Showing papers on "Zinc published in 1973"

Significance of pH and Chloride Concentration on Behavior of Heavy Metal Pollutants: Mercury(II), Cadmium(II), Zinc(II), and Lead(II)

Abstract: Calculations were performed (i) to assess the degree to which Hg(II), Cd(II), Zn(II), and Pb(II) complex with hydroxyl and chloride ions and (ii) to evaluate the significance of such complexation in natural systems. Results indicate that both the hydroxy and chloride complexes may contribute to the mobilization of these heavy metal ions in the environment. Hydrolysis of Hg(II) becomes important at pH values above 1 whereas Pb(II), Zn(II), and Cd(ll) hydrolyze above pH 5, 7, and 8, respectively. Chlorides complex with Hg(II) at chloride concentrations above 10⁻⁹M (35 × 10⁻⁶ ppm). HgCl₂ forms above 10⁻⁷.⁵M Cl⁻(1.1 × 10⁻³ ppm), and HgCl₃⁻ and HgCl₄²⁻ formation occurs above 10⁻²M Cl⁻(350 ppm). The MCl⁺ species of Zn(II), Cd(II), and Pb(II) appear at chloride concentrations above 10⁻³M (35 ppm), and MCl₂ complexes occur above 10⁻²M (350 ppm Cl⁻). The respective MCl₃⁻ and MCl₄²⁻ species become important above 10⁻¹M Cl⁻(3,500 ppm). Hydrolysis and chloride complexation of these heavy metal ions are important factors affecting the solubility of the sparingly soluble salts of these metal ions. This is most pronounced for mercuric salts. Intrinsic solubilities of the metal-ion hydroxides allow for 160 ppm Zn(II) and 107 ppm Hg(II) to be soluble as complexed Zn(OH)₂ and Hg(OH)₂, respectively. These values are higher than calculated solubilities based on solubility products. An example of the competition between hydroxy and chloride complexes shows that at pH 8.5 and a chloride concentration range of 350–60,000 ppm, Hg(II) and Cd(II) are mainly complexed by chlorides. Zn(II) and Pb(II), under these conditions, are predominantly in the form of hydroxy complexes.

Contamination of soil and vegetation near a zinc smelter by zinc, cadmium, copper, and lead

Abstract: Metal oxide fumes escaping from two zinc smelters in Palmerton, Pa., have highly contaminated soil and vegetation with zinc, cadmium, copper, and lead. Within 1 km of the smelters, 135,000 parts per million (ppm) zinc, 1750 ppm cadmium, 2000 ppm copper, and 2000 ppm lead have been measured in the O/sub 2/ horizon. Approximately 90% of metals deposited on the soil surface have been retained in the top 15 cm of the soil profile. Depauperate trees within 2 km of the smelters contained up to 4500 ppm zinc and 70 ppm cadmium by weight in washed, oven-dried foliage. Metal aerosols may enter the leaves directly, presumably through open stomates.

Zinc: a trace element essential in vitamin A metabolism.

Abstract: Zinc is necessary to maintain normal concentrations of vitamin A in plasma. By using animals deficient in both zinc and vitamin A, it was demonstrated that zinc is necessary for normal mobilization of vitamin A from the liver. These results suggest that cases of depressed vitamin A in plasma, unresponsive to vitamin A therapy, may respond to zinc supplementation.

Acute toxicology to an estuarine teleost of mixtures of cadmium, copper and zinc salts

Abstract: Effects of mixtures of chloride salts of cadmium, copper and zinc on survival, whole body residues, and histopathology of mummichog, Fundulus heteroclitus (L.), were investigated in synthetic sea water at 20‰ salinity and 20°C. Mixtures of Cu2+ and Zn2+ as indicated by 96 h bioassay studies produced more deaths than expected on the basis of toxicities of individual components. Concentrations of Cd2+ not ordinarily lethal exerted a negative effect on survival of fish intoxicated by salts of copper, zinc, or both. Atomic absorption determinations of Cd, Cu, and Zn residues in mummichog which survived 96 h exposures to each of these toxicants provided useful indices of total body burdens for these metals. Residues from survivors held in mixtures, especially Cd2+ and Zn2+ mixtures, did not conform to patterns observed for single elements. Whole body aggregates of Cd, Cu, and Zn from dead mummichogs were of limited worth owing to possible accumulation of these metals from the medium after death. Renal and lateral line canal lesions were noted in all fish subjected to copper concentrations of 1 mg/1 and higher. Renal lesions observed in fish immersed in mixtures of Cu2+ and Cd2+ assumed a damage pattern characteristic of Cd2+; with mixtures of Cu2+ and Zn2+, lesion were typical of Cu2+-induced damage. Lesions induced in lateral line epithelium by Cu2+ were not affected by either Cd2+ or Zn2+. Epithelia lining the oral cavity were necrotized by the caustic action of high levels of Zn2+ (60 mg/1) and of Cu2+ (8 mg/1).

Zinc Deficiency, Carbonic Anhydrase, and Photosynthesis in Leaves of Spinach

Abstract: A shortage in the zinc supply to spinach (Spinacia oleracea L.) drastically reduced carbonic anhydrase levels with little effect on net CO2 uptake per unit leaf area, except with the most severe zinc stresses. Under these conditions, carbonic anhydrase was below 10% and photosynthesis 60 to 70% of the control levels. When photosynthesis was measured at a range of CO2 supply levels, zinc-deficient leaves were less efficient at 300 to 350 microliters per liter CO2 and above, but the same as controls at lower CO2 levels. This suggests that carbonic anhydrase does not affect the diffusion of CO2, and that the effect of zinc deficiency was on the photosynthetic process itself. Our evidence does not support the hypothesis that carbonic anhydrase has some role in facilitating the supply of CO2 to the sites of carboxylation within the chloroplast.

Arsenic, Cadmium, Copper, Mercury, and Zinc in Some Species of North Atlantic Finfish

Abstract: Arsenic, cadmium, copper, mercury, and zinc analyses of 91 individuals representing 35 species of North Atlantic finfish (Chondrichthys and Osteichthys) indicate that these metals occur at similar ...

Metabolic balance of zinc, copper, cadmium, iron, molybdenum and selenium in young New Zealand women.

Abstract: 1. Metabolic balance studies of zinc, copper, cadmium, iron, molybdenum and selenium were made on four young New Zealand women, using brilliant blue and chromic oxide as faecal markers.2. Zn, Cu, Cd and Fe concentrations in foods, faeces and urine were measured by atomic absorption spectrophotometry, whereas Mo was determined spectrophotometrically with dithiol and Se fluorimetrically with diaminonaphthalene.3. The dietary intakes of Zn, Cu and Fe were similar to those reported in the USA and the UK, whereas those of Cd, Mo and Se were less. The subjects ate a diet consisting of foods normally consumed by New Zealand women.4. For each subject there was little variation in the urinary output of each element for three 6 d periods. Day-to-day variation was small for each subject. The individual variation in urinary output of each element among the subjects was smaller when expressed as a ratio of intake, except for Mo.Retentions were small for Zn, Cu and Fe, all elements which are poorly absorbed. Balances of Se, Mo and possibly Cd were in equilibrium.

Effect of zinc on growth and development of larvae of the Pacific oyster Crassostrea gigas

Abstract: Following the observation of periodic high concentrations of zinc in estuarine waters used in the White Fish Authority's oyster hatchery at Conway, North Wales, two beaker trials were conducted to study the effect of zinc, over the range recorded, on the young stages of larvae of Crassostrea gigas. Zinc, added to sea water both as zinc sulphate and as a natural mine-adit water, was applied for a period of 5 days, after which larvae were maintained for a further 5 days in sea water alone. Increasing concentrations over the range 125 to 500 μg/l Zn resulted in decreasing growth, and increasing incidence of abnormality and larval mortality. A second trial with zinc sulphate showed 50 μg/l Zn to have little effect on larval development, a progressive decrease in growth at 100 and 150 μg/l, and no growth at 200 μg/l. It is suggested that the deleterious effect of short-term exposure to zinc may well have contributed to the intermittent failure of larvae and irregular productivity previously recorded at the hatchery. It is also possible that zinc contamination in estuaries may affect natural oyster breeding, and may have to be considered in the future siting of hatcheries for seed production.

Occurrence, diagnosis, and correction of zinc deficiency of lowland rice

Abstract: Zinc deficiency occurs widely in lowland rice in Asia. The incidence of zinc deficiency is correlated positively with high pH, low available zinc content, and high organic matter in the soil. The problem fields often have poor drainage. An example of zinc deficiency was recorded for a “normal field” that had been cropped continuously. Visible symptoms and plant analyses were used as diagnostic techniques. The application of zinc sulfate, zinc chloride, zinc oxide, and FTE to the soil, and dipping roots of seedlings in 1 or 2% zinc oxide suspension were quite effective. Merits and shortcomings of these methods are discussed.

1:1 Zinc methionine complexes

Abstract: Novel salts are prepared wherein the cation of the salt comprises a 1:1 ratio of a complex ion formed between zinc and methionine and any suitable anion, either inorganic or organic. The novel salts have the generic formula: [CH.sub.3 SCH.sub.2 CH.sub.2 CH(NH.sub.2)COO.Zn.sup.+.sup.+].sub.w X wherein X is an anion and w is an integer equal to the anionic charge of X. These novel compounds are useful nutritional supplements, both for animals and humans, in that they provide a readily-available source of the zinc ions necessary for dietary balance. In addition, certain of the compounds falling within the formula disclosed herein have been found to have therapeutic utility in the treatment of acne and colitis.

Copper and Zinc Concentration in the Plasma of Leukaemic Children

Abstract: Summary. The concentrations of copper and zinc have been measured in the plasma of children with acute lymphoblastic leukaemia before and after treatment, and compared with healthy controls. The plasma copper concentrations were higher and the plasma zinc concentrations lower for the untreated leukaemic children than for the other two groups. The concentrations of both metals were altered after treatment to values approaching the normal range. The plasma copper: zinc ratio discriminated well between the untreated leukaemic children and the other two groups. This ratio might prove useful in monitoring the response to treatment.