An Ecological Risk Assessment of Air Emissions of Trace Metals from Copper and Zinc Production Facilities

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 25^th-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.     

The IRT1 protein from Arabidopsis thaliana is a metal transporter with a broad substrate range

The molecular basis for the transport of manganese across membranes in plant cells is poorly understood. We have found that IRT1, an Arabidopsis thaliana metal ion transporter, can complement a mutant Saccharomyces cerevisiae strain defective in high-affinity manganese uptake (smf1). The IRT1 protein has previously been identified as an iron transporter. The current studies demonstrated that IRT1, when expressed in yeast, can transport manganese as well. This manganese uptake activity was inhibited by cadmium, iron(II) and zinc, suggesting that IRT1 can transport these metals. The IRT1 cDNA also complements a zinc uptake-deficient yeast mutant strain (zrt1zrt2), and IRT1-dependent zinc transport in yeast cells is inhibited by cadmium, copper, cobalt and iron(III). However, IRT1 did not complement a copper uptake-deficient yeast mutant (ctr1), implying that this transporter is not involved in the uptake of copper in plant cells. The expression of IRT1 is enhanced in A. thaliana plants grown under iron deficiency. Under these conditions, there were increased levels of root-associated manganese, zinc and cobalt, suggesting that, in addition to iron, IRT1 mediates uptake of these metals into plant cells. Taken together, these data indicate that the IRT1 protein is a broad-range metal ion transporter in plants.     

Influence of spontaneous diabetes on tissue status of zinc, copper, and manganese in the BB Wistar rat

The concentrations of zinc, copper, and manganese in liver, kidney, duodenum, pancreas, testes, bone, and serum from control and untreated, spontaneously diabetic BB Wistar rats were compared. Chronic insulin deficiency resulted in significant alterations in the concentrations of one or more of these essential micronutrients in several tissues. The amounts of zinc and copper bound to metallothionein in the liver and kidney of untreated spontaneously diabetic rats were also markedly increased. The tissue trace metal status in diabetic rats was altered similarly in both male and female rats. Daily injections of insulin blocked many of the changes in the tissue concentrations of the metals. The effects of spontaneous diabetes on tissue trace metal status are quite similar to those reported for chemically induced diabetes. Thus, these results demonstrate that chronic endocrine imbalance is responsible for a series of tissue specific changes in the transport and metabolism of zinc, copper, and manganese.     

Larval development of hermit crab Clibanarius longitarsus: Synergistic effect of heavy metals

The levels of heavy metals copper and zinc were found to be high in the Vellar estuary. Therefore their effects on the larval development of the abundant hermit crab Clibanarius longitarsus were studied individually and in combination from hatching till moulting to glaucothoe stage in the laboratory using freshly hatched Artemia nauplii as food. The 96 h LC50 values found with 100 larvae each kept in 10 different concentrations of copper and zinc (350, 300, 250, 200, 150, 100, 50, 25, 10 and 5 ppb) were 50 ppb for copper and 90 ppb for zinc. Based on these 96 h LC50 values, three sublethal concentrations were chosen for the metals copper and zinc at 50%, 25% and 10% levels of the LC50 values. With increase in concentration of the test medium, the survival rate decreased and the time required for the completion of each zoeal stage increased. Copper was found to be more toxic than zinc as the survival rate in copper concentrations was lower than those in zinc concentrations. The survival rate in the mixed concentrations of metals was lower than in individual concentrations.     

Asymmetric distribution of metals in the Xenopus laevis oocyte: a synchrotron X-ray fluorescence microprobe study.

The asymmetric distribution of many components of the Xenopus oocyte, including RNA, proteins, and pigment, provides a framework for cellular specialization during development. During maturation, Xenopus oocytes also acquire metals needed for development, but apart from zinc, little is known about their distribution. Synchrotron X-ray fluorescence microprobe was used to map iron, copper, and zinc and the metalloid selenium in a whole oocyte. Iron, zinc, and copper were asymmetrically distributed in the cytoplasm, while selenium and copper were more abundant in the nucleus. A zone of high copper and zinc was seen in the animal pole cytoplasm. Iron was also concentrated in the animal pole but did not colocalize with zinc, copper, or pigment accumulations. This asymmetry of metal deposition may be important for normal development. Synchrotron X-ray fluorescence microprobe will be a useful tool to examine how metals accumulate and redistribute during fertilization and embryonic development.     

The importance of juveniles in structuring a littoral macrobenthic community

The relationships between individual dry weight and bodycontent of the essential metals copper and zinc and of therespiratory pigment haemocyanin have been investigated in fourBritish species of caridean decapod crustaceans, Palaemonelegans, Palaemon longirostris, Palaemonetesvarians and Crangon crangon. Also considered were thebody concentrations of soluble copper and copper associatedwith haemocyanin. These decapods regulate total bodyconcentrations of copper and zinc to approximately constantlevels which can vary interspecifically. An attempt is made tointerpret these regulated concentrations in terms of essentialrequirements for the metals in the physiological functioningof haemocyanin, the body concentration of which variesinterspecifically and intraspecifically with environmentalvariables.     

非生物因子对河蚬重金属富集量的影响

对影响长江口滨岸带河蚬体内重金属富集量的4个主要非生物因子依次进行分析。结果表明,较高温度有助于河蚬对Cu、Zn、Cr、Ni的吸收;盐度对河蚬的重金属累积量影响比较复杂,仅在秋季表现出一定相关性,春季盐度影响不大;河蚬体内Cu含量与沉积物粒径存在显著正相关,Zn与沉积物中有机质含量存在一定正相关,Pb与沉积物中有机质含量存在着负相关;河蚬体内重金属元素两两间的相关性明显,多种元素间的相互作用机理值得进一步探讨。     

The behaviour of copper and zinc in the Scheldt estuary

The behaviour of copper and zinc in the Scheldt estuary, both in the particulate and the dissolved phase, is discussed for the period 1982–1983. The longitudinal particulate copper and zinc profiles fall below the dilution line, which is attributed to mixing and mobilization processes. In the dissolved phase both metals show a production region in the end member of the estuary, for copper a pronounced mid estuarine maximum is observed. Study of the metal speciation suggested that organic ligands might keep heavy metals in solution, especially in area of intensive production, and promote the subsequent export of these metals downstream the estuary.     

The Correlation of Serum Trace Elements and Heavy Metals with Carotid Artery Atherosclerosis in Maintenance Hemodialysis Patients

Changes in essential trace elements and heavy metals may affect the atherosclerotic state of patients on maintenance hemodialysis (HD). The aim of the study was to evaluate the relation between the serum levels of some trace elements and heavy metals (iron, zinc, manganese, copper, magnesium, cobalt, cadmium, lead, and copper/zinc ratio) and carotid artery intima-media thickness (CIMT) in HD patients. Fifty chronic HD patients without known atherosclerotic disease and 48 age- and sex-matched healthy individuals were included in the study. The serum levels of trace elements (iron, zinc, manganese, copper, and magnesium) and heavy metals (cobalt, cadmium, and lead) were measured by Atomic Adsorption Spectrophotometer (UNICAM-929). CIMT was assessed by carotid artery ultrasonography. The serum levels of iron, zinc, and manganese were lower; levels of copper, magnesium, cobalt, cadmium, lead, and copper/zinc ratio were higher in HD patients compared to controls. CIMT in HD patients were higher than the control group (0.64?±?0.11 vs 0.42?±?0.05, p?相似文献   

Bacterial ATP-driven transporters of transition metals: physiological roles, mechanisms of action, and roles in bacterial virulence

Maintaining adequate intracellular levels of transition metals is fundamental to the survival of all organisms. While all transition metals are toxic at elevated intracellular concentrations, metals such as iron, zinc, copper, and manganese are essential to many cellular functions. In prokaryotes, the concerted action of a battery of membrane-embedded transport proteins controls a delicate balance between sufficient acquisition and overload. Representatives from all major families of transporters participate in this task, including ion-gradient driven systems and ATP-utilizing pumps. P-type ATPases and ABC transporters both utilize the free energy of ATP hydrolysis to drive transport. Each of these very different families of transport proteins has a distinct role in maintaining transition metal homeostasis: P-type ATPases prevent intracellular overloading of both essential and toxic metals through efflux while ABC transporters import solely the essential ones. In the present review we discuss how each system is adapted to perform its specific task from mechanistic and structural perspectives. Despite the mechanistic and structural differences between P-type ATPases and ABC transporters, there is one important commonality: in many clinically relevant bacterial pathogens, transporters of transition metals are essential for virulence. Here we present several such examples and discuss how these may be exploited for future antibacterial drug development.     

Reference ranges of copper and zinc and the prevalence of their deficiencies in an Arab population aged 15-80 years

Serum concentrations of copper and zinc were measured by flame atomic absorption spectrophotometry in 560 Kuwaitis aged from 15 to 80 yr who were in apparent good health to establish reference ranges and determine the prevalence of the deficiency of the trace metals. Zinc/copper ratios were derived by calculation. Because the mean +/- SD (microM) for copper in females (24.9 +/- 7) was significantly higher (p<0.0001) than in males (21.0 +/- 5.8) and vice versa for zinc (17.0 +/- 3.5 [males] vs 15.5 +/- 3.4 [females]) and zinc/copper ratios (0.87 +/- 0.28 [males] vs 0.67 +/- 0.27 [females]), gender-specific reference ranges were established in addition to reference ranges for the total population. The reference range for zinc was closer to those reported for other populations than was copper. Body mass index (BMI) and copper values were lower and the zinc/copper ratio was higher in the young (15-24 yr) compared to the older subjects. Copper concentrations were positively associated with BMI values (r=0.302, p<0.0001). Smokers had significantly lower (p=0.011) BMI than nonsmokers. The prevalence of copper and zinc deficiency, 0.36% and 0.53%, respectively, was low. Generally, the values for serum copper and zinc obtained for the Kuwaiti population studied suggest adequate dietary intake of the trace metals.     

Multilevel Anthropogenic Cycles of Copper and Zinc: A Comparative Statistical Analysis

Contemporary cycles for copper and zinc are coanalyzed with the tools of exploratory data analysis. One-year analyses (circa 1994) are performed at three discrete spatial levels-country (52 countries that comprise essentially all anthropogenic stocks and flows of the two metals), eight world regions, and the planet as a whole-and are completed both in absolute magnitude and in per capita terms. This work constitutes, to our knowledge, the first multiscale, multilevel analysis of anthropogenic resources throughout their life cycles. The results demonstrate that (1) A high degree of correlation exists between country-level copper and country-level zinc rates of fabrication and manufacturing, entry into use, net addition to in-use stocks, discard, and landfilling; (2) Regional-level rates for copper and zinc cycle parameters show the same correlations as exist at country level; (3) On a per capita basis, countries add to in-use stock almost 50% more copper than zinc; (4) The predominant discard streams for copper and zinc at the global level are different for the two metals, and relative rates of different loss processes differ geographically, so that resource recovery policies must be designed from metalspecific and location-specific perspectives; (5)When absolute magnitudes of life-cycle flows are considered, the standard deviations of the data sets decrease from country level to regional level for both copper and zinc, which is not the case for the per capita data sets, where the statistical properties of the data sets for both metals approach being independent of spatial level, thus providing a basis for predicting unmeasured per capita metal flow behavior.     

Transition metal homeostasis: from yeast to human disease

Transition metal ions are essential nutrients to all forms of life. Iron, copper, zinc, manganese, cobalt and nickel all have unique chemical and physical properties that make them attractive molecules for use in biological systems. Many of these same properties that allow these metals to provide essential biochemical activities and structural motifs to a multitude of proteins including enzymes and other cellular constituents also lead to a potential for cytotoxicity. Organisms have been required to evolve a number of systems for the efficient uptake, intracellular transport, protein loading and storage of metal ions to ensure that the needs of the cells can be met while minimizing the associated toxic effects. Disruptions in the cellular systems for handling transition metals are observed as a number of diseases ranging from hemochromatosis and anemias to neurodegenerative disorders including Alzheimer??s and Parkinson??s disease. The yeast Saccharomyces cerevisiae has proved useful as a model organism for the investigation of these processes and many of the genes and biological systems that function in yeast metal homeostasis are conserved throughout eukaryotes to humans. This review focuses on the biological roles of iron, copper, zinc, manganese, nickel and cobalt, the homeostatic mechanisms that function in S. cerevisiae and the human diseases in which these metals have been implicated.     

Hepatic metallothionein production and resistance to heavy metals by rainbow trout (Salmo gairdneri)--I. Exposed to an artificial mixture of zinc, copper and cadmium

Rainbow trout developed elevated hepatic metallothionein concentrations after 4 weeks in a solution containing zinc, copper and cadmium in a fixed ratio of 400:20:1. Resistance to a combination of these metals increased in proportion to the concentration to which they were exposed for 4 weeks. The concentration of copper but not zinc or cadmium in the low molecular weight proteins separated by gel filtration was related to the concentrations of metallothionein present. The combined toxicity of the metals in the mixture was additive.     

Effect of replacement of "zinc finger" zinc on estrogen receptor DNA interactions.

Exposure of bovine estrogen receptor to the metal chelators EDTA and 1,10-phenanthroline results in a loss of nonspecific DNA binding, presumably because of the removal of "zinc finger" zinc. Nonspecific DNA binding, as measured by a DNA-cellulose binding assay, can be restored by dialysis of the aporeceptor against buffer containing zinc, cadmium, and cobalt but not with buffer containing copper or nickel. More detailed studies were carried out using a bacterially expressed polypeptide encompassing the DNA binding domain of the human estrogen receptor. Apopolypeptide fails to bind DNA specifically, as measured by mobility shift assay using a consensus estrogen response element hexamer containing oligonucleotide, but DNA binding was restored by dialysis of the apopolypeptide against buffer containing zinc, cadmium, and cobalt but not with buffer containing copper or nickel. Dissociation constants of zinc- and cadmium-reconstituted polypeptide for the estrogen response element hexamer (66 and 48 nM, respectively) are virtually indistinguishable from native polypeptide (Kd = 48 nM) whereas cobalt-reconstituted polypeptide has a lower affinity (Kd = 720 nM). However, native, zinc-, cadmium-, and cobalt-reconstituted polypeptides gave identical results in a methylation interference assay. Competition experiments with zinc and copper or nickel suggest that copper and nickel are able to bind to zinc finger residues but do so nonproductively. The relative affinities copper greater than cadmium greater than zinc greater than cobalt greater than nickel for the polypeptide were determined by a zinc blot competition assay. The ability of cadmium and cobalt to substitute for zinc in the zinc fingers demonstrates a structural "flexibility" in the DNA binding domain as each of these metals has slightly different ionic radii. On the other hand, subtle differences in DNA binding affinity and/or specificity could exist, which may not be detectable here. Also, the ability of metals to substitute for zinc in the DNA binding domain suggests that metal substitution in these zinc fingers in vivo may be of relevance to the toxicity and/or carcinogenicity of some of these metals.     

Microbial leaching of zinc concentrate in fresh‐water microcosms: Comparison between aerobic and oxygen‐limited conditions

Microbially mediated leaching and solubilization of zinc ore concentrate by native aquatic microbial communities incubated under aerobic and oxygen‐limited conditions were examined in static microcosms consisting of stream sediment and water. Sterile controls provided information on abiotic sulfide oxidation and leaching of zinc, lead, cadmium, and copper. The flux of these heavy metals from the sediments to the water column was greatest under biotic oxygen‐limited conditions. When calculated as the percentage of total metal available in zinc concentrate‐amended microcosms, the order of metal solubilization under oxygen‐limited conditions was lead, copper, zinc, and cadmium. Under biotic aerobic conditions, the order of solubilization was zinc, lead, cadmium, and copper. This study indicates that aquatic heterotrophs are capable of leaching and solubilizing metallic sulfides under conditions of neutral to slightly acidic pH and are effective in releasing heavy metals to the water column under oxygen‐limited conditions.     

Active Uptake of Copper and Zinc during Haemodialysis

The uptake of copper and zinc by patients undergoing regular haemodialysis has been assessed by measuring the dialysis fluid for copper and zinc concentration, and the blood entering and leaving the dialysis coil for red cell copper, plasma free copper, and plasma zinc levels during priming of the coil and subsequent haemodialysis, and by in-vitro studies.Red cells avidly removed copper from dialysis fluid when mixed with saline during priming, but did not take up copper during the haemodialysis. At both these stages plasma actively took up both copper and zinc from dialysis fluid, even against a concentration gradient, so that loss of these metals from plasma to dialysis fluid did not occur.In the dialysis systems investigated the sources of the copper in the dialysis fluid were the copper plumbing of the tap-water and the dialysis coil, and the major source of zinc was the zinc oxide of the adhesive plaster around the dialysis coil.