The mechanism of Zn2+ adsorption on calcite

Zachara, John M.; Kittrick, J. A.; Harsh, James B.

doi:10.1016/0016-7037(88)90130-5

Cited by 158 publications

(88 citation statements)

References 47 publications

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“…Cr, Cu, Pb and Zn) but particularly in elements like Zn, and to a lesser extent Cu, which have a higher tendency to sorb onto calcite. The interaction of divalent metals with calcite has been extensively investigated (Crockett and Winchester, 1966;Kitano et al, 1976;McBride, 1979McBride, , 1980Morse, 1982, 1983;Kornicker et al, 1985;Davis et al, 1987, Zachara et al, 1988Tesoriero and Pankow, 1996;Parkman et al, 1998). As a result, several mechanisms have been proposed to explain the retention of these elements by calcite surfaces, i.e.…”

Section: Description and Interpretation Of Resultsmentioning

confidence: 99%

“…adsorption, ion exchange, surface complexation, solid solution precipitation and pure-phase precipitation, depending on factors such as ionic radii and solvation energies of the cations, concentration of metals in solution, recrystallization rates of calcite, etc. In the specific case of Zn, Zachara et al (1988) concluded that adsorption onto calcite mainly occurs through exchange of Zn + and ZnOH + with Ca + in a hydrated layer adsorbed to the calcite surface, and that the surface complex thus formed had a marked covalent character. Thus, the considerable desorption of Zn from the carbonate surface at moderately low pH values observed in our work is attributed by Zachara et al (1988) to the reversibility of the sorption process in the presence of Ca + which increases in concentration as the pH of the CaC0 3(aq ) solution is lowered.…”

Section: Description and Interpretation Of Resultsmentioning

confidence: 99%

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Geochemical fingerprints and controls in the sediments of an urban river: River Manzanares, Madrid (Spain)

Miguel¹,

Charlesworth

Ordóñez

et al. 2005

Science of The Total Environment

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The geochemical fingerprint of sediment retrieved from the banks of the River Manzanares as it passes through the City of Madrid is presented here. The river collects the effluent water from several Waste Water Treatment (WWT) plants in and around the city, such that, at low flows, up to 60% of the flow has been treated. A total of 18 bank-sediment cores were collected along the course of the river, down to its confluence with the Jarama river, to the south-east of Madrid. Trace and major elements in each sample were extracted following a double protocol: (a) "Total" digestion with HN0 3 , HC10 4 and HF; (b) "Weak" digestion with sodium acetate buffered to pH=5 with acetic acid, under constant stirring. The digests thus obtained were subsequently analysed by ICP-AES, except for Hg which was extracted with aqua regia and sodium chloride-hydroxylamine sulfate, and analysed by Cold Vapour-AAS. X-ray diffraction was additionally employed to determine the mineralogical composition of the samples. Uni-and multivariate analyses of the chemical data reveal the influence of Madrid on the geochemistry of Manzanares' sediments, clearly manifested by a marked increase in the concentration of typically "urban" elements Ag, Cr, Cu, Pb and Zn, downstream of the intersection of the river with the city's perimeter. The highest concentrations of these elements appear to be associated with illegal or accidental dumping of waste materials, and with the uncontrolled incorporation of untreated urban runoff to the river. The natural matrix of the sediment is characterised by fairly constant concentrations of Ce, La and Y, whereas changes in the lithology intersected by the river cause corresponding variations in Ca-Mg and Al-Na contents. In the final stretch of the river, the presence of carbonate materials seems to exert a strong geochemical control on the amount of Zn and, to a lesser extent, Cu immobilised in the sediments. This fact suggests that a variable but significant proportion of both elements may be susceptible to reincorporation in the aqueous phase under realistic environmental conditions.

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Section: Description and Interpretation Of Resultsmentioning

confidence: 99%

Section: Description and Interpretation Of Resultsmentioning

confidence: 99%

Geochemical fingerprints and controls in the sediments of an urban river: River Manzanares, Madrid (Spain)

Miguel¹,

Charlesworth

Ordóñez

et al. 2005

Science of The Total Environment

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“…particularly Ca, Mg. trivalent cations, and actinides. Zachara et al (1988) showed that Zn adsorbed to calcite by exchanging for Ca. Exchange was greatest when Ca levels were lowest, which was generally at high pH and low Pco,.…”

Section: Introductionmentioning

confidence: 99%

“…1985;McBride. 1979a,b;Zachara et al, 1991;Zachara et al, 1988). Am3+ adsorption onto calcite was measured by Shanbhag and Morse (1982) and found to be largely irreversible.…”

Section: Introductionmentioning

confidence: 99%

Metal sorption to dolomite surfaces

Brady

Papenguth

Kelly

1999

Applied Geochemistry

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Potential human intrusion into the Waste Isolation Pilot Plant (WIPP) might release actinides into the Culebra Dolomite where sorption reactions will affect of radiotoxicity from the repository. Using a limited residence time reactor the authors have measured Ca, Mg, Nd adsorption/exchange as a function of ionic strength, Pcoz, and pH at 25°C. By the same approach, but using as input radioactive tracers, adsorption/exchange of Am, Pu, U, and Np on dolomite were measured as a function of ionic strength, Pcoz, and PH at 25"C. Metal adsorption is tYPical@ favored at high pH. Calcium and Mg adsorb in near-stoichiometric proportions except at high pH. Adsorption of Ca and Mg is diminished at high ionic strengths (e.g., 0.5M NaCl) pointing to association of Na + with the dolomite surflce, and the possibility that Ca and Mg sorb as hydrated, outer-sphere complexes. Sulfate amplifies sorption of Ca and Mg, and possibly Nd as well. Exchange of Nd for surface Ca is favored at high pH, and when Ca levels are low. Exchange for Ca appears to control attachment of actinides to dolomite as well, and high levels of Ca2 + in solution will decrease Kds. At the same time, t~the extent that high Pcojs increase Ca2 + levels, &S will decrease with C02 levels as well, but only if sorbing actinide-carbonate complexes are not observed to form (Amcarbonate complexes appear to sorb; Pu-complexes might sorb as well. U-carbonate complexation leads to resorption). This indirect C02 effect is observed primarily at, and above, neutral pH. High NaCl levels do not appear to atTect to actinide Kds

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“…Mg est lié au carbonate des nodules comme on a pu le montrer en analyse X. Il y a quelques différences mineures entre les sites: -à Tillabéri, le quartz semble moins abondant, tandis que l'on trouve beaucoup d'oxyde de fer que l'on peut relier à la teinte fortement ocrée. est particulièrement élevé à Namardé Goungou, signe peut-être de milieu plus réducteur dans ce sol (Zachara et al, 1988). Les teneurs varient d'un site à l'autre et, à l'intérieur d'un même nodule les hétérogénéités sont importantes et on note systématiquement un enrichissement du centre vers la périphérie des teneurs en éléments en traces dans la calcite.…”

Section: Chimieunclassified

Interprétation paléoclimatique et paléohydrologique de l'origine des nodules carbonatés des terrasses du Niger aux environs de Niamey (Niger) au moyen des outils isotopiques et géochimiques

Taupin¹

2003

Hydrological Sciences Journal

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Résumé Cette étude se situe au Niger en région sahélienne, près de la ville de Niamey, et a pour but la reconstitution des conditions de formation des différents types de nodules carbonatés que l'on trouve sur les anciennes terrasses du fleuve Niger. La chimie, la géochimie isotopique (radioactif et stable) et l'étude minéralogique des carbonates ont été utilisées pour dater les nodules et reconstituer les conditions de précipitation. Les résultats montrent bien l'authigénie et l'accrétion dans le premier mètre du sol des nodules de la vallée du Niger. L'âge de formation des nodules apparaît ancien, entre 1500 et 7000 ans BP. Cette plage de temps correspondrait à une période transitoire entre les conditions de sécheresse actuelles et l'importante phase humide régionale située entre 10 000 et 4500 ans BP. Cependant, la diversité des âges obtenus, ainsi que les différentes formes de nodules montrent que des facteurs très locaux (état de la nappe localement, végétation, texture du sol) ont dû aussi jouer un rôle dans le processus de précipitation des nodules.Mots clefs profil de sol; nodule carbonaté; paléoclimatologie; Niger; Sahel Palaeoclimatic and palaeohydrological interpretation on the origin of carboneous nodules in the Niger River terraces close to Niamey (Niger) using isotopic and geochemical tools Abstract This study is located in Niger in the Sahelian area, close to the city of Niamey and its aim is to determine the conditions for the formation of carboneous nodules which may be found on the old terraces of the Niger River. The chemistry, the isotopic geochemistry (radioactive and stable)and mineralogical studies of the carbonates were used to date the nodules and reconstruct the precipitation conditions. The results show that the nodules were formed in the first metre of soil and demonstrate the contribution of the shallow groundwater in this process. The nodules seem old; they appear to have been formed between 1500 and 7000 BP. This time interval could agree with the transitional period between the present dry conditions and the regional humid phases that occurred between 10 000 and 4500 BP. However the diversity of dating and the different types of nodules show that local parameters (groundwater, vegetation, soil texture) must also have contributed in the precipitation process of nodules.

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The mechanism of Zn2+ adsorption on calcite

Cited by 158 publications

References 47 publications

Geochemical fingerprints and controls in the sediments of an urban river: River Manzanares, Madrid (Spain)

Geochemical fingerprints and controls in the sediments of an urban river: River Manzanares, Madrid (Spain)

Metal sorption to dolomite surfaces

Interprétation paléoclimatique et paléohydrologique de l'origine des nodules carbonatés des terrasses du Niger aux environs de Niamey (Niger) au moyen des outils isotopiques et géochimiques

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