;, which, if clay precipitation rate constants are sufficiently slower than feldspar dissolution rate constant, could rationalize the well-known discrepancy between field feldspar dissolution (bulk, effective) rates and rates measured in laboratory dissolution experiments at conditions far from equilibrium . Field studies often focused on the dissolution rates only.…”

Section: Discussionmentioning

confidence: 99%

“…Establishing reliable rates for low-temperature feldspar dissolution is essential to quantify many basic geological and environmental processes. Among these are the functional relationship between silicate weathering and the global climate over geologic time (Berner and Berner, 1997), controls on surface and groundwater quality, global elemental cycling (Lasaga et al, 1994), the availability of inorganic nutrients in soils (Federer et al, 1989;Likens et al, 1998), impacts of acid mine drainage, neutralization of acid precipitation in watersheds , safety of nuclear waste repositories (Spycher et al, 2003), and geological carbon sequestration .…”

Section: Discussionmentioning

confidence: 99%

“…Although the assumption of partial equilibrium has been questioned in the intervening years Nagy and Lasaga, 1993;Small, 1993;Lasaga et al, 1994;Price et al, 2005;Ganor et al, 2007), until now there has never been a rigorous examination of this hypothesis. Here, we systematically analyzed our own feldspar hydrolysis batch experiments and those in the literature.…”

Section: Discussionmentioning

confidence: 99%

“…A large body of literature on silicate weathering has focused on feldspar dissolution rates in soils and groundwater, with little references to the kinetics of product mineral precipitation (see reviews in White and Brantley, 2003;Bricker et al, 2004). Over the years, it has been shown through numerical modeling of feldspar hydrolysissecondary mineral precipitation reactions, that if the partial equilibrium assumption does not hold, aqueous chemistry evolution, mineral paragenesis, and reaction rates can deviate significantly from the Helgeson classic reaction path model Lasaga et al, 1994;Ganor et al, 2007). However, to date, the partial equilibrium hypothesis has yet to be systematically tested.…”

Section: Introductionmentioning

confidence: 99%

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A Novel Approach to Experimental Studies of Mineral Dissolution Kinetics

Chen¹

2008

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Currently, DOE is conducting pilot CO 2 injection tests to evaluate the concept of geological sequestration. The injected CO 2 is expected to react with the host rocks and these reactions can potentially alter the porosity, permeability, and mechanical properties of the host or cap rocks. Reactions can also result in precipitation of carbonate-containing minerals that favorably and permanently trap CO 2 underground. Many numerical models have been used to predict these reactions for the carbon sequestration program. However, a firm experimental basis for predicting silicate reaction kinetics in CO 2 injected geological formations is urgently needed to assure the reliability of the geochemical models used for the assessments of carbon sequestration strategies. The funded experimental and theoretical study attempts to resolve this outstanding scientific issue by novel experimental design and theoretical interpretation of silicate dissolution rates at conditions pertinent to geological carbon sequestration.In this four year research grant (three years plus a one year no cost extension), seven (7) laboratory experiments of CO 2 -rock-water interactions were carried out. An experimental design allowed the collection of water samples during experiments in situ and thus prevented back reactions. Analysis of the in situ samples delineated the temporal evolution of aqueous chemistry because of CO 2 -rock-water interactions. The solid products of the experiments were retrieved at the end of the experimental run, and analyzed with a suite of advanced analytical and electron microscopic techniques (i.e., atomic resolution transmission electron microscopy (TEM), scanning electron microscopy (SEM), electron microprobe, X-ray diffraction, X-ray photoelectron spectroscopy (XPS)). As a result, the research project probably has produced one of the best data sets for CO 2 -rock-water interactions in terms of both aqueous solution chemistry and solid characterization. Three experiments were performed using the Navajo sandstone. Navajo sandstone is geologically equivalent to the Nugget sandstone, which is a target formation for a regional partnership injection project. Our experiments provided the experimental data on the potential CO 2 -rock-water interactions that are likely to occur in the aquifer. Geochemical modeling was performed to interpret the experimental results.Our single mineral (feldspar) experiments addressed a basic research need. i.e., the coupled nature of dissolution and precipitation reactions, which has universal implication to the reaction kinetics as it applied to CO 2 sequestration. Our whole rock experiments (Navajo sandstone) addressed the applied research component, e.g., reacting Navajo sandstone with brine and CO 2 has direct relevance on the activities of a number of regional partnerships.The following are the major findings from this project:1. The project generated a large amount of experimental data that is central to evaluating CO 2 -water-rcok interactions and providing ground truth to pred...

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87Sr/86Sr-Verhältnisse als Tracer für geochemische Prozesse in einem Lockergesteinsaquifer (Liebenau, NW-Deutschland)

Wiegand¹,

Dietzel²,

Bielert³

et al. 2001

Acta hydrochim. hydrobiol.

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Grundwässer aus den quartären Lockersedimenten im Einzugsgebiet des Wasserwerkes Liebenau II (NW‐Deutschland) sind durch heterogene Verteilungen der gelösten Inhaltsstoffe charakterisiert. Zur Bestimmung der Herkunft der Lösungskomponenten und zur Ermittlung von Grundwasserfließwegen wurden Sr‐Isotopenuntersuchungen an Grundwässern, Niederschlagswässern und Sedimentproben durchgeführt. Die 87Sr/86Sr‐Verhältnisse der Grundwässer liegen im Bereich von 0.708 bis 0.719 und ermöglichen eine Unterscheidung von vier Grundwasserhorizonten. Unterschiede in den 87Sr/86Sr‐Verhältnissen resultieren aus verschiedenen Quellen des gelösten Strontiums im Grundwasser. Diese sind geprägt durch die Mineralverwitterung, die Niederschläge und anthropogene Einträge. Für den oberflächennahen Grundwasserbereich sind Einflüsse aus den Niederschlägen und vermutlich aus der landwirtschaftlichen Düngung durch niedrige 87Sr/86Sr‐Verhältnisse zwischen 0.710 und 0.713 indiziert. Mit zunehmender Tiefe dominieren Verwitterungsprozesse die Grundwasserchemie. Über das 87Sr/86Sr‐Verhältnis kann zwischen Silikat‐ und Karbonatauflösung unterschieden werden. Im mittleren Grundwasserhorizont bestätigen hohe 87Sr/86Sr‐Verhältnisse zwischen 0.713 und 0.719 und Sättigungsindices < –3.5 für Calcit den Einfluss verwitternder Silikate. Niedrige 87Sr/86Sr‐Verhältnisse von 0.708 bis 0.709 bei gleichzeitig hohem Sättigungsgrad für Calcit sind auf die Auflösung von Karbonatmineralen in den tiefen Grundwässern zurückzuführen.

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Chemical weathering rate laws and global geochemical cycles

Cited by 663 publications

References 83 publications

Impact of intermittent rainwater and wastewater flow on coated and uncoated fractures in chalk

Impact of intermittent rainwater and wastewater flow on coated and uncoated fractures in chalk

A Novel Approach to Experimental Studies of Mineral Dissolution Kinetics

87Sr/86Sr-Verhältnisse als Tracer für geochemische Prozesse in einem Lockergesteinsaquifer (Liebenau, NW-Deutschland)

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