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Cu Concentration (cu + concentration)
Selected AbstractsChronic copper toxicity in the estuarine copepod Acartia tonsa at different salinitiesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2010Mariana M. Lauer Abstract Chronic Cu toxicity was evaluated in the euryhaline copepod Acartia tonsa. Male and female copepods were exposed (6 d) separately to different combinations of Cu concentration and water salinity (5, 15, and 30 ppt) using different routes of exposure (waterborne, waterborne plus dietborne, and dietborne). After exposure, groups of one male and three female copepods were allowed to reproduce for 24,h. In control copepods, egg production augmented with increasing water salinity. However, egg hatching rate did not change. Copper exposure reduced egg production and hatching rate in all water salinities tested, but the reproductive response was dependent on the route of Cu exposure. Median effective concentration (EC50) values for egg production after waterborne exposure were 9.9, 36.8, and 48.8,µg/L dissolved Cu at water salinities of 5, 15, and 30 ppt, respectively. For waterborne plus dietborne exposure, they were significantly higher (40.1, 63.7, and 109.9,µg /L, respectively). After dietborne exposure, approximately 40% decrease in egg production was observed, independently of Cu concentration and water salinity tested. At water salinities of 5 and 30 ppt, egg hatching rate reduced after waterborne exposure, together or not with the dietborne exposure. At water salinity of 15 ppt, Cu toxicity was only observed after dietborne exposure. Data indicate that egg production is a more reliable reproductive endpoint to measure chronic Cu toxicity in copepods than egg hatching rate in a wide range of water salinities. They also suggest that both water salinity and route of Cu exposure should be taken into account in the development of a chronic biotic ligand model version for estuarine and marine environments. Environ. Toxicol. Chem. 2010;29:2297,2303. © 2010 SETAC [source] Acute copper toxicity in the euryhaline copepod Acartia tonsa: implications for the development of an estuarine and marine biotic ligand modelENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2010Grasiela Lopes Leães Pinho Abstract Copepods (Acartia tonsa) were exposed (48 h) to waterborne, diet-borne (non-Cu-equilibrated and Cu-equilibrated food), and waterborne plus diet-borne Cu in either the absence or the presence of food (diatom Thalassiosira weissflogii). Toxicity tests were run in different salinities (5, 15, and 30 ppt) together with measurements of physicochemical parameters and total and dissolved Cu concentrations in the experimental media. Results show that most of the toxic Cu fraction was in the dissolved phase. In general, Cu toxicity was higher in low (5 ppt) than in high salinity (30 ppt), regardless of the pathway of Cu exposure tested. In the absence of food, data clearly indicate that differences in waterborne Cu toxicity can be explained by changes in water chemistry. However, addition of food (either non-Cu-equilibrated or Cu-equilibrated) to the experimental media protected against acute Cu toxicity in salinities 5 and 15 ppt, suggesting that A. tonsa requires extra energy to cope with the stressful condition imposed by Cu exposure associated with the ionoregulatory requirements in low salinities. For diet-borne exposure, a very high Cu concentration was necessary to precontaminate the diatoms to a level resulting in copepod mortality. Therefore, availability of food exerted a more important positive impact in protecting against acute Cu toxicity than its potential negative impact via contamination resulting in toxicity. Findings indicate the need for incorporation of both salinity and food in a future biotic ligand model (BLM) version for Cu in estuarine and marine waters. In this context, the euryhaline copepod A. tonsa would be a suitable model species with which to perform experiments to validate and calibrate any future saltwater BLM. Environ. Toxicol. Chem. 2010; 29:1834,1840. © 2010 SETAC [source] Analysis of glutathione endpoints for measuring copper stress in Chlamydomonas reinhardthENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2007Tasha L. Stoiber Abstract Glutathione (GSH) is the most abundant nonprotein thiol in eukaryotic cells and it protects cells by functioning as an antioxidant and a metal-binding ligand. Because glutathione readily undergoes oxidation-reduction reactions to combat oxidative stress, intracellular ratios of the reduced (GSH) to the oxidized (GSSG) forms of glutathione may serve as an important biomarker of exposure and effect of trace metals in eukaryotic cells. We compared sensitivity of glutathione ratios in the freshwater alga Chlamydomonas reinhardtii to the traditional endpoints of cell growth rates and chlorophyll a following exposure to Cu for periods of 6 and 24 h. A response of the GSH:GSSG ratio to Cu concentration was observed at Cu levels of 40 and 80 nM after exposure for both 6 and 24 h. The concentration of total GSH at 24 h was roughly half the value at 6 h after exposure to either 40 or 80 nM Cu. A response for cell growth rate was observed only at 24 h, whereby the average specific growth rate decreased from about 1.1 to 0.4 d,1. The total Cu concentrations eliciting a cell response of 50%, effect concentrations (EC50s), after 24 h of exposure were similar (49.2, 49.8, and 38.2 nM Cu) and not significantly different for GSH:GSSG ratio, GSH levels, and specific growth, respectively. Total cell-associated Cu concentrations after exposure for 24 h were calculated from the EC50 endpoints and ranged from 13.3 to 17.0 fg/cell. Overall, thiol ratios were indicative of toxicity resulting from exposure to Cu, but precision may be greater for the cell growth rate endpoints. [source] Concentration of copper, iron, manganese and zinc in muscle, fat and bone tissue of lambs of the breed German Merino Landsheep in the course of the growing period and different feeding intensitiesJOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 3-4 2007G. Bellof Summary A growth experiment with 108 lambs (breed German Merino Landsheep) was carried out in order to examine how gender, body weight and feeding intensity affect trace element concentrations in tissues and carcass. The lambs (50% male and 50% female) were fattened at three levels of feeding intensity (,low', ,medium' and ,high' by varying daily amounts of concentrate and hay) and slaughtered at different final body weights (30, 45 or 55 kg). Six male and six female animals were sacrificed at 18 kg live weight at the beginning of the comparative slaughter experiment. The left half carcass of each animal was divided into muscle tissue, fat tissue as well as bones and sinews and analysed for the trace elements copper (Cu), iron (Fe), manganese (Mn) as well as zinc (Zn). The body weight level influenced the Zn concentrations significantly in all tissues. In addition, the Fe concentration in the fat tissue was influenced by the body weight as well as the Cu content in the bone tissue. An influence due to gender could be seen for the Zn concentration in the muscle and fat tissue and for the Fe content in the fat and bone tissue as well as for the Cu concentration in the bones. The feeding intensity affected the Cu content in the muscle and bone tissue and also the Zn content in the muscle tissue. In the present study with lambs at body weight range from 18 to 55 kg on an average, 127 mg Fe, 87 mg Zn, 1.5 mg Cu as well as 1.1 mg Mn per kilogram dry matter were found in the bone tissue. In lamb muscle tissue combined from all parts (body weight range from 18 to 45 kg, both genders) the highest concentrations were for Zn and Fe [3.42 and 1.31 mg/100 g meat (wet weight basis)], while Cu remained far below these levels (0.08 mg/100 g meat and Mn was even below the detection limit of 0.025 mg/kg). Lamb muscle is a valuable source for highly available haem-Fe as well as for Zn and Cu in human nutrition. [source] Structures of the pseudo-trigonal polymorphs of Cu2(OH)3ClACTA CRYSTALLOGRAPHICA SECTION B, Issue 3 2009Thomas Malcherek The crystal structure of Cu2(OH)3Cl has been determined using two natural samples with almost ideal stoichiometry. While one of the samples exhibits a twinned clinoatacamite structure, the other sample is characterized by the appearance of additional weak diffraction maxima at half integer positions of h and k. Structure refinement was carried out with the space group . The relationship between the triclinic phase, clinoatacamite, paratacamite and the herbertsmithite structure is discussed in terms of symmetry as a function of Cu concentration. [source] Response of potted grapevines to increasing soil copper concentrationAUSTRALIAN JOURNAL OF GRAPE AND WINE RESEARCH, Issue 1 2009M. TOSELLI Abstract Background and Aims:, Copper accumulation in soil may promote phytotoxicity in grapevines. Nutritional implications of potted vines to increasing concentrations of copper (Cu) in either clay loam soil or clay loam soil mixed with 85% sand were tested on Vitis vinifera (L.) cv Sangiovese and crop toxicity threshold and symptoms determined. Methods and Results:, Soils were mixed at planting with Cu at the rates (mg Cu/kg) of 0 (control, native soil Cu only), 50, 100, 200, 400, 600, 800 and 1000, and non-bearing vines were grown in these for two seasons. Reduction of root growth was observed after addition of ,400 mg Cu/kg to both soils; reduction of shoot growth, leaf number and chlorosis of leaf edges were detected only in sand-enriched soil. Root Cu concentration increased in response to soil Cu addition. Unlike that of leaf Cu and N, the amount of P and Fe (in both soils) and Mg and Ca (in sand-enriched soil only) were reduced by soil Cu. Conclusion:, Vines grown in sand-enriched soil tolerated lower concentrations of Cu than in clay loam soil, probably because of the lower nutritional status and the higher root Cu concentration. Significance of the Study:, Results provide information on the concentration of soil Cu that grapevine can tolerate and on the nutrients involved in the response to toxic levels of soil Cu in clay loam and sandy clay loam soils. [source] Self-Assembly of a Two-Dimensional Bimetallic Coordination Framework and Dynamic Control of Reversible Conversions to Homo-Metallic Hydrogen-Bond ArraysCHEMPHYSCHEM, Issue 1 2010Ziliang Shi A novel 2D coordination bimetallic framework composed of Cu and Zn is obtained at a Au(111) surface by the supramolecular assembly of Cu and zinc-5,10,15,20-tetra(4-pyridyl)porphyrin molecules (see figure). Suppressing Cu concentration at high temperature transforms the 2D bimetallic frameworks into 2D homo-metallic hydrogen-bond arrays. Enriching the Cu concentration can reverse the structural transformation. [source] Acute copper toxicity in the euryhaline copepod Acartia tonsa: implications for the development of an estuarine and marine biotic ligand modelENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2010Grasiela Lopes Leães Pinho Abstract Copepods (Acartia tonsa) were exposed (48 h) to waterborne, diet-borne (non-Cu-equilibrated and Cu-equilibrated food), and waterborne plus diet-borne Cu in either the absence or the presence of food (diatom Thalassiosira weissflogii). Toxicity tests were run in different salinities (5, 15, and 30 ppt) together with measurements of physicochemical parameters and total and dissolved Cu concentrations in the experimental media. Results show that most of the toxic Cu fraction was in the dissolved phase. In general, Cu toxicity was higher in low (5 ppt) than in high salinity (30 ppt), regardless of the pathway of Cu exposure tested. In the absence of food, data clearly indicate that differences in waterborne Cu toxicity can be explained by changes in water chemistry. However, addition of food (either non-Cu-equilibrated or Cu-equilibrated) to the experimental media protected against acute Cu toxicity in salinities 5 and 15 ppt, suggesting that A. tonsa requires extra energy to cope with the stressful condition imposed by Cu exposure associated with the ionoregulatory requirements in low salinities. For diet-borne exposure, a very high Cu concentration was necessary to precontaminate the diatoms to a level resulting in copepod mortality. Therefore, availability of food exerted a more important positive impact in protecting against acute Cu toxicity than its potential negative impact via contamination resulting in toxicity. Findings indicate the need for incorporation of both salinity and food in a future biotic ligand model (BLM) version for Cu in estuarine and marine waters. In this context, the euryhaline copepod A. tonsa would be a suitable model species with which to perform experiments to validate and calibrate any future saltwater BLM. Environ. Toxicol. Chem. 2010; 29:1834,1840. © 2010 SETAC [source] Analysis of glutathione endpoints for measuring copper stress in Chlamydomonas reinhardthENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2007Tasha L. Stoiber Abstract Glutathione (GSH) is the most abundant nonprotein thiol in eukaryotic cells and it protects cells by functioning as an antioxidant and a metal-binding ligand. Because glutathione readily undergoes oxidation-reduction reactions to combat oxidative stress, intracellular ratios of the reduced (GSH) to the oxidized (GSSG) forms of glutathione may serve as an important biomarker of exposure and effect of trace metals in eukaryotic cells. We compared sensitivity of glutathione ratios in the freshwater alga Chlamydomonas reinhardtii to the traditional endpoints of cell growth rates and chlorophyll a following exposure to Cu for periods of 6 and 24 h. A response of the GSH:GSSG ratio to Cu concentration was observed at Cu levels of 40 and 80 nM after exposure for both 6 and 24 h. The concentration of total GSH at 24 h was roughly half the value at 6 h after exposure to either 40 or 80 nM Cu. A response for cell growth rate was observed only at 24 h, whereby the average specific growth rate decreased from about 1.1 to 0.4 d,1. The total Cu concentrations eliciting a cell response of 50%, effect concentrations (EC50s), after 24 h of exposure were similar (49.2, 49.8, and 38.2 nM Cu) and not significantly different for GSH:GSSG ratio, GSH levels, and specific growth, respectively. Total cell-associated Cu concentrations after exposure for 24 h were calculated from the EC50 endpoints and ranged from 13.3 to 17.0 fg/cell. Overall, thiol ratios were indicative of toxicity resulting from exposure to Cu, but precision may be greater for the cell growth rate endpoints. [source] Assessment of zinc phytoavailability by diffusive gradients in thin filmsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 4 2005Osman Sonmez Abstract Asessment of Zn phytoavailability can be predicted with routine soil extractants, but these methods generally do not perform well across a wide range of soils. The newly developed technique of diffuse gradients in thin films (DGT) has been employed to determine phytoavailable Cu concentrations, but its suitability for determining plant available Zn concentrations has not been evaluated. A greenhouse study was conducted to assess the phytotoxicity thresholds and the phytoavailability of Zn to sorghum-sudan (Sorghum vulgare var. sudanese) grass by DGT, compared with CaCl2 extraction. A range of phytoavailable Zn concentrations was created by amending sand with ZnSO4 or with two different Zn mine wastes. Plant nutrients were added as Hoagland solution. In general, increasing Zn concentrations in the sand mixtures increased Zn adsorption by DGT and decreased the sorghum-sudan yield. A critical value for 90% of the control yield was chosen as an indicator of Zn toxicity. Critical values of DGT Zn, CaCl2 -extractable Zn, and plant tissue Zn were similar statistically across the three Zn sources. The performances of DGT and CaCl2 extraction for assessing Zn phytoavailability were similar. Shoot and root Zn concentrations of sorghum-sudan grass exceeded 500 mg kg,1 for many treatments. Calcium-to-Zn ratios for shoots were <32, suggesting Zn phytotoxicity. The data suggested that Zn phytotoxicity can be induced with mine wastes, although further evaluation is needed to establish a link between mine waste and Zn phytotoxicity. [source] Partitioning of copper at concentrations below the marine water quality criteria,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 5 2001Anthony J. Paulson Abstract Partitioning of Cu between the aqueous and particulate phases and among their components was examined in six ambient Puget Sound, Washington State, USA, samples (6,10 nM Cu). Most of the particulate Cu (4,12% of the total Cu) was associated with particulate organic matter, and resulted in distribution coefficients (Kd) ranging between 104,55 and 105,1. For the dissolved phase, the portion of Cu extracted by C18 -packed cartridges averaged 44% (+ 11%). Radioactive 64Cu was added to these samples to total stable Cu concentrations (17,33 nM). After 24 h of equilibration, the portion of 64Cu associated with the particulate matter in five of the six samples (Kd between 1047 and 1053) was an average of 70% higher than that of natural Cu in the ambient samples. In contrast, only 19 ± 7% of the 64Cu was extracted by C18 -packed cartridges. The partitioning of natural Cu and 64Cu onto particles was not significantly different when the equilibria were based on dissolved Cu passing through the C18 cartridges. Further research is warranted on utilizing the hydrophilic component of the dissolved phase as a parameter on which water quality criteria are based. [source] Variation of metallothionein and metal concentrations in the digestive gland of the clam Ruditapes decussatus: Sex and seasonal effectsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2001Maria A. Serafim Abstract Metallothionein (MT) and metal (Cd, Cu, and Zn) concentrations were determined in the digestive gland of male and female Ruditapes decussatus. Clams were collected monthly during the period of sexual development, from June to September, at two different sites of a coastal lagoon, the Ria Formosa Lagoon, on the south coast of Portugal. The MT concentrations were determined in the heat-treated cytosolic fraction of the digestive gland of both male and female clams. Total metal (Cd, Cu, and Zn) concentrations in the heat-treated cytosol of the digestive gland were also determined in both sexes. The MT and metal concentrations in the digestive gland were not sex dependent in this species. Therefore, these results suggest that random samples can be used to determine MT and metal concentrations in the digestive gland of R. decussatus. Seasonal and site-specific dependency, however, were detected for MT, Cd, and Cu concentrations. The maximum concentration levels of MT, Cd, and Cu were detected in July and August for both sexes in the same area. Zinc concentrations, however, did not show marked seasonal variations, indicating that this species is able to regulate zinc concentrations. The highest MT concentrations were significantly related to the highest metal concentrations. [source] Maternally derived Cu tolerance in larval fathead minnows: how long does it persist?JOURNAL OF FISH BIOLOGY, Issue 5 2006M. K. Sellin Fathead minnow Pimephales promelas larvae were produced by either copper (Cu)-exposed or naïve females and then subjected to a 96 h survival test using Cu concentrations of 400 and 800 ,g l,1. Three survival challenges were conducted: the first survival test featured 0 day-old larvae while the second and third featured 8 and 15 day-old larvae, respectively. The results of this study show that maternally derived Cu tolerance was relatively short-lived as it persisted for <8 days. [source] Iron, Manganese and Copper Equilibria with Wood Fibres in Single Salt Aqueous SuspensionsTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2005Robin Susilo Abstract Ions of Fe, Mn and Cu were introduced into suspensions of protonated or metal-free fibres and the equilibrium concentration of each metal in the fibre and surrounding solution was measured. The results were compared with the Donnan equilibrium model. Mn and Cu concentrations on the fibres were found to be pH dependent and in agreement with the model. An increased amount of Fe on the Kraft pulp fibres was found and attributed to iron containing precipitates trapped within the fibres. Precipitates in mechanical pulps had a very small amount (1-2 wt%) of iron. Des ions de Fe, Mn et Cu ont été introduits dans des suspensions de fibres protonatées ou « sans métaux » et la concentration d'équilibre de chaque métal dans la fibre et la solution environnante a été mesurée. Les résultats ont été comparés avec le modèle d'équilibre de Donnan. On a trouvé que les concentrations de Mn et Cu sur les fibres étaient dépendantes du pH et en accord avec le modèle. Une quantité accrue de Fe a été trouvée sur les fibres de pâte kraft et attribuée aux précipitats contenant du fer retenus dans les fibres. Les précipitats dans les pâtes mécaniques ont une très petite quantité (1-2% en poids) de fer. [source] | |||||||||||||