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Zn Concentrations (zn + concentration)
Selected AbstractsSilver Amalgam Film Electrode of Prolonged Application in Stripping ChronopotentiometryELECTROANALYSIS, Issue 18 2007Kapturski Abstract The utility of the cylindrical silver-based mercury film electrode of prolonged analytical application in stripping chronopotentiometry (SCP) was examined. This electrode allowed us to obtain good reproducibility of results owing to the special electrode design, which enables regeneration of the thin layer before each measurement cycle. The accessible potential window in KNO3 (pH,2), acetate and ammonia buffers was defined, and the optimal conditions (i.e., stripping current, deposition potential and deposition time) for the determination of Cd and Pb traces were selected. The detection limits, obtained for an accumulation time of 60,s, were 0.023,,g/L for Cd and 0.075,,g/L for Pb. The response increases linearly with Cd, Pb and Zn concentration, up to at least 100,,g/L. It was also shown that the proposed procedure ensures excellent separation of the In and Tl, Pb and Tl or the In and Cd signals. The method was tested with dolomite and lake sediment samples, and good agreement with reference values was achieved. The obtained results showed good reproducibility (RSD=5,6%) and reliability. [source] Subcellular distribution of zinc in Daphnia magna and implication for toxicityENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2010Wen-Xiong Wang Abstract We examined the subcellular partitioning of zinc (Zn) in Daphnia magna both under acute and chronic exposures. In the acute Zn toxicity tests, the daphnids were exposed to different Zn concentrations for 48,h or to one lethal concentration (1,000,µg/L) for different durations (time to death for up to 47,h). Significant mortality of daphnids was observed when the newly accumulated Zn concentration reached a threshold level of approximately 40,µg/g wet weight (or 320,µg/g dry wt), approximately 3.5 times higher than the background tissue concentration (92,µg/g dry wt). Chronic exposure (14 d) to Zn resulted in nonobservable effect on survivorship and growth at newly accumulated tissue concentration of over 40,µg/g wet weight. With increasing Zn acute exposure, more Zn was partitioned into the cellular debris fraction, indicating that this fraction was presumably the first targeted site of binding for Zn upon entering the animals. The importance of other subcellular fractions either decreased accordingly or remained comparable. We found that the metal-sensitive fraction (Zn distribution in the organelles and heat-denatured proteins) did not predict the acute Zn toxicity in Daphnia. During chronic exposure, however, no major change of the subcellular partitioning of Zn with increasing Zn exposure was documented. Zinc was mainly found in the organelles and heat-stable protein fractions during chronic exposure, suggesting that any subcellular repartitioning occurred primarily during acute exposure. Metallothioneins were induced upon chronic Zn exposure, but its induction evidently lagged behind the Zn accumulation. Our present study showed that the subcellular fractionation approach could not be readily used to predict the acute and chronic toxicities of Zn in Daphnia. A tissue-based Zn accumulation approach with a threshold Zn tissue concentration was better in predicting acute Zn toxicity. Environ. Toxicol. Chem. 2010; 29:1841,1848. © 2010 SETAC [source] Biokinetics of cadmium and zinc in a marine bacterium: Influences of metal interaction and pre-exposureENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2008Dongshi Chen Abstract The uptake kinetics of Cd and Zn, as influenced by metal interaction and metal pre-exposure, was examined in the gram-positive marine bacterium Bacillus firmus over a wide range of ambient free-Cd and -Zn concentrations. Bacteria were exposed to experimental media with different concentrations of Cd and Zn over a short, 15-min period. Zinc was found to be an effective competitive inhibitor of Cd uptake when the Zn2+ concentration ([Zn2+]) was increased to 10,8 M, whereas the Cd concentration (ranging from 10,9 to 10,6 M) did not affect Zn uptake. Inhibition of Cd uptake was dependent on [Zn2+] instead of the [Zn2+] to Cd2+ concentration ratio. Cadmium uptake at different [Zn2+] was significantly inhibited by a sulfur ligand (SH) blocker (N -ethylmaleimide) and a Ca-channel blocker (lanthanum), suggesting that competition between Cd and Zn most likely occurred via binding to the same transport sites. Cadmium efflux also was determined in the presence of different [Zn2+]. A biphasic depuration of Cd was found when [Zn2+] was greater than 10,8 M, whereas the calculated Cd efflux rate was independent of [Zn2+]. We further exposed B. firmus at different Cd or Zn concentrations for 24 h, then determined the metal uptake and efflux kinetics as well as the metallothionein (MT) induction. Both the Cd and Zn cellular concentrations increased with greater exposed metal concentration, but the MT levels and efflux were little affected by the elevated metal concentration. To some extent, however, the Cd uptake was reduced with an elevated intracellular Zn concentration, suggesting that at high Cd concentrations, intracellular Zn can suppress the Cd uptake in B. firmus. These results help to understand the interactions of metals in the marine environments. [source] Influence of in-stream diel concentration cycles of dissolved trace metals on acute toxicity to one-year-old cutthroat trout (Oncorhynchus clarki lewisi)ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2007David A. Nimick Abstract Extrapolating results of laboratory bioassays to streams is difficult, because conditions such as temperature and dissolved metal concentrations can change substantially on diel time scales. Field bioassays conducted for 96 h in two mining-affected streams compared the survival of hatchery-raised, metal-näive westslope cutthroat trout (Oncorhynchus clarki lewisi) exposed to dissolved (0.1-,m filtration) metal concentrations that either exhibited the diel variation observed in streams or were controlled at a constant value. Cadmium and Zn concentrations in these streams increased each night by as much as 61 and 125%, respectively, and decreased a corresponding amount the next day, whereas Cu did not display a diel concentration cycle. In High Ore Creek (40 km south of Helena, MT, USA), survival (33%) after exposure to natural diel-fluctuating Zn concentrations (range, 214,634 ,g/L; mean, 428 ,g/L) was significantly (p = 0.008) higher than survival (14%) after exposure to a controlled, constant Zn concentration (422 ,g/L). Similarly, in Dry Fork Belt Creek (70 km southeast of Great Falls, MT, USA), survival (75%) after exposure to diel-fluctuating Zn concentrations (range, 266,522 ,g/L; mean, 399 ,g/L) was significantly (p = 0.022) higher than survival (50%) in the constant-concentration treatment (392 ,g/L). Survival likely was greater in these diel treatments, both because the periods of lower metal concentrations provided some relief for the fish and because toxicity during periods of higher metal concentrations was lessened by the simultaneous occurrence each night of lower water temperatures, which reduce the rate of metal uptake. Based on the present study, current water-quality criteria appear to be protective for streams with diel concentration cycles of Zn (and, perhaps, Cd) for the hydrologic conditions tested. [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] Effect of Zn deficiency and subsequent Zn repletion on bone mineral composition and markers of bone tissue metabolism in 65Zn-labelled, young-adult ratsJOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 7-8 2002W. Windisch Summary The objective of the present study was to investigate the effect of changing skeletal Zn load (mobilization/restoring) on bone mineral composition and bone tissue metabolism. For this purpose, 36 65Zn-labelled, young-adult female rats were fed with either a purified diet with sufficient Zn (21 ,g/g, control) for 26 days, or deficient Zn (1.4 ,g/g) for 12 days followed by 14 days repletion with the control diet. The animals were killed at the onset of the study (reference: n=4), at the end of the Zn deficiency episode (control: n=4; Zn deficiency: n=4), subgroups (n=4) of Zn repleted animals at repletion days 2, 4, 7, 10 and 14, and at day 14 the remaining controls also (n=4). Zn deficiency reduced skeletal Zn concentration from 198 to 155 ,g/g of bone dry matter. About half of mobilized skeletal Zn was refilled within 2 days of repletion and was completely restored until the end of the study. Concentrations of bone ash, Ca, P and Mg remained constant (means in bone dry matter: 51% bone ash, 191 mg Ca/g, 95 mg P/g, 4.4 mg Mg/g). Blood plasma concentrations of osteocalcin and daily urinary excretions of pyridinoline PYD and dexoxypyridinoline DPD were unaffected by treatment (mean: 57 ng/ml, 222 nmol/day, 137 nmol/day). Also daily urinary excretions of Ca, P and Mg remained fairly constant (means: 0.26 mg/day, 16 mg/day, 1.5 mg/day). 65Zn autoradiography of femur sections revealed a pronounced Zn exchange in the area of the metaphysis and epiphysis. We conclude that transient mobilization and restoration of skeletal Zn occurs mainly in trabecular bone, and does not involve major changes in bone mass, macro mineral content, or bone tissue turnover in young-adult rats. [source] Soil-plant relationships, micronutrient contents, and cardenolide production in natural populations of Digitalis obscuraJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 1 2004Luis Roca-Pérez Abstract The production of secondary metabolites by plants growing in natural populations is conditioned by environmental factors. In the present study, we have investigated the relationships among soil properties, micronutrients in soils and plants, and cardenolide production from wild Digitalis obscura (Scrophulariaceae) populations. Young and mature leaves and soil samples were collected in ten different populations, corresponding to three Mediterranean bioclimatic belts (Thermo-, Meso-, and Supramediterranean belts). Soil (total and EDTA-extractable) and leaf micronutrients (Fe, Mn, Zn, and Cu), and leaf cardenolide accumulation have been determined. Significant negative correlations were observed between Fe, Mn or Zn concentration in leaves and soil pH, as well as between Fe or Mn in leaves and carbonate content of soils. Only EDTA-extractable Mn was significantly correlated with Mn content in the plants. With regard to cardenolide content in leaves, this parameter was negatively correlated with Znleaf in young leaves and with Mnleaf in old leaves. Positively correlated, however, were Fe and cardenolide content in young leaves. The influence of environmental conditions and leaf micronutrient contents on cardenolide accumulation is discussed. Boden-Pflanze-Wechselwirkungen im Hinblick auf Mikroelement- und Cardenolidgehalte in wilden Digitalisobscura -Populationen Die Produktion von sekundären Stoffwechselprodukten in Pflanzen ist in hohem Grad abhängig von Umweltfaktoren. In dieser Studie wurde bei Wildtypen von Digitalis obscura der Einfluss bodenchemischer Eigenschaften (pH, Karbonatgehalt, Gesamt- und EDTA-extrahierbare Mikronährstoffgehalte) auf die Mikronährstoff- (Fe, Mn, Zn und Cu) und Cardenolidgehalte in den Pflanzen untersucht. Verwendet wurden Proben von jungen und reifen Blättern sowie Bodenproben aus zehn verschiedenen Populationen in drei bioklimatischen Zonen (Thermo-, Meso- und Supramittelmeergebiet). Festgestellt wurden signifikant negative Beziehungen zwischen Fe-, Mn- oder Zn-Gehalten in den Blättern und dem pH des Bodens, sowie zwischen Fe- oder Mn-Konzentration in den Blättern und dem Karbonatgehalt der Böden. Nur EDTA-extrahierbares Mn wies eine positive Beziehung zu den Mn-Gehalten in den Pflanzen auf. Die Ergebnisse deuten darauf hin, dass die Gehalte von Mikroelementen in den Blättern von D. obscura stärker vom pH des Bodens abhängig sind als von den Gesamt- oder den extrahierbaren Mikroelementgehalten der Böden. Ebenso wurden signifikant negative Beziehungen zwischen Cardenolidgehalten und Zn-Gehalten in jungen Blättern, sowie Mn-Gehalten in älteren Blättern festgestellt. Die Fe-Gehalte in jungen Blättern waren jedoch positiv mit dem Cardenolidgehalt korreliert. Diese Befunde werden im Hinblick auf die Cardenolidbiosynthese diskutiert. [source] Zinc bioavailability in wheat grain in relation to phosphorus fertiliser, crop sequence and mycorrhizal fungiJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 7 2008Megan H Ryan Abstract BACKGROUND: While human diets are often deficient in zinc (Zn), the impacts of crop management on Zn in cereal grains are rarely examined. In this study the effect of phosphorus (P) fertiliser and crop sequence (wheat following canola, linola, fallow or pasture) on wheat grain Zn concentration and bioavailability for humans was investigated. RESULTS: The Zn concentration of wheat grain decreased by 33,39% in response to P fertiliser. It was also 30,40% lower for crops following canola and fallow than for those following linola and pasture. P fertiliser decreased the colonisation of arbuscular mycorrhizal fungi (AMF) in wheat roots, and canola and fallow led to lower colonisation than linola and pasture. Since AMF are known to assist in soil uptake of immobile nutrients such as Zn, it is hypothesised that P fertiliser and crop sequence affected grain Zn concentration through AMF. P fertiliser also increased the concentrations of grain P by 17% and grain phytic acid (PA) by 19%, but had little effect on the concentrations of calcium (Ca), iron (Fe) and polyphenols. Other impacts of crop sequence were slightly higher concentrations in grain of P after pasture and Fe after canola. The bioavailability of grain Zn, as shown by the PA:Zn and Ca × PA:Zn molar ratios, mostly reflected Zn concentration and was low in all treatments. After milling, the PA:Zn molar ratio suggested low Zn bioavailability for flour from wheat grown with P fertiliser after canola or fallow. CONCLUSION: Crop management can affect the bioavailability of Zn in wheat grain, with practices leading to high yields potentially leading to low Zn bioavailability. Copyright © 2008 Society of Chemical Industry [source] Within and between population genetic variation for zinc accumulation in Arabidopsis halleriNEW PHYTOLOGIST, Issue 1 2002Mark R. Macnair Summary ,,Hyperaccumulator plants in the field show significant variation in the metal concentration in their aerial parts, but little is known of the causes of this variation. This paper investigates the role of soil zinc (Zn) concentration and genetic variation in causing between and within population variation in Zn accumulation in Arabidopsis halleri. ,,Seed from 17 populations of A. halleri collected in central Europe were grown under standard conditions at three external Zn concentrations and tested for Zn concentration in the leaves. ,,Between population variation was highest at low external zinc concentrations. At 10 µm Zn some plants had very low leaf Zn concentrations, and were indistinguishable from nonaccumulators. However, at higher Zn concentrations, all plants showed hyperaccumulation. There were no differences in the accumulating abilities of populations from sites with different degrees of contamination. ,,Heritability of accumulation, determined for individual families from three populations, was quite high (25,50%), indicating that selection for increased accumulating ability should be possible, although selection would be easier at low external Zn concentrations. The Zn concentration of field collected plants was affected partly by plant genotype but not by the total soil Zn around their roots. [source] Determination of true absorption and fecal endogenous loss of zinc in goatsANIMAL SCIENCE JOURNAL, Issue 5 2010Ryota HATTORI ABSTRACT We determined the true absorption and endogenous fecal loss of zinc (Zn) in goats using its stable isotope. Three goats were fed with the diet containing 50 mg/kg Zn twice a day for 17 days. In the morning of day 11, the goats were given a meal labeled by 67Zn as the tracer with dysprosium as the unabsorbed marker. Then the goats were given unlabeled diet as the rest of the morning feed. We measured dietary and fecal Zn concentration, 67Zn abundance and dysprosium concentration in feces. The excretion pattern of the tracer Zn into feces differed from that of dysprosium. Therefore, we directly calculated the true absorption of Zn from Zn concentration and 67Zn abundance in fecal samples collected after the labeled diet was given. The apparent absorption of Zn was ,0.009 ± 0.016 mg/kg bodyweight (fractional absorption, ,1.07 ± 1.85%). The true absorption of Zn was 0.162 ± 0.018 mg/kg bodyweight (fractional absorption, 18.25 ± 2.01%). The endogenous fecal loss of Zn was 0.172 ± 0.004 mg/kg bodyweight and the intestinal secretion of Zn was 0.210 ± 0.009 mg/kg bodyweight. The present experiment indicates that stable isotopic Zn is a powerful tool for examining Zn metabolism in ruminants. [source] Dietary phytase increases the true absorption and endogenous fecal excretion of zinc in growing pigs given a corn-soybean meal based dietANIMAL SCIENCE JOURNAL, Issue 1 2009Gyo-Moon CHU ABSTRACT We investigated the effect of dietary phytase on the true absorption and endogenous fecal excretion of zinc (Zn) using 67Zn in growing pigs given a corn-soybean meal based diet. Ten crossbred barrows were fed the control diet containing 90-mg/kg Zn, 2.3-g/kg phytate-phosphorus and 3.7-g/kg non-phytate-phosphorus or the phytase diet containing similar amounts of Zn and phytate-phosphorus, and 1.4-g/kg non-phytate-phosphorus with 750-PU/kg phytase for 12 h/day. On day 6, the pigs were given 200 g of the corresponding diet labeled by 67Zn for 2 h. We measured feed intake, fecal Zn concentration and 67Zn abundance for the determination of apparent absorption, true absorption and endogenous fecal excretion of Zn. Although the apparent absorption of Zn did not significantly differ between the dietary groups, the phytase group had significantly more (P < 0.05) true absorption of Zn than the control group. The endogenous fecal excretion of Zn tended to be more (P = 0.07) in the phytase group than in the control group. These results suggest that dietary phytase improves Zn bioavailability through increasing the true absorption of Zn in growing pigs, which results in stimulating the endogenous fecal excretion of Zn when dietary Zn satisfies its requirement. [source] Subcellular distribution of zinc in Daphnia magna and implication for toxicityENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2010Wen-Xiong Wang Abstract We examined the subcellular partitioning of zinc (Zn) in Daphnia magna both under acute and chronic exposures. In the acute Zn toxicity tests, the daphnids were exposed to different Zn concentrations for 48,h or to one lethal concentration (1,000,µg/L) for different durations (time to death for up to 47,h). Significant mortality of daphnids was observed when the newly accumulated Zn concentration reached a threshold level of approximately 40,µg/g wet weight (or 320,µg/g dry wt), approximately 3.5 times higher than the background tissue concentration (92,µg/g dry wt). Chronic exposure (14 d) to Zn resulted in nonobservable effect on survivorship and growth at newly accumulated tissue concentration of over 40,µg/g wet weight. With increasing Zn acute exposure, more Zn was partitioned into the cellular debris fraction, indicating that this fraction was presumably the first targeted site of binding for Zn upon entering the animals. The importance of other subcellular fractions either decreased accordingly or remained comparable. We found that the metal-sensitive fraction (Zn distribution in the organelles and heat-denatured proteins) did not predict the acute Zn toxicity in Daphnia. During chronic exposure, however, no major change of the subcellular partitioning of Zn with increasing Zn exposure was documented. Zinc was mainly found in the organelles and heat-stable protein fractions during chronic exposure, suggesting that any subcellular repartitioning occurred primarily during acute exposure. Metallothioneins were induced upon chronic Zn exposure, but its induction evidently lagged behind the Zn accumulation. Our present study showed that the subcellular fractionation approach could not be readily used to predict the acute and chronic toxicities of Zn in Daphnia. A tissue-based Zn accumulation approach with a threshold Zn tissue concentration was better in predicting acute Zn toxicity. Environ. Toxicol. Chem. 2010; 29:1841,1848. © 2010 SETAC [source] Biokinetics of cadmium and zinc in a marine bacterium: Influences of metal interaction and pre-exposureENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2008Dongshi Chen Abstract The uptake kinetics of Cd and Zn, as influenced by metal interaction and metal pre-exposure, was examined in the gram-positive marine bacterium Bacillus firmus over a wide range of ambient free-Cd and -Zn concentrations. Bacteria were exposed to experimental media with different concentrations of Cd and Zn over a short, 15-min period. Zinc was found to be an effective competitive inhibitor of Cd uptake when the Zn2+ concentration ([Zn2+]) was increased to 10,8 M, whereas the Cd concentration (ranging from 10,9 to 10,6 M) did not affect Zn uptake. Inhibition of Cd uptake was dependent on [Zn2+] instead of the [Zn2+] to Cd2+ concentration ratio. Cadmium uptake at different [Zn2+] was significantly inhibited by a sulfur ligand (SH) blocker (N -ethylmaleimide) and a Ca-channel blocker (lanthanum), suggesting that competition between Cd and Zn most likely occurred via binding to the same transport sites. Cadmium efflux also was determined in the presence of different [Zn2+]. A biphasic depuration of Cd was found when [Zn2+] was greater than 10,8 M, whereas the calculated Cd efflux rate was independent of [Zn2+]. We further exposed B. firmus at different Cd or Zn concentrations for 24 h, then determined the metal uptake and efflux kinetics as well as the metallothionein (MT) induction. Both the Cd and Zn cellular concentrations increased with greater exposed metal concentration, but the MT levels and efflux were little affected by the elevated metal concentration. To some extent, however, the Cd uptake was reduced with an elevated intracellular Zn concentration, suggesting that at high Cd concentrations, intracellular Zn can suppress the Cd uptake in B. firmus. These results help to understand the interactions of metals in the marine environments. [source] Influence of in-stream diel concentration cycles of dissolved trace metals on acute toxicity to one-year-old cutthroat trout (Oncorhynchus clarki lewisi)ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2007David A. Nimick Abstract Extrapolating results of laboratory bioassays to streams is difficult, because conditions such as temperature and dissolved metal concentrations can change substantially on diel time scales. Field bioassays conducted for 96 h in two mining-affected streams compared the survival of hatchery-raised, metal-näive westslope cutthroat trout (Oncorhynchus clarki lewisi) exposed to dissolved (0.1-,m filtration) metal concentrations that either exhibited the diel variation observed in streams or were controlled at a constant value. Cadmium and Zn concentrations in these streams increased each night by as much as 61 and 125%, respectively, and decreased a corresponding amount the next day, whereas Cu did not display a diel concentration cycle. In High Ore Creek (40 km south of Helena, MT, USA), survival (33%) after exposure to natural diel-fluctuating Zn concentrations (range, 214,634 ,g/L; mean, 428 ,g/L) was significantly (p = 0.008) higher than survival (14%) after exposure to a controlled, constant Zn concentration (422 ,g/L). Similarly, in Dry Fork Belt Creek (70 km southeast of Great Falls, MT, USA), survival (75%) after exposure to diel-fluctuating Zn concentrations (range, 266,522 ,g/L; mean, 399 ,g/L) was significantly (p = 0.022) higher than survival (50%) in the constant-concentration treatment (392 ,g/L). Survival likely was greater in these diel treatments, both because the periods of lower metal concentrations provided some relief for the fish and because toxicity during periods of higher metal concentrations was lessened by the simultaneous occurrence each night of lower water temperatures, which reduce the rate of metal uptake. Based on the present study, current water-quality criteria appear to be protective for streams with diel concentration cycles of Zn (and, perhaps, Cd) for the hydrologic conditions tested. [source] Transfer of Cd, Cu, Ni, Pb, and Zn in a soil-plant-invertebrate food chain: A microcosm study,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2006Renaud Scheifler Abstract The transfer of Cd, Cu, Ni, Pb, and Zn was evaluated in a soil-plant (lettuce, Lactuca sativa),invertebrate (snail, Helix aspersa) food chain during a microcosm experiment. Two agricultural soils, polluted and unpolluted, were studied. Lettuce was cultivated for eight weeks before introduction of snails into the microcosms (M-snails). In a parallel experiment, snails were exposed to lettuce only (i.e., without soil) in simpler exposure devices called containers (C-snails). Snail exposure duration was eight weeks for both M- and C-snails. No effects on snail survival were found. Both M- and C-snails exposed to polluted soil showed a growth reduction, but only after two weeks of exposure. Time-dependent accumulation in M-snails exposed to the polluted environment showed a regular increase of Cd and Zn concentrations over time and a rapid increase of Pb concentrations within the first two weeks, which then remained stable. Copper and Ni concentrations did not increase during any of the experiments. Concentrations in M- and C-snails were compared to estimate the relative contribution of soil and plant to the total bioaccumulation. The results suggest that the soil contribution may be higher than 80% for Pb, from 30 to 60% for Zn, and from 2 to 40% for Cd. [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] Dynamic coupled metal transport-speciation model: Application to assess a zinc-contaminated lakeENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2004Satyendra P. Bhavsar Abstract A coupled metal transport and speciation/complexation model (TRANSPEC) has been developed to estimate the speciation and fate of multiple interconverting species in surface aquatic systems. Dynamic-TRANSPEC loosely, sequentially couples the speciation/complexation and fate modules that, for the unsteady state formulation, run alternatively at every time step. The speciation module first estimates species abundance using, in this version, MINEQL+ considering time-dependent changes in water and pore-water chemistry. The fate module is based on the quantitative water air sediment interaction (QWASI) model and fugacity/aquivalence formulation, with the option of using a pseudo-steady state solution to account for past discharges. Similarly to the QWASI model for organic contaminants, TRANSPEC assumes the instantaneous equilibrium distribution of metal species among dissolved, colloidal, and particulate phases based on ambient chemistry parameters that can be collected through conventional field methods. The model is illustrated with its application to Ross Lake (Manitoba, Canada) that has elevated Zn concentrations due to discharges over 70 years from a mining operation. Using measurements from field studies, the model reproduces year-round variations in Zn water concentrations. A 10-year projection for current conditions suggests decreasing Zn remobilization and export from the lake. Decreasing Zn loadings increases sediment-to-water transport but decreases water concentrations, and vice versa. Species distribution is affected by pH such that a decrease in pH increases metal export from the lake and vice versa. [source] Induction of morphological deformities in Chironomus tentans exposed to zinc- and lead-spiked sedimentsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2001Edward A. Martinez Abstract Laboratory experiments were used to assess morphological responses of Chironomus tentans larvae exposed to three levels of zinc and lead. Chironomus tentans egg masses were placed into triplicate control and metal-spiked aquaria containing the measured concentrations 1,442, 3,383, and 5,562 ,g/g Pb dry weight and 1,723, 3,743, and 5,252 ,g/g Zn dry weight. Larvae were collected at 10-d intervals after egg masses were placed in aquaria until final emergence. Larvae were screened formouthpart deformities and metal body burdens. Deformities increased with time of exposure in both Zn and Pb tanks. Deformity rates between the three Zn concentrations differed statistically, with low and medium Zn levels containing the highest overall deformity rates of 12%. Deformity rates for larvae held in the Pb aquaria were found to differ significantly. Larvae in the low-Pb tanks had a deformity rate of 9%. Larvae and water from both the Zn and Pb aquaria had increasing metal concentrations with increasing sediment metal concentration. Results demonstrate that Zn and Pb each induce chironomid mouthpart deformities at various concentrations. However, a clear dose-related response was not demonstrated. Our research provides more support for the potential use of chironomid deformities as a tool for the assessment of heavy metal pollution in aquatic systems. [source] Decline in the quality of suspended fine particulate matter as a food resource for chironomids downstream of an urban areaFRESHWATER BIOLOGY, Issue 5 2004Emma J. Rosi-MarshallArticle first published online: 16 APR 200 Summary 1. Urbanization and its associated contamination could degrade the quality of suspended fine particulate organic matter (SFPM) (20 ,m to 1 mm) as a food resource for aquatic insects. SFPM was collected at four sites along the main stem of the Chattahoochee River, which drains metropolitan Atlanta at base and high flow during four seasons. 2. Composition of SFPM was estimated using measures conventionally associated with food quality: bacteria, N/C ratio, caloric content, % inorganic, and % lipids, and metal (Cd, Cu, Pb, and Zn) concentration. In SFPM collected during base flow, % inorganic matter, calories, Cu, Pb, and Zn concentrations increased with cumulative permitted wastewater treatment discharge (an indicator of extent of urbanization upstream). In SFPM samples collected during high flow, % diatoms, Cu, Pb and Zn concentrations increased with urbanization. 3. A growth assay was used as an integrated and direct measure of SFPM quality as a food resource. The instantaneous growth rate (IGR) of chironomids fed SFPM collected during base flow declined downstream of the city. IGRs of chironomids fed SFPM collected at all sites during high flow were as low as the lowest IGR measured during base flow. 4. Insects fed SFPM collected from the Chattahoochee River had IGRs only 20% of those of chironomids fed SFPM collected from the Little Tennessee River, a relatively undisturbed river in North Carolina. The mortality rate of chironomids fed SFPM was not different among sites or rivers. While the decline in SFPM quality in the Chattahoochee River is probably attributable to some aspect of urbanization, the decline was not related to conventional measures of food quality or metal contamination. [source] Development of Cu and Zn Isotope MC-ICP-MS Measurements: Application to Suspended Particulate Matter and Sediments from the Scheldt EstuaryGEOSTANDARDS & GEOANALYTICAL RESEARCH, Issue 2 2008Jérôme C.J. Petit isotopes de Cu et Zn; interférences spectrales et non spectrales; fractionnement de masse instrumental; MC-ICP-MS; sédiments The present study evaluates several critical issues related to precision and accuracy of Cu and Zn isotopic measurements with application to estuarine particulate materials. Calibration of reference materials (such as the IRMM 3702 Zn) against the JMC Zn and NIST Cu reference materials were performed in wet and/or dry plasma modes (Aridus I and DSN-100) on a Nu Plasma MC-ICP-MS. Different mass bias correction methods were compared. More than 100 analyses of certified reference materials suggested that the sample-calibrator bracketing correction and the empirical external normalisation methods provide the most reliable corrections, with long term external precisions of 0.06 and 0.07, (2SD), respectively. Investigation of the effect of variable analyte to spike concentration ratios on Zn and Cu isotopic determinations indicated that the accuracy of Cu measurements in dry plasma is very sensitive to the relative Cu and Zn concentrations, with deviations of ,65Cu from ,0.4, (Cu/Zn = 4) to +0.4, (Cu/Zn = 0.2). A quantitative assessment (with instrumental mass bias corrections) of spectral and non-spectral interferences (Ti, Cr, Co, Fe, Ca, Mg, Na) was performed. Titanium and Cr were the most severe interfering constituents, contributing to inaccuracies of ,5.1, and +0.60, on ,68/64Zn, respectively (for 500 ,g l,1 Cu and Zn standard solutions spiked with 1000 ,g l,1 of Ti or Cr). Preliminary isotopic results were obtained on contrasting sediment matrices from the Scheldt estuary. Significant isotopic fractionation of zinc (from 0.21, to 1.13, for ,66Zn) and copper (from ,0.38, to 0.23, for ,65Cu), suggest a control by physical mixing of continental and marine water masses, characterized by distinct Cu and Zn isotopic signatures. These results provide a stepping-stone to further evaluate the use of Cu and Zn isotopes as biogeochemical tracers in estuarine environments. L'étude présentée ici porte sur l'évaluation critique d'un certain nombre de paramètres contrôlant la précision et la justesse des mesures des isotopes de Cu et Zn, dans le cadre d'une application à du matériel particulaire estuarien. Une calibration de matériaux de référence (tels que le Zn IRMM 3702) par rapport aux matériaux de référence JMC Zn et NIST Cu a été effectuée avec des plasmas humides et secs (avec Aridus I et DSN-100) sur un MC-ICP-MS Nu. Différentes méthodes de correction de biais de masse ont été comparées. Plus de 100 analyses de matériaux de référence certifiés ont montré que la correction par l'intercalation d'un calibrateur entre chaque échantillon et la calibration externe empirique fournissaient les corrections les plus fiables, avec des précisions externes sur le long terme de 0.06 et 0.07, (2SD) respectivement. Les effets de la variation des rapports de concentrations entre analyte et spike sur les mesures des rapports isotopiques de Cu et Zn ont montré que la justesse des mesures pour Cu en plasma sec est très tributaire des concentrations relatives de Cu et Zn, avec des déviations de ,65Cu allant de ,0.4, (Cu/Zn = 4) à+0.4, (Cu/Zn = 0.2). Une estimation quantitative des interférences spectrales et non spectrales (Ti, Cr, Co, Fe, Ca, Mg, Na) a été faite. Ti et Cr se sont révélés être les constituants interférents les plus importants pouvant entraîner des erreurs de ,5.1, et +0.60, sur ,68/64Zn respectivement (pour des solutions standards à 500 ,g l,1 de Cu et Zn dopées avec 1000 ,g l,1 de Ti ou Cr). Des données isotopiques préliminaires ont été obtenues sur des matrices sédimentaires très différentes provenant de l'estuaire de Scheldt. Les fractionnements significatifs du zinc (de 0.21,à 1.13, pour ,66Zn) et du cuivre (de ,0.38,à 0.23, pour ,65Cu) suggèrent un contrôle par un processus physique de mélange entre des masses d'eaux continentales et marines ayant des signatures isotopiques de Cu et Zn distinctes. Ces résultats constituent un tremplin vers une utilisation future des isotopes de Cu et Zn comme traceurs biogéochimiques des environnements estuariens. [source] Supplementation of diets for lactating sows with zinc amino acid complex and gastric nutriment-intubation of suckling pigs with zinc methionine on mineral status, intestinal morphology and bacterial translocation in lipopolysaccharide-challenged weaned pigsJOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 2 2010B. U. Metzler-Zebeli Summary Sixty-four pigs from 16 sows were used to evaluate addition of zinc amino acid complex (ZnAA) to lactating sows and gastric nutriment-intubation of zinc methionine (ZnMet) to suckling pigs on mineral status, intestinal morphology and bacterial translocation after weaning. Sows were fed a barley-based diet supplying 120 ppm zinc (Zn; control) or the control diet supplemented with 240 ppm Zn from ZnAA. At birth, day-10 and day-21 (weaning) of age, pigs from each litter were nutriment-intubated with 5 ml of an electrolyte solution without or with 40 mg Zn from ZnMet. At weaning, 24 h prior to the collection of small and large intestinal lymph nodes and sections of the duodenum, jejunum and ileum, the pigs received an intramuscular injection of saline without or with 150 ,g/kg body weight of Escherichia coli O26:B6 lipopolysaccharide (LPS). With the exception of a tendency (p = 0.09) for lower serum concentration of copper in pigs at weaning from ZnAA-supplemented sows, there were no differences (p > 0.1) than for pigs from control-fed sows for mineral status or intestinal morphology. Nutriment-intubation of ZnMet increased serum (p = 0.001) and liver (p = 0.003) Zn concentrations, number of goblet cells per 250 ,m length of jejunal villous epithelium (p = 0.001) and tended (p = 0.06) to enhance jejunum mucosa thickness. Interactive effects (p < 0.05) for higher jejunal villi height and villi:crypt ratio and increased ileal goblet cell counts were apparent for pigs from ZnAA-supplemented sows that also received nutriment-intubation of ZnMet. Challenge with LPS increased (p = 0.05) ileal villous width. Nutriment-intubation of ZnMet decreased (p = 0.05) anaerobic bacteria colony forming unit counts in the large intestinal mesenteric lymph nodes. In conclusion, nutriment-intubation of ZnMet increased serum and liver tissue concentrations of Zn and resulted in limited improvement to intestinal morphology of weaned pigs. [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] Cadmium and zinc accumulation in willow and poplar species grown on polluted soils,JOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 2 2007Maria N. Dos Santos Utmazian Abstract Woody plant species that produce high biomass have been proposed for use in phytoremediation technology. We investigated the accumulation of cadmium (Cd) and zinc (Zn) in Salix babylonica, S. caprea, S. dasyclados, S. matsudana × alba, S. purpurea, S. smithiana, Populus tremula, and P. nigra clones grown in a pot experiment on a Calcaric and a Eutric Cambisol (pH 7.2 and 6.4) of different levels of contamination (total metal concentrations in mg,kg,1 in soil A: 32.7 Cd, 1760 Zn; soil B: 4.34 Cd, 220 Zn). Generally, the tested clones tolerated large metal concentrations in soils and had larger Cd and Zn concentrations in leaves compared to the roots. The largest Cd concentrations in leaves were found in two clones of S. smithiana (440 mg,kg,1 on soil A; 70 mg,kg,1 on soil B). One of the S. smithiana clones had also the largest Zn concentrations (870 mg,kg,1) on soil B but accumulated slightly less Zn than a S. matsudana × alba clone (2430 mg,kg,1) on soil A. The Cd concentrations in leaves of both S. smithiana clones on soil A are the largest ever reported for soil-grown willows. The bioconcentration factors of the best performing clone reached 15.9 for Cd and 3.93 for Zn on the less contaminated soil B. Also based on the metal contents in leaves, this clone was identified as the most promising for phytoextraction. The metal concentrations in leaves observed in the pot experiment do not reflect those found in a previous hydroponic study and the leaf-to-root ratios are clearly underestimated in hydroponic conditions. This demonstrates the need for testing candidates for phytoextraction crops on soils rather than in hydroponics. Our data also show that the phytoextraction potential should be tested on different soils to avoid misleading conclusions. [source] Zinc alleviates growth inhibition and oxidative stress caused by cadmium in riceJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 2 2005Muhammad Jaffar Hassan Abstract A hydroponic experiment with two rice cultivars differing in cadmium (Cd) tolerance was conducted to investigate the alleviating effect of zinc (Zn) on growth inhibition and oxidative stress caused by Cd. Treatments consisted of all combinations of two Zn concentrations (0.2 and 1 ,M), three Cd concentrations (0, 1, and 5 ,M), and two rice cultivars (Bing 97252, Cd-tolerant; Xiushui 63, Cd-sensitive). Cd toxicity caused a dramatic reduction in plant height and biomass, chlorophyll concentration and photosynthetic rate, and an increase in Cd concentration in both roots and shoots, malondialdehyde (MDA) concentration, and superoxide dismutase (SOD) and peroxidase (POD) activities in shoots. The response of all these parameters was much larger for Xiushui 63 than for Bing 97252. Addition of Zn to the medium solution alleviated Cd toxicity, which was reflected in a significant increase in plant height, biomass, chlorophyll concentration, and photosynthetic rate, and a marked decrease in MDA concentration and activity of anti-oxidative enzymes. However, it was noted that Zn increased shoot Cd concentration at higher Cd supply, probably due to the enhancement of Cd translocation from roots to shoots. Therefore, further studies are necessary to determine the effect of Zn supply on Cd translocation from vegetative organs to grains or grain Cd accumulation before Zn fertilizer is applied to Cd-contaminated soils to alleviate Cd toxicity in rice. [source] Dietary Zinc Supplementation Throughout Pregnancy Protects Against Fetal Dysmorphology and Improves Postnatal Survival After Prenatal Ethanol Exposure in MiceALCOHOLISM, Issue 4 2009Brooke L. Summers Background:, We have previously demonstrated that ethanol teratogenicity is associated with metallothionein-induced fetal zinc (Zn) deficiency, and that maternal subcutaneous Zn treatment given with ethanol in early pregnancy prevents fetal abnormalities and spatial memory impairments in mice. Here we investigated whether dietary Zn supplementation throughout pregnancy can also prevent ethanol-related dysmorphology. Methods:, Pregnant mice were injected with saline or 25% ethanol (0.015 ml/g intraperitoneally at 0 and 4 hours) on gestational day (GD) 8 and fed either a control (35 mg Zn/kg) or a Zn-supplemented diet (200 mg Zn/kg) from GD 0 to 18. Fetuses from the saline, saline + Zn, ethanol and ethanol + Zn groups were assessed for external birth abnormalities on GD 18. In a separate cohort of mice, postnatal growth and survival of offspring from these treatment groups were examined from birth until postnatal day 60. Results:, Fetuses from dams treated with ethanol alone in early pregnancy had a significantly greater incidence of physical abnormalities (26%) compared to those from the saline (10%), saline + Zn (9%), or ethanol + Zn (12%) groups. The incidence of abnormalities in ethanol + Zn-supplemented fetuses was not different from saline-treated fetuses. While ethanol exposure did not affect the number of fetal resorptions or pre- or postnatal weight, there were more stillbirths with ethanol alone, and cumulative postnatal mortality was significantly higher in offspring exposed to ethanol alone (35% deaths) compared to all other treatment groups (13.5 to 20.5% deaths). Mice supplemented with Zn throughout pregnancy had higher plasma Zn concentrations than those in un-supplemented groups. Conclusions:, These findings demonstrate that dietary Zn supplementation throughout pregnancy ameliorates dysmorphology and postnatal mortality caused by ethanol exposure in early pregnancy. [source] Zinc Supplementation at the Time of Ethanol Exposure Ameliorates Teratogenicity in MiceALCOHOLISM, Issue 1 2003Luke C. Carey Background: We have previously demonstrated that ethanol teratogenicity in mice is related to the maternal expression of metallothionein (MT), a zinc (Zn)-binding protein. Ethanol induces maternal liver MT, which causes plasma Zn concentrations to decrease as Zn moves into the liver. During pregnancy it is suggested that this change decreases fetal Zn supply and contributes to abnormal development. Here we investigated whether maternal Zn supplementation at the time of ethanol exposure reduces teratogenicity. Methods: Mice were injected with 25% ethanol (0.015 ml/g intraperitoneally at 0 and 4 hr) and ZnSO4 (2.5 ,gZn/g subcutaneously at 0 hr) and were killed over 16 hr to ascertain changes in plasma Zn. Plasma Zn concentrations peaked at 2 hr, where levels were 5-fold normal and then returned toward normal over 14 hr. Pregnant mice were treated in a similar manner on gestation day 8 with saline, saline + Zn, ethanol + Zn, or ethanol alone, and fetal abnormalities were assessed on gestation day 18. Results: External abnormalities were most prevalent in offspring from dams treated with ethanol. Zn treatment at the time of ethanol exposure reduced the incidence of fetal abnormalities to basal levels. Litters from dams treated with ethanol + Zn contained more fetuses and fewer fetal resorption sites compared with those from ethanol-treated dams. Conclusions: These findings demonstrate that Zn supplementation at the time of ethanol exposure significantly negates the deleterious effects of ethanol on the fetus. [source] Reaction norms of life history traits in response to zinc in Thlaspi caerulescens from metalliferous and nonmetalliferous sitesNEW PHYTOLOGIST, Issue 1 2007Caroline Dechamps Summary ,,We examined phenotypic plasticity of fitness components in response to zinc (Zn) in the Zn hyperaccumulator, Thlaspi caerulescens. ,,Two populations from Zn-enriched soils (M) and two populations from normal soils (NM) were grown in pots at three Zn concentrations (0, 1000 and 8000 mg kg,1 Zn), for an entire life cycle. Growth, Zn accumulation and fitness components were assessed. ,,Based on vegetative growth, M and NM populations had similar Zn tolerance at 1000 mg kg,1 Zn. However, reproductive output was markedly decreased in NM at 1000 and 8000 mg kg,1 Zn. In M populations, Zn did not affect fitness. However, low Zn status enhanced reproductive output in year 1 compared with year 2 and decreased survival after the first flowering season. ,,M populations are able to achieve equal fitness across a broad range of Zn concentrations in soil by different combinations of fecundity and longevity. No cost of higher tolerance was demonstrated in M populations. Reproductive traits appeared to be a more sensitive indicator of tolerance than vegetative growth. [source] Within and between population genetic variation for zinc accumulation in Arabidopsis halleriNEW PHYTOLOGIST, Issue 1 2002Mark R. Macnair Summary ,,Hyperaccumulator plants in the field show significant variation in the metal concentration in their aerial parts, but little is known of the causes of this variation. This paper investigates the role of soil zinc (Zn) concentration and genetic variation in causing between and within population variation in Zn accumulation in Arabidopsis halleri. ,,Seed from 17 populations of A. halleri collected in central Europe were grown under standard conditions at three external Zn concentrations and tested for Zn concentration in the leaves. ,,Between population variation was highest at low external zinc concentrations. At 10 µm Zn some plants had very low leaf Zn concentrations, and were indistinguishable from nonaccumulators. However, at higher Zn concentrations, all plants showed hyperaccumulation. There were no differences in the accumulating abilities of populations from sites with different degrees of contamination. ,,Heritability of accumulation, determined for individual families from three populations, was quite high (25,50%), indicating that selection for increased accumulating ability should be possible, although selection would be easier at low external Zn concentrations. The Zn concentration of field collected plants was affected partly by plant genotype but not by the total soil Zn around their roots. [source] Distribution of Zn in functionally different leaf epidermal cells of the hyperaccumulator Thlaspi caerulescensPLANT CELL & ENVIRONMENT, Issue 7 2000B. Frey ABSTRACT The aim of this study was to show the potential of Thlaspi caerulescens in the cleaning-up of a moderately Zn -contaminated soil and to elucidate tolerance mechanisms at the cellular and subcellular level for the detoxification of the accumulated metal within the leaf. Measured Zn concentrations in shoots were high and reached a maximum value of 83 mmol kg,1 dry mass, whereas total concentrations of Zn in the roots were lower (up to 13 mmol kg,1). In order to visualize and quantify Zn at the subcellular level in roots and leaves, ultrathin cryosections were analysed using energy-dispersive X-ray micro-analysis. Elemental maps of ultrathin cryosections showed that T. caerulescens mainly accumulated Zn in the vacuoles of epidermal leaf cells and Zn was almost absent from the vacuoles of the cells from the stomatal complex, thereby protecting the guard and subsidiary cells from high Zn concentrations. Observed patterns of Zn distribution between the functionally different epidermal cells were the same in both the upper and lower epidermis, and were independent of the total Zn content of the plant. Zinc stored in vacuoles was evenly distributed and no Zn-containing crystals or deposits were observed. From the elemental maps there was no indication that P, S or Cl was associated with the high Zn concentrations in the vacuoles. In addition, Zn also accumulated in high concentrations in both the cell walls of epidermal cells and in the mesophyll cells, indicating that apoplastic compartmentation is another important mechanism involved in zinc tolerance in the leaves of T. caerulescens. [source] Phytoremediation: The uptake of metals and metalloids by rhodes grass grown on metal-contaminated soilREMEDIATION, Issue 2 2005Scott M. Keeling An experiment was performed to examine the phytoremediation potential of Rhodes grass (Chloris gayana Kunth cv. ,Pioneer'). The study sought to determine substrate tolerance, biomass production, and plant uptake of antimony (Sb), arsenic (As), cadmium (Cd), lead (Pb), silver (Ag), and zinc (Zn). The plants were grown on weight percent mixtures (5 percent, 15 percent, 25 percent, 35 percent, 50 percent) of a vertisol soil and base-metal mine tailings (7,2,040 ,g/g As, , 30 ,g/g Cd, 30,12,000 ,g/g Pb, and 72,4,120 ,g/g Zn). The 5 percent and 15 percent amendment of mine tailings increased the biomass production of Rhodes grass (from 0.1 g/plant to , 3.5 g/plant) without appreciably elevating plant concentrations of the elements. Plant growth decreased by greater than 50 percent for the substrate containing greater than 25 percent tailings (3,023 ,g/g Pb and 1,084 ,g/g Zn). Reduced biomass production coincided with maximal Zn uptake by Rhodes grass (249.8 ,g/g), indicating tailings induced phytotoxicity. The total concentrations of metals and metalloids tolerated by Rhodes grass in the plant-growth medium indicated hypertolerance to elevated As, Pb, and Zn concentrations. Partial extraction of the plant-growth medium determined that plant-available Pb was ten times higher than Ag, As, Cd, and Zn availability. However, Rhodes grass accumulated low levels of Pb, in addition to As and Cd, over the experimental range, indicating low fodder toxicity risk to browsing livestock. This study concludes that if there are no invasive species issues associated with conservation land uses, Rhodes grass is well suited to metalliferous mined land revegetation and would therefore be highly effective for such programs in subtropical and tropical Australia. © 2005 Wiley Periodicals, Inc. [source] | ||||||||||||||||||||||||||||