Zn Hg Research Articles

Potentially toxic elements in the soils of Campi Flegrei (south Italy) and the immediate surroundings: Spatial distribution, origin and probabilistic human health risk

Campi Flegrei is an active volcanic field in south Italy where the potentially toxic elements (PTEs) are of growing concern because the intensive anthropogenic and volcanic activities might pose adverse human health effects. In this article, 394 topsoils (0–15 cm) are collected for instrumental analysis of the <2 mm fraction. The geochemical maps indicate that higher concentrations of Pb, Zn, Cd, Cr, Hg, Ni and Sb are related to the urban area, but greater levels of As, Tl, Co, Cu, Se and V are observed in the other parts. A robust principal component analysis detected: (1) the Pb–Zn–Hg–Cd–Sb–Cr–Ni association that probably highlights anthropogenic activities such as heavy traffic load and fossil fuel combustion in the urbanized area; (2) the Al–Fe–Mn–Ti–Tl–V–Co–As–U–Th association that mostly reveals the contribution of pyroclastic deposits; and (3) the Na–K–B association that feasibly indicates the weathering degree. The probabilistic health risk modeling for the children under 6 years old shows negligible Pb and Zn non-carcinogenic risk and unexpected Pb carcinogenic risk for exposure through soil ingestion. However, for the inhalation pathway, the children aged <1 year old have the highest chance (90%) of acceptable (i.e. between 1E-6 and 1E-4) Pb carcinogenic health risk. This should not be overlooked because Naples is under high environmental pressure and previous studies reported the increased Pb and Zn quantities in soil over a 26-year timespan. Overall, the results of geostatistical interpolation, compositional data analysis and probabilistic health risk modeling potentially uncover the link between soil geochemistry and human health.

Synthesis, Characterization and Reactivity of Nitrosyl Ruthenium Complexes with the Non-stereoidal Anti-inflammatory Diflunisal

The Na2[Ru(NO)Cl3 (df)] (I) and cis-[Ru(NO)(df)(cyclen)]Cl2 (II) complexes (df=diflunisal (5-(2,4-difluorophenyl)-2-hydroxybenzoic acid, cyclen=1, 4, 7, 10-tetraazacyclododecane) have been synthesized and characterized by elemental analysis, electronic (UV-Vis) and vibrational (FTIR) spectroscopic techniques. FTIR data suggests different modes of coordination of the ligand diflunisal in these complexes, i.e., coordinated in the bidentate form in the compound I and in the monodentate form in the compound II, and that df is coordinated to ruthenium by carboxylate group in a monodentate mode for both complexes. The FTIR spectra also display v(NO) at 1880 cm-1 and 1892 cm-1 for I and II, respectively, indicating a nitrosonium (NO+) character. Electronic spectra suggest that df is coordinated to the metal center in both complexes in catecholate form. Detailed electrochemical studies showed that complexes I and II display {RuNO}6/7 process at -420 mV and at -400 mV (vs. Ag/AgCl) respectively, and df ligand is oxidized at 1120 mV and at 770 mV, respectively. Controlled potential electrolysis at -750 mV or chemical reduction with Zn(Hg) amalgam results in NO release from both complexes.

Mineralogy of Zn–Hg–S and Hg–Se–S Series Minerals in Carbonate-Hosted Mercury Deposits in Western Hunan, South China

Among the Zn–Hg–S and Hg–Se–S series minerals, Hg-bearing sphalerite and metacinnabar are uncommon in ore deposits, but they are useful indicators of temporal variation of ore forming fluids, as well as presenting metallurgical implications for Hg-bearing deposits. To understand the Hg–Zn–Se mineralization system of the Tongren–Fenghuang Hg Belt (TFHB), the Zn–Hg–S and Hg–Se–S series minerals of the Chashula Hg–Zn and Dongping Hg–Ag–Se carbonate-hosted deposits were studied by microscopic observation, electron-probe microanalysis, and X-ray diffraction analysis. Observations show that the Chashula and Dongping deposits experienced two stages of mineralization (Stages 1 and 2). The pyrite, sphalerite I (Hg-poor sphalerite), and quartz formed in Stage 1, while the Zn-bearing cinnabar, sphalerite II (Hg-bearing sphalerite), cinnabar, selenium metacinnabar, and Ag minerals formed in Stage 2. The Hg-bearing sphalerite, containing 13.36–22.26 wt % Hg (average 18.73 wt % Hg), replaces sphalerite I (0.00–1.31 wt % Hg). The Hg-bearing sphalerite of the Dongping Hg–Ag–Se deposit contains lower Hg (10.12–14.67 wt % Hg) than that of the Chashula deposit. The unit cell a of the Hg-bearing sphalerite gradually increases with increasing Hg content. The texture of the Zn-bearing cinnabar shows it is not stable and easily breaks down to Hg-bearing sphalerite and cinnabar through the chemical reaction: (Hg,Zn)S → (Zn,Hg)S + HgS. Selenium metacinnabar intergrowths with tetrahedrite and miargyrite were found only in the Dongping deposit. The selenium metacinnabar contains 76.57–83.97 wt % Hg, and extensive isomorphic substitution of Se and S (6.81–19.21 wt % Se, 4.14–10.32 wt % S). Based on our mineralogical studies, the Zn, Hg, Hg–Zn, and Hg–Se mineralization styles in the TFHB are interpreted as the product of different stages in the mineralization process.

Cadmium complexes bearing Me2N^E^O- (E = S, Se) organochalcogenoalkoxides and their zinc and mercury analogues.

Heteroleptic zinc and cadmium complexes of the type [{Me2N^E^OR2}M-Nu]n (M = Zn, Cd; E = S, Se; R = CH3, CF3; Nu = N(SiMe3)2, I, Cl; n = 1-2) were prepared by reacting the alcohol proteo-ligands {Me2N^E^OR2}H with [M(N(SiMe3)2)2] (M = Zn, Cd) or [XMN(SiMe3)2] (M = Zn, X = Cl; M = Cd, X = I) in an equimolar ratio. These group 12 metal complexes were characterised in solution by multinuclear NMR spectroscopy and their solid-state structures were determined by X-ray diffractometry. The ligands {Me2N^E^O(CH3)2}- bearing CH3 groups in α position to the alkoxide behave as κ2-O,E-bidentate moieties (E = S, Se) and form centro-symmetric dinuclear O-bridged heteroleptic alkoxo-amido complexes both with zinc and cadmium, with four-coordinate metal centres resting in tetrahedral environments. By contrast, complexes supported by the CF3-substituted {Me2N^E^O(CF3)2}- crystallise as tetrahedral mononuclear species, with tridentate κ3-N,O,E-coordinated ligands. These structural differences resulting from changes in the ligand skeleton and in the electron-donating properties of the alkoxide were also observed in solution. Attempts to prepare congeneric heteroleptic mercury complexes from [Hg(N(SiMe3)2)2] unexpectedly only afforded homoleptic bis(alkoxide)s such as [{Me2N^S^O(CF3)2}2Hg]. Owing to the strong Hg-C bond, treatment of [PhHgN(SiMe3)2] with {Me2N^S^O(CF3)2}H afforded the heteroleptic, T-shaped [{Me2N^S^O(CF3)2}HgPh] mercuric alkoxide upon elimination of hexamethyldisilazane. [{Me2N^S^O(CF3)2}2Hg] and [{Me2N^S^O(CF3)2}HgPh] constitute very rare examples of structurally characterised mercuric alkoxides.

Uticaj gustine struje i sastava rastvora na iskorišćenje struje elektrohemijske redukcije benzaldehida

This research deals with the effect of current density and benzaldehyde and ethanol concentrations on current efficiency for benzaldehyde reduction at the cathodes: a)-Raney-Ni; b)-a titanium substrate having an electrochemically deposited Ni92Mo8 alloy coating; c)-a titanium substrate having a Ni93Mo7 alloy coating produced by the plasma spraying process; d)-a cathode made from pressed electrogenerated Ni92.8Mo7.2 powder and e)-a zinc amalgam cathode Zn(Hg). Current efficiency increases with benzaldehyde concentration in the solution increasing from 0.4 mol dm-3 to 1.2 mol dm-3. The increase in current efficiency is due to the increased rate of the reaction of adsorbed benzol intermediates with water molecules. The increase in current density leads to a decrease in the cathodic current efficiency. The decrease is caused by the small effect of the cathodic over potential on the rate of the chemical reaction of benzol intermediates with water. As ethanol content in the solution increases, the cathodic current efficiency decreases.

Synthesis, molecular and electronic structure, and reactions of a Zn-Hg-Zn bonded complex.

Reaction of ((Ar')NacNac)ZnI with potassium/mercury amalgam gave the trimetallic compound {((Ar')NacNac)Zn}2Hg (1) containing a Zn-Hg-Zn unit and the first example of a bond between two different Group 12 metals; DFT and QTAIM analyses suggest that 1 is best described as two formally Zn(I) atoms with a Hg(0) atom positioned between them; reactions of 1 with stoichiometric I2, FpI or Fp2 gave addition products of the type ((Ar')NacNac)ZnX (X = I, Fp) and Hg. (Ar')NacNac = HC{C(Me)N(2,6-C6H3(i)Pr2)}2; Fp = CpFe(CO)2.

Metal derivatives of N-substituted imidazolidine-2-thiones with d10 metal ions (Zn–Hg): Synthesis, spectroscopy, ESI-mass and structures

N-substituted 1,3-imidazolidine-2-thiones (LI-NMe; LII-NEt; LIII-NPrn) on reacting with Zn(II), Cd(II) and Hg(II) halides in methanol have yielded the mononuclear complexes [ZnCl2(LII-NEt-S)2] 1, [ZnI2(LI-NMe-S)2] 2, [CdBr2(LI-NMe-S)2] 3, [CdBr2(LII-NEt-S)2] 4, [CdI2(LI-NMe-S)2] 5, [HgCl2(LI-NMe-S)2] 6, [HgCl2(LIII-NPrn-S)2] 7 and [HgI2(LI-NMe-S)2] 8. All these complexes have been characterized by elemental analysis, spectroscopy (IR, 1H NMR), ESI-mass and X-ray crystallography. Complexes 1–6 and 8 crystallized in the monoclinic system, with each having the space group P21/c except for complex 4 which has the space group C2/c, and complex 7 crystallized in the trigonal system with the space group R-3c. Interestingly, the complex molecules adopt four types of conformations which give rise to different patterns of intermolecular interactions and hence 2D (1–6, 8) or 1D (7) polymeric networks are obtained. ESI mass data support the formation of [M−X]+ ions (X=halogen) in complexes 1–7.

Assessment on Heavy Metals in Edible Univalves in Dandong Market

From April to July 2012, four species of univalves were selected and 60 samples were chosen from each species of univalves by random sampling in Dandong market. The heavy metal contents of Pb, Cd, Cr, Cu, Zn, total As and total Hg in the edible parts of the univalves were determined by using incomplete digestion - AAS method, and the assessment on the pollution situation of the four species of univalves was made by using the single factor index method. The results showed that bullacta exarata was slightly polluted by Zn, the pollution index was 0.65, and the edible value was threatened, which should be paid attention to. The heavy metal contents in the edible parts of the other univalves were far lower than the pollution limit of the national standard of food safety and the edible value was safe. The heavy metal accumulation ability in bullacta exarata is higher than in the other three species of univalves. Bullacta excta should be the biological indicator for the monitoring of heavy metal pollution.

Spectrophotometric determination of non-transition elements (Zn Hg) in environmental sample by the metal substitution after fractional extraction

Spectrophotometric determination of non-transition elements (Zn Hg) in environmental sample by the metal substitution after fractional extraction

ChemInform Abstract: Group 2 (Be—Ba) and Group 12 (Zn—Hg)

AbstractReview: structures and synthesis of organometallics; 113 refs.

New data on the composition of metacinnabar and Hg-sphalerite with an isomorphous Cd admixture

The data on the composition of metacinnabar and Hg-sphalerite with an isomorphous Cd admixture from some mercury and complex ore objects are summarized. There are two varieties of metacinnabar: (1) cadmium-rich (9.25–15.80 wt.%), with the minimum quantity of Zn admixture (0.67–3.94 wt.%), which has the idealized formula (Hg,Cd,Zn)S (Ulandu) and (2) with increased amounts of Zn (2.21–10.83 wt.%) and Cd (6.00–14.10 wt.%), having the formula (Hg,Zn,Cd)S (Arzak, Kadyrel’, Murzinskoe, Ravnou-1, Ravnou-2). The maximum content of isomorphous Cd (15.80 wt.%) was determined in the metacinnabar from the Ulandu ore occurrence. The Hg-sphalerites are compositionally divided into two groups: (1) with an increased Cd concentration (up to 7.96 wt.%) and (2) mainly with a low content of Cd admixture (0.0 n–1.63 wt.%). The sphalerites of the first group are typical of mineral assemblages including Cd-Zn-enriched metacinnabar (Arzak, Kadyrel’, Murzinskoe, Sarasa). The sphalerite of the Sarasa deposit is included into this group arbitrarily, because it contains more cadmium than the sphalerites of the second group, which are constituents of parageneses only with Zn-metacinnabar or lacking it (Nikitovka, Khaidarkan, Dzhizhikrut, Bayan-Khan, Aktash). There are some Hg-bearing varieties of sphalerite with the idealized formulas (Zn,Hg,Fe)S, (Zn,Hg,Cd)S, (Zn,Cd,Hg,Fe)S, (Zn,Fe,Cd,Hg)S, (Zn,Hg,Cd,Fe)S, (Zn,Fe,Hg,Cd)S, and (Zn,Hg,Cu)S, which transforms into (Zn,Cu,Hg)S. The maximum Cd admixture (7.96 wt.%) was established in Hg-sphalerite from the Kadyrel’ ore occurrence. It is the highest content observed in natural Hg-bearing β-ZnS. The studied metacinnabar and sphalerite varieties are the only cubic phases of the natural system Zn–Hg–Cd–S, which is sometimes expanded because of minor admixtures of other metals. These varieties have a structure identical to the cubic phases of the synthetic systems Me–S and Me–Me–S, where Me = Zn, Cd, and Hg. None of Hg-bearing hexagonal solid solutions were found in the natural system Zn–Hg–Cd–S. The continuity of the natural isomorphous series ZnS cub–HgS cub has not been confirmed by finding of natural intermediate solid solutions at the series fragment between (Zn 0.752Hg 0.248)S and (Hg 0.539Zn 0.461)S. The metacinnabar varieties enriched in both Zn and Cd show no correlation between these elements. It is assumed that the host rocks with an increased content of cadmium compounds were the source of Cd for the formation of specific varieties β-HgS and β-ZnS.

Fractionation and ecological risk of metals in urban river sediments in Zhongshan City, Pearl River Delta

Surface sediments collected from nine urban rivers located in Zhongshan City, Pearl River Delta, were analyzed for total concentration of metals with digestion and chemical fractionation adopting the modified European Community Bureau of Reference (BCR) sequential extraction procedure. The results showed that concentration and fractionation of metals varied significantly among the rivers. The total concentration of eight metals in most rivers did not exceed the China Environmental Quality Standard for Soil, Grade III. The potential ecological risk of metals to rivers were related to the land use patterns, in the order of manufacturing areas > residential areas > agriculture areas. The concentration of Pb in the reducible fraction was relatively high (60.0-84.3%). The dominant proportions of Cd, Zn and Cu were primary in the non-residual fraction (67.0%, 71.8% and 81.4% on average respectively), while the percentages of the residual fractions of Cr and Ni varied over a wide range (43-85% and 24-71% respectively). The approaches of the Håkanson ecological risk index and Secondary Phase Enrichment Factor were applied for ecological risk assessment and metal enrichment calculation. The results indicated Hg and Cd had posed high potential ecological risk to urban rivers in this region. Meanwhile, there was widespread pollution and high enrichment of Cu in river sediments in this region. Multiple regression analysis showed that five water quality parameters (pH, DO, COD(Mn), NH(4)(+)-N, TP) had little influence on the distribution of metal fractionation. This result revealed that the ecological risk of metals was not eliminated along with the improvement in water quality. Correlation studies showed that among the metals, Group A (Cd, As, Pb, Zn Hg, r = 0.730-0.924) and Group B (Cr, Cu, Ni, r = 0.815-0.948) were obtained, and the metal contaminations were from industrial activities rather than residential.

Changes in levels of essential elements in suckling rats exposed to zinc and mercury

The effect of mercury and its interaction with zinc on the content of essential metals in tissues from neonate rats was investigated. Three-day-old Wistar rats were treated with saline or 27 mg kg −1 d −1 ZnCl 2 (s.c.) for five consecutive days. From the 8th to the 12th day of life, the rats received one daily dose of saline or 5.0 mg kg −1 HgCl 2 (s.c). Twenty-four hours after the last injection liver, kidneys and blood were collected for metal quantification. The HgCl 2 exposure induced alterations on metal levels, such as increase of Fe, Hg and Zn in liver, decrease of Fe and Mg and increase of Cu and Hg contents in kidneys. The Hg exposure also increased Hg levels in the blood. The treatment with ZnCl 2, administered previously to HgCl 2, partially prevented the increase of Fe in the liver, and not only prevented the decrease of renal Mg but also increased it to levels higher than those found in control group. The Zn–Hg rats also presented higher renal Cu levels, and showed partially lower blood and hepatic Hg levels and higher renal Hg levels. The pre-administration of Zn caused no severe alterations in levels of essential metals (Cu, Fe, Mg and Mn). In short, Zn appears to be an alternative treatment of Hg poisoning in young animals in comparison to chelating drugs since these have low metal selectivity.

ChemInform Abstract: Be—Ba and Zn—Hg

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Metallothionein, zinc, and mercury levels in tissues of young rats exposed to zinc and subsequently to mercury

Several studies have described mercury toxicity and the role of metallothioneins (MT) in the detoxification and regulation of metal homeostasis. However, little data exist on this topic during the specific post-natal developmental phase in young mammals. This developmental phase is particularly important since young animals are more sensitive to toxicants than adults. The objective of this work was to investigate whether MT participates in the mechanism of protection conferred by zinc pre-treatment on the toxic effects induced by mercury in neonate rats. Pups were exposed to ZnCl 2 (5 doses of 27 mg/kg/day, s.c.) and subsequently to HgCl 2 (5 doses of 5 mg/kg/day, s.c.); metal (Zn and Hg) and MT contents were analyzed in the liver, kidney, and blood. MT was induced in the liver and kidney of pups of both Zn–sal and Zn–Hg groups, although the greatest increase was in neonates exposed to Zn only. A direct relationship exists between MT and metals for both hepatic and renal tissues, which indicates that the increase in metal levels occurs in parallel to the increase in MT content. Although the heat-treated cytosolic fraction is rich in MT and metals, higher Zn and Hg contents were detected in the insoluble fraction of all tissues. These results suggest that MT is, at least in part, responsible for preventing Hg accumulation in the liver and blood and decreasing renal toxicity.

Synthesis of pelargonidin 3- O-6″- O-acetyl-β- d-glucopyranoside, an acylated anthocyanin, via the corresponding kaempferol glucoside

The first total synthesis of pelargonidin 3- O-6″- O-acetyl-β- d-glucopyranoside, an acylated anthocyanin of magenta-colored Verbena flowers, was successfully carried out. The key intermediate, protected kaemferol 3- O-glucoside, was constructed by the Baker–Venkataraman rearrangement from a glucosyloxyacetophenone followed by Zn–Hg reduction to the corresponding acylated anthocyanin.

Mechanism of amalgam formation electrode reactions in nonaqueous solvents. Combined analysis of interfacial distance parameters and steric factors

The study of the electroreductions Cd(II)/Cd(Hg) and Zn(II)/Zn(Hg) in solutions of methanol, formamide, acetonitrile and propylene carbonate, in the presence of suitable inhibitors, by the method of interfacial distance parameters at constant electrode coverage, combined with the method of steric factors of the activated complex and the inhibitor indicates a two step IA mechanism for both reactions and gives information about the structure of the activated complex at the various reaction sites.

Group 2 (Be—Ba) and Group 12 (Zn—Hg)

AbstractFor Abstract see ChemInform Abstract in Full Text.

The Place of Zinc, Cadmium, and Mercury in the Periodic Table

Following an earlier article on the positions of lanthanium and lutetium in the periodic table (J. Chem. Educ. 1982, 59, 634-636), the author notes that introductory textbooks, inorganic textbooks, and advanced monographs on coordination and organometallic chemistry are increasingly treating zinc, cadmium, and mercury as transition or d-block elements, rather than as main-block elements. The author reviews the historical evolution of the concepts of transition elements and d-block elements, evaluates the chemical and spectrosopic evidence for each placement, and concludes that these elements are unambiguously main-block elements and that there is a fundamental bifurcation of group 2 at magnesium into a Ca–Ra branch and a Zn–Hg branch. The author also reviews various ways of representing this bifurcation using spatial position in the periodic table and various labeling schemes.

Studies of the Accelerating Effect of Thiourea on the Reduction of ZnII in Mixed Water–Organic Solvents at the Mercury Electrode

The accelerating influence of thiourea on the Zn II /Zn(Hg) reduction process was investigated in the following mixed solutions: water-methanol (MeOH); water-ethanol (EtOH); water-dimethyl sulphoxide (DMSO); water-dimethylformamide (DMF). It was suggested that the dominant role in acceleration of the electrode process is played by the composition of the activated complex, which is presumably composed of solvent molecules and thiourea molecules adsorbed on to the electrode. A mechanism was proposed for the process occurring.