Trace metals are components of releases to air emitted by copper and zinc production facilities in Canada. Six metals (copper, zinc, nickel, lead, cadmium, and arsenic) are examined as part of an overall environmental assessment of these releases. Estimates of metal deposition rates to soils and surface waters were derived from monitoring data in the vicinity of the production facilities and also through dispersion modelling studies. Fate and transport modelling of the metals deposited allowed an estimation of critical loads. Estimated annual deposition rates were compared with 25th-percentile critical loads typically representative of effects on sensitive organisms under 25% of conditions in sandy soils or circumneutral to acidic lake waters. The results of the comparison suggest that there is a potential for adverse effects on aquatic and/or soil-dwelling organisms from exposure to steadystate concentrations of metals in the vicinity of copper and zinc production facilities. Approaches of particular significance in these assessments include probabilistic estimation of critical loads for metals, allowance for the speciation of metals defining the bioavailable fraction and limiting critical effect levels to the high end of natural background metal concentrations. 相似文献
The genetic basis of Cd tolerance and hyperaccumulation was investigated in Arabidopsis halleri. The study was conducted in hydroponic culture with a backcross progeny, derived from a cross between A. halleri and a non-tolerant and non-accumulating related species Arabidopsis lyrata ssp. petraea, as well as with the parents of the backcross. The backcross progeny segregates for both cadmium (Cd) tolerance and accumulation. The results support that (i) Cd tolerance may be governed by more than one major gene, (ii) Cd tolerance and Cd accumulation are independent characters, (iii) Cd and Zn tolerances co-segregate suggesting that they are under pleiotropic genetic control, at least to a certain degree, (iv) the same result was obtained for Cd and Zn accumulation. 相似文献
Pisum sativum L. cv. Phenomen plants were grown in pots in greenhouse and their growth, and ATP and chlorophyll (Chl) a and b contents were assessed after 9-d exposure to sodium arsenate [0.04 and 0.07 mmol kg–1(soil)], or to lead acetate [2.0 and 4.0 mmol kg–1(soil)], or zinc acetate [5.3 and 9.3 mmol kg–1(soil)]. The luciferin-luciferase method was used for ATP analyses. Soil pollution reduced significantly the growth, but the low toxicant concentrations elevated the cotyledon and shoot ATP concentrations per fresh matter content. The ATP/Chl ratio was increased in the zinc-treated seedlings as compared with the respective controls. The ATP concentration and a number of growth parameters were negatively correlated, and thus the high ATP content might contribute to the significantly reduced growth of seedlings. 相似文献
This study was conducted to determine effects of nitrogen supply (75 and 150 kg(N) ha−1) and CO2 enrichment on partitioning of macro and micro nutrients in wheat (Triticum aestivum L. cv. HD-2285). Plants were grown from seedling emergence to maturity inside open top chambers under ambient CO2 (CA, 350 ± 50 μmol mol−1) and elevated CO2 (CE, 600 ± 50 μmol mol−1). Leaves, stems and roots of the same physiological age were analyzed for carbon, nitrogen, calcium, copper, iron, zinc and
manganese content at 40, 60 and 90 d after germination. C, Cu, Mn and Zn content was higher in the stem, leaves and roots
on dry mass basis under CE than CA. However, N and Fe contents decreased in CE grown plants. Ca content was unaffected due
to CE and variable N supplies.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
The objective of this study was to determine the effects of an oxygen enriched environment on the induction of the metalloprotein metallothionein (MT) and its relation to zinc metabolism in rats supplied with different levels of dietary zinc. Male albino rats were fed purified diets based on maize starch, egg white, saccharose and soybean oil differing in the concentration of zinc (1; 20; 100; 500 mg Zn/kg diet). At a dietary zinc supply of 1 mg/kg, the rats developed a zinc deficiency indicated by visual and biochemical parameters. At the end of the 37-day feeding period, half of the rats were exposed to 100% oxygen for 12 h.
The oxygen treatment significantly reduced plasma zinc in the zinc supplemented rats and reduced it in tendency in the zinc deficient rats. The MT concentration was increased in the zinc supplemented groups in the liver, kidney and lung. The oxygen treatment elevated the metallothionein concentration in the two high zinc supplemented groups (100 and 500 mg Zn/kg diet) in the liver. The response of the zinc concentration in plasma and of hepatic metallothionein levels to oxygen exposure indicates a role of metallothionein in zinc distribution or interactions with other trace elements to support antioxidant capacity, rather than an impact on direct scavenging activity of free radicals. 相似文献
The ability of the biofilms of a three-stage rotating biological contactor (RBC) to treat wastewater contaminated with cadmium, copper and zinc was investigated. The system successfully removed the metals, in the order Cu > Zn > Cd with removal capacities of approximately 73, 42 and 33% respectively. Analysis of the contribution of each reactor indicated that metal removal was not uniform, with Reactor 1 showing a much higher removal capacity than Reactors 2 and 3. Energy dispersive X-ray spectroscopy (EDS) revealed the presence of all three metals on the surface of the biofilms in all three reactors. Closer inspection of the biofilms, in terms of biomass and biofilm thickness, revealed that the low metal removal in Reactors 2 and 3 was probably attributable to poor biofilm development in these two reactors compared to that in Reactor 1. The poor biofilm development was substantiated by low chemical oxygen demand (COD) removal in the latter two reactors. 相似文献
Micronuclei (MN) in blood lymphocytes were determined in 31 male workers occupationally exposed to lead (Pb), zinc (Zn), and
cadmium (Cd) and 20 control workers matched for age and smoking habits. Exposed workers have higher MN mean values than control
workers (p<0.01). In exposed workers, blood Pb concentrations were also significantly higher than in control workers (p<0.001), but the mean concentrations of Zn and Cd in the blood were not statistically significant compared to the controls
(p>0.05). These results suggest that lead may be genotoxic and the human lymphocyte micronucleus test can be used to assess
genotoxic effects that result from occupational exposures. 相似文献
We hypothesized that plasma extracellular superoxide dismutase (EC-SOD) activity reflects the zinc nutriture of healthy pregnant
women. Sixty-three women were selected from 580 African-American women who participated in a clinical trial to evaluate the
effect of prenatal zinc supplementation on pregnancy outcome. Half of the women received zinc (25 mg/d) and the other half
was given a placebo from about 19 wk gestation to delivery. In the trial, a positive effect of zinc supplementation on birthweight
was observed, indicating that the population as a whole had suboptimal zinc nutriture. Using plasma samples obtained during
the trial, EC-SOD activities were measured and the values were compared with plasma zinc concentrations and plasma alkaline
phosphatase activities. Plasma EC-SOD activities in our subjects were lower than previously published values for healthy adults
in Korea. Although plasma EC-SOD activity may reflect severe zinc deficiency, it is not a sensitive marker for marginal deficiency
status. Plasma EC-SOD activities did not prove to be a better indicator of zinc nutriture of pregnant women than either plasma
zinc or plasma alkaline phosphatase activities. 相似文献