Concentrations Of Individual Metals Research Articles

Transfer Kinetics of Metals from Molten Fission Product Chloride to Liquid Lead Cathode during Electrolysis in Pyrometallurgical Treatment of Highly Radioactive Waste

It is sought to describe the interphase transfer kinetics governing the electrolytic reduction of chloride salt mixtures in the process performed for the purpose of recovering alkali, alkaline earth and rare earth metals from the salt mixture containing fission products generated during pyrometallurgical processing of highly radioactive waste from the Purex process of spent fuel. Data for analyzing the two-phase transfer kinetics of the metals of interest are acquired on simulated chloride mixtures submitted to experimental electrolysis in a system comprising anode immersed in molten salt mixture and cathode of liquid lead. Approximating the concentrations of individual metals remaining in the mixture as exponential functions of the duration of electrolysis, the apparent overall transfer coefficients of the metals in reductive reaction are estimated to range from 1.5 × 10−6 to 3.8 × 10−5 m/s. The metal ions prove to rank in descending order of transfer coefficient: Eu3+>Ba2+>Sr2+>Na+>Li+>K+>Cs+, thus indicating the likely effect of ionic valence influencing the interphanse transfer of metals.

Transfer Kinetics of Metals from Molten Fission Product Chloride to Liquid Lead Cathode during Electrolysis in Pyrometallurgical Treatment of Highly Radioactive Waste.

It is sought to describe the interphase transfer kinetics governing the electrolytic reduction of chloride salt mixtures in the process performed for the purpose of recovering alkali, alkaline earth and rare earth metals from the salt mixture containing fission products generated during pyrometallurgical processing of highly radioactive waste from the Purex process of spent fuel. Data for analyzing the two-phase transfer kinetics of the metals of interest are acquired on simulated chloride mixtures submitted to experimental electrolysis in a system comprising anode immersed in molten salt mixture and cathode of liquid lead. Approximating the concentrations of individual metals remaining in the mixture as exponential functions of the duration of electrolysis, the apparent overall transfer coefficients of the metals in reductive reaction are estimated to range from 1.5 × 10−6 to 3.8 × 10−5 m/s. The metal ions prove to rank in descending order of transfer coefficient: Eu3+>Ba2+>Sr2+>Na+>Li+>K+>Cs+, thus indi...

Accumulation of heavy metals by some wood-rotting fungi

Accumulation of aluminum, cadmium, lead and calcium was studied in the wood-roting fungiDaedalea quercina, Ganoderma applanatum, Stereum hirsutum andSchizophyllum commune. The heavy metal content was measured in mycelia cultured in liquid media in the presence of either individual Al, Cd, Pb and Ca salts or of their mixtures. After 8-d cultivations in media containing 1 mmol/L concentration of individual heavy metals, the lead content was maximal in the mycelium ofStereum hirsutum (90.6 mmol/g) while the mycelium ofGanoderna applanatum contained maximal values of cadmium (272 mmol/g), aluminum (600 mmol/g) and calcium (602 mmol/g). When the mycelia were grown on mixtures of all metal salts, lead was the preferentially accumulated ion except inG. applanatum which had a higher affinity for aluminum.

Chemical Fractionation and Plant Uptake of Heavy Metals in Soils Amended with Co‐Composted Sewage Sludge

AbstractA sequential extraction method (KNO3, H2O, NaOH, Na2‐EDTA, HNO3) was used to determine the soil fractions and plant availability of Cd, Cr, Cu, Ni, Pb, and Zn in three Atlantic coastal plain soils amended with four rates of Co‐composted sewage sludge (CCSS:0, 11, 22, and 44 Mg/ha), limed to four pH values (pH 5.3–7.2) used to grow wheat (Triticum aestivum L.) and soybean (Glycine max L.) under greenhouse conditions. The average (across soils) increases in total soil Cd, Cr, Cu, Ni, Pb, and Zn, at the highest rate of CCSS were 0.1, 2, 7, 5, 14, and 14 mg/kg, respectively. Distribution of all metals, except Cd, differed in CCSS‐amended soils, with greater percentages found in the NaOH and EDTA fractions and less in the HNO3 form than in unamended soils. The more labile fractions (KNO3, H2O) of Cu, Ni, Pb, and Zn, but not Cd and Cr, increased slightly (<1 mg/kg) when CCSS was added. Liming usually resulted in minor (<5%) changes in the distribution of Cd, Cr, Ni, and Pb among soil fractions. However, liming consistently decreased NaOH extractable Cu and (KNO3 + H2O) extractable Zn, and increased the percentage of these metals in the EDTA and HNO3 fractions. Amendment with CCSS reduced wheat dry matter production in all soils, probably from decreased N availability caused by the high C/N ratio (52:1) of the compost, and slightly increased soybean growth (6–12%). The CCSS had little effect on concentrations of Cd, Cr, or Pb in either crop, but consistently increased Cu, Ni, and Zn in vegetative tissues of wheat and soybean, and Ni and Zn in soybean grain. Liming decreased Mn and Zn in wheat and soybean, and Ni in soybean grain, but rarely affected plant Cd, Cr, Cu, or Pb. With the exception of Zn, consistent correlations between total soil metal content or individual metal fractions and plant metal concentrations or uptake were not observed. However, significant multiple regression models between soil metal fractions and pH and metal concentrations in wheat and soybean were obtained for Ni (R2 = 0.42***–0.86***), Cu (R2 = 0.37**–0.57***), and Zn (R2 = 0.62***–0.82***) with all three soils.

Short term and long term studies on individual and combined toxicities of copper, zinc and lead to Scenedesmus quadricauda

The toxicity of three metals (Cu, Zn, Pb) individually and in combination in a short term study (photosynthesis) and a long term study (growth) of a freshwater green alga, Scenedesmus quadricauda, was investigated. The relative metal toxicity to S. quadricauda was Cu > Zn ⪢ Pb, which corresponds with their respective electronegativities. This order was observed for both short term and long term studies. Specific individual and multiple heavy metal toxicities differed between short term and long term studies. Primary productivity was more sensitive to low concentrations of individual metals. Interactive effects between Cu, Zn and Pb were also assessed. In general, metal mixtures behaved antagonistically to photosynthesis. Both antagonism and synergism between Cu, Zn and Pb were observed to growth of S. quadricauda, although synergistic effects seemed to predominate.

On the metal content and metal ion uptake of botanically specific peats and the derived humic acids

With respect to ten metals (Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga) which are continguous in the Periodic Table the natural metal content and the ability to take up metal ions has been determined for three peats of defined botanical origin, each peat being sampled at three different levels. A correlation is found between the natural metal content and botanical origin. Apart from aluminium, the concentration of individual metals increased in the series Sphagnum < fen sedge < reed, the increase being statistically significant ( P = 0.001) for V, Mn, Co, Ni, and Ga and for the sum of the metal ions measured. No clear correlation emerged between botanical origin and metal uptake. The metal uptake by the humic acid derived from each peat sample was also determined, and correlated with the metal uptake of the source peat itself. In all the humic acid and peat metal-uptake experiments the selectivities were very similar. V, Cr, Cu, Ga were readily taken up while Mn, Co and Zn were consistently less preferred.

Zinc, copper and nickel concentrations in ryegrass grown on sewage sludge‐contaminated soils of different pH

AbstractSewage sludges containing high concentrations of zinc, copper and nickel were added separately to samples of two soils, a silty clay loam and a sandy loam, on which pH levels between 4.5 and 7.5 had been established; there were also treatments with sludge of low metal content or no‐sludge. Soil‐sludge mixtures were either continuously cropped with ryegrass or kept uncropped in pots in the glasshouse for 6 months. Zinc and nickel concentrations in 0.1 μM calcium chloride extracts of soils from the cropped pots and in solutions displaced from the fallow pots decreased with increasing pH over the range tested, but copper concentrations remained steady above pH 5.5; individual metal concentrations in ryegrass tops followed the same pattern with pH as those in extracted solutions. Squared correlation coefficients (R7) between shoot metal concentrations and concentrations of metals in EDTA, DPTA or calcium chloride extracts or displaced solutions, when taken over all soil, pH and sludge treatments, were &gt;0.60 (P&lt;0.001). Ryegrass yield reductions occurred on soils contaminated with each of the three metal sludges when soil pH was 5.5 or below.

Heavy metals in a contaminated Australian estuary—Dispersion and accumulation trend

Very high concentrations of Zn, Pb, Cu and Cd occur in the muddy bottom sediments of Lake Macquarie, a saline coastal lagoon in southeastern Australia. The trace metals emanate from industrial sources, especially a lead-zinc smelter, at the northern end of the lake. Individual metal concentrations decrease progressively away from the source area but at differing rates; Zn is most mobile and Cd appears to be deposited first. They approach natural background levels in the southern part of the lake. Mn shows a reverse trend but Ni, Co, Ag and Fe rarely rise above background levels.Shallow cores in the lake bed penetrated a metal enriched surface zone 15–35 cm thick underlain by uncontaminated sediments with natural (background) metal concentrations. Sedimentation rates determined from radiocarbon ages on shells in the cores mainly range between 0·15 and 0·5 mm yr−1. Over the 85 years since industrialization commenced, less than 5 cm of mud has accumulated on the lake bed. Bioturbation is invoked to account for the depth to which the sediment has been enriched in heavy metals.

Dilute-acid trace-metal fraction in northeastern Gulf of Mexico sediments

Variations in dilute-acid (partial digest) metal concentrations in bottom sediments from 49 stations on the Mississippi, Alabama and Florida continental margin are investigated with the aid of ordination and other multivariate statistical techniques. Total iron, carbonate content, clay fraction and water depth correlate well with the overall leachable sediment metal values for pooled station replicates over four sampling periods. Individual metal concentrations also are correlated with these and other environmental parameters using stepwise multiple linear regression techniques. A weak positive association between Ba, Cu, Cr, Ni, Pb, and V burdens in the demersal fishSyacium papillosum and the dilute-acid leachable sediment metal TOC and carbonate concentrations is demonstrated.

Absorption of drugs and other xenobiotics during development in experimental animals

Metal exposure alters neurodevelopmental outcomes; little is known about critical windows of susceptibility when exposure exerts the strongest effect.To examine associations between dentine biomarkers of manganese (Mn), zinc (Zn) and lead (Pb) and later childhood behaviors.Subjects enrolled in a longitudinal birth cohort study in Mexico City provided naturally shed deciduous teeth. We estimated weekly prenatal and postnatal dentine Mn, Zn and Pb concentrations in teeth using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) and measured behavior at ages 8–11 years of age using the Behavior Assessment System for Children, 2nd edition (BASC-2). We used distributed lag models and lagged weighted quantile sum regression to identify the role of individual and combined dentine biomarkers of Mn, Zn and Pb on behavioral outcomes controlling for maternal education and gestational age.Among the 133 subjects included in this study, prenatal and early postnatal dentine Mn appeared protective against childhood behavioral problems, specifically hyperactivity and attention. Postnatal dentine Mn was associated with increased reporting of internalizing problems, specifically anxiety. At 6 months, a 1-unit increase (unit = 1 SD of log concentration) in Mn was associated with a 0.18-unit (unit = 1 SD of BASC-2 score) increase in internalizing symptoms score and a 0.25-unit increase in anxiety. Postnatal Pb was associated with increasing anxiety symptoms; at 12 months, a 1-unit increase in Pb was associated with a 0.4 unit increase in anxiety symptoms. When examined as a metal mixture, we observed two potential windows of susceptibility to increased anxiety symptoms: the first window (0–8 months) appeared driven by Mn, the second window (8–12 months) was driven by the metal mixture and dominated by Pb. A 1-unit increase in the mixture index was associated with a 0.7-unit increase in SD of anxiety symptoms.Childhood behaviors may demonstrate postnatal windows of susceptibility to individual and mixed metal concentrations measured in deciduous teeth. Prenatal dentine Mn may be protective, while excessive early postnatal Mn may increase risk for adverse behaviors. In combination, higher concentrations of Mn, Zn and Pb may have an adverse impact on behavior.

Cadmium, copper, lead, zinc and manganese in the polychaete Arenicola marina from sediments around the coast of wales

Cadmium, copper, lead, zinc and manganese concentrations in the marine polychaete Arenicola marina and sediments it inhabits were investigated at 24 sites around the coast of Wales. Except for copper in A. marina, the highest concentrations of all metals were recorded in the upper region of the Bristol Channel. Metal concentrations in A. marina were related to body weight for lead, zinc and manganese, but inter-site differences still remained after adjustment to a common weight by covariance analysis. Significant negative correlations were obtained between mean body weight and the mean concentration of individual metals in A. marina. A partial correlation analysis, holding mean weight constant, revealed a positive correlation between the concentration in A. marina and the sediment for both zinc and cadmium.

Sublethal effects of heavy metal contaminated sediments on the bivalve Macoma balthica (L.)

Sublethal effects of estuarine sediments containing high levels of heavy metals were studied using the marine bivalve, Macoma balthica. Burrowing behaviour was inhibited in all contaminated sediments compared to the control. The time required for 50% of the population to burrow (ET50) ranged from 0.17 h in the control to 4.8 h in the most contaminated substrate. A comparison of linear regressions of the concentrations of individual metals in the sediments vs the burrowing response times showed the regressions for mercury and cadmium to be significant ( P < 0.05 and < 0.001 respectively). An active threshold avoidance response by burrowed M. balthica was also demonstrated as clams showed a significant ( P < 0.05) avoidance of the sediment containing the highest metal levels. Both behavioural responses were considered useful sublethal tests to assess the impact of polluted sediments.

Evidence for multiple hydrogen-ion donor systems in rain

An integrated analytical system consisting of combined scanning electron microscopy and x-ray analysis, atomic absorption, colorimetry and coulometry was used to study rain water chemistry. The coulometry facilitated the determination in molarities of strong and non-volatile and volatile weak acids. The pH of individual rains in St. Paul - Minneapolis, Minnesota ranged from 4.0 to 5.65 during the summer of 1974. Samples of a given rain from different sites had different qualitative and quantitative bases for the measured pH. Increase in strong acid concentrations with a decrease in pH was not an exclusive phenomenon. Molarities of weak acids (volatile and/or non-volatile) also increased with an increase in the acidity. Studies conducted on Twin Cities rain samples indicated that the total salt content expressed from the electrical conductivity could not be accounted for by the total concentrations of individual metals quantified (Fe, Pb, Zn, Mn, Cu, Cr, Cd, Ca, Mg, Na, and K). In addition, no correlation could be shown between the contents of SO4-2, NO3-1, Cl2-1, & PO4-1 and the observed changes in pH.

The Role of Factor and Regression Analysis in the Interpretation of Geochemical Reconnaissance Data

The interpretation of exploration oriented geochemical data frequently requires the recognition of subtle features related to mineralization, from the more obvious geochemical expressions of bedrock and surface environments. A number of previous investigations have indicated the potential of various computerized interpretational procedures as aids in identifying these features in geochemical data. The present investigation was concerned with the interpretation of multi-element data from a 750 mile2 {1942.5 km2) area of the Notre Dame Bay district of Newfoundland. The area is underlain by a series of Ordovician and Silurian sediments and volcanics and intrusives overlain by glacial deposits mostly composed of glacial till. Massive sulfide mineralization including the Whalesback and Gullbridge deposits occur within the Ordovician volcanics. R mode factor analysis was employed to establish the character and distribution of the principle metal associations related to bedrock and surface environment contributing to the overall data distribution. The factor scores were regressed against the individual metal concentrations of the elements composing the respective factors, the resulting residuals of the metals reflecting the component of metal related to some sources other than those reflected by the metal associations established by factor analysis. Anomalous areas of residual copper and zinc distributions indicate the areas of known sulfide mineralization more closely than the untreated metal distributions. On this basis, anomalous areas of residual copper and zinc, unrelated to known sulfide mineralization warrant further exploration investigation. It is therefore concluded that a combination of factor and regression analysis on multi-element data from the Notre Dame Bay district of Newfoundland serves to highlight subtle though significant features in multi-element data possibly related to mineralization that were not apparent from a consideration of the untreated data.