Exposure Of Cu Research Articles

(Invited) Efficient Recycling of Dilute Nitrate to Ammonia Using Cu-Based Electrocatalyst

The use of nitrogen fertilizers has contributed significantly to the growth of agricultural production, but the nitrogen use efficiency is typically lower than 40%, so most of the nitrogen readily leaches into ground water, rivers, and lakes, causing an increase of nitrate (NO3 −) concentration and severe environmental problems. Electrochemical reduction of nitrate has emerged as a promising route for the recycling of nitrate from wastewater and sustainable production of ammonia when powered by renewable electricity. Here I present our recent studies of the intrinsic activity and selectivity of Cu for nitrate electroreduction, as well as a rational design of Cu-based catalysts for single-pass conversion of nitrate to ammonia. Using polycrystalline Cu foils for benchmarking, we elucidated the impact of often overlooked factors on nitrate reduction, including Cu facet exposure, nitrate concentration, and electrode surface area. We find that an electropolished Cu foil exhibits a higher activity and selectivity for nitrate reduction to ammonia than a wet-etched Cu foil, benefiting from a greater exposure of Cu(100) facets that are more favorable for the reaction. The NH3 selectivity shows no apparent dependence on the nitrate concentration, but it increases monotonically with Cu electrode area, which is attributed to a promoted conversion of intermediately produced NO2 − to NH3 on a larger electrode. Based on the understandings, we further developed a Cu/Co-based tandem electrocatalyst, which achieved nearly 100% single-pass conversion of dilute nitrate (5−50 mM) to NH3 at a low overpotential using a flow cell.

Mitigating potential of polystyrene microplastics on bioavailability, uptake, and toxicity of copper in maize (Zea mays L.)

The coexistence of polystyrene microplastics (PSMPs) and copper (Cu) has become a pressing issue for croplands. However, limited literature is available regarding the interaction of PSMPs with essential micronutrients in Cu-contaminated soils. Therefore, the present study aimed to analyze the immobilization potential of PSMPs for micronutrient bioavailability in soil and Cu toxicity in maize (Zea mays L.). A pot experiment was conducted with maize variety “Islamabad gold” exposed to varying Cu concentrations (0, 50, 100, 200, and 400 mg/kg) and PSMPs (150–250 μm size, 0, 1, and 3% w/w) via soil spiking for 60 days. The concentrations of essential micronutrients (Zn, Cu, Mn, Fe) in soil and plant tissues were measured using an atomic absorption spectrophotometer. Moreover, malondialdehyde (MDA) and antioxidant activities (superoxide dismutase, ascorbate peroxidase, catalase, and peroxidase) were recorded. The concentration of Cu showed significant reduction in post-harvesting soil by 21, 24.8, 27.6, 29.2, and 30.2% from Cu0 to Cu400 mg/kg respectively from pre-sowing soil. On the other hand, the addition of 1%PSMPs and 3%PSMPs declined Cu by 16, 21.6, 24.4, 25.9, 27.8, and 12.6, 16.5, 19.9, 23.2, 25% from Cu0 to Cu400 mg/kg respectively. Maize showed significant improvement in growth under combined exposure of Cu and 3% PSMPs compared to individual exposure. The MDA level was decreased under the combined presence of Cu and PSMPs compared to individual Cu exposure. The percentage difference with 1%PSMPs was 98.1, 95.0, 92.0, 90.0, and 89.6%, while with 3%PSMPs was 93.2, 93.2, 87.7, 81.4, and 79.2% from Cu0 to Cu400 mg/kg respectively. Moreover, the impact of PSMPs was more prominent at a 3% dose compared to a 1% dose. The findings provided significant knowledge about the potential of PSMPs to mitigate Cu toxicity in maize. Future research should incorporate a variety of particle size distributions at natural conditions for variety-specific differences.

In situ copper faceting enables efficient CO2/CO electrolysis

The copper (Cu)-catalyzed electrochemical CO2 reduction provides a route for the synthesis of multicarbon (C2+) products. However, the thermodynamically favorable Cu surface (i.e. Cu(111)) energetically favors single-carbon production, leading to low energy efficiency and low production rates for C2+ products. Here we introduce in situ copper faceting from electrochemical reduction to enable preferential exposure of Cu(100) facets. During the precatalyst evolution, a phosphate ligand slows the reduction of Cu and assists the generation and co-adsorption of CO and hydroxide ions, steering the surface reconstruction to Cu (100). The resulting Cu catalyst enables current densities of > 500 mA cm−2 and Faradaic efficiencies of >83% towards C2+ products from both CO2 reduction and CO reduction. When run at 500 mA cm−2 for 150 hours, the catalyst maintains a 37% full-cell energy efficiency and a 95% single-pass carbon efficiency throughout.

Grain boundary-abundant copper nanoribbons on balanced gas-liquid diffusion electrodes for efficient CO2 electroreduction to C2H4

The electrocatalytic CO2 reduction reaction (CO2RR) is a promising technology to produce value-added hydrocarbon chemicals, however, achieving a high selectivity to C2+ products at the industrial current density remains a great challenge. Herein, we demonstrate grain boundary-abundant copper (Cu) nanoribbons on balanced gas-liquid diffusion electrodes for efficient CO2RR to ethylene (C2H4). The Cu(II) carbonate basic (Cu2CO3(OH)2) nanoribbon is used as a precursor to convert into metal Cu under in situ electrochemical reduction. Unexpectedly, the generated Cu nanoribbon is formed by stacking tiny nanoparticles with exposure of Cu(111), Cu(200) and Cu(220) facets, which creates abundant grain boundaries (GBs). During CO2RR test, the thickness of the catalyst layer is identified as a crucial factor for the mass transfer of CO2 and electrolyte. By tailoring the thickness of catalytic layer, CO2 and electrolyte can simultaneously reach the surface of catalyst and participate in CO2RR. Under the synergetic effects of GBs and balanced gas-liquid diffusion, the optimized electrode delivers the Faradaic efficiencies toward C2H4 and C2+ products as high as 67.2% and 82.1% at the current density of 700 mA cm−2, respectively. Moreover, the partial current density of C2H4 can reach up to 505 mA cm−2, which is significantly higher than most reported results. The in situ Raman and attenuated total reflection surface-enhanced infrared absorption spectra show that abundant GBs enhance the activation of CO2 and significantly promote the formation and adsorption of *CO intermediates, which accelerate C-C coupling to form *OCCO and *OCCOH intermediates and improve the production of C2H4 and other C2+ products.

An often-overestimated ecological risk of copper in Chinese surface water: bioavailable fraction determined by multiple linear regression of water quality parameters

BackgroundRisks of adverse ecological effects of copper (Cu) consider of water quality parameters were not fully understood in China. Here, a national-scale exposure of Cu in Chinese surface water was investigated, and the first report using multiple linear regression approach to predict and correct toxicity data based on water chemistries in China. Risk of Cu was overestimated without considering water quality parameters in the previous studies.ResultsUnder prevalent water quality conditions of hardness = 150.0 mg/L, pH = 7.8, and dissolved organic carbon (DOC) = 3.0 mg/L, across China, the predicted no effect concentration for total, dissolved Cu was 9.71 μg/L. Based on results of the preliminary risk quotients method, 1.19% (a total of 43 in 3610 sites) were classified as “high risk”, only one sixth of the percentage of sites with “high risk” than the proportion predicted when not considering water quality parameters, which was 7.51%. Similar results were obtained by application of both the margin of safety method (0.71% compared to 2.81%) and joint probability curve method (3.34% compared to 16.29%), both of which overestimated risks posed by Cu to aquatic organisms in China.ConclusionAfter correcting for bioavailability based on water quality parameters, consider both concentrations and frequencies during ecological risk assessment, regions of China at greatest risk from adverse effects of Cu were the Hai River (Haihe), Huai Rivers (Huaihe) and Chao Lake. These findings provide a comprehensive method for a more accurate assessment of risks of adverse effects of Cu to aquatic life in surface waters.

Ultra‐Stable Zinc Metal Anodes Enabled by Uniform Zn Deposition on A Preferential Crystal Plane

AbstractThe unsatisfactory electrochemical performance of Zn metal batteries (ZMBs) caused by uncontrollable Zn dendrite growth and detrimental parasitic reactions has significantly hindered their large‐scale applications. Herein, periodic hemispherical structures with a preferential exposure of Cu (100) crystal plane are designed and obtained using facile photolithography, which is followed by wet etching treatment. An exposed zincophilic Cu (100) crystal plane with low nucleation barriers acts as the preferred deposition site to induce homogeneous Zn deposition. Additionally, the periodic hemispherical structure with an enlarged surface area not only suppresses the Zn dendrite growth by reducing the local current density, but also synergistically buffers the volume expansion during the cycling process. As a result, the as‐prepared faceted Cu hemispherical electrodes achieve ultra‐stable Coulombic efficiency of over 99.9% for 1500 cycles at a current density of 5 mA cm−2. This work has significant potential for the rational design of dendrite‐free Zn anodes to boost their potential for practical applications.

Comparative study of electrical properties of chalcogenide films produced by reaction of Cu, Ag, Ni and NiCu with Sb2S3 in hot wall epitaxy

Films of transition-metal–chalcogen alloys are produced using hot wall epitaxy by means of sulphurization in the exposure of Cu, Ag, Ni and NiCu films to Sb2S3 vapor. The properties of the resultant chalcogenide films change widely depending on the material combination and the synthesis conditions. We investigate the influences of the coexistence of Sb in the alloys on the electrical properties of the films. The Ni-containing films are highly conductive, whereas the resistivity of the films produced from Cu and Ag is large. The sulphurization occurs two-dimensionally as homogeneous films consisting of Cu-Sb-S and Ag-Sb-S ternary alloys, giving rise to weak and negligible dependencies of the resistivity on the synthesis temperature in the respective cases. The thermal activation energy for the electrical transport varies in correspondence to the resistivity values. The Cu- and Ag-based films exhibit a suppression of current when Ag electrodes are used in comparison to using Au electrodes. The transient of photocurrent is shown for these films to be remarkably slow with an order of magnitude change of the current. The spontaneous reaction with Al contacts to trigger interfacial resistance switching is weak for the Sb-containing materials. The structural properties of the films are furthermore presented together with the Raman spectra to identify the synthesized alloys. A catalytic effect of Ni in the sulphurization of Cu and the surfactant effect of Sb are thereby revealed.

Crystal facet effect induced by different pretreatment of Cu2O nanowire electrode for enhanced electrochemical CO2 reduction to C2+ products

Electrocatalytic CO2 conversion has been considered as a promising way to recycle CO2 and produce sustainable fuels and chemicals. However, the efficient and highly selective electrochemical reduction of CO2 directly into multi-carbon (C2+) products remains a great challenge. Herein, we synthesized three type catalysts with different morphologies based on Cu2O nanowires, and studied their morphology and crystal facet reconstruction during the pre-reduction process. Benefiting from abundant exposure of Cu (100) crystal facet, the nanosheet structure derived Cu catalyst showed a high faradaic efficiency (FE) of 67.5% for C2+ products. Additionally, electrocatalytic CO2 reduction studies were carried out on Cu(100), Cu(110), and Cu(111) single crystal electrodes, which verified that Cu(100) crystal facets are favorable for the C2+ products in electrocatalytic CO2 reduction. Our work showed that catalysts would reconstruct during the CO2 reduction process and the importance in morphology and crystal facet control to obtain desired products.

Nitric oxide overcomes copper and copper oxide nanoparticle-induced toxicity in Sorghum vulgare seedlings through regulation of ROS and proline metabolism.

This study aimed to investigate the phytotoxic effect of copper (Cu) and copper nanoparticles (CuONPs) and ameliorative potential of nitric oxide (NO) against these toxic materials in Sorghum vulgare Pers. seedlings. Data suggested that exposure of Cu and CuONPs significantly reduced growth, chlorophyll, carotenoids and protein in root and shoot, which coincided with increased Cu accumulation. However, addition of sodium nitroprusside (SNP, a donor of NO) lowered Cu and CuONPs mediated toxicity through restricting Cu accumulation and improving photosynthetic pigments and total soluble protein contents. Data further suggested that exposure of Cu and CuONPs significantly increased hydrogen peroxide (H2 O2 ), superoxide radicals (O2 •- ), and malondialdehyde (MDA) contents. Enhanced level of oxidative stress severely inhibited the enzymatic activities of glutathione reductase (GR), ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR) and monodehydroascorbate reductase (MDHAR) but enhanced superoxide dismutase (SOD) and catalase (CAT) activity. However, addition of SNP positively regulated antioxidants enzymes activity, particularly the enzymes involved in the ascorbate-glutathione cycle to overcome Cu- and CuONPs-induced stress in Sorghum seedlings. Further, Cu and CuONPs enhanced accumulation of free proline through inducing Δ1 -pyrroline-5-carboxylate synthetase (P5CS) activity while lowering the proline dehydrogenase (PDH) activity. However, addition of SNP reversed these responses. Therefore, overall results revealed that SNP has enough potential of reducing the toxicity of Cu and CuONPs in Sorghum seedlings through regulation of proline metabolism and activity of enzymes of the ascorbate-glutathione cycle. These findings can be employed in developing new resistant varieties of Sorghum having enhanced tolerance against Cu or CuONP stress and improved productivity.

Assessing Copper Risk in Honey Sold in City of Yerevan

Mining, including copper (Cu) production, is one of the primary economic activities in Armenia. Besides having an adverse environmental impact, it can lead to Cu accumulation in food, including honey. Considering the wide production and consumption of honey, this study aims to assess the dietary exposure of Cu through honey consumption in Yerevan, Armenia. Seventeen honey samples were included in the study. Food Frequency Questionnaire was used to evaluate honey consumption. While Cu contents exceed the Maximum Residue Level, dietary exposure estimates do not exceed the oral reference dose. Hence, the consumption of honey sold in Yerevan does not have the potential to cause adverse health effects.

КАНЦЕРОГЕННЫЙ И НЕКАНЦЕРОГЕННЫЙ РИСК ДЛЯ НАСЕЛЕНИЯ ОТ ПОТРЕБЛЕНИЯ КАРТОФЕЛЯ И ОВОЩЕЙ, ВЫРАЩИВАЕМЫХ В ПРЕДЕЛАХ АГРОСЕЛИТЕБНЫХ ЛАНДШАФТОВ

One of the most effective methods of preventing the danger caused by the impact of carcinogenic and non-carcinogenic chemicals on humans is to establish the risk of undesirable effects in order to further development methods to minimize it. The purpose of this study is to establish the magnitude of the non-carcinogenic and carcinogenic risk caused by the intake of heavy metals when consuming potatoes and vegetables grown within the agro-residential landscapes of Gorki, as well as when contaminants enter the human body by the oral, inhalation and percutaneous route directly from the soil. It has been established that the maximum contribution to the exposure of Cu, Zn, Mn and Cd entering the body of the adult population of the city of Gorki is made by beetroot, potatoes and white cabbage. Table carrots and potatoes make the maximum contribution to the exposure of Cu and Cd for the child population, while the main sources of Zn, Mn, and Pb intake are potatoes and white cabbage. The total level of carcinogenic risk from the consumption of potatoes and vegetables due to such carcinogens as Pb and Cd is estimated as average according to the international criterion scale. The non-carcinogenic risk to the health of both adults and children due to inhalation, oral and percutaneous intake of heavy metals from contaminated soil is assessed as negligible, and the carcinogenic risk is at an acceptable level. The results of the studies performed can be used to develop a risk management strategy for the population due to pollution of urban soils, potatoes and vegetables with heavy metals, providing for the sequential passage of the following stages: comparative assessment and ranking of risk; determination of risk acceptability levels; risk reduction and control; response to risk.

Estimation of health risks due to copper-based nanoagrochemicals.

This study estimated health risks due to two types of copper-based nanoagrochemicals (Cu (OH)2 and CuO nanoparticles (NPs)), during inadvertent ingestion of soil and consumption of leafy vegetables for a hypothetical exposure scenario. The dissolution of copper-based nanoagrochemicals in human digestive system was considered for estimating realistic doses. No risk was found during soil ingestion (hazard quotient (HQ) <1). HQ (no dissolution of Cu (OH) 2 nanopesticides) (HQ= 0.015) comes out to be 2 times higher than that of HQ (100% dissolution of Cu (OH)2 nanopesticides into copper ions) (HQ= 0.007). In case of risk from consumption of leafy vegetables, the following order of risk was found (high to low HQ value): Cu (OH)2 (HQ= 1925) >CuO NPs (1402). Combined exposure of Cu (OH)2 nanopesticide through soil ingestion as well as consumption of contaminated edible leafy vegetables resulted in health risks. The calculated maximum allowable applicable concentration values of Cu (OH)2 and CuO NPs without posing risk to human and plant toxicity were found to be 1.14 and 0.45 mg/L, respectively. These findings can be used now for deciding safe use of copper-based nanoagrochemicals.

Efficient CO2 electroreduction on facet-selective copper films with high conversion rate

Tuning the facet exposure of Cu could promote the multi-carbon (C2+) products formation in electrocatalytic CO2 reduction. Here we report the design and realization of a dynamic deposition-etch-bombardment method for Cu(100) facets control without using capping agents and polymer binders. The synthesized Cu(100)-rich films lead to a high Faradaic efficiency of 86.5% and a full-cell electricity conversion efficiency of 36.5% towards C2+ products in a flow cell. By further scaling up the electrode into a 25 cm2 membrane electrode assembly system, the overall current can ramp up to 12 A while achieving a single-pass yield of 13.2% for C2+ products. An insight into the influence of Cu facets exposure on intermediates is provided by in situ spectroscopic methods supported by theoretical calculations. The collected information will enable the precise design of CO2 reduction reactions to obtain desired products, a step towards future industrial CO2 refineries.

Comparison of the Potential Ecological and Human Health Risks of Heavy Metals from Sewage Sludge and Livestock Manure for Agricultural Use.

Sewage sludge and livestock (chicken, swine and cattle) manure samples were collected from the Yanmenguan Cattle Herbivorous Livestock Area to compare the potential ecological and human health risks caused by heavy metals contained in them. In this study, the Class II level of Quality Control of Imported Organic Fertilizers is selected as the limit standard value of heavy metals. Based on the mean content values, no heavy metal in cattle manure was higher than the limit standard value; the content of Cu in swine manure was higher than the limit of Cu; the content of Zn in sewage sludge, chicken manure and swine manure were all higher than the limit of Zn; and the content of Cr in sewage sludge and chicken manure were all higher than the limit of Cr. Results indicated that sewage sludge and livestock manure all had high contents of Zn, Cu and Cr. The mean pollution index (PI) suggested that Cu, Zn, As and Cr in sewage sludge and livestock manures all induced potential ecological risks. According to the mean Nemerow’s synthetic pollution index (PN) values, swine manure had the highest potential ecological risk for agricultural use. Daily exposure to Cu, Zn and Cr was higher than other heavy metals from sewage sludge and livestock manures, and heavy metal exposure was always higher for children than adults, with ingestion as the main pathway. Non-carcinogenic risk was caused mainly by Cu and Cr, based on the higher hazard quotient (HQ) values for adults and children. There was no non-carcinogenic risk for all people, except exposure of Cu from swine manure for children, which was 1.76 times higher than the threshold value of 1. According to the mean hazard index (HI) values, only swine manure had a non-carcinogenic risk for children. As the carcinogenic risk index (Risk) values were continuously greater for As than Cd, As had a higher carcinogenic risk than Cd. There was no carcinogenic risk for any single heavy metal, although As exposure from sewage sludge was found to have an inapparent carcinogenic risk for both adults and children. Regarding the RISK value, sewage sludge had an unacceptable carcinogenic risk for adults and children, and swine manure had an unacceptable risk for children only. In general, for both non-carcinogenic and carcinogenic risks, ingestion was the main pathway, and children were more sensitive than adults. Comparing the four kinds of organic waste, cattle manure was the safest for agricultural use in terms of ecological and human health risks. In multiple comparisons, swine manure was significantly different regarding potential ecological risk and non-carcinogenic risk, and sewage sludge was significantly different regarding carcinogenic risk.

Toxicity of copper pollution on sperm quality of Cyprinus carpio

Water pollution by heavy metal waste from industry, agriculture, and other human activities affect the reproductive health of aquatic biota, especially freshwater fish. This study aimed to evaluate the quality of Cyprinus carpio sperm contaminated with copper (Cu). The sample used was gonad from mature fish. The sperm and eggs were taken by stripping, six times of repetition. Cu with a concentration of 0, 10, 25, 50, and 75 ppm were used to examine the sperm quality (duration of motility and viability, DNA fragmentation, malondialdehyde level) and the ability of sperm to fertilize. The data was collected after sperm incubation with the variation of Cu concentration for five seconds. The sperm observation was done under inverted and fluorescence microscopes. The results showed that Cu exposure caused fertilization failure, thus reducing the number of fertilized eggs. The increase of Cu concentration from 10 ppm to 25 ppm caused a decrease in sperm quality and sperm fertilization. The increase in Cu concentration also raised the percentage of DNA fragmentation. In conclusion, in vitro exposure of Cu reduced sperm motility and viability as well as reduced the fertility in Cyprinus carpio

Toxic effects of heavy metals on the freshwater benthic organisms in sediments and research on quality guidelines in Poyang Lake, China

Sediment Quality Guidelines (SQGs) are the standard for protecting organisms from chemical hazards. Species Sensitivity Distribution (SSD), a typical derivation method of the SQGs, has been widely used for organic pollutants, whereas there are few studies applied on metals. This study investigated the toxic effects of Cu, Cd, Zn, and Pb to Limnodrilus hoffmeisteri and Chironomus larvas, obtained the SQGs by the SSD method, and evaluated the ecological risks of Poyang Lake, China. The test endpoints of L. hoffmeisteri (mortality and autotomy rates) and C. larvas (mortality and growth inhibition rates) after 21- and 14-day exposure of Cu, Cd, Zn, and Pb in the sediments of Poyang Lake were conducted, respectively. The SSD method was used for the curve optimal fitting and the SQG calculation based on the biotoxicity data of the local species in Poyang Lake. The ecological risk of Poyang Lake was assessed by calculating the potential ecological risk index (RI). The toxicity quotient Q was used for the SQGs verification of Cu, Cd, Zn, and Pb. According to the results of toxicity tests, C. larvas are more sensitive to the stress effects of heavy metals compared to L. hoffmeisteri. The Criteria Continuous Concentration (CCC) of Cu, Cd, Zn, and Pb were 34.9, 0.5, 58.2, and 35.0 mg kg−1, respectively. The Criteria Maximum Concentration (CMC) of Cu, Cd, Zn, and Pb were 56.35, 2.0, 151.3, and 175.0 mg kg−1, respectively. We selected C. larvas as experimental organisms to verify the SQGs and the results conformed to the meaning of guidelines. The RI values for heavy metals in all sampled sediments (P1 to P10) showed low potential ecological risks (RI 120) of P2, P6, and P10 are mainly attributed to Cd. In general, the CCC and CMC of Cu, Cd, Zn, and Pb conformed to the meaning of guidelines. The ecological risk index method showed that Poyang Lake was slightly polluted by Cu, Zn, and Pb, while heavily polluted by Cd. The results of the SQGs of heavy metals and ecological risk assessment can provide theoretical support for monitoring heavy metal pollution and biodiversity protection in Poyang Lake.

The response of larvae Brachymystax lenok during continuous and single pulses exposure to copper, zinc, lead and cadmium

The continuous and single pulses exposure of Cu, Zn, Pb and Cd on larvae Brachymystax lenok were tested in this study. The first-order kinetics was employed to obtain better comprehension on the time-toxicity relationship of tested heavy metals in continuous exposure test. For difference in time-varying exposure or recovery, 50% lethal time-averaged concentration (TAC) was used to assess the pulsed toxicity, which took both time and concentration into consideration in exposure and post-exposure period. TAC assessment to the single pulses and the regression analysis of first-order kinetic to continuous exposures demonstrated that Cu and Zn showed greater toxicity than Pb and Cd, indicating a slower uptake and/or depuration effect for zinc or copper. Furthermore, the results showed that recovery effect of larvae to all four metals was found in 24 h exposure followed by 72 h in fresh water, while for 72 h exposure and 24 h non-exposure the delayed lethal phenomenon occurred.

Bioaccumulation and biochemical responses of Vetiveria zizanioides grown under Cadmium and Copper stresses

Pot experiments were carried out to investigate the effects of Copper (Cu) and Cadmium (Cd) on Vetiveria zizanioides. Results revealed that increasing metal concentration in growing medium caused reduction in dry biomass, water content, leaf chlorophyll and soluble protein on exposure of Cu and Cd for 30 days. Cu and Cd accumulation in root and shoot enhanced on increasing Cu and Cd concentration in soil and reached a maximum of 514 and 1069 mg kg−1 dry weight (DW) in root and 58.03 and 17.87 mg kg−1 DW in shoot at exposure of 150 and 75 mg kg−1 of Cu and Cd respectively. Results also showed that the exposure of Cu and Cd in combination was more phytotoxic than the individual treatments. However, Bioconcentraion Factor (BCF) was found to be greater than one indicating suitability of V. zizanioides for phytoremdiation of Cu and Cd from soil. Metal accumulation in roots was much higher than shoots (TF ≪ 1) indicating that the mechanism involved was of phytoextraction.

Plasma impact on structural, morphological and optical properties of copper acetylacetonate thin films

The influence of plasma exposure on structural, morphological and optical properties of copper (II) acetylacetonate thin films deposited by thermal evaporation technique was investigated. Copper (II) acetylacetonate as-grown thin films were exposed to the atmospheric plasma for different times. The exposure of as-grown cu(acac)2 thin film to atmospheric plasma for 5min modified its structural, morphological and optical properties. The effect of plasma exposure on structure and roughness of cu(acac)2 thin films was evaluated by XRD and AFM techniques, respectively. The XRD results showed an increment in crystallinity due to exposure for 5min, but, when the exposure time reaches 10min, the film was transformed to an amorphous state. The AFM results revealed a strong modification of films roughness when the average roughness decreased from 63.35nm to ~1nm as a result of interaction with plasma. The optical properties of as-grown and plasma exposured cu(acac)2 thin films were studied using spectrophotometric method. The exposure of cu(acac)2 thin films to plasma produced the indirect energy gap decrease from 3.20eV to 2.67eV for 10min exposure time. The dispersion parameters were evaluated in terms of single oscillator model for as-grown and plasma exposured thin films. The influence of plasma exposure on third order optical susceptibility was studied.

Effect of copper on the accumulation and elimination kinetics of fluoroquinolones in the zebrafish (Danio rerio)

Fluoroquinolones (FQs) have attracted wide concerns due to their pseudo-persistent and universal presence in natural water. Here we exposed zebrafish separately to two FQs (enrofloxacin (ENR) and ofloxacin (OFL)) in different copper (Cu) concentrations for 20 days (d) in a flow-through system, followed by a 11 d depuration period in clean water to investigate compound specific bioaccumulation and tissue distribution. Two FQs could accumulate in zebrafish, and the high concentration was observed in liver. Moreover, the levels of FQs in different treatment groups were higher than the corresponding control fish group. The uptake rates (k1), elimination rates (k2), BCF value, and half-lives (t1/2) of FQs ranged from 0.02 to 3.28 d−1, 0.01 to 0.97 d−1, 0.33 to 109.33, 9.90 to 69.31 d, respectively. With Cu exposure concentration's increasing, k1 values in three tissues (liver, skin and gill) obviously decreased. The exposure concentration affected the BCF value significantly, but didn’t change their relative compositions in liver, gill, skin, and muscle after long time exposure. BCF values of ENR were always a little bit higher than those of OFL in almost all the tissues (liver, skin and gill) in the low Cu concentration treatments, whereas, in the high Cu concentration treatments the bioconcentration factors (BCF) values of ENR were lower than the values of OFL. The exposure of Cu played an important role in the FQs bioconcentration and BCF. These results are meaningful for improved understanding and prediction of the behavior and fate of metallic and antibiotics in aqueous environments.