Proportion Of Cu Research Articles

Variation in soil chemistry related to different classes and eras of urbanisation in the London area

Systematic mapping of the chemical environment of urban areas from around the world has demonstrated the strong impact of urbanisation on topsoil geochemical distributions originally controlled by the underlying parent material (PM). The variance of some elements including As, Ba, Ca, Cr, Cu, Mo, P, Pb, Sb, Se, Sn and Zn in urban domains appears to be impacted by a mixture of geogenic and anthropogenic controls. This study evaluates how soil chemistry has been influenced by different eras of urbanisation within London and other UK urban areas using (a) the pre-1940 Dudley Stamp First Land Utilisation Survey data and (b) the modern urban domain principally defined by the aggregate classes of the 2007 Land Cover Map. In the London area, calcium, and possibly a substantial proportion of Cu, Pb, Sn and Zn enrichment observed in soils impacted by pre-1940 urbanisation relative to soils impacted only by post-1940 urbanisation, may be partly related to the destruction of buildings during the period 1940–1941 rather than from the disposal or aerial dispersion of coal ash from domestic fires. Some Pb, Cu, Sb, Sb, Sn and Zn contamination appears to be caused by road traffic (leaded petrol and brake dust). The relationships between pre- and post-1940 urbanised areas in London also characterise most of 20 other urban centres in England and Wales for which BGS holds soil chemistry data.

Small changes in Cu redox state and speciation generate large isotope fractionation during adsorption and incorporation of Cu by a phototrophic biofilm

Despite the importance of phototrophic biofilms in metal cycling in freshwater systems, metal isotope fractionation linked to metal adsorption and uptake by biofilm remains very poorly constrained. Here, copper isotope fractionation by a mature phototrophic biofilm during Cu surface adsorption and incorporation was studied in batch reactor (BR) and open drip flow reactor (DFR) systems at ambient conditions. X-ray Absorption Spectroscopy (both Near Edge Structure, XANES, and Extended Fine Structure, EXAFS) at Cu K-edge of the biofilm after its interaction with Cu in BR experiments allowed characterizing the molecular structure of assimilated Cu and quantifying the degree of CuII to CuI reduction linked to Cu assimilation. For both BR and DFR experiments, Cu adsorption caused enrichment in heavy isotope at the surface of the biofilm relative to the aqueous solution, with an apparent enrichment factor for the adsorption process, ε65Cuads, of +1.1±0.3‰. In contrast, the isotope enrichment factor during copper incorporation into the biofilm (ε65Cuinc) was highly variable, ranging from −0.6 to +0.8‰. This variability of the ε65Cuinc value was likely controlled by Cu cellular uptake via different transport pathways resulting in contrasting fractionation. Specifically, the CuII storage induced enrichment in heavy isotope, whereas the toxicity response of the biofilm to Cu exposure resulted in reduction of CuII to CuI, thus yielding the biofilm enrichment in light isotope. EXAFS analyses suggested that a major part of the Cu assimilated by the biofilm is bound to 5.1±0.3 oxygen or nitrogen atoms, with a small proportion of Cu linked to sulfur atoms (NS<0.6) of sulfhydryl groups. XANES analyses showed that the proportion of CuIIvs CuI, compared to the initial CuII/CuI ratio, decreased by 14% after the first hour of reaction and by 6% after 96h of reaction. The value of ε65Cuinc of the biofilm exhibited a similar trend over time of exposure. Our study demonstrates the complexity of biological processes associated with live phototrophic biofilms, which produce large and contrasting isotope fractionations following rather small Cu redox and speciation changes during uptake, storage or release of the metal, i.e., favoring heavy isotopes during complexation with carboxylate ligands and light isotopes during reduction of CuII-O/N to CuI-sulfhydryl moieties.

Calculation of thermodynamic properties and transport coefficients of CO2–O2–Cu mixtures

The thermodynamic properties and transport coefficients of CO2–O2–Cu gas mixtures in the temperature range from 300 K to 30 000 K and the pressure range from 0.1 to 0.8 MPa are calculated. Special attention is paid to the influence of different oxygen and copper proportions and different gas pressures on the CO2–O2–Cu mixture properties. It can be concluded that the addition of oxygen has a strong influence on both thermodynamic properties and transport coefficients. A small proportion of Cu does not lead to a significant change to the properties, apart from the electrical conductivity at low temperatures. However, Cu mole fractions above 10% start to affect all properties. Increasing gas pressure can cause an increase in the transport coefficients, especially in the high-temperature range. The calculation results provide the necessary data for the further study of the behaviour of plasmas using magnetohydrodynamics arc models. The results can be also used to optimize the ratio of the component gases for different applications; some examples are presented.

Subcellular distribution of hepatic copper in beef cattle receiving high copper supplementation

Previous studies of intensively reared cattle in NW Spain have reported significantly higher copper (Cu) accumulation in the liver in Holstein-Friesian (HF) animals than in Galician Blonde (GB) or GBxHF crosses when receiving a diet supplemented at the maximum Cu concentrations allowed in the EU legislation (35mg/kg). The present study aimed to evaluate whether this difference is due to the pattern of subcellular accumulation of Cu in the liver. For this purpose, liver samples from 10 GB, 9 HF and 10 GBxHF young bulls were analysed to determine the content of metallothionein (MT) and Cu and zinc (Zn) (in the liver (Cu-liver and Zn-liver) and bound to metallothionein (Cu-MT and Zn-MT)). The Cu distribution within the main subcellular compartments (nuclei, large granule, microsomes and cytosol) was also determined. Even though HF animals showed significantly higher (P<0.05) Cu concentrations in the liver (161±10mg/kg wet weight) compared with GB (132±8mg/kg), no breed-related differences were observed for any of the parameters considered in this study. Overall, the pattern of hepatic subcellular accumulation was similar to that previously described in cattle: (i) MT concentrations were lower than in other animal species but strongly related to hepatic Zn; (ii) a low proportion of Cu (6.61%) was bound to MT but this was strongly and negatively related to the Cu:Zn ratio in the liver cell; and (iii) the highest proportion of Cu (57.3%) was found in the large granule (lysosome containing) fraction. All these results indicate a low capacity of cattle to excrete Cu by the bile resulting in a high Cu accumulation in the liver cell.

Mechanism study of sulfur fertilization mediating copper translocation and biotransformation in rice (Oryza sativa L.) plants

Metabolism of sulfur (S) is suggested to be an important factor for the homeostasis and detoxification of Cu in plants. We investigated the effects of S fertilizers (S0, Na2SO4) on Cu translocation and biotransformation in rice plants by using multiple synchrotron-based techniques. Fertilization of S increased the biomass and yield of rice plants, as well as the translocation factor of Cu from root to shoot and shoot to grain, resulting in enhanced Cu in grain. Sulfur K-edge X-ray near edge structure (XANES) analysis showed that fertilization of S increased the concentration of glutathione in different rice tissues, especially in rice stem and leaf. Copper K-edge XANES results indicated that a much higher proportion of Cu (I) species existed in rice grain than husk and leaf, which was further confirmed by soft X-ray scanning transmission microscopy results. Sulfur increased the proportion of Cu (I) species in rice grain, husk and leaf, suggesting the inducing of Cu (II) reduction in rice tissues by S fertilization. These results suggested that fertilization of S in paddy soils increased the accumulation of Cu in rice grain, possibly due to the reduction of Cu (II) to Cu (I) by enhancing glutathione synthesis and increasing the translocation of Cu from shoot to grain.

High-performance Ag-CuOx nanocomposite catalyst galvanically deposited onto a Ni-foam for gas-phase dimethyl oxalate hydrogenation to methyl glycolate

A foam-structured Ag-CuOx nanocomposite catalyst obtained by sequential galvanic-deposition of 0.4wt% Ag and 28wt% Cu onto a Ni-foam, is highly active, selective and stable for the gas-phase hydrogenation of dimethyl oxalate (DMO) to methyl glycolate (MG). The best catalyst 0.4-Ag-28-CuOx/Ni-foam was capable of converting more than 96% DMO into MG with a high selectivity of more than 96% and was stable for at least 200h at 210°C and a WLHSVDMO of 0.25h−1 for a feed of 13wt% DMO dissolved in MeOH. Silver is responsible to apportion the proportion of Cu+ and Cu0 to an appropriate scale of optimal potency for converting DMO-to-MG.

In situ study on liquid structure of Sn during Sn/Cu liquid–solid interfacial reaction by fluorescence XAFS

Fluorescence X-ray Absorption Fine Structure (XAFS) was used to in situ study the local structure around Cu atoms in liquid Sn solder during Sn/Cu liquid–solid interfacial reaction. The extended edge data were analyzed by cumulant expansion method. The results showed that both the atomic distance and the coordination number in the first shell decreased with the increase of temperature. It is an intrinsic trend that high-coordinated polyhedrons could transform into low-coordinated ones with relatively high stability in the liquid Sn solder with increasing temperature, and the high-coordinated polyhedrons always had larger atomic distance. The atomic distance in the first shell decreased with decreasing coordination number. Based on the fitting results, the proportion of Cu–Sn atomic coordination increased with rising soldering temperature from 250 to 310 °C. That is, Cu atoms preferred to form Cu–Sn interaction with Sn atoms, which promoted the nucleation and growth of Cu6Sn5 intermetallic compound at the Sn/Cu interface during soldering process.

Distribution of trace metals (Cu, Pb, Ni, Zn) between particulate, colloidal and truly dissolved fractions in wastewater treatment

The distribution of Cu, Pb, Ni and Zn between particulate, colloidal and truly dissolved size fractions in wastewater from a trickling filter treatment plant was investigated. Samples of influent, primary effluent, humus effluent, final effluent and sludge holding tank returns were collected and separated into particulate (i.e. > 0.45 μm), colloidal (i.e. 1 kDa to 0.45 μm), and truly dissolved (i.e. < 1 kDa) fractions using membrane filters. In the influent, substantial proportions of Cu (60%), Pb (67%), and Zn (32%) were present in the particulate fraction which was removed in conjunction with suspended particles at the works in subsequent treatment stages. In final effluent, sizeable proportions of Cu (52%), Pb (32%), Ni (44%) and Zn (68%) were found within the colloidal size fraction. Calculated ratios of soluble metal to organic carbon suggest the metal to be adsorbed to or complexed with non-humic macromolecules typically found within the colloidal size range. These findings suggest that technologies capable of removing particles within the colloidal fraction have good potential to enhance metals removal from wastewater.

Preparation of CuO/NiO composite nanofibers by electrospinning and their application for electro-catalytic oxidation of hydrazine

Abstract In present work, polyvinyl alcohol/copper acetate-nickel acetate composite nanofibers (PVA/Cu(OAc) 2 -Ni(OAc) 2 NFs) with various weight percentages of Cu(OAc) 2 :Ni(OAc) 2 such as 25:75, 50:50 and 75:25 are fabricated by electrospinning method. After this, the CuO/NiO composite NFs are produced after thermal treatment. A calcination temperature at about 600 °C is determined by thermal gravimetric analysis. Field-emission scanning electron microscopy (FE-SEM) for morphology characterization indicates that large quantities of the prepared PVA/Cu(OAc) 2 -Ni(OAc) 2 composite fibers have smooth and bead-free surfaces. Fourier transform infrared spectroscopy, FE-SEM and energy dispersive X-ray spectroscopy are used to characterize the CuO/NiO composites. According to FE-SEM results, with increasing of Cu(OAc) 2 content in polymeric solution, the fibers don't remain as continuous structures after calcination and accumulate in the form of nanoparticles. Also, a carbon paste electrode (CPE) bulky modified with CuO/NiO composites is used for investigation of the electro-catalytic oxidation of hydrazine hydrate in NaOH solution. The catalytic activities of the synthesized catalysts are studied through cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy. The obtained results demonstrate that the most appropriate proportion of Cu(OAc) 2 :Ni(OAc) 2 in electrospinning solution to enhance the electro-catalytic ability is 25:75.

Hydrogenation of methyl acetate to ethanol by Cu/ZnO catalyst encapsulated in SBA‐15

The hydrogenation of methyl acetate (MA) is one of the important key processes for synthesis of ethanol from syngas. This work reports a highly efficient Cu‐ZnO/SBA‐15 catalyst prepared by facile solid‐state grinding method. Both copper and zinc species were encapsulated in SBA‐15 in high dispersion with the presence of organic template. The mixed homogeneity and interaction between copper and zinc species was enhanced as well with the help of organic template, resulting in the formation of Cu+ species in the reduced catalysts. Moreover, TOFCu(0) linearly increased with the Cu+/Cu0 ratio, indicating that a high proportion of Cu+/Cu0 induced by ZnO should be a key prerequisite to achieve favorable hydrogenation performance. It seems that the Cu+ species originated from Cu‐ZnOx species are more active than that from Cu‐O‐Si species in the activation of MA. These results may provide an inspiration in rational design of Cu‐ZnO‐based catalysts for esters hydrogenation. © 2017 American Institute of Chemical Engineers AIChE J, 63: 2839–2849, 2017

Energy-level variations of Cu-doped ZnO fabricated through sol-gel processing

We evaluated the properties and energy levels of Cu-doped ZnO (CZO) crystals synthesized in different Cu ion additions through sol-gel processing. Different CZO crystals were synthesized with Zn-OH and Cu-OH as precursors under sol-gel reactions in base solutions. The properties of the synthesized CZO samples were characterized and the energy levels of the samples were determined. Results showed that the grain size and bandgap energy (Eg) of the CZO crystals decreased, as the proportion of Cu in the ZnO increased. The lattice volume of the CZO crystals was distorted in the presence of Cu. The lowest resistivity of the CZO sample films was determined for the CZO sample with 3% Cu addition (3CZO). The conduction band energy (Ec), valence band energy (Ev), and Fermi energy (EF) levels were estimated and varied because of the presence of Cu in ZnO. The lower resistivity of CZO was analyzed and attributed to the energy level variations that occurred on the basis of the lattice distortion in the CZO crystals.

Selective hydrogenation of ethylene carbonate to methanol and ethylene glycol over Cu/SiO2 catalysts prepared by ammonia evaporation method

A series of Cu/SiO2-AE catalysts with different copper loadings were prepared by ammonia evaporation method with silica sol as the silica source. The systematic catalyst characterization revealed that different proportions of Cu0 and Cu+ species co-existed in the Cu/SiO2-AE catalysts, which derived from the reduction of CuO and copper phyllosilicate, respectively. The as-prepared catalysts were employed in the hydrogenation of ethylene carbonate (EC) to co-produce methanol (MeOH) and ethylene glycol (EG). Among the catalysts investigated, the 10%Cu/SiO2-AE catalyst with a moderate copper loading exhibited better catalytic activity and product selectivities, which was mainly ascribed to the synergetic effect of Cu0 and Cu+ species and the suitable proportion of Cu+/(Cu++Cu0). It was proposed that the Cu0 species promoted the dissociation of H2, while Cu+ species adsorbed on the carbonyl group of EC. Under the optimized conditions, EC conversion of 100%, MeOH selectivity of 70.8% and EG selectivity of 98.0% were obtained over the 10%Cu/SiO2-AE catalyst. The catalyst reusability results showed that the agglomeration of Cu and Cu2O particles was responsible for the gradually decreasing activity of 10%Cu/SiO2-AE catalyst along with recycling runs.

Effect of Cu on the microstructures and properties of WC-6Co cemented carbides fabricated by SPS

The aim of this work is to study the effect of Cu on sintering temperature, densification, microstructure and mechanical properties of WC-6Co cemented carbides fabricated by spark plasma sintering (SPS). Fine grained WC powders with an average size of 1.2μm, were investigated. Microstructures, hardness, fracture toughness and wear resistance of WC-6(Co/Cu) cemented carbides were measured and observed using SEM, mechanical property test. The results show that the sintering temperature of WC-6Co cemented carbides can be decreased obviously with Cu added; addition of Cu reduced grain size to 0.85μm, but led to lower density. The adding amount of Cu should be controlled within a certain range, and the samples adding the appropriate proportion of Cu can obtain higher hardness and wear resistance.

Research on the stability of heavy metals (Cu, Zn) in excess sludge with the pretreatment of thermal hydrolysis

Thermal hydrolysis (TH) has been used to improve anaerobic digestion performance as well as the stability of heavy metals in sludge. Because the toxicity of heavy metals is closely related to both the concentration and the chemical speciation, more exhaustive studies on speciation distribution are urgently needed. This research aimed to investigate the effects of TH treatment (especially the time and temperature) on the concentration and stability of heavy metals in sludge, and to define the optimal TH conditions. The TH experiment indicated that the content of the stable form of Cu and Zn reached 83% and 47.4%, respectively, with TH at 210°C and 30 min. Compared with the raw sludge, the proportion of Cu and Zn increased by 11.88% and 7.3%, respectively. Results indicated that the heavy metals were combined with sludge in a more stable form with the pretreatment of TH, which improved the stability of heavy metals.

Catalytic synthesis of diethyl carbonate with supported Pd-Cu bimetallic nanoparticle catalysts: Cu(I) as the active species

Cupric oxide (CuO) and copper-cuprous oxide (Cu-Cu2O) nanoparticles were prepared by a simple hydrothermal method for the synthesis of diethyl carbonate (DEC) from ethanol. During these syntheses, varying NaOH and glucose concentrations were applied to explore and pinpoint the active species. It was found that PdCl2/CuO and PdCl2/Cu-Cu2O both catalysts exhibited good thermal stability and morphology. The results of catalytic tests showed that the catalysts prepared with 5 mol/L NaOH show superior catalytic performances because of their lower extent of agglomeration. It is noteworthy that the PdCl2/Cu-Cu2O catalysts were the most active, especially the PdCl2/Cu-Cu2O catalyst prepared with 10 mmol glucose and having a higher Cu2O concentration. In Pd(II)-Cu(II) (PdCl2/CuO) catalysts, there is an induction period, during which Pd(II) is reduced to Pd(0), that must occur prior to electron transfer between Pd and Cu, and this can slow the catalytic reaction. To further pinpoint the active species, PdCl2/Cu-Cu2O catalysts with different Cu2O contents were prepared by controlling the dosages of glucose. The maximum DEC yield obtained with these catalysts was 151.9 mg·g−1·h−1, corresponding to an ethanol conversion of 7.2% and 97.9% DEC selectivity on an ethanol basis. Therefore, it was concluded that Cu+ was the active species in this catalytic system, possibly because a higher proportion of Cu+ reduces the Pd2+ concentration and limits the CO oxidation side reaction, thus increasing DEC selectivity. In addition, Cu+ promotes electron transfer between Pd and Cu without an induction period, which could also promote the catalytic activity.

Soil trace elements contamination in the vicinity of Khatoon Abad copper smelter, Kerman province, Iran

Continuous deposition from Khatoon Abad smelter stack particulates has resulted in trace elements contamination in soil. To investigate the regional distribution and fractionation of trace elements in soils, soil samples were collected and examined. The results demonstrate that the highest trace element concentrations in top soil are: >10000 mg Cu kg-1, 2000 mg Mo kg-1, >10000 mg Zn kg-1, 2694.2 mg As kg-1, 2006.2 mg Pb kg-1, 420.4 mg Sb kg-1, and 90.7 mg Cd kg-1. The concentrations of the trace elements are much higher than the normal concentrations in the uncontaminated soil and geochemical background. The most contaminated areas are located in the vicinity of smelter in the prevailing wind directions. Calculated geoaccumulation index and contamination load index indicate surface soil enrichment in potentially toxic metals (Cu, Mo, As, Sb, Cd, Zn, and Pb). Combined multivariate statistical and geostatistical methods successfully separate the contaminant metals (As, Cd, Cu, Pb, Sb, Mo, and Zn) from the uncontaminated ones (Al, Fe, Mn, and Cr). Furthermore, it was found that the As, Cd, Cu, Pb, Sb, Mo, and Zn mainly come from the copper smelter. The modified BCR three-step sequential extraction technique was applied to assess the four fractions (residual, acid, reducible and oxidizable) in smelter dust and surface soil samples. The results demonstrate that a high proportion of Cu, Mo, As, Pb, Sb, and Zn is extracted in the mobile fractions, indicating high mobility and probably hazardous environmental consequences.

Presence of golden ratio relationships in Fe–Fe3C, Cu–Zn and Cu–Sn alloy systems

Iron–carbon, copper–zinc and copper–tin are the three most significant alloy systems. Iron–carbon system is commonly known for steels, copper–zinc for brasses and copper–tin for bronzes. This paper shows how eutectoid, peritectic, eutectic, cementite-intermetallic, maximum solubility of carbon in ferrite, maximum solubility of carbon in austenite points in Fe–Fe 3 C phase diagram are linked to one another through golden ratio relationships. This paper also shows the ratios between proportions of Cu and Zn at maximum solubility of Zn in Cu at 456 and 0°C and the ratio of proportions of Cu–Sn at e-Cu 3 Sn (IMC) in Cu–Zn and Cu–Sn phase diagrams, respectively, are related to golden ratio. It is predicted that the occurrence of these relationships at vital points in mentioned systems is in accordance with Constructal law of design in nature and golden ratio is the reason for uniqueness and usefulness of these points.

The competing effects of sulfide saturation versus degassing on the behavior of the chalcophile elements during the differentiation of hydrous melts

AbstractThere is a lack of consensus regarding the roles of sulfide saturation versus volatile degassing on the partitioning of Cu and Ag during differentiation and eruption of convergent margin magmas. Because of their oxidized character, volatile‐rich magmas from the Eastern Manus Back‐arc Basin (EMBB) only reach sulfide saturation following magnetite‐driven reduction of the melt: the so‐called “magnetite crisis.” If sulfide saturation typically precedes volatile saturation, the magnetite crisis will limit the proportion of Cu and Ag that can partition from the melt into an exsolving volatile‐rich phase, which may contribute to the sporadic occurrence of magmatic‐hydrothermal ore deposits at convergent margins. However, it is unclear whether the magnetite crisis is a common or rare event during differentiation of volatile‐rich magmas. We report major and trace element data for submarine volcanic glasses from the Tonga arc‐proximal Valu Fa Ridge (VFR; SW Pacific). Cu‐Se‐Ag systematics of samples erupting at the southern VFR suggest magnetite fractionation‐triggered sulfide saturation. The similarity in chalcophile element systematics of the southern VFR and EMBB samples is unlikely to be coincidental, and may indicate that the magnetite crisis is a common event during differentiation of hydrous melts. However, unlike many convergent margin magmas, it is unlikely that the evolving VFR and EMBB were saturated in a S‐bearing volatile phase prior to magnetite fractionation. Hence, the metal‐depleting magnetite crisis may be restricted to back‐arc basin magmas that do not degas volatiles prior to magnetite fractionation and potentially convergent margin magmas fractionating at high pressures in the continental crust.

Assessment of Post-eutectic Reactions in Multicomponent Al-Si Foundry Alloys Containing Cu, Mg, and Fe

Post-eutectic reactions occurring in Al-Si hypoeutectic alloys containing different proportions of Cu, Mg, and Fe were thoroughly investigated in the current study. As-cast microstructures were initially studied by optical and electron microscopy to investigate the microconstituents of each alloy. Differential scanning calorimetry (DSC) was then used to examine the phase transformations occurring during the heating and cooling processes. Thermodynamic calculations were carried out to assess the phase formation under equilibrium and in nonequilibrium conditions. The Q-Al5Cu2Mg8Si6 phase was predicted to precipitate from the liquid phase, either at the same temperature or earlier than the θ-Al2Cu phase depending on the Cu content of the alloy. The AlCuFe-intermetallic, which was hardly observed in the as-cast microstructure, significantly increased after the solution heat treatment in the alloys containing high Cu and Fe contents following a solid-state transformation of the β-Al5FeSi phase. After the solution heat treatment, the AlCuFe-intermetallics were mostly identified with the stoichiometry of the Al7Cu2Fe phase. Thermodynamic calculations and microstructure analysis helped in determining the DSC peak corresponding to the melting temperature of the N-Al7Cu2Fe phase. The effect of Cu content on the formation temperature of π-Al8Mg3FeSi6 is also discussed.

Accumulation and effects of metal mixtures in two seaweed species

Metal pollution, due to various anthropogenic sources, may pose a threat to marine ecosystems. Metals can be introduced into food chains via bioaccumulation in primary producers, and may potentially lead to toxic effects. Macroalgae are used as food by a wide variety of organisms, and are therefore extremely important in aquatic systems. This study investigated the accumulation and effects of metals in two macroalgae species. The green seaweed, Ulva lactuca and the red seaweed, Agardhiella subulata were each concurrently exposed to five metals (Cu, Ni, Pb, Cd, and Zn) and U. lactuca was also exposed to each metal individually for 48h. Metal accumulation in the seaweed was measured, and various photosynthetic parameters were assessed, using imaging pulse amplitude modulated (PAM) fluorometry. Increased metal accumulation occurred in both seaweed species after 48h exposure to metal mixtures and each metal individually. The distribution of metals in both seaweed species changed with increasing metal exposure concentrations, resulting in higher proportions of Cu and Zn in the metal-exposed groups, as compared to respective controls. Further, U. lactuca accumulated higher concentrations of metals when exposed to each metal individually rather than in metal mixtures, suggesting interactions among metals for uptake and/or bioaccumulation. Significant impairment of photosynthetic parameters in U. lactuca was observed after exposure to 100 and 1000μg/L metal mixtures, as well as 100μg/L of either Cd or Cu. These results demonstrate metal bioaccumulation and toxic effects in important primary producers, and may have implications for higher trophic levels.