scholarly journals Modeling the formation of high metal concentration zones in man-made deposits

2018 ◽  
Vol 12 (2) ◽  
pp. 76-84 ◽  
Author(s):  
Z Malanchuk ◽  
◽  
V Korniienko ◽  
Ye Malanchuk ◽  
V Soroka ◽  
...  
Keyword(s):  
Metal Concentration ◽  
High Metal Concentration ◽  
High Metal

Anisotropic Magnetoresistance and Weak Localization in Granular System Ni-MgO

2015 ◽  
Vol 233-234 ◽  
pp. 501-504 ◽  
Author(s):  
Anton Grebennikov ◽  
Oleg Stognei
Keyword(s):  
Percolation Threshold ◽  
Metal Concentration ◽  
Weak Localization ◽  
Negative Magnetoresistance ◽  
Anisotropic Magnetoresistance ◽  
Granular System ◽  
High Metal Concentration ◽  
High Metal ◽  
Magnetoresistive Effect ◽  
Granular Composites

Magnetoresistive effect and electrotransport properties of Niх(MgO)100-х (x: 21-48 at.%) granular composites have been investigated. It is found that prepercolated composites (x < 24 at.%) do not exhibit magnetoresistive properties. After percolation threshold (x: 27-29 at.%) the composites exhibit isotropic negative magnetoresistance (-0,2 %) which has not tunneling nature. Also weak localization is realized in these samples at temperatures below 100 K. At high metal concentration (32 at.% < x) the composites exhibit anisotropic magnetoresistance.

Properties of nitric acid palladium solutions with a high metal concentration

2007 ◽  
Vol 80 (5) ◽  
pp. 695-704 ◽  
Author(s):  
A. B. Venediktov ◽  
S. V. Korenev ◽  
S. P. Khranenko ◽  
S. V. Tkachev ◽  
P. E. Plyusnin ◽  
...  
Keyword(s):  
Nitric Acid ◽  
Metal Concentration ◽  
High Metal Concentration ◽  
High Metal

scholarly journals Heavy Metal Concentration in Neotropical Aquatic Snakes (Helicops Pastazae) and Its Potential as a Bioindicator of Water Pollution

2021 ◽  
Author(s):  
María Jose Hurtado-Morales ◽  
Manuel Rodríguez ◽  
Adolfo Amezquita
Keyword(s):  
Water Pollution ◽  
Heavy Metal ◽  
Metal Concentration ◽  
Heavy Metal Concentration ◽  
Atomic Absorption Spectrophotometry ◽  
Trophic Chain ◽  
Sampling Point ◽  
High Metal ◽  
Metal Excretion

Abstract The purpose of the present study was to test the potential role of the aquatic snake Helicops pastazae as indicators of water pollution caused by heavy metals. In particular, we tested whether the total heavy metal concentration is related to (1) the position (upstream vs downstream) of the sampling point and its distance from the point where wastewater is discharged; (2) the taxonomic group studied and its place in the trophic chain: piscivorous snakes vs characid fish that co-occur with them; and (3) the organ or tissue examined: snake liver versus muscle. We quantified cadmium (Cd), chromium (Cr) and lead (Pb) by using atomic absorption spectrophotometry with electrothermal atomization. Significant differences were found between some of the sampling points, particularly high metal concentrations were detected upstream at point 1, but no clear spatial pattern was found. There were no significant differences in the concentration of any of the metals between fish and snake muscle, suggesting potential mechanisms of metal excretion in snakes. With regard to interactions, the snake liver had the highest concentrations of cadmium and the muscle of lead and chromium, which may indicate tissue affinity differences for certain metals. Altogether, our results indicate that H. pastazae accumulates contaminants differentially, depending on the tissue and location, which render them useful bioindicators of water contamination.

scholarly journals Nitrogen fixation and growth response of Alnus rubra amended with low and high metal content biosolids

2006 ◽  
Vol 63 (4) ◽  
pp. 351-360 ◽  
Author(s):  
Linda S. Gaulke ◽  
Charles L. Henry ◽  
Sally L. Brown
Keyword(s):  
Metal Concentration ◽  
Land Application ◽  
Total Carbon ◽  
Shoot Biomass ◽  
Alnus Rubra ◽  
N Fixation ◽  
Metal Concentrations ◽  
Compost Amendment ◽  
High Metal ◽  
Soil Metal

Forest application of biosolids offers a potential environmentally friendly alternative to landfilling. This two-year investigation was designed to analyze the effects of elevated soil metal concentration resulting from the land application of biosolids on the symbiotic, nitrogen (N) fixing relationship between Alnus rubra Bong. (red alder) and Frankia. High metal biosolids and a modern-day composted biosolid applied at high loading rates of 250, 500, and 1000 Mg ha-1, were used to represent a worst-case scenario for metal contamination. The high metal biosolids were obtained before the current regulations were formulated and had been lagooned prior to use in this study. Total cadmium (Cd), lead (Pb) and zinc (Zn) in the high metal biosolids were 45, 958, and 2623 mg kg-1 respectively. These metal concentrations are above current regulatory limits in the US. The compost was made using biosolids that are currently produced and had Cd, Pb and Zn of 0.8, 20 and 160 mg kg-1 respectively. Trees were harvested and analyzed for rate of N fixation (as measured by acetylene reduction activity), biomass, and foliar metals. Soils were analyzed for available N, total carbon and N, pH and total Cd, Pb and Zn. Rates of N fixation were not affected by soil amendment. In year 2, shoot biomass of trees grown in both the compost and high metal amendments were higher than the control. Shoot biomass increased with increasing amount of compost amendments, but decreased with increasing amount of high metal amendments. There was no relationship between soil metal concentration and plant biomass. Foliar Cd and Pb were below detection for all trees and foliar Zn increased with increasing amount of both compost and high metal amendment, with concentrations of 249 mg kg-1 for trees grown in the compost amendment and 279 mg kg-1 for the high metal amendment. The results from this study indicate that the growth of A. rubra benefited from both types of biosolids used in the study and that the Alnus/Frankia relationship was not negatively impacted by metal concentrations resulting from the high metal biosolids amendments.

scholarly journals Heavy metal concentration in Neotropical Aquatic Snakes (Helicops pastazae) and its potential as a bioindicator of water pollution

2021 ◽  
Author(s):  
María Jose Hurtado-Morales ◽  
Manuel Rodríguez ◽  
Adolfo Amezquita
Keyword(s):  
Water Pollution ◽  
Heavy Metal ◽  
Metal Concentration ◽  
Heavy Metal Concentration ◽  
Atomic Absorption Spectrophotometry ◽  
Trophic Chain ◽  
Sampling Point ◽  
High Metal ◽  
Metal Excretion

Abstract The present study aimed at testing the potential role of the aquatic snake Helicops pastazae as indicators of water pollution by heavy metals. In particular, we tested whether the total heavy metal concentration is related to (1) the distance and position (upstream vs downstream) of the sampling point with the discharge of wastewater; (2) the taxonomic group studied and its place in the trophic chain: piscivorous snakes vs characid fish that co-occur with them; and (3) the organ or tissue examined: snake liver versus muscle. We quantified cadmium (Cd), chromium (Cr) and lead (Pb) by using atomic absorption spectrophotometry with electrothermal atomization. Significant differences were found between some of the sampling points, particularly high metal concentrations were detected upstream on point 1, but no clear spatial pattern was found. There were no significant differences in the concentration of any metal between fish and snake muscle, suggesting potential mechanisms of metal excretion in snakes. With regard to interactions, the snake liver had the highest concentrations of cadmium and the muscle of lead and chromium, which may indicate tissue affinity differences for certain metals. Altogether, our results indicate that H. pastazae differentially accumulates contaminants, depending on the tissue and location, which render them useful bioindicators of water contamination.

PREDICTIVE SIMULATION AND OPTIMIZATION ORIENTED MODELING FOR THE EXTRACTION OF METAL IONS FROM SOLUTIONS INTO A NOVEL BIS-SCHIFF BASE

2019 ◽  
pp. 1-8
Author(s):  
F. S. Nworie ◽  
S. O. Ngele ◽  
J. C. Onah
Keyword(s):  
Metal Ions ◽  
Metal Concentration ◽  
Acid Concentration ◽  
Aqueous Media ◽  
Industrial Effluents ◽  
Ligand Concentration ◽  
Simulation And Optimization ◽  
Chemometric Technique ◽  
Model Equations ◽  
Level Of Significance

Metal ions present in waste samples, industrial effluents, acid mines and other aqueous media constitute a serious challenge in different human activities. Solvent extraction a technique for preconcentration, separation and identification of trace amount of metal ions coupled with multivariate chemometric technique was used for the determination of Fe(II) and Cr(III) from solutions in the presence of bis(salicylidene)ethylenediamine (SALEN). The influence of main extraction variables affecting the extraction efficiency was simultaneously studied and regression model equations illustrating the relationship between variables predicted. The extraction parameters (time of extraction, acid concentration, ligand concentration, temperature and metal concentration) were optimized using experimental designs with the contributions of the various parameters to extraction of the metal ions bound to the complexone evaluated using SPSS19.0 software. The statistically determined simulated models for the parameters were R2 = 0.946, 0.727, 0.793, 0.53, 0.53, 1.000 and F- values of 70.400, 13. 285, 15.348, 4.646 and 2.569×105 respectively for time of extraction, acid concentration, ligand concentration, temperature and metal concentration for Cr (III). For Fe (II), R2 = 0.243, 0.371, 0.519, 0.446, 1.000 and F-values of 0.964, 2.953, 4.310, 3.216 and 2.516×105 for time of extraction, acid concentration, ligand concentration, temperature and metal concentration respectively. The level of significance of the models as predicted was both lower than 5% making it feasible, efficient, reproducible and accurate. This means that metal ions at the conditions stated could be removed from waste samples, industrial effluents, acid mines and other aqueous media with extension in industrial scale application.

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