Showing papers on "Zinc toxicity published in 1978"

Toxicity of zinc to fungi, bacteria, and coliphages: influence of chloride ions.

Abstract: A 10 mM concentration of Zn2+ decreased the survival of Escherichia coli; enhanced the survival of Bacillus cereus; did not significantly affect the survival of Pseudomonas aeruginosa, Norcardia corallina, and T1, T7, P1, and phi80 coliphages; completely inhibited mycelial growth of Rhizoctonia solani; and reduced mycelial growth of Fusarium solani, Cunninghamella echinulata, Aspergillus niger, and Trichoderma viride. The toxicity of zinc to the fungi, bacteria, and coliphages was unaffected, lessened, or increased by the addition of high concentrations of NaCl. The increased toxicity of zinc in the presence of high concentrations of NaCl was not a result of a synergistic interaction between Zn2+ and elevated osmotic pressures but of the formation of complex anionic ZnCl species that exerted greater toxicities than did cationic Zn2+. Conversely, the decrease in zinc toxicity with increasing concentrations of NaCl probably reflected the decrease in the levels of Zn2+ due to the formation of Zn-Cl species, which was less inhibitory to these microbes than was Zn2+. A. niger tolerated higher concentrations of zinc in the presence of NaCl at 37 than at 25 degrees C.

Heavy metals in soils, vegetation development and heavy metal tolerance in plant populations from metalliferous areas

Abstract: SUMMARY The development of vegetation (mainly the Violetum calaminariae Schwick.) in heavy metal-contaminated areas depends on the metals mobility in soils and on metal availability for plants. Moreover, the ability of plant populations to evolve metal tolerance is one of the most important characters which determines the structure, density and development of the vegetation in such areas. In this work, metal mobility in soils and availability to plants in both calcareous and non-calcareous situations were investigated in relation to the development of genetical heavy metal tolerance in plant populations. In soils, exchangeable metals amounts are linearly related to total amounts. Availability of metals for plants depends on soil pH and on organic matter contents. High calcium content in soils reduced lead toxicity more than zinc toxicity and generally reduced metal uptake but some exceptions were found. The structure and the density of the vegetation colonizing calcareous and non-calcareous places is related to the interaction between lead, zinc and exchangeable non-toxic cations. A relationship between exchangeable Pb++/Ca++ in soils and the lead tolerance level of plant populations was found. The relation between exchangeable Zn++/Ca++ and zinc tolerance level was not satisfactory.

Toxic effects of zinc on fathead minnows Pimephales promelas in soft water

Abstract: A fathead minnow life-cycle exposure to various zinc concentrations demonstrated that the most sensitive indicators of zinc toxicity were egg adhesiveness and fragility, which were significantly affected at 145 μg Zn 1−1 and above, but were not affected at 78 μg Zn 1−1 and below. These effects occurred shortly after the eggs were spawned (during water hardening) and therefore were not related to effects on the parental fish. Hatchability and survival of larvae were significantly reduced, and deformities at hatching were significantly increased at 295 ug Zn 1−1 and above. Acclimated and unacclimated groups of larvae exposed to identical zinc concentrations for 8 weeks after hatch showed only slight differences in sensitivity.

Chronic Effects of Cadmium and Zinc Mixtures on Flagfish (Jordanella floridae)

Abstract: Flagfish were exposed to cadmium and zinc as individual metals and as mixtures (4.3-8.5 μg Cd/liter and 73.4-139 μg Zn/liter) through one complete life cycle in Lake Superior water (45 mg/liter total hardness). Cadmium and zinc did not act additively at sublethal concentrations when combined as mixtures; however, a joint action of the toxicants was indicated. Effects on survival showed that the toxicity of cadmium and zinc mixtures was little if any greater than the toxicity of zinc alone. Mechanisms of zinc toxicity in this test were similar to those in previous chronic tests of individual metals, indicating that the presence of cadmium did not influence the mode of action of zinc. Comparisons between metal residues in fish exposed to each individual metal or to the metal mixtures showed that the uptake of one metal was not influenced by the presence of the other.

Effects of Continuous Zinc Exposure on Sockeye Salmon during Adult-to-Smolt Freshwater Residency

Abstract: This chronic zinc toxicity test with sockeye salmon (Oncorhynchus nerka) consisted of a 3-mo adult exposure followed by an 18-mo exposure of embryonic through smolt stages. The zinc concentrations utilized were 30 to 112 μg/liter during the adult-to-smolt exposure period, and an additional 242 μg/liter concentration was used for the embryo-to-smolt exposure period. These zinc concentrations produced no adverse effects on survival, fertility, fecundity, growth, or on the subsequent survival of smolts transferred to seawater. Exposure to 242 μg/liter produced sufficient acclimation to markedly decrease acute mortality at zinc levels lethal to unacclimated sockeye salmon juveniles. The 112- and 242-μg/liter concentrations were 0.15 and 0.32, respectively, of the 749-μg/liter, 96-h LC50 for the 8-mo-old sockeye salmon. An application factor relating 96-h LC50 and “safe” concentrations of zinc to anadromous sockeye salmon in soft water appears to be >0.15 and at least 15 times larger than the often re...

Local absorption of zinc from wounds treated with different concentrations of zinc sulphate.

Abstract: In the present study it was shown in rats that zinc is absorbed from excisional wounds treated with zinc sulphate. Systemic toxic effects were observed in the group treated with 20% zinc sulphate. Local toxic effects were seen in wounds treated with 0.2%, 2% and 20% zinc sulphate. An inhibitory effect of zinc on the migration of granulocytes was suggested on the basis of microscopic observation. In the operated groups which were not treated with zinc and the group treated with 0.02% zinc sulphate a decline was observed in the concentration of zinc in serum. The zinc concentration in serum increased in proportion to the zinc sulphate concentration (0.2%, 2% and 20%) applied to the wounds, while the copper concentration decreased in the groups treated with 2% and 20% zinc sulphate. In all operated groups an increase in zinc and copper concentrations was observed in liver. This was most pronounced in groups treated with higher concentrations of zinc sulphate (0.2%, 2% and 20%). The groups treated with higher concentrations of zinc sulphate also had higher pancreas zinc concentrations than the remaining groups.

Zinc toxicity in corn as a result of a geochemical anomaly

Abstract: Corn grown on zinc-rich soil (adjacent to an abandoned zinc mine) showed severe chlorosis and stunting. Soil zinc content was positively correlated with leaf zinc content, but not correlated with leaf iron content. Soil zinc was negatively correlated, and soil iron positively correlated, with chlorophyll content. Excess zinc may interfere with iron metabolism in the plant, but does not appear to affect the iron supply to the leaf.

Comparison of the toxicity of some metals and their tetracyanide complexes on the respiration of non acclimated activated sludges.

Abstract: The toxic effect of the metal ions of cadmium, zinc, nickel and mercury and their tetracyanide salt complexes, on the activated sludge not previously acclimated, has been studied. The evaluation of the effect was carried out using both the Warburg and TTC-method. The results obtained have shown that the toxicity of the cadmium and zinc complexes is higher than that of the corresponding metals, while the toxicity of Ni(CN)4(2-) is lower than that of the corresponding metals. No differences have been found between the effect of mercury and the corresponding tetracyanide complex. From the data obtained it appears that it is not possible to generalize about the biological effect of complexation with the CN- group, but it should be stated that, generally, there are substantial differences between metals and their cyanide complexes as far as toxicity for activated sludge is concerned.