Chemical speciation of Cd, Cu, Pb, and Zn in mixed freshwater, seawater, and brine solutions

Long, David T.; Angino, Ernest E.

doi:10.1016/0016-7037(77)90064-3

Cited by 115 publications

(41 citation statements)

References 17 publications

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“…Because Zn sulfate complexes (12) stand out as particularly enriched in heavy isotopes, the effect of Zn complexation by sulfate in hydrothermal fluids must be considered. At ambient temperature and for sulfate concentration typical of modern seawater (28.6 mmol kg −1 ), Zn-sulfate complexes are subordinate, making up less than a few percent of the metallic ion and chloride complexes (12,28). Seawater-like abundances are too low to induce a substantial isotopic shift of the sulfide species, and therefore of the sulfide minerals precipitated from the solutions, toward negative δ 66 Zn values.…”

Section: Resultsmentioning

confidence: 99%

“…For want of a strong isotopic effect induced by sulfates, complexation by carbonate ions is a potential alternative. In seawater and in other hydrous fluids equilibrated under surface conditions, carbonate complexes are not abundant (13,28). High carbonate concentrations are unlikely along midocean ridges because there is no other source of CO 2 than mantle outgassing and even that CO 2 is largely reduced to methane by hydrogen.…”

Section: Resultsmentioning

confidence: 99%

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Early Archean serpentine mud volcanoes at Isua, Greenland, as a niche for early life

Pons

Quitté

Fujii

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

100

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The Isua Supracrustal Belt, Greenland, of Early Archean age (3.81-3.70 Ga) represents the oldest crustal segment on Earth. Its complex lithology comprises an ophiolite-like unit and volcanic rocks reminiscent of boninites, which tie Isua supracrustals to an island arc environment. We here present zinc (Zn) isotope compositions measured on serpentinites and other rocks from the Isua supracrustal sequence and on serpentinites from modern ophiolites, midocean ridges, and the Mariana forearc. In stark contrast to modern midocean ridge and ophiolite serpentinites, Zn in Isua and Mariana serpentinites is markedly depleted in heavy isotopes with respect to the igneous average. Based on recent results of Zn isotope fractionation between coexisting species in solution, the Isua serpentinites were permeated by carbonate-rich, high-pH hydrothermal solutions at medium temperature (100-300°C). Zinc isotopes therefore stand out as a pH meter for fossil hydrothermal solutions. The geochemical features of the Isua fluids resemble the interstitial fluids sampled in the mud volcano serpentinites of the Mariana forearc. The reduced character and the high pH inferred for these fluids make Archean serpentine mud volcanoes a particularly favorable setting for the early stabilization of amino acids.hydrothermal fluids | serpentinization | origin of life | subduction zone T he discovery of oceanic black smokers and their unique fauna prompted the idea that life may have sprung from hydrothermal vent fields at the bottom of the ocean (1-3). The highly reducing conditions of the vent fields associated with midocean ridges fulfill one of the most stringent conditions for the stabilization of biomolecules. These conditions are a consequence of the metamorphic hydration and oxidation of ultramafic rocks of the oceanic lithosphere-a series of reactions known as serpentinization-that release highly reduced hydrothermal fluids with high concentrations of methane, ammonia, and hydrogen (4, 5). Serpentinization also produces FeNi 3 , which catalyses formation of complex organic compounds (5). Serpentinization thus provides both a source of reduced carbon and a potential energy source, which, together, create an environment suitable for the emergence of the first biomolecules. The vast majority of hydrothermal vent fields, however, especially those hosted by midocean ridges, spout solutions with pH well below the pK of amino acids, which makes them unsuitable for Strecker synthesis (6, 7). Attention therefore shifted toward high-pH hydrothermal vent sites (8, 9) and notably toward the modern vent fluids from the unusual midocean ridge locality of Lost City.The search for an Archean environment in which reducing and high-pH conditions coexist at temperatures appropriate for supporting early life prompted us to investigate Isua serpentinites and their associated hydrothermal carbonates (10). Precipitation of large amounts of carbonates suggests that carbonate ions were abundant in the parent fluid and therefore signals that the pH of this fluid was...

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Early Archean serpentine mud volcanoes at Isua, Greenland, as a niche for early life

Pons

Quitté

Fujii

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

100

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“…The salts deposits in the saline ponds contain between 1.6 and 16 µmoles kg -1 . It is necessary to note that, like Lead, Copper is strongly complexed by chlorides and carbonates ions, even in the dilute solutions (Long and Eangino, 1977). The general pace of the curve Cu versus FC recalls those of calcium and strontium (Amdouni, 2000).…”

Section: Cadmium Behaviourmentioning

confidence: 98%

“…According to the physico-chemical conditions (pH, temperature and salinity), several complex shapes (CdCl + , CdCl 2°, CdCl 3 -and CdCO 3 ) can appear in solution. In neutral or slightly acidic solutions, the speciation of the cadmium is extensively dominated by the chlorides complex (Long and Eangino, 1977). In brines of Sfax Saline, the general evolution of the content in cadmium shows a certain resemblance to those of strontium and calcium (Amdouni, 2000).…”

Section: Cadmium Behaviourmentioning

confidence: 99%

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Behaviour of trace elements during the naturel evaporation of sea water: case of solar salt works of Sfax saline (S.E. of Tunisia)

2013

Issue 1

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We have carried out a geochemical study on the behaviour of certain trace elements during the evaporative concentration of free brines (salinity from 41 to 400 ‰) of the solar salt works of Sfax saline (S.E of Tunisia). The elements concerned by this survey are Zinc, Cadmium, Manganese, Molybdenum, Lead, Copper, Aluminium, Iron and Barium. Adequate analytical techniques, adapted to this environment of high salinity, have been used to follow the evolution of the concentration of concerned elements in brines subjected to the evaporation. The results obtained have been presented in function of concentration factor calculated on the basis of the Lithium content in seawater (Coast of Sfax) and those in the brines of salt works. During the evaporation process, the concentration of trace elements in brines was affected by the evaporation phenomenon for the same reason as the major elements. Nevertheless, their concentrations remain very weak and don't reach their saturation doorsteps. The participation of these elements in the mineral phases can take place only by co-precipitation with saline paragenesis. It is the case of Zinc that can precipitate with Sulphates Salts, the Cadmium, Barium and Copper with Carbonate and Gypsum, the Manganese and the Molybdenum with Potassium Salts; others like Iron and Aluminium, are characterized by a very complex behaviour and are subjected, therefore to effects others than those of the evaporation and the co-precipitation. We can mention the activity of the biological system and adsorption phenomena, in particular, on the organic and mineral particles. They are frequent in ponds where brines are not yet very concentrated; allowing an important biological productivity. Contents in these elements are then variable and very dependent on the growth and the physiological state of the organic matter. These micro-organisms use some metals in their metabolic activities, and notably those that act like vitamin factors. The analysis of sediment and algae sampled from the first ponds of the saline, shows that they are capable as well to fix some important quantities of trace elements. The liberation of these elements by deterioration of organic matter, provoke the important fluctuations of their contents in free brines. In basins where the biologic activity is very limited because of the increase of brines salinity, the evolution of the concentration of trace elements translate the only effect of the evaporation, counterbalanced by adsorption phenomenon and the co-precipitation with the salts deposit. KEYWORDS:Brines, salinity, salt, salt works, concentration factor, saturation, biological system, adsorption, algae co-precipitation, saline paragenesis. BEHAVIOUR OF TRACE ELEMENTS DURING NATURAL EVAPORATION 97 INTRODUCTIONSolar Salt works of Sfax saline were installed in the south of Sfax City. They cover nearly 1500 hectares area divided on several ponds along seacoast about 12 km (Figure 1). From the sea, the initial solutions (salinity ≈ 40 ‰) are progressively concentrated; to reach ...

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Activity Coefficients of Strongly Complexing Compounds

Zemaitis¹,

Clark

Rafal

et al. 1986

Handbook of Aqueous Electrolyte Thermodynamics

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Chemical speciation of Cd, Cu, Pb, and Zn in mixed freshwater, seawater, and brine solutions

Cited by 115 publications

References 17 publications

Early Archean serpentine mud volcanoes at Isua, Greenland, as a niche for early life

Early Archean serpentine mud volcanoes at Isua, Greenland, as a niche for early life

Behaviour of trace elements during the naturel evaporation of sea water: case of solar salt works of Sfax saline (S.E. of Tunisia)

Activity Coefficients of Strongly Complexing Compounds

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