Metals In Seawater Research Articles

Inhibition of corrosion by poly( N-hexadecylaniline)/docosanol mixed Langmuir–Blodgett films on copper in sea water

Electrochemical and weight loss techniques have been used for investigation of inhibition of corrosion on copper metal by Langmuir–Blodgett (LB) films of poly( N-hexadecylaniline)/docosanol in sea water. LB films of poly( N-hexadecylaniline)/docosanol were deposited onto the copper specimens. The open-circuit potential and potentiodynamic polarization curves were observed to shift in noble direction, which indicated that these LB films could inhibit the corrosion of copper metal in sea water.

The effect of pressure on the sorption/precipitation of metal cations, and its possible role in spontaneous removal of heavy metal cations from sea water

The actual concentration of heavy metals in sea water is low compared with the amount delivered on the one hand, and with saturated solution of sparingly soluble hydroxides and salts on the other. We show here that the high pressure on the ocean floor induces dissolution of sparingly soluble metal hydroxides and release of metal cations pre-sorbed on iron hydrous oxides. The concentration of divalent cations of a heavy metal in equilibrium with the metal hydroxide at a 5 km depth is four-times higher than on the ocean surface (at atmospheric pressure, and otherwise the same conditions), and this result is practically independent of the nature of the heavy metal. Then the solid particles, which are brought from the surface onto the ocean floor by sedimentation or by thermohaline circulation are potential carriers of heavy metals. The heavy metals bound by the solid particles at atmospheric pressure can be mobilized at sufficiently high pressures and then built into the marine ferromanganese nodules or bottom sediment.

Relationship between ore deposits in river catchments and geochemistry of suspended particulate matter from six rivers in southwest France

Here we present original data on the geochemical composition of fluvial particulate matter transported by the rivers of the Adour/Garonne basin, which drains one-fifth of the French land surface. Suspended particulate matter from the six main rivers in the basin, sampled at ‘normal’ flow and during a flood, is compared in terms of: grain size; particulate organic carbon; Fe; Mn; and trace element concentrations (e.g. Zn, Cd, Pb, Cu, Mo, Sn, Ni, Co, Cr, V, As, Hg, U, Th, W, Au, Ag, Ta). Three of the six studied rivers (Garonne, Dordogne and Isle Rivers) are the main tributaries of the Gironde estuary (southwest France), known for Cd pollution. The Adour and Gaves Rivers enter the Adour Estuary and the Charente River reaches the ocean by the Charente Estuary. Our data show, that Cd (and Zn) are not the only trace elements of eco-toxicological relevance transported into the Gulf of Biscay by these six rivers. Potentially toxic elements (e.g. As, Sn, U, Cu, Ag) show elevated concentrations in river particulates entering the estuaries, compared to world average concentrations [Martin and Whitfield, 1983, The significance of the river input of chemical elements to the oceans. In: C.S. Wong, E. Boyle, K.W. Bruland, J.D. Burton, E.D. Goldberg (editors), Trace Metals in Sea Water, Plenum, New York: pp. 265–296]. Comparing SPM sampled during ‘normal’ discharge and flood, the basin shows a distinct trace element composition of SPM mostly related to ore deposits in the upper basins (Massif Central and Pyreneans). This geochemical signal is partly masked during floods due to changes in grain size, but also due to increased erosion of the lower parts of the basins. This study proves pumping/centrifugation to be the most appropriate sampling/separation technique (recovery, representativity, contamination) by comparing different methods of SPM recovery.

A new voltammetric method for the simultaneous monitoring of heavy metals in sea water, sediments, algae and clams: application to the Goro Bay ecosystem.

Arsenic(III), selenium(IV), copper(II), lead(II), cadmium(II), zinc(II) have been determined in sea water, sediments, algae and clams by differential pulse cathodic (DPCSV) and anodic (DPASV) stripping voltammetry. The voltammetric measurements are carried out using a conventional three-electrode cell and the ammonia-ammonium chloride buffer pH 9.2 as supporting electrolyte. The analytical procedure has been verified by the analysis of the standard reference materials (Estuarine Sediment BCR- CRM 277, Ulva Lactuca BCR-CRM 279 and Mussel Tissue BCR-CRM 278). The precision and the accuracy are less than 5%. This procedure is utilized for the monitoring of heavy metals in the Po river mouth area (Italy).

Determination of lead and mercury in sea water by preconcentration in a flow injection system followed by atomic absorption spectrometry detection

The capabilities of three solid chelating reagents were compared for the preconcentration of lead and mercury in high salinity aqueous samples (sea waters). The tested materials were 7-(4-ethyl-1-methyloctyl)-8-hydroxiquinoline (Kelex 100) adsorbed on Bondapack C18 (Kelex-100/C18), 8-hydroxiquinoline immobilized on vinyl co-polymer Toyopearl gel (TSK) and the commercial polystyrene/DVB ion exchange resin with paired iminodiacetate groups (Chelex-100). The two metals preconcentration and final determination were carried out in a flow injection system, coupled on-line to an atomic absorption spectrometric detector. Analytes were preconcentrated in the minicolumn, packed with the materials under investigation, while elution was achieved by injection of 500 μl of an adequate mineral acid solution. The different packing materials and minicolumn designs have been evaluated in terms of sensitivity for simultaneous preconcentration of both metals in sea water. Regarding the solid support, the best results were obtained for the TSK solid phase. Concerning the minicolumn design, the behavior was different for lead and mercury. Lead was quantitatively eluted with 0.5 M HCl and best performance was achieved when packing the solid material in a minicolumn with relatively small volume (1 cm length and 2.5 mm i.d.). In the case of mercury, bigger minicolumn volumes (5.5 cm length and 5.0 mm i.d.) and mixtures, 2 M HCl+1 M HNO 3, were required for its quantitative recovery and elution. The system has been evaluated for quantitative determination of the two metals under study in different Asturian coastal aqueous samples.

Effects of copper and zinc on the heart rate of the limpet Patella vulgata L.

Physiological modifications leading to death in marine organisms stressed by xenobiotics are poorly understood. Here we examine the effect of acute exposure to copper and zinc on the heart rate of the limpet Patella vulgata L. At 0.01 mg l −1 copper there was no effect on heart rate over a 1-week period of exposure. At 0.1 mg l −1 copper, a progressive bradycardia was evident after 24 h and the test animals were dead after 1 week. At 1 mg l −1 copper, the bradycardia was induced after 30 min and all animals were dead after 24 h. Limpets appeared to tolerate 0.5 mg l −1 zinc, though a bradycardia was evident after 24 h. At 5 mg l −1 zinc the heart rate slowed after 4 h and extrapolation indicates all animals would be dead by 1 week. The bradycardia may be adaptive in that it reduces blood flow and uptake of metal across the gills. Natural levels of metals in sea water indicate that heart rate will normally not be affected by the metals, but in areas of severe pollution there will be an effect. The current UK marine environmental quality standards for copper and zinc are well below the treatment levels used in this study and so are supported by this work.

Voltammetric and Spectroscopic Determination of Toxic Metals in Sediments and Sea Water of Salerno Gulf

In this present work the distribution of heavy metals in sea water and sediments of the Salerno Gulf is measured. The elements determined were Cu, Pb, Cd, Zn and Hg, employing, as instrumental techniques, either differential pulse anodic stripping voltammetry (DPASV) or graphite furnace atomic absorption spectroscopy (GFAAS). A comparison of the results of the two analytical techniques is also made. Mercury determination was carried out employing the cold vapour atomic absorption spectroscopy (CVAAS) technique, with SnCl2 as the reducing agent. The sample digestion was performed by a new procedure using concentrated suprapure H2SO4–K2Cr2O7 mixture. The accuracy and precision of the analytical procedure were evaluated employing Sea Water BCR-CRM 403 and Estuarine Sediment BCR-CRM 277 as reference materials. Accuracy, expressed as relative error e and precision, expressed as relative standard deviation sr, were in order of 2 to 5%. For both matrices, the detection limits, for all the elements, were in the range μg g-1 to ng g-1.

Inductively coupled plasma mass spectrometry for the sequential determination of trace metals in sea water after electrothermal vaporization of their dithiocarbamate complexes in methyl isobutyl ketone

A sensitive method has been developed for the sequential determination of V, Mn, Fe, Co, Ni, Cu, Zn, Mo and Sb in sea water using inductively coupled plasma mass spectrometry (ICP-MS) after electrothermal vaporization of their dithiocarbamate complexes in methyl isobutyl ketone (MIBK). After complexion with sodium diethyldithiocarbamate (NaDDTC), all trace analyte elements were simultaneously separated from sea water matrix and concentrated 20 fold in a single extract of MIBK, followed by introduction of 10 μL of the extract into argon plasma using a pyrolytic graphite rod electrothermal vaporizer (ETV). Sensitivity enhancement due to chemical modification using a mixed modifier of Pd(NO3)2-Mg(NO3)2 was observed for all the elements. The limits of detection ranged from 2 ng/L for Co to 329 ng/L for V. For replicate determinations of the elements in sea water, the repeatability was within 10% (as a coefficient variation), except for V (12.8%). The recovery test performed on a sea water sample resulted in a range value from 87% for Sb to 119% for V. The method has been successfully applied to sea water samples collected from the surface to the depth of 5000 m at a sampling station in the northwest Pacific Ocean.

Evaluation on chemical neutron activation analysis for trace metals in seawater using magnesium oxide as the preconcentration agent

Attempts have been made to employ magnesium oxide as the preconcentration agent for determination of trace metal sin seawater by neutron activation analysis. Hydrous magnesium oxide can efficienthy adsorb most cationic transition metals and rare earths in a simple water system. The adsorption behavior is believed to depend mainly from the association of the cationic species of the metals with MgO 2 2− adsorbent. In seawater matrix some of the metal ions such as Hg2+, Ni2+, etc. may become inefficiently adsorbed owing to the formation of highly stable metal-chloro complexes with chloride ion. Usually the adsorption efficiencies of the metals can be recovered to be as high as the case in the simple water system if an acidified seawater (to pH≤1) is subjected to the adsorption experiment. In practice, a large volume of seawater (5 1) is stirred with a small amount of hydrous MgO (1 g). Thereafter, the trace metals adsorbed MgO is separated and taken to be neutron activated. The abundant sodium ion and ubiquitous bromide ion can be obviated by the adsorption process, thereby beneficial to the γ-spectrometry of the metals enriched on MgO.

Sequential determination of trace metals in sea water by inductively coupled plasma mass spectrometry after electrothermal vaporization of their dithiocarmabamate complexes in methyl isobutyl ketone

A sensitive method for sequential determination of V, Mn, Fe, Co, Ni, Cu, Zn, Mo and Sb in sea water using an inductively coupled plasma mass spectrometry (ICP-MS) after electrothermal vaporization of their dithiocarbamate complexes in methyl isobutyl ketone (MIBK) has been investigated. All analyte elements were simultaneously concentrated 20 fold in a single extract and introduced into the plasma using a graphite rod electrothermal vaporizer (ETV). A sensitivity enhancement due to a chemical modification using a mixed modifier of palladium nitrate and magnesium nitrate was observed for all analyte elements. The limits of detection of the method ranged from 2 ng l-1 for Co to 329 ng l-1 for V. For the replicate determinations of the analyte elements in a sea water sample, the repeatability was within 10% (as a coefficient variation), except for V (12.8%). The recovery test performed on a sea water sample resulted in values ranging from 87% for Sb to 119% for V. With the exception of Mo, the application of this method for the determination of the analyte elements in sea water samples collected from the surface to the depth of 5000 m at the sampling station of 34°12.08′N, 141°57.50′E (Oct. 12, 1994) in the northwest Pacific Ocean resulted in vertical distributions and concentration ranges which were in a good agreement with those reported in literatures.

海洋付着生物に対する付着誘引物質に関する研究ＩＩ ムラサキイガイの足糸付着誘引実質

Search for substances that promote attachment of marine sessile organisms using the blue mussel, Mytilus edulis galloprovincialis, is not only important in aquaculture, but also provides information on the modes of action of repellents, Curcumin, BHT, and their derivatives were found to be attachment promoting for M. edulis galloprovincialis. Metal chelates were active. Compounds capable of forming chelated structure may be active because of the presence of free metals in sea water. Some of these active compounds also showed antioxidant activity.

Trace metal chemistry of the North Sea particulate aerosol; concentrations, sources and sea water fates

The long-term averaged concentrations of trace metals in particulate aerosols sampled over large areas of the southern North Sea are generally similar to those at fixed stations in the same region. This averaged North Sea aerosol can therefore be used to define a number of chemical characteristics which constrain the fates of the trace metals in sea water. Anthropogenic processes are the most important source of particulate trace metals to the North Sea atmosphere, and the anthropogenic fraction of the North Sea aerosol approximates in composition to that of the average anthropogenic European trace metal emissions. Solid state speciation data indicate that large fractions of the total Cu(45%), Pb(77%) and Zn(77%) in the aerosol are in exchangeable “potentially environmentally mobile” (PEM) associations. The actual environmental mobility of the trace metals was then assessed experimentally in terms of “dry” (direct deposition to sea water) and “wet” (rain water scavenging) aerosol deposition modes to the sea surface. The data revealed the following trends; (a) similar amounts of the PEM Zn in the aerosol are soluble in both sea water (average 98%) and rain water (average 95%); (b) the PEM Cu in the aerosol which is soluble in rain water (average 98%) is greater than that soluble in sea water (80%); and (c) on average only ∼66% of the PEM Pb is soluble in sea water, but ∼95% is soluble in rain water. Clearly, precipitation scavenging, at the average pH for North Sea rain water (pH 4.0), initially releases most of the PEM fractions of Cu, Zn and Pb into the dissolved trace metal pool, but sea water is less corrosive with respect to the aerosols for Cu and particularly for Pb.

Preconcentration of trace metals in sea water matrix for differential pulse anodic stripping voltammetry

A preconcentration procedure with two-step extraction was proposed to be used in conjunction with differential pulse anodic stripping voltammetry (DPASV) for the determination of trace metals in sea water. The two-step extraction involved extraction of trace metals from sea water with dithiocarbamate into chloroform followed by backextraction with a Hg 2+ solution at pH 3.5, as previously reported. The aqueous solution containing simply the enriched metals and the nonreacted Hg 2+ was analysed by DPASV using a glassy carbon electrode. Anodic stripping voltammetry of the metals including Zn, Cd, Pb and Cu was conducted in the preconcentrated solution after adding 0.025 M KCl. The preconcentrated solution was observed not to cause any interference in the anodic stripping voltammetry. Besides, the Hg 2+ could be in situ utilized as the source of the mercury film coated on the glassy carbon electrode, rendering it as an efficacious working electrode. The detection limits achieved were as low as 0.004 μg/1 for Zn, 0.002 μg/1 for Cd, 0.002 μg/1 for Pb and 0.003 μg/1 for Cu in sea water by DPASV coupled with the preconcentration procedure with an enrichment factor of 20. The analytical reliability was confirmed by checking with NASS-3 (NR-A4) open ocean sea water.

Determination of trace metals in sea waters of the Albanian coast by energy-dispersive X-ray fluorescence

Preconcentration of trace transition and heavy metal ions by precipitation with APDC has been combined with energy-dispersive X-ray fluorescence for environmental sea water analysis. The preconcentration procedure implies adding of 500 μg Mo ion and 10 ml of 1% water solution of APDC to a 500 ml water sample at pH 4, filtering off on a Millipore filter and analyzing after drying. Realistic detection limits are at 1 μg·l−1 level and precision varies between 10–25% at about 5 μg·l−1 level, depending on the element. Eleven sea water samples, covering Albanian Adriatic and Ionian coast, are analyzed for trace metal ions.

Conditional stability constants of metal complexes of organic ligands in sea water: past and present, and a simple coordination chemistry model

The conditional stability constants of complexes of organic ligands with trace metals (Cu and Zn) that have been determined by solution chemistry techniques since 1980 are summarized. The present common understanding on the chemical speciation of trace metals is that > 99% of copper dissolved in sea water is complexed with natural organic ligands; more than strongly binding organic ligand exists in sea water. A simple coordination model, including two non-specific discrete strong organic ligands such as EDTA, is introduced to understand the complex features of recent metal speciation. The model, consistent with the result of the ligand titration, permits the wide range of conditional stability constants determined by metal titrations and the present concentration levels of several trace metals in sea water to be explained. These findings suggest that organic metal complexes play a significant role in the geochemical cycle of reactive trace metals.

Automatic on-line preconcentration system for graphite furnace atomic absorption spectrometry for the determination of trace metals in sea water

An automatic on-line preconcentration system for graphite furnace atomic absorption spectrometry (GFAAS) for the determination of trace metals in sea water was developed. This system was modified from a Perkin-Elmer AS-40 autosampler by mounting a silica gel C 18 microcolumn near the tip of the automsampler capillary. The preconcentration procedure was performed by using the pumps of the AS-40 autosampler and a four-way valve and controlled by a programmable controller. The chelating agent ammonium tetramethylenedithiocarbamate [ammonium pyrrolidinedithiocarbamate APDC)] was added to the sample solution and only 0.2–2 ml of sample was required to determine cadmium and copper in sea water. The calibration graph method was used and the detection limits of cadmium and copper were 1.26 and 6.5 ng l −1, respectively.

Direct graphite furnace atomic absorption spectrometric determination of metals in sea water: application of palladium modifiers and a fractal approach to their analytical support

Sea water, like other high-salinity matrices, causes severe interferences in the direct determination of metals by graphite furnace atomic absorption spectrometry (GFAAS), even when Zeeman-effect background corrections is applied. A method for eliminating these interferences by the application of mixed modifier system of ammonium oxalate and tetraamminepalladium(II) chloride is presented. In particular these modifiers optimize the direct GFAAS determination of lead and manganese. For cadmium, however, only ammonium oxalate should be used as a modifier. The geometry of the microdistribution of palladium on the palladium-conditioned graphite platform was investigated in order to elucidate possible stabilizing effects of palladium on the analytes which were observed with the different modifiers. Fractal characteristics of the palladium elemental distribution were ascertained by a scanning electron microscope-energy-dispersive x-ray spectrometer image box-counting analysis. The fractal dimension [ D B(0) = 1.77 ± 0.04 and 1.81 ± 0.04] and electron microscopic investigations indicated differences in the structure of palladium deposits on the platform. These variations in the palladium geometry affect the analytes to a certain extent.

Determination and data evaluation of copper complexation by organic ligands in sea water using cathodic stripping voltammetry at varying detection windows

Published data of trace metals in sea water show very large differences in strength of organic complexation. These differences are incompatible with the expected order of complexation by reversible and nonspecific complexing ligands. Comparison revealed a linear relationship between the detection windows of the analytical techniques and the detected metal complexation. A possible explanation for this relationship is that the apparent differences between organic complexation of different metals are artifacts when the analytical techniques detect only one or two of many complexing ligands of greatly varying complexing ability in the natural water samples. Detailed complexation measurements of copper in samples from the Sargasso Sea and the North Sea were carried out at several detection windows using cathodic stripping voltammetry and confirmed the presence of several complexing ligands. The detected ligand concentration was found to decrease with increasing magnitude of the detection window, whereas the conditional stability constant was found to increase. The overall effect was that the degree of metal complexation [(Σα CuLi) − i + 1], where i is the number of α coefficients, increased with the detection window whereas the complexation due to the individual ligands (α CuLi) increased until a maximum had been reached when the ligand concentration was approximately equal to the metal concentration whereafter it decreased at very high detection windows. An additional observation was that the dissociation rate of organically complexed copper in sea water is very slow the process requiring more than 1 h to reach equilibrium with an added competing ligand. The complexation data were used to estimate the total number of ligands and the range of conditional stability constants. The overall complexation of copper in sea water was calculated giving values for pCu between 13.5 and 15.4.

Determination of heavy metals in sea water and in marine organisms by graphite furnace AAS

Determination of heavy metals in sea water and in marine organisms by graphite furnace AAS

Simultaneous multi-element analysis for trace metals in sea water by inductively-coupled plasma/atomic emission spectrometry after batch preconcentration on a chelating resin

Batch treatment with Chelex-100 resin was investigated for preconcentration of trace metals in sea water followed by determination by inductively-coupled plasma atomic emission spectrometry. The preconcentration conditions such as resin weight, stirring time, and amount of ammonium acetate buffer solution were carefully examined for effective multi-element preconcentration from sea water. The resin weight could be decreased to 0.5 g (dry weight) for 1 l of sea water, which was much less than that required in the column method, and a preconcentration factor of 100 was achieved. Al, Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Y, Mo, Cd and Pb in sea water were measured with good precision. The detection limits ranged from 6 to 180 ng l −1. The time required for one sample by the batch method was only 3 h.