Zinc In Seawater Research Articles

Study of corrosion product of zinc in natural sea water

AbstractThe electrochemical behaviour of zinc has been studied with special emphasis on the corrosion product formed in natural sea water under laboratory conditions and during in situ tests at sea. The behaviour of corrosion products was studied by a cathodic polarisation method, and the type and amount of zinc compound contained therein were assessed from cyclic polarisation curves. The corrosion product consisted mainly of basic hydroxychloride, which enhanced the compactness of the adherent corrosion product layer. From the cyclic polarisation curves, the area inside the hysteresis loop Q provided a measure of the specific surface area coated by corrosion products and was found to increase as the duration of exposure of zinc in sea water was increased in both laboratory and field tests. It was shown that the corrosion product compactness factor C = Q/Icorr was of value for characterising the barrier to oxygen diffusion provided by this layer.

Preconcentration of Trace Amounts of Zinc in Seawater Using a Dynamically Coated Column of Methyltricaprylylammonium Chloride on Octadecylsilylsilica and Determination by Graphite-Furnace AAS

An octadecylsilylsilica (C18) column dynamically coated with methyltricaprylylammonium chloride (C18-Aliquat 336) was examined for the preconcentration of trace amounts of Zn in water samples. Zinc was quantitatively retained on the column from an HCl solution at between 0.5 and 3mol dm-3, or seawater acidified with HCl, ranging from 0.5 to 1.0mol dm-3. The retention capacity of the C18-Aliquat 336 for zinc was about 50μmol g-1 from a 1mol dm-3 HCl solution. The Zn retained on the column was completely eluted with 3.5ml of 0.1mol dm-3 nitric acid, and was directly determined by graphite-furnace atomic absorption spectrometry. The precision and accuracy of the present method were demonstrated by analyzing certified reference materials, such as Coastal Seawater (CASS-2) and Riverine Water (SLRS-3). The total procedural blank was 1.9±0.4ng for Zn. The detection limit (3σ of the blanks) was 2.4ng dm-3 for Zn based on a 125-fold concentration of a 500-ml sample.

Direct determination of zinc in seawater by graphite furnace atomic absorption spectrometry

Zinc in seawater was determined directly by graphite furnace atomic absorption spectrometry (GFAAS), using a stabilized temperature platform furnace (STPF) technique, and Zeeman background correction. Zinc in seawater was determined directly without modifier; the detection limit was 0.11 μg/1. Unpolluted seawater can be analyzed by this simple method generating results with high accuracy and precision. Significantly improved sensitivity and precision of the atomic signal were achieved when zinc in seawater was atomized from a graphite surface pretreated with vanadium (NH 4VO 3). With vanadium as modifier, the detection limit is decreased to 0.024 μg/l. The method of standard additions was used. The accuracy and precision of the developed methods were confirmed by analysis of certified reference saline waters.

Determination of Zinc in Seawater Using Flow Injection Analysis with Fluorometric Detection

A sensitive technique for the shipboard determination of zinc in seawater has been developed. The technique couples flow injection analysis with fluorometric detection (FIA-FL). A cation exchange column was used to separate zinc from interering alkali and alkaline earth ions and to concentrate Zn from seawarer. The organic indicator ligan, p-tosyl-8-aminoquinoline, was used to form a complex with zinc, the fluorescence of which was determined with a flow-through fluorometer. The deterction limit (defined as three times the standard deviation of the blank, n=4) was 0.1 nM for a 4.4-mL sample

Embryo-larval tolerance of Mytilus galloprovincialis, exposed to elevated seawater metal concentrations—II. Stage-specific fluctuations in sensitivity toward Zn and Cd and their bioaccumulation into veliger larvae

Acute intoxication of selected embryo-larval stages of M. galloprovincialis within successive 8-hr exposure intervals by elevated zinc and cadmium seawater concentrations, indicated stage- and metal-specific variations appearing in different proportions in normally developed straight-hinge veliger larvae. Zinc was found to be markedly more toxic than cadmium, particularly within the period of early cleavage and blastula stages. Embryos undergoing tissue differentiation and formation of the trochophora stage were substantially more sensitive regarding both metals tested in comparison with later veliger stages. Combined cadmium-zinc toxicity within each exposure interval tested appears to be less than additive, possibly associated with a markedly higher level of induced MT. The ability of developing embryos to concentrate seawater zinc (CF65Zn = 399) was approximately 2.5 times higher than for cadmium (CF109Cd = 160), which may also contribute to the observed difference in their tolerance levels

Direct determination of zinc in sea-water using electrothermal atomic absorption spectrometry with Zeeman-effect background correction: effects of chemical and spectral interferences

The determination of zinc in sea-water using an electrothermal atomic absorption spectrometry system with Zeeman-effect background correction is presented. The influence of various chloride and nitrate salts on the atomization signal of zinc was examined. In chloride medium particularly, the interference effect induced through losses of zinc chloride, by the thermohydrolysis of magnesium chloride and simultaneous generation of HCl during the pyrolysis step is noted. In nitrate medium, zinc is more stabilized by Mg > Ca > Na > NH+4. The effect of various inorganic and organic acids, used as chemical modifiers, on the atomization of zinc and background absorption signals in sea-water were examined. In unmodified sea-water, a Zeeman interference effect related to the vaporization of the chloride matrix leading to a systematic under-compensation and consequently to erroneous zinc concentration values was observed. In sea-water, modified with 1 mol l–1 nitric acid, a spectral Zeeman interference effect induced by the Zeeman splitting of the absorption bands of NO molecules generated during the decomposition–reduction of nitrate was observed; the induced over-compensation is eliminated by selective pyrolysis at about 850 °C. The chemical interference effect (25%) is related to the simultaneous vaporization of zinc and sodium oxides; the detection limit (3σ) being about 80 ng l–1 for a 10 µl injected volume of sea-water. In sea-water modified with 0.7 mol l–1 oxalic acid, there is no significant interference effect and the detection limit in this medium is about 60 ng l–1 for a 10 µl injected volume of sea-water.

Determination of trace elements in sea water by flow-injection anodic stripping voltammetry preceded by immobilized quinolin-8-ol silica gel preconcentration

Procedures based on the application of immobilized quinolin-8-ol silica gel and stripping voltammetry were developed for the determination of copper, lead, cadmiun, bismuth, indium and zinc in sea water. As two concentration steps are involved, better sensitivity and lower detections limits could be achieved with application of smaller sample volumes. The feasibility and reliability of the developed procedures were confirmed by the analysis of a near-shore sea-water sample and CASS-2 references sea water.

Effect of zinc on the growth and development of larvae of bay scallopArgopecten Irradians

The 48-h straight-hinge larvae ofArgopecten irradians were exposed for 9 days to various concentrations of zinc in seawater. The growth rate of larvae in the 50 ppb Zn mediums was 77% that of the controls, and nearly zero in the 200 ppb Zn mediums. A progressive decrease in growth and increase in larval deformity and mortality was observed with increasing zinc concentrations from 50 to 200 ppb. 50 and 100 ppb Zn resulted in delayed development of eye spot and metamorphosis and reduced numbers of larvae at both stages. All larvae subjected to higher zinc concentrations died before attaining the eye-spot stage. The zinc concentrations which caused 50% reduction in growth (G C50) and 50% mortality (LC50) were 109 and 120 ppb respectively. Growing in the medium with 100 ppb Zn, the larvae fed withIsochrysis galbana cultured in a medium with 100 ppb Zn showed more suppressed growth and development than those fed with normal food. It is suggested that zinc contaminated food has strong influence on the bay scallop larvae.

Determination of trace amounts of copper and zinc in sea water with polymer-supported 1,4,8,11-tetraazacyclotetradecane

The very low affinity of tetraaza macrocycles for alkali and alkaline earth metals make them attractive for the preconcentration of transition metals from seawater. Three different procedures for determinations of copper and zinc with 1,4,8,11-tetraazacyclotetradecane (cyclam) bound to poly(chloromethyl)vinylbenzene are described. Results for both metals in estuarine and oceanic waters, compared to those obtained with Chelex-100 resin, show that the polymer-supported cyclam provides > 95% extraction of these two metals. The resin is used as a solid sample for electrothermal atomic absorption spectrometry, or the metal is back-extracted with nitric acid for injection.

Rapid determination of zinc in seawater by column preconcentration/AAS.

Atomic absorption spectrometry with on-line chelating-resin column preconcentration has been applied to rapid determination of zinc in seawater. Filtered coastal seawater samples adjusted to pH 2.2 by adding 1 ml of conc. nitric acid against to 1 l of seawater was pumped at 6.0 ml min-1 and mixed with a stream of ammonium acetate buffer (pH 7) at 0.5 ml min-1. The sample was then passed through a microcolumn (3.2 mm i.d. 16 mm long) packed with Chelex-100 for 1 min. The column was washed with distilled water for 30 s and sequentially chelated zinc was eluted with about 160 μl of 2 M nitric acid at 3.0 ml min-1 for AAS determination. This method gave enhanced sensitivityof zinc by over 19 times better than that of a conventional AAS. The detection limit of the present method was 0.5 ppb (S/N=2). Precision of this method was 2.7% (R.S.D.) at the 10 ppb level of zinc aqueous standard. About 30 samples could be analyzed for 1 h. The present method was successfully applied to the rapid determination of zinc in seawater of Beppu Bay.

Interaction between copper and zinc accumulation in the barnacle Elminius modestus Darwin

Uptake and depuration of copper and zinc by the barnacle Elminius modestus was investigated. During exposure to either metal, uptake of one was accompanied by the loss of the other, i.e. they acted antagonistically. For this reason the barnacle appears to be unsuitable as a monitoring organism for copper and zinc in seawater.

Direct determination of sub-nanomolar levels of zinc in sea-water by cathodic stripping voltammetry

A novel technique for the determination of nanomolar levels of zinc in aqueous solution is presented. The zinc complex with ammonium pyrrolidine dithiocarbamate is adsorbed on a hanging mercury-drop electrode and the reduction current of zinc is measured by voltammetry. The detection limit for zinc is 3 × 10 −11 M, with 10-min collection time. A procedure is suggested for the simultaneous determination of Ni and Zn in a single sample.

Zinc uptake and its effect on calcification in the scales of the mummichog, Fundulus heteroclitus

In two separate experiments, juvenile and laboratory-reared mummichogs ( Fundulus heteroclitus L.) were exposed to zinc in sea water at concentrations of 0, 0.21, 0.81 or 7.88 mg Zn · 1 −1 (Experiment 1) and 0, 0.11, 0.76 or 7.10 mg Zn · 1 −1 (Experiment 2). Following 8 wk of exposure, the Zn content of the scales from juvenile fish was linearly correlated with environmental Zn concentrations. At elevated environmental Zn concentrations, the fraction of the total Zn body burden contained by the scales increased. X-ray microprobe analysis of scales from laboratory reared fish showed that following 10 wk of exposure, Zn was concentrated in the calcified regions of the scales. The elemental analysis showed that high environmental Zn concentrations have an apparent affect on scale calcification, causing a reduction in the Ca/P molar ratio. In the 0.76 and 7.10 mg Zn · 1 −1 treatments, the Ca/P ratio in the scales was related to the Zn/Ca ratio. The results suggest that fish scales may play an important role in the metabolism and detoxification of heavy metal pollutants. The relationship between metal uptake and calcification is discussed.

Selective spectrofluorimetric determination of zinc with benzyl 2-pyridyl ketone 2-quinolylhydrazone and its application to sea-water analyses

A method is described for the fluorimetric determination of zinc at the nanogram level, with benzyl 2-pyridyl ketone 2-quinolyl-hydrazone as fluorogenic complexing reagent. The reaction is done at pH 10.5–13.5, in aqueous ethanol medium (80% v/v ethanol). Of 43 foreign ions tested, only cadmium interferes seriously. The method has been applied to the determination of zinc in sea-water, after 25-fold concentration of the sample water.

Zinc Gluconate as an Inhibitor of the Corrosion of Copper and Zinc in Sea Water

The efficiency of zinc gluconate (ZnGl) as an inhibitor of the corrosion of copper and zinc in natural sea water was studied by means of weight loss tests, potentiostatic polarisation and X-ray diffractometry.It was shown that, in naturally aerated conditions, up to 60% inhibition of copper corrosion is achieved with ZnGl concentrations ranging from 6.10−4 to 8.10−3 mol/l, and that this efficiency increases up to 70% as the period of immersion is increased; in fully aerated conditions, and with ZnGl concentrations ranging from 4.10−4 to 10−2 mol/l, the inhibitive efficiency reaches 95%.It was further observed that the Zn2+−CH2OH(CHOH)4COO− system is an inhibitor with synergistic properties: maximum inhibition of copper corrosion (90%) is achieved at a Zn2+/CH2OH(CHOH)4COO− molar ratio of 3:2. The mechanism of action of ZnGl on copper ispurely cathodic.The maximum percentage inhibition obtained on zinc was 70% for ZnGl concentrations ranging from 10−3 to 4.10−3 mol/l. Acceleration of corrosion was, however, observed at ZnGl concentrations below 8.10−4 mol/l. Inhibition also tends to decrease when the immersion period is increased. The mechanism of action of ZnGl for zinc is also cathodic.

Determination of zinc in sea-water by anodic stripping voltammetry

The horizontal distribution of zinc in surface waters from Guanabara Bay has been studied by use of optimized voltammetric techniques and ultraclean working procedures. The non-linearity observed between the peak current for zinc and the electrolysis time, as well as the appearance of a peak at −1.16 V, are discussed. The values found for total zinc in the samples range between 0.3 and 22 μg/l.

Zinc in seawater and sediments of the Gulf of Elefsis, Greece

Dissolved and particulate Zn were measured in the sea water of the small Gulf of Elefsis, near Athens, Greece, for one year and as a function of depth. Particulate Zn was correlated with magnetic properties. Total Zn distribution in surface and subsurface sea bottom sediments and the partitioning of Zn among various sediment fractions were studied on a number of cores. The results for the Gulf of Elefsis are compared to recent results from other areas.

Organic matrix modifiers for direct determination of zinc in sea water by graphite furnace atomic absorption spectrometry

Organic matrix modifiers for direct determination of zinc in sea water by graphite furnace atomic absorption spectrometry

Determination of trace metals in sea water by chelex-100 or solvent extraction techniques and atomic absorption spectrometry

Determinations of cadmium, lead, nickel, copper and zinc in sea water are discussed. Two different methods of preconcentration are compared: the trace metals are preconcentrated either by extraction with ammonium pyrrolidinedithiocarbamate/diethylammonium diethyldithiocarbamate into freon followed by back-extraction into nitric acid, or by collection on a Chelex-100 resin followed by elution with nitric acid. Cd, Pb, Ni, and Cu are determined by graphite-furnace atomic absorption spectrometry, while zinc is determined by flame atomic absorption spectrometry. The comparison of methods shows that cadmium can be determined accurately whereas results for the other trace metals may be biased by reagent contamination in the Chelex-100 method. Recovery data are given for both methods of preconcentration. Filtering experiments with Chelex-100 method are described. Results are compared for sea-water samples preconcentrated immediately after sampling and some weeks after sampling, with only freezing for preservation. The present results are consistent with other recent work. The importance of blank values is discussed.

Simultaneous determination of trace metals in sea water using dithiocarbamate pre-concentration and inductively coupled plasma emission spectrometry

A method based on dithiocarbamate pre-concentration and inductively coupled plasma emission spectrometry is described for the simultaneous determination of cadmium, copper, iron, molybdenum, nickel, vanadium and zinc in sea water. The metals are extracted from 500 g of sea water with ammonium tetramethylenedithiocarbamate-diethylammonium diethyldithiocarbamate in chloroform and back-extracted into nitric acid; the sea water concentration factor is 250 or 500. Advantages of the method include high precision, simplicity of calibration and a detection capability in the nanograms per litre range. The method has been applied to Japan Sea, Pacific Ocean and Atlantic Ocean samples.