Dear Editor,Fungicide treatment has a profound effect on controlling plant pathogens in modern agriculture,however,it also carries the risk of undesirable outcomes.For decades,scientists have been concerned about the ...Dear Editor,Fungicide treatment has a profound effect on controlling plant pathogens in modern agriculture,however,it also carries the risk of undesirable outcomes.For decades,scientists have been concerned about the harmful impacts of heavy metals like copper(Cu)on crop performance and soil microorganisms.Use of various copper fungicides,like Bordeaux mixture,have been a component of conventional agricultural practices to control fungal and bacterial pathogens,especially in vineyards,tea gardens,or fruit tree orchards[9,10].This treatment increases the accumulation of high levels of Cu in surface soils,and despite the critical role of Cu as an essential trace element in wide biological and metabolic processes,it becomes toxic to plants when applied at high levels[4].The regular application of copper fungicides has also been linked to affecting microbial communities at the levels of diversity[8],population structure[2],abundance,and growth[1,3].Understanding the undesired effects of fungicides on microorganisms’beneficial activities is therefore important for evaluating the hazards associated with the fungicide used in agriculture.Yet,the effects of copper fungicide on full microbial communities remains relatively understudied,especially in tea plants.Thus,we herein explored the inf luence of Bordeaux mixture under different management regimes(raking or without raking leaf litter)on microbial communities of root,bulk soil,and rhizosphere compartments of tea plants planted in a ten-year-old tea garden.We provided insights into the ecological consequences of tea management practices that might help to identify specific fungicide treatment regimens,environmental characteristics,and microbial community members to minimize the negative environmental outcomes and optimize the positive anti-pathogen aspects of fungicide treatment.展开更多
The application of pressure leaching technology in the treatment of high-copper and high-arsenic dust was studied.The pressure leaching technique was determined as follows:the liquid to solid ratio(mL/g)of 5:1,the lea...The application of pressure leaching technology in the treatment of high-copper and high-arsenic dust was studied.The pressure leaching technique was determined as follows:the liquid to solid ratio(mL/g)of 5:1,the leaching temperature of 453 K,the retention time of 2 h,the initial sulfuric acid concentration of 0.74 mol/L,the oxygen partial pressure of 0.7 MPa,and the agitation speed of 500 r/min.Under these conditions,95%of copper and 99%of zinc and only 6%of iron in the dust were leached,while about 20%of arsenic was also leached.The leaching technique was optimized further to restrain the leaching of arsenic by adding a small quantity of ferrous iron into the leaching system(c(Fe2 +)=0.036 mol/L).Copper and zinc can be effectively separated from arsenic and iron in the leach.The optimal pressure leaching technique of high-copper and high-arsenic smelter dust is proved to be effective.展开更多
Invasive plant species may significantly alter plant species community composition and structure thereby negatively impacting on ecosystem services. Their impacts on plant communities may be both direct and indirect. ...Invasive plant species may significantly alter plant species community composition and structure thereby negatively impacting on ecosystem services. Their impacts on plant communities may be both direct and indirect. The direct effects may include a reduction in the abundance and diversity of palatable plant species that constitute important forage for livestock, wildlife, and medicines for the local communities. Declines in ecosystem resilience are of the notable indirect effects of invasive species. The aim of this study was to assess the impacts of a plant species, copper leaf (<em>Acalypha fruticosa</em>) on floral diversity and abundance at Chemeron, Baringo County in Kenya. The study was guided by three questions: What is the plant composition in terms of grasses, herbs, shrubs, and trees in the study area? Are there any variations in plant abundance between the two sites (sites with and without <em>Acalypha fruticosa</em>)? Are there variations in plant species diversity between the two study sites? Two sites (one with <em>A. fruticosa</em> and another two without this invasive species) were selected within the Chemeron Research Centre. Two belt transects measuring 100 m × 20 m on each site were laid parallel to each other. Plant samples were collected from five 1 m × 1 m quadrats that were laid at intervals of 20 m. The plant species or specimens were identified to the species level using available taxonomic keys. Various indices including Shannon-Wiener (<em>H</em>’), Evenness Index, Richness Index and Simpson’s Index of Diversity Index (SDI) were calculated. All the diversity, richness and evenness indices were considerably higher in the site without <em>A. fruticosa</em> compared to that where this invasive species was present. Higher <em>H’</em> (3.14 to 3.21) and SDI (0.93 to 0.94) values were noted in sites without the invasive species compared to <em>H</em>’ (2.11 to 2.20) and SDI (0.77 to 0.85) in sites with <em>A. fruticosa</em> present. Out of the 47 plant species identified, 39 and 20 of them occurred in the site without and with <em>A. fruticosa</em>, respectively. Further, there were more grasses (<em>Aristida keniensis</em>, <em>Cynodon dactylon</em>, <em>Brachiaria lucrantha</em>, <em>Eragrostis racemosa</em>, and <em>Enteropogon macrostachyus</em>) in the site without <em>A. fruticosa</em> compared to that with the invasive plant. The plants were also more evenly distributed in the site without <em>A. fruticosa</em> compared to that where the invasive plant was present. We conclude that <em>A. fruticosa</em> has a significant effect on plant species abundance and diversity as well as distribution. Its removal created a favourable environment for the growth of a variety of grasses. We therefore recommend to the agro-pastoralists and rangeland managers that <em>A. fruticosa</em> be mechanically removed by uprooting from grazing lands so as to increase forage availability and quality in the rangelands of South-Baringo.展开更多
One purpose of this research is to present accumulation of cadmium(Cd) and copper(Cu) by female Oxya chinensis(Orthopera: Acridoidea) in a simulated s oil-plant-insect ecosystem treated with Cd. Fourth-instar nymphs o...One purpose of this research is to present accumulation of cadmium(Cd) and copper(Cu) by female Oxya chinensis(Orthopera: Acridoidea) in a simulated s oil-plant-insect ecosystem treated with Cd. Fourth-instar nymphs of O. chinensis had been fed on wheat(Triticum aestivum) seedlings contaminated with Cd and Cu for one month. In the ecosystem, the Cd concentration in wheat seedlings rose gr eatly with the increasing of Cd in the soil, but the Cu concentration in wheat s eedlings was not found elevated. There was a highly significant difference(P<0. 05) in Cd concentrations of wheat seedlings and not any significant difference(P >0.05) in Cu concentrations of wheat seedlings. The Cd and Cu concentration in different body part-head, thorax, abdomen, and hind femur, varied under differen t Cd concentrations in soil. There were significant differences(P<0.05) in the four parts of Cd and Cu accumulations with all treatments. The order of Cd accum ulation was thorax>abdomen>head>hind femur and the Cu was abdomen>thorax>he ad>hind femur. The results indicated that Cd and Cu were accumulated from the s oil to grasshoppers through the plant; that is to say, Cd and Cu in environment could be transported to animal or human via food chain.展开更多
The preparation of granulated adsorption material of water-quenched slag/rectorite composite and the treatment of Cu(Ⅱ)-containing copper smelter wastewater with the adsorption material were studied. The experimental...The preparation of granulated adsorption material of water-quenched slag/rectorite composite and the treatment of Cu(Ⅱ)-containing copper smelter wastewater with the adsorption material were studied. The experimental results showed that under the conditions with the mass ratio of water-quenched slag to rectorite of 1:1,10%additive of industrial starch(IS),and 50%water,and a calcination temperature of 400 ℃,the granulated adsorption material prepared had a density of 1.06 kg/m3,a porosity of 62.29%,water absorption rate of 58.82%,and compressive strength of 2.22 MPa.The efficiency of wastewater treatment was the best,whereas the rate of spallation loss was low.Under the conditions of natural pH,with the addition of the granulated adsorption material of 0.05 g/mL,a reaction time of 40 minutes,and temperature of 25℃, the efficiency of the granulated adsorption material for the removal of Cu(Ⅱ)ions from the copper smelter wastewater attained 98.2%,and the quality indexes of the wastewater after treatment conformed with the first level of integrated wastewater discharge standard(GB8978-1996).The reclamation of the used granulated adsorption material was carried out by de-sorption of the Cu(Ⅱ)ions from the surface with 1 mol/L sodium chloride solution.The de-sorption rate was 96.4%,and the adsorption material can be reused many times to treat copper smelter wastewater.展开更多
The use of pig compost (PC) in agricultural land has increased in Chile in the last years. This organic amendment is a valuable nutritional source for crops, but its applying must be done in a controlled manner since ...The use of pig compost (PC) in agricultural land has increased in Chile in the last years. This organic amendment is a valuable nutritional source for crops, but its applying must be done in a controlled manner since it exhibited high copper (Cu) and zinc (Zn) concentrations. A short-term field experiment was conducted out to study the effects of increasing PC rates on the production and quality corn crop in two soils located at south central Chile. Five treatments were evaluated: control without fertilization (C), conventional fertilization (CF) (350 kg N ha-1), and three increasing PC rates (15.33, 30.65, and 61.31 Mg·ha-1, corresponding to 350, 700, and 1400 kg N ha-1, respectively) in a split plot design with four replicates. The overall results indicated that dry matter production, grain yield, and plant Zn and Cu concentrations were similar among fertilization sources and rates. Extractable soil Zn concentration exhibited a rate-related increase of PC in both locations, while Cu concentration exhibited this behavior only at the soil located in Chillan. Nevertheless, the values obtained were below of those considered phytotoxic levels. Therefore, the contribution of Zn and Cu through PC applying at different rates to the soils studied showed a slight affect in soil extractable Zn and Cu values without negatively effects on quantity and quality corn crop. The organic amendment applied can be a good and cheaper substitute to conventional fertilization, although further monitoring of Zn and Cu soil levels should be carried out to avoid any environmental risk.展开更多
Seedlings of the medicinal plant Hyoscyamus albus were supplied with an excess of Cu to examine the possible application in phytoremediation. The seedlings were cultured in B5 medium supplied with basal 0.1 μM Cu and...Seedlings of the medicinal plant Hyoscyamus albus were supplied with an excess of Cu to examine the possible application in phytoremediation. The seedlings were cultured in B5 medium supplied with basal 0.1 μM Cu and 200 μM Cu under various light conditions: short day (SD);long day (LD);and continuous light (CL). In addition, the effect of supplying 200 μM Cu under Fe deficiency was determined, in order to elucidate the interaction between Cu and Fe. Interestingly, Fe-deficiency symptoms that developed in plants grown with basic levels of Cu under LD almost disappeared when excess Cu was supplied. Plant growth mainly depended on the photo irradiation period (SD < LD^CL);and 200 μM Cu did not inhibit growth at all when Fe was available, whereas in the absence of Fe, CL caused damage to growth. Analysis of the Cu and Fe contents of the plants revealed that Cu was distributed equally in both the aerial parts and roots, whereas most of the Fe was found in the roots;under Fe deficiency, Cu accumulation in the roots apparently increased. Cu was mainly distributed in the soluble fraction, which included vacuoles and the cell-wall fraction. These results provide evidence indicating that H. albus seedlings are tolerant of Cu present in excess. Furthermore, excess Cu was able to compensate for Fe deficiency, depending on the light conditions. Continuous light inhibited this effect, probably as a result of the induction of Mn deficiency. The possible applications of this newly discovered cuprophyte are discussed.展开更多
In this paper, prediction of copper and molybdenum grades and their recoveries of an industrial flotation plant are investigated using the Artificial Neural Networks (ANN) model. Process modeling has done based on 92 ...In this paper, prediction of copper and molybdenum grades and their recoveries of an industrial flotation plant are investigated using the Artificial Neural Networks (ANN) model. Process modeling has done based on 92 datasets collected at different operational conditions and feed characteristics. The prominent parameters investigated in this network were pH, collector, frother and F-Oil concentration, size percentage of feed passing 75 microns, moisture content in feed, solid percentage, and grade of copper, molybdenum, and iron in feed. A multilayer perceptron neural network, with 10:10:10:4 structure (two hidden layers), was used to estimate metallurgical performance. To obtain the optimal hidden layers and nodes in a layer, a trial and error procedure was done. In training and testing phases, it achieved quite correlations of 0.98 and 0.93 for Copper grade, of 0.99 and 0.92 for Copper recovery, of 0.99 and 0.92 for Molybdenum grade and of 0.99 and 0.94 for Molybdenum recovery prediction, respectively. The proposed neural network model can be applied to determine the most beneficial operational conditions for the expected Copper and Molybdenum grades and their recovery in final concentration of the industrial copper flotation process.展开更多
A copper-inducible, Cre-loxP recombination-mediated DNA excision system has been developed in transgenic tobacco plants. The copper inducible system derived from yeast was used for the control of the expression of the...A copper-inducible, Cre-loxP recombination-mediated DNA excision system has been developed in transgenic tobacco plants. The copper inducible system derived from yeast was used for the control of the expression of the Cre recombinase. Upon copper induction, the GUS reporter gene expression unit flanked by two direct lox sites was excised from the transgenic tobacco genome. Quantitative fluorometric GUS assays,Northern blot and PCR analyses showed a high-efficient, copper-dependent and Cre-loxP mediated DNA recombination in all the tested transgenic lines. The copper inducible foreign gene excision might be of great potential in genetic control of transgenic crops.展开更多
Large quantities of sludge are produced during water treatment processes. Recently, sludge has been treated as waste and disposed of in landfills, which increases the environmental burdens and the operational cost. Th...Large quantities of sludge are produced during water treatment processes. Recently, sludge has been treated as waste and disposed of in landfills, which increases the environmental burdens and the operational cost. Therefore, sludge reuse has become a significant environmental issue. In this study, adsorption of copper ions (Cu^2+) onto calcined sludge was investigated under various operational conditions (with varying temperature, Cu^2+ initial concentration, pH, and sludge dosage). The prepared sludge material was characterized with transmission electron microscopy (TEM), X-ray diffraction (XRD), dynamic light scattering (DLS), and Brunauer-Emmett-Teller (BET) surface area. The sorption capacity of sludge was directly proportional to the initial Cu^2+ concentration and inversely proportional to the sludge dosage. The optimum operational pH and solution temperature were 6.6 and 80℃, respectively. The experimental results followed a Langmuir isotherm and pseudo-first-order adsorption kinetics. Thermodynamic parameters such as activation energy, change in free energy, enthalpy, and entropy were calculated. Thermodynamic analyses indicated that the sorption of copper ions onto the calcined sludge was driven by a physical adsorption process. The prepared sludge was proven to be an excellent adsorbent material for the removal of Cu^2+ from an aqueous solution under optimum conditions.展开更多
This work describes the experimental results of pyrometallurgical removing of arsenic from the dust collected in the electrostatic copper precipitators within the gas cleaning system of a Copper Flash Smelting Furnace...This work describes the experimental results of pyrometallurgical removing of arsenic from the dust collected in the electrostatic copper precipitators within the gas cleaning system of a Copper Flash Smelting Furnace. The generation of dust in the copper smelting worldwide ranges from 2 - 15 wt% per ton of a copper concentrate. In Chile, copper smelters produce approximately 110 kt/y of dust with a concentration of arsenic between 1 and 15 wt%. The dust is a complex of metals oxides and sulfurs with copper concentrations greater than 10 wt% and relatively high silver concentrations. Since its high arsenic concentration, it is difficult to recover valuable metals through hydrometallurgical processes or by direct recirculation of the dust in a smelting furnace. Thus, the development of pyrometallurgical processes aimed at reducing the concentration of arsenic in the dust (<0.5 wt%) is the main objective of this study, giving particular attention to the production of a suitable material to be recirculated in operations of copper smelting. The work provides a detailed characterization of the dust including the Quantitative Evaluation of Minerals by Scanning Electron Microscopy (QEMSCAN), Scanning Electron Microscope-Energy Dispersive X-ray Analysis (SEM/EDS), X-Ray Diffraction (XRD), the elemental chemical analysis using Atomic Adsorption (AAS), and X-Ray Fluorescence (X-RF). By considering that arsenic volatilization requires a process of sulfidation-decomposition-oxidation, this work seeks to explore the roasting of mixtures of copper concentrate/dust, sulfur/dust, and pyrrhotite/dust. By the elemental chemical analysis of the mixture after and before the roasting process, the degree of arsenic volatilization was determined. The results indicated the effects of parameters such as roasting temperature, gas flow, gas composition, and the ratio of mixtures (concentrate/dust, sulfur/dust, or pyrrhotite/dust) on the volatilization of arsenic. According to the findings, the concentration of arsenic in the roasted Flash Smelting dust can be reduced to a relatively low level (<0.5 wt%), which allows its recirculation into an smelting process.展开更多
The potential use of Myriophyllum spicatum L. biomass as a biosorbent for the removal of copper(Ⅱ) from aqueous solution was investigated in laboratory condition. The sorption experiments were undertaken to obtain co...The potential use of Myriophyllum spicatum L. biomass as a biosorbent for the removal of copper(Ⅱ) from aqueous solution was investigated in laboratory condition. The sorption experiments were undertaken to obtain copper(Ⅱ) biosorption properties of M. spicatum L., i.e. equilibrium time, the maximum capacity, and rate constants. Copper(Ⅱ) biosorption was fast and equilibrium was attained within 35 min at initial copper(Ⅱ) concentration of 6 mg/L. Different isotherm models including the Langmuir, Freundlich, Temkin and Redlich-Peterson model, were used to investigate the sorption capacity and isotherm. These models showed an excellent match with the experimental data except for the Freundlich model. According to the Langmuir coefficients, the maximum sorption capacity of copper onto M. spicatum L. was 10.80 mg/g. The kinetics of copper(Ⅱ) sorption was also analysed and rate constants were derived. It was found that the overall sorption process was best described by the pseudo second-order equation, and that intraparticle diffusion was not the rate determining step. The results of this study showed that M. spicatum L. can be considered as useful vehicles for the removal and recovery of copper(Ⅱ) from aqueous solutions.展开更多
The objective of the present study was to gain better insight into the physiological mechanisms on the effects of copper (Cu) on photosynthesis and active oxygen metabolism in three-colored amaranth plant (Amaranthus ...The objective of the present study was to gain better insight into the physiological mechanisms on the effects of copper (Cu) on photosynthesis and active oxygen metabolism in three-colored amaranth plant (Amaranthus tricolor). Three- colored amaranth seedlings were subjected to different Cu levels in soils during the entire experimental period. The parameters of growth, photosynthesis, mineral elements contents, and active oxygen metabolism were investigated using plant physiological methods. The results showed that 2.0 and 4.0 mmol Cu kg-1 treatments decreased the whole plant biomass to 91 and 73% of the control, respectively. The net photosynthetic rate (Pn) and the stomatal conductance (gs) were similarly reduced in the third leaves of three-colored amaranth seedlings treated with 2.0 and 4.0 mmol Cu kg-1 soil, respectively. None of the investigated Cu levels decreased the internal CO2 concentration (Ci). The effect of Cu on the potential efficiency of photosystem Ⅱ(Fv/Fm) was negligible, whereas the effect of Cu on the PS Ⅱ quantum efficiency (ΦPSⅡ) after plant adaptation in actinic irradiation was more noticeable. On the other hand, decreases in water percentage, contents of photosynthetic pigments and mineral elements including Fe, K, and Mg, and significant increase in the Cu content were observed in the third leaves of Cu-treated plants. Superoxide dismutase (SOD) and peroxidase (POD) activities as well as the proline (Pro) content significantly increased in the third leaves of the three-colored amaranth seedlings treated with 2.0 and 4.0 mmol Cu kg-1 soil, while catalase (CAT) and ascorbate peroxidase (APX) activities as well as the contents of carotenoid (Car), glutathione (GSH), and ascorbic acid (AsA) decreased, and accompanied by the increases in the contents of hydrogen peroxide (H2O2), superoxide anion (O2·- ), and malondialdehyde (MDA), and electrolyte leakage. As a result of the imbalance of active oxygen metabolism, Pn and ΦPSⅡ decreased, and peroxidization enhanced under levels of 2.0 and 4.0 mmol Cu kg-1 soil. Finally, the growth of three-colored amaranth plant was significantly inhibited.展开更多
Surface soil samples were collected from Sarcheshmeh Copper Smelter Plant and analyzed for 16 Polycyclic Aromatic Hydrocarbons (PAHs), polychlorinated dibenzo-p-dioxin/furans (PCDD/Fs), and heavy metals to determine t...Surface soil samples were collected from Sarcheshmeh Copper Smelter Plant and analyzed for 16 Polycyclic Aromatic Hydrocarbons (PAHs), polychlorinated dibenzo-p-dioxin/furans (PCDD/Fs), and heavy metals to determine their concentrations, distributions, and probable sources of contamination. The mean concentrations of ΣPAHs, As, Pb, Zn, Se, Cd, and Cr in the soil samples were 878.8, 850, 2185, 2455, 21, and 24 mg/kg, respectively. Besides, their Toxic Equivalents (TEQs) were calculated. The samples generally displayed elevated concentrations of heavy metals when finding the toxic values of dioxin/furan compounds in comparison to the limit values for industrial uses. The background concentrations, molecular indices, and ring classes of the heavy metals indicated that their sources and those of PAHs were both geogenic and pyrolitic. The mean concentrations of total PAHs, PCDD/Fs, and heavy metals were compared with the reports from industrial areas throughout the world and the contamination rates at Sarcheshmeh Copper Plant were found to be moderate.展开更多
Copper(Cu)was designated as a specific substance in the Agricultural Land Soil Pollution Prevention Act in Japan.It has been known that high Cu concentrations in soil layers reduce rice crop production and thus agricu...Copper(Cu)was designated as a specific substance in the Agricultural Land Soil Pollution Prevention Act in Japan.It has been known that high Cu concentrations in soil layers reduce rice crop production and thus agricultural practices such as soil dressing have been applied to minimize the damages to crops by copper pollution.In this study,authors investigated the effects of percolation patterns of the under-plowsole and subsoil on growth and yield,and copper uptake of paddy rice.Six stratified paddy field models were constructed to conduct the growth tests under the condition in which the percolation patterns of the under-plowsole and subsoil were in an open and closed system.These models have a plow layer(10 cm thickness)and upper-plowsole(2.5 cm thickness)made with 12.5 cm-thickness of non-polluted soil dressing(3.7 mgCu?kg-1)and an underlying 15 cm-thickness of polluted under-plowsole(7.5 cm thickness)and subsoil whose Cu concentration was higher or lower than Japanese safety standard(approximately 100 mgCu?kg-1,150 mgCu?kg-1 and 500 mgCu?kg-1,respectively).During the tests,a constant water-ponding system was adopted,and mid-summer drainage was not done.As a result,Cu concentrations of the rice grains were 5%significantly higher in the open system percolation models regardless of the original amount of Cu in the under-plowsole and subsoil.On the other hand,authors did not recognize any significant differences in growth and yield of rice plants among the models.Authors concluded that the Cu concentrations in rice plants are affected by percolation patterns of polluted plowsole and subsoil even though they are covered with non-polluted soil dressing layers.展开更多
基金supported by the National Natural Science Founda-tion of China(No.32002086)the Natural Science Research Project of University in Anhui Province(No.202244)+1 种基金the Top Talent Team Project of Anhui Agriculture University(No.03082021)Key Program in the Joint Funds of National Natural Science Founda-tion of China(No U19A2034).
文摘Dear Editor,Fungicide treatment has a profound effect on controlling plant pathogens in modern agriculture,however,it also carries the risk of undesirable outcomes.For decades,scientists have been concerned about the harmful impacts of heavy metals like copper(Cu)on crop performance and soil microorganisms.Use of various copper fungicides,like Bordeaux mixture,have been a component of conventional agricultural practices to control fungal and bacterial pathogens,especially in vineyards,tea gardens,or fruit tree orchards[9,10].This treatment increases the accumulation of high levels of Cu in surface soils,and despite the critical role of Cu as an essential trace element in wide biological and metabolic processes,it becomes toxic to plants when applied at high levels[4].The regular application of copper fungicides has also been linked to affecting microbial communities at the levels of diversity[8],population structure[2],abundance,and growth[1,3].Understanding the undesired effects of fungicides on microorganisms’beneficial activities is therefore important for evaluating the hazards associated with the fungicide used in agriculture.Yet,the effects of copper fungicide on full microbial communities remains relatively understudied,especially in tea plants.Thus,we herein explored the inf luence of Bordeaux mixture under different management regimes(raking or without raking leaf litter)on microbial communities of root,bulk soil,and rhizosphere compartments of tea plants planted in a ten-year-old tea garden.We provided insights into the ecological consequences of tea management practices that might help to identify specific fungicide treatment regimens,environmental characteristics,and microbial community members to minimize the negative environmental outcomes and optimize the positive anti-pathogen aspects of fungicide treatment.
文摘The application of pressure leaching technology in the treatment of high-copper and high-arsenic dust was studied.The pressure leaching technique was determined as follows:the liquid to solid ratio(mL/g)of 5:1,the leaching temperature of 453 K,the retention time of 2 h,the initial sulfuric acid concentration of 0.74 mol/L,the oxygen partial pressure of 0.7 MPa,and the agitation speed of 500 r/min.Under these conditions,95%of copper and 99%of zinc and only 6%of iron in the dust were leached,while about 20%of arsenic was also leached.The leaching technique was optimized further to restrain the leaching of arsenic by adding a small quantity of ferrous iron into the leaching system(c(Fe2 +)=0.036 mol/L).Copper and zinc can be effectively separated from arsenic and iron in the leach.The optimal pressure leaching technique of high-copper and high-arsenic smelter dust is proved to be effective.
文摘Invasive plant species may significantly alter plant species community composition and structure thereby negatively impacting on ecosystem services. Their impacts on plant communities may be both direct and indirect. The direct effects may include a reduction in the abundance and diversity of palatable plant species that constitute important forage for livestock, wildlife, and medicines for the local communities. Declines in ecosystem resilience are of the notable indirect effects of invasive species. The aim of this study was to assess the impacts of a plant species, copper leaf (<em>Acalypha fruticosa</em>) on floral diversity and abundance at Chemeron, Baringo County in Kenya. The study was guided by three questions: What is the plant composition in terms of grasses, herbs, shrubs, and trees in the study area? Are there any variations in plant abundance between the two sites (sites with and without <em>Acalypha fruticosa</em>)? Are there variations in plant species diversity between the two study sites? Two sites (one with <em>A. fruticosa</em> and another two without this invasive species) were selected within the Chemeron Research Centre. Two belt transects measuring 100 m × 20 m on each site were laid parallel to each other. Plant samples were collected from five 1 m × 1 m quadrats that were laid at intervals of 20 m. The plant species or specimens were identified to the species level using available taxonomic keys. Various indices including Shannon-Wiener (<em>H</em>’), Evenness Index, Richness Index and Simpson’s Index of Diversity Index (SDI) were calculated. All the diversity, richness and evenness indices were considerably higher in the site without <em>A. fruticosa</em> compared to that where this invasive species was present. Higher <em>H’</em> (3.14 to 3.21) and SDI (0.93 to 0.94) values were noted in sites without the invasive species compared to <em>H</em>’ (2.11 to 2.20) and SDI (0.77 to 0.85) in sites with <em>A. fruticosa</em> present. Out of the 47 plant species identified, 39 and 20 of them occurred in the site without and with <em>A. fruticosa</em>, respectively. Further, there were more grasses (<em>Aristida keniensis</em>, <em>Cynodon dactylon</em>, <em>Brachiaria lucrantha</em>, <em>Eragrostis racemosa</em>, and <em>Enteropogon macrostachyus</em>) in the site without <em>A. fruticosa</em> compared to that with the invasive plant. The plants were also more evenly distributed in the site without <em>A. fruticosa</em> compared to that where the invasive plant was present. We conclude that <em>A. fruticosa</em> has a significant effect on plant species abundance and diversity as well as distribution. Its removal created a favourable environment for the growth of a variety of grasses. We therefore recommend to the agro-pastoralists and rangeland managers that <em>A. fruticosa</em> be mechanically removed by uprooting from grazing lands so as to increase forage availability and quality in the rangelands of South-Baringo.
文摘One purpose of this research is to present accumulation of cadmium(Cd) and copper(Cu) by female Oxya chinensis(Orthopera: Acridoidea) in a simulated s oil-plant-insect ecosystem treated with Cd. Fourth-instar nymphs of O. chinensis had been fed on wheat(Triticum aestivum) seedlings contaminated with Cd and Cu for one month. In the ecosystem, the Cd concentration in wheat seedlings rose gr eatly with the increasing of Cd in the soil, but the Cu concentration in wheat s eedlings was not found elevated. There was a highly significant difference(P<0. 05) in Cd concentrations of wheat seedlings and not any significant difference(P >0.05) in Cu concentrations of wheat seedlings. The Cd and Cu concentration in different body part-head, thorax, abdomen, and hind femur, varied under differen t Cd concentrations in soil. There were significant differences(P<0.05) in the four parts of Cd and Cu accumulations with all treatments. The order of Cd accum ulation was thorax>abdomen>head>hind femur and the Cu was abdomen>thorax>he ad>hind femur. The results indicated that Cd and Cu were accumulated from the s oil to grasshoppers through the plant; that is to say, Cd and Cu in environment could be transported to animal or human via food chain.
基金National"973"Plan Research Project(No.2004CB619204)Educational Ministry Scientific and Technological Research Key Project(No.02052)
文摘The preparation of granulated adsorption material of water-quenched slag/rectorite composite and the treatment of Cu(Ⅱ)-containing copper smelter wastewater with the adsorption material were studied. The experimental results showed that under the conditions with the mass ratio of water-quenched slag to rectorite of 1:1,10%additive of industrial starch(IS),and 50%water,and a calcination temperature of 400 ℃,the granulated adsorption material prepared had a density of 1.06 kg/m3,a porosity of 62.29%,water absorption rate of 58.82%,and compressive strength of 2.22 MPa.The efficiency of wastewater treatment was the best,whereas the rate of spallation loss was low.Under the conditions of natural pH,with the addition of the granulated adsorption material of 0.05 g/mL,a reaction time of 40 minutes,and temperature of 25℃, the efficiency of the granulated adsorption material for the removal of Cu(Ⅱ)ions from the copper smelter wastewater attained 98.2%,and the quality indexes of the wastewater after treatment conformed with the first level of integrated wastewater discharge standard(GB8978-1996).The reclamation of the used granulated adsorption material was carried out by de-sorption of the Cu(Ⅱ)ions from the surface with 1 mol/L sodium chloride solution.The de-sorption rate was 96.4%,and the adsorption material can be reused many times to treat copper smelter wastewater.
文摘The use of pig compost (PC) in agricultural land has increased in Chile in the last years. This organic amendment is a valuable nutritional source for crops, but its applying must be done in a controlled manner since it exhibited high copper (Cu) and zinc (Zn) concentrations. A short-term field experiment was conducted out to study the effects of increasing PC rates on the production and quality corn crop in two soils located at south central Chile. Five treatments were evaluated: control without fertilization (C), conventional fertilization (CF) (350 kg N ha-1), and three increasing PC rates (15.33, 30.65, and 61.31 Mg·ha-1, corresponding to 350, 700, and 1400 kg N ha-1, respectively) in a split plot design with four replicates. The overall results indicated that dry matter production, grain yield, and plant Zn and Cu concentrations were similar among fertilization sources and rates. Extractable soil Zn concentration exhibited a rate-related increase of PC in both locations, while Cu concentration exhibited this behavior only at the soil located in Chillan. Nevertheless, the values obtained were below of those considered phytotoxic levels. Therefore, the contribution of Zn and Cu through PC applying at different rates to the soils studied showed a slight affect in soil extractable Zn and Cu values without negatively effects on quantity and quality corn crop. The organic amendment applied can be a good and cheaper substitute to conventional fertilization, although further monitoring of Zn and Cu soil levels should be carried out to avoid any environmental risk.
文摘Seedlings of the medicinal plant Hyoscyamus albus were supplied with an excess of Cu to examine the possible application in phytoremediation. The seedlings were cultured in B5 medium supplied with basal 0.1 μM Cu and 200 μM Cu under various light conditions: short day (SD);long day (LD);and continuous light (CL). In addition, the effect of supplying 200 μM Cu under Fe deficiency was determined, in order to elucidate the interaction between Cu and Fe. Interestingly, Fe-deficiency symptoms that developed in plants grown with basic levels of Cu under LD almost disappeared when excess Cu was supplied. Plant growth mainly depended on the photo irradiation period (SD < LD^CL);and 200 μM Cu did not inhibit growth at all when Fe was available, whereas in the absence of Fe, CL caused damage to growth. Analysis of the Cu and Fe contents of the plants revealed that Cu was distributed equally in both the aerial parts and roots, whereas most of the Fe was found in the roots;under Fe deficiency, Cu accumulation in the roots apparently increased. Cu was mainly distributed in the soluble fraction, which included vacuoles and the cell-wall fraction. These results provide evidence indicating that H. albus seedlings are tolerant of Cu present in excess. Furthermore, excess Cu was able to compensate for Fe deficiency, depending on the light conditions. Continuous light inhibited this effect, probably as a result of the induction of Mn deficiency. The possible applications of this newly discovered cuprophyte are discussed.
文摘In this paper, prediction of copper and molybdenum grades and their recoveries of an industrial flotation plant are investigated using the Artificial Neural Networks (ANN) model. Process modeling has done based on 92 datasets collected at different operational conditions and feed characteristics. The prominent parameters investigated in this network were pH, collector, frother and F-Oil concentration, size percentage of feed passing 75 microns, moisture content in feed, solid percentage, and grade of copper, molybdenum, and iron in feed. A multilayer perceptron neural network, with 10:10:10:4 structure (two hidden layers), was used to estimate metallurgical performance. To obtain the optimal hidden layers and nodes in a layer, a trial and error procedure was done. In training and testing phases, it achieved quite correlations of 0.98 and 0.93 for Copper grade, of 0.99 and 0.92 for Copper recovery, of 0.99 and 0.92 for Molybdenum grade and of 0.99 and 0.94 for Molybdenum recovery prediction, respectively. The proposed neural network model can be applied to determine the most beneficial operational conditions for the expected Copper and Molybdenum grades and their recovery in final concentration of the industrial copper flotation process.
基金supported by the 863 Program,China(2002AA224011 and 2001AA212161).
文摘A copper-inducible, Cre-loxP recombination-mediated DNA excision system has been developed in transgenic tobacco plants. The copper inducible system derived from yeast was used for the control of the expression of the Cre recombinase. Upon copper induction, the GUS reporter gene expression unit flanked by two direct lox sites was excised from the transgenic tobacco genome. Quantitative fluorometric GUS assays,Northern blot and PCR analyses showed a high-efficient, copper-dependent and Cre-loxP mediated DNA recombination in all the tested transgenic lines. The copper inducible foreign gene excision might be of great potential in genetic control of transgenic crops.
文摘Large quantities of sludge are produced during water treatment processes. Recently, sludge has been treated as waste and disposed of in landfills, which increases the environmental burdens and the operational cost. Therefore, sludge reuse has become a significant environmental issue. In this study, adsorption of copper ions (Cu^2+) onto calcined sludge was investigated under various operational conditions (with varying temperature, Cu^2+ initial concentration, pH, and sludge dosage). The prepared sludge material was characterized with transmission electron microscopy (TEM), X-ray diffraction (XRD), dynamic light scattering (DLS), and Brunauer-Emmett-Teller (BET) surface area. The sorption capacity of sludge was directly proportional to the initial Cu^2+ concentration and inversely proportional to the sludge dosage. The optimum operational pH and solution temperature were 6.6 and 80℃, respectively. The experimental results followed a Langmuir isotherm and pseudo-first-order adsorption kinetics. Thermodynamic parameters such as activation energy, change in free energy, enthalpy, and entropy were calculated. Thermodynamic analyses indicated that the sorption of copper ions onto the calcined sludge was driven by a physical adsorption process. The prepared sludge was proven to be an excellent adsorbent material for the removal of Cu^2+ from an aqueous solution under optimum conditions.
文摘This work describes the experimental results of pyrometallurgical removing of arsenic from the dust collected in the electrostatic copper precipitators within the gas cleaning system of a Copper Flash Smelting Furnace. The generation of dust in the copper smelting worldwide ranges from 2 - 15 wt% per ton of a copper concentrate. In Chile, copper smelters produce approximately 110 kt/y of dust with a concentration of arsenic between 1 and 15 wt%. The dust is a complex of metals oxides and sulfurs with copper concentrations greater than 10 wt% and relatively high silver concentrations. Since its high arsenic concentration, it is difficult to recover valuable metals through hydrometallurgical processes or by direct recirculation of the dust in a smelting furnace. Thus, the development of pyrometallurgical processes aimed at reducing the concentration of arsenic in the dust (<0.5 wt%) is the main objective of this study, giving particular attention to the production of a suitable material to be recirculated in operations of copper smelting. The work provides a detailed characterization of the dust including the Quantitative Evaluation of Minerals by Scanning Electron Microscopy (QEMSCAN), Scanning Electron Microscope-Energy Dispersive X-ray Analysis (SEM/EDS), X-Ray Diffraction (XRD), the elemental chemical analysis using Atomic Adsorption (AAS), and X-Ray Fluorescence (X-RF). By considering that arsenic volatilization requires a process of sulfidation-decomposition-oxidation, this work seeks to explore the roasting of mixtures of copper concentrate/dust, sulfur/dust, and pyrrhotite/dust. By the elemental chemical analysis of the mixture after and before the roasting process, the degree of arsenic volatilization was determined. The results indicated the effects of parameters such as roasting temperature, gas flow, gas composition, and the ratio of mixtures (concentrate/dust, sulfur/dust, or pyrrhotite/dust) on the volatilization of arsenic. According to the findings, the concentration of arsenic in the roasted Flash Smelting dust can be reduced to a relatively low level (<0.5 wt%), which allows its recirculation into an smelting process.
文摘The potential use of Myriophyllum spicatum L. biomass as a biosorbent for the removal of copper(Ⅱ) from aqueous solution was investigated in laboratory condition. The sorption experiments were undertaken to obtain copper(Ⅱ) biosorption properties of M. spicatum L., i.e. equilibrium time, the maximum capacity, and rate constants. Copper(Ⅱ) biosorption was fast and equilibrium was attained within 35 min at initial copper(Ⅱ) concentration of 6 mg/L. Different isotherm models including the Langmuir, Freundlich, Temkin and Redlich-Peterson model, were used to investigate the sorption capacity and isotherm. These models showed an excellent match with the experimental data except for the Freundlich model. According to the Langmuir coefficients, the maximum sorption capacity of copper onto M. spicatum L. was 10.80 mg/g. The kinetics of copper(Ⅱ) sorption was also analysed and rate constants were derived. It was found that the overall sorption process was best described by the pseudo second-order equation, and that intraparticle diffusion was not the rate determining step. The results of this study showed that M. spicatum L. can be considered as useful vehicles for the removal and recovery of copper(Ⅱ) from aqueous solutions.
基金the Natural Science Foundation of Zhejiang Province, China （Y504256）.
文摘The objective of the present study was to gain better insight into the physiological mechanisms on the effects of copper (Cu) on photosynthesis and active oxygen metabolism in three-colored amaranth plant (Amaranthus tricolor). Three- colored amaranth seedlings were subjected to different Cu levels in soils during the entire experimental period. The parameters of growth, photosynthesis, mineral elements contents, and active oxygen metabolism were investigated using plant physiological methods. The results showed that 2.0 and 4.0 mmol Cu kg-1 treatments decreased the whole plant biomass to 91 and 73% of the control, respectively. The net photosynthetic rate (Pn) and the stomatal conductance (gs) were similarly reduced in the third leaves of three-colored amaranth seedlings treated with 2.0 and 4.0 mmol Cu kg-1 soil, respectively. None of the investigated Cu levels decreased the internal CO2 concentration (Ci). The effect of Cu on the potential efficiency of photosystem Ⅱ(Fv/Fm) was negligible, whereas the effect of Cu on the PS Ⅱ quantum efficiency (ΦPSⅡ) after plant adaptation in actinic irradiation was more noticeable. On the other hand, decreases in water percentage, contents of photosynthetic pigments and mineral elements including Fe, K, and Mg, and significant increase in the Cu content were observed in the third leaves of Cu-treated plants. Superoxide dismutase (SOD) and peroxidase (POD) activities as well as the proline (Pro) content significantly increased in the third leaves of the three-colored amaranth seedlings treated with 2.0 and 4.0 mmol Cu kg-1 soil, while catalase (CAT) and ascorbate peroxidase (APX) activities as well as the contents of carotenoid (Car), glutathione (GSH), and ascorbic acid (AsA) decreased, and accompanied by the increases in the contents of hydrogen peroxide (H2O2), superoxide anion (O2·- ), and malondialdehyde (MDA), and electrolyte leakage. As a result of the imbalance of active oxygen metabolism, Pn and ΦPSⅡ decreased, and peroxidization enhanced under levels of 2.0 and 4.0 mmol Cu kg-1 soil. Finally, the growth of three-colored amaranth plant was significantly inhibited.
文摘Surface soil samples were collected from Sarcheshmeh Copper Smelter Plant and analyzed for 16 Polycyclic Aromatic Hydrocarbons (PAHs), polychlorinated dibenzo-p-dioxin/furans (PCDD/Fs), and heavy metals to determine their concentrations, distributions, and probable sources of contamination. The mean concentrations of ΣPAHs, As, Pb, Zn, Se, Cd, and Cr in the soil samples were 878.8, 850, 2185, 2455, 21, and 24 mg/kg, respectively. Besides, their Toxic Equivalents (TEQs) were calculated. The samples generally displayed elevated concentrations of heavy metals when finding the toxic values of dioxin/furan compounds in comparison to the limit values for industrial uses. The background concentrations, molecular indices, and ring classes of the heavy metals indicated that their sources and those of PAHs were both geogenic and pyrolitic. The mean concentrations of total PAHs, PCDD/Fs, and heavy metals were compared with the reports from industrial areas throughout the world and the contamination rates at Sarcheshmeh Copper Plant were found to be moderate.
文摘Copper(Cu)was designated as a specific substance in the Agricultural Land Soil Pollution Prevention Act in Japan.It has been known that high Cu concentrations in soil layers reduce rice crop production and thus agricultural practices such as soil dressing have been applied to minimize the damages to crops by copper pollution.In this study,authors investigated the effects of percolation patterns of the under-plowsole and subsoil on growth and yield,and copper uptake of paddy rice.Six stratified paddy field models were constructed to conduct the growth tests under the condition in which the percolation patterns of the under-plowsole and subsoil were in an open and closed system.These models have a plow layer(10 cm thickness)and upper-plowsole(2.5 cm thickness)made with 12.5 cm-thickness of non-polluted soil dressing(3.7 mgCu?kg-1)and an underlying 15 cm-thickness of polluted under-plowsole(7.5 cm thickness)and subsoil whose Cu concentration was higher or lower than Japanese safety standard(approximately 100 mgCu?kg-1,150 mgCu?kg-1 and 500 mgCu?kg-1,respectively).During the tests,a constant water-ponding system was adopted,and mid-summer drainage was not done.As a result,Cu concentrations of the rice grains were 5%significantly higher in the open system percolation models regardless of the original amount of Cu in the under-plowsole and subsoil.On the other hand,authors did not recognize any significant differences in growth and yield of rice plants among the models.Authors concluded that the Cu concentrations in rice plants are affected by percolation patterns of polluted plowsole and subsoil even though they are covered with non-polluted soil dressing layers.
