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1.
This paper discusses the modeling of anion and cation leaching from complex matrixes such as weathered steel slag. The novelty of the method is its simultaneous application of the theoretical models for solubility, competitive sorption, and surface precipitation phenomena to a complex system. Selective chemical extractions, pH dependent leaching experiments, and geochemical modeling were used to investigate the thermodynamic equilibrium of 12 ions (As, Ca, Cr, Ba, SO4, Mg, Cd, Cu, Mo, Pb, V, and Zn) with aqueous complexes, soluble solids, and sorptive surfaces in the presence of 12 background analytes (Al, Cl, Co, Fe, K, Mn, Na, Ni, Hg, NO3, CO3, and Ba). Modeling results show that surface complexation and surface precipitation reactions limit the aqueous concentrations of Cd, Zn, and Pb in an environment where Ca, Mg, Si, and CO3 dissolve from soluble solids and compete for sorption sites. The leaching of SO4, Cr, As, Si, Ca, and Mg appears to be controlled by corresponding soluble solids.  相似文献   

2.
The concentrations of 12 metals (Cd, Pb, Ni, Cr, Cu, Co, Fe, Mn, Zn, Ca, Mg and K) in 13 classes of alcoholic beverages were determined by atomic spectrometry after HNO3/H2O2 digestion. The mean concentrations of metals (µg mL?1) in these alcoholic beverages varied in the ranges 0.01–0.04, 0.02–0.24, 0.04–0.13, 0.01–0.28, 0.01–0.77, <0.001–0.12, 0.28–1.48, 0.004–0.33, 0.10–1.02, 1.43–162.86, 0.26–25.46 and 0.49–322.58 for Cd, Pb, Ni, Cr, Cu, Co, Fe, Mn, Zn, Ca, Mg and K respectively. The concentrations of metals found in these particular alcoholic beverages were below the International Statutory Limits for metals in alcoholic beverages. The estimated daily intake of the metals based on a per capita consumption of 3.6 L per annum pure alcohol was <3% of the tolerable daily intake of each metal. The individual and combined target hazard quotients of the metals were <1, indicating no long‐term health concerns from the consumption of these alcoholic beverages based on their metal content alone. Copyright © 2014 The Institute of Brewing & Distilling  相似文献   

3.
The aim of this study was to determine the levels of metals (Ca, K, Na, Mg) and trace metals (Ni, Fe, Cu, Mn, Zn, Pb, Cd) in two fish species (gilthead bream [Sparus aurata] and sea bass [Dicentrarchus labrax]) collected from fish farms located along the coast of Tenerife Island. Ca, K, Na, Mg, Fe, Cu, Zn, and Mn were measured by flame atomic absorption spectrometry, whereas Pb, Cd, and Ni were determined using graphite furnace atomic absorption spectrometry. Mean Fe, Cu, Mn, and Zn contents were 3.09, 0.59, 0.18, and 8.11 mg/kg (wet weight) in S. aurata and 3.20, 0.76, 0.24, and 10.11 mg/kg (wet weight) in D. labrax, respectively. In D. labrax, Ca, K, Na, and Mg levels were 1,955, 2,787, 699.7, and 279.2 mg/kg (wet weight), respectively; in S. aurata, they were 934.7, 3,515, 532.8, and 262.8 mg/kg (wet weight), respectively. The Pb level in S. aurata was 7.28 ± 3.64 μg/kg (wet weight) and, in D. labrax, 4.42 ± 1.56 μg/kg (wet weight). Mean Cd concentrations were 3.33 ± 3.93 and 1.36 ± 1.53 μg/kg (wet weight) for D. labrax and S. aurata, respectively. All Pb and Cd levels measured were well below the accepted European Commission limits, 300 and 50 μg/kg for lead and cadmium, respectively.  相似文献   

4.
Surface chemistry and dissolution kinetics of divalent metal carbonates   总被引:2,自引:0,他引:2  
A surface complexation model (SCM) for divalent metal carbonates (Ca, Mg, Sr, Ba, Mn, Fe, Co, Ni, Zn, Cd, and Pb) is developed based on new electrophoretic measurements and correlation between aqueous and surface reactions stability constants. This SCM postulates the formation of the following surface species: >CO3H0, >CO3-, >CO3Me+, >MeOH0, >MeO-, >MeOH2+, >MeHCO30, and MeCO3- within the framework of a constant capacitance of the electric double layer. It can be used to describe the surface-controlled dissolution kinetics of divalent metal carbonates and allows determination of the order of dissolution reactions with respect to rate-controlling protonated carbonate surface groups in acid solutions (>CO3H0) and hydrated metal groups (>MeOH2+) in neutral to alkaline solutions. The reaction order with respect to protonated carbonate groups increases from 2 for MnCO3 and ZnCO3 to 4 for NiCO3, whereas for hydrated surface metals, it augments from 2 for ZnCO3 to approximately 4 for MnCO3 and NiCO3. The dissolution rates at 5 < or = pH < or = 8 increase in the order Ni < Mg < Co < Fe < Mn < Zn < Cd < Sr < or = Ca approximately = Ba approximately = Pb and correlate nicely with water exchange rates from the aqueous solution into the hydration sphere of the corresponding dissolved cations. Such a correlation allows the generation for all carbonates of a model describing their dissolution/precipitation kinetics, including the effect of various ligands, provided that rate constants and their activation volumes for water exchange around Me(II)-ligand dissolved complexes are available.  相似文献   

5.
Three sour cherry and three table grape cultivars were analyzed using inductively coupled plasma optical emission spectrometry. The elements: Na, K, Ca, Mg, Fe, Cu, Zn, Mn, Cr, Cd, Co, Pb, and Ni were detected in all samples; four elements are very abundant (K, Na, Ca, and Mg), and four are not abundant (Cu, Fe, Mn, and Zn). Five of them are trace elements (Cr, Cd, Co, Pb, and Ni) at <0.1 mg/kg. Among the 13 elements analyzed, potassium was the most abundant element distributed throughout all categories of fruits. Iron was the predominant minor element constituents. Manganese concentration was the highest in table grape cultivars. The accuracy of the results was evaluated by spike recovery tests. Analysis of variance was used to establish the metals with significant difference in mean content between the cultivars from sour cherries and between table grapes. Principal component analysis was used to evaluate the distribution of metals.  相似文献   

6.
Results are presented for the determination of levels of Ca, Cd, Ni, Cr, Cu, Pb, Mn, Zn Fe, Co and Mg in candies and chocolates consumed in southern Nigeria. Mean concentrations of metals in both confectionaries ranged 7.7–1405.2?µg/g1 for Ca, <0.001–0.2?µg/g for Cd, 1.4–7.9?µg/g for Ni, 0.4–3.0?µg/g for Cr, <0.08–2.3?µg/g for Pb, 0.4–12.6?µg/g for Mn, 0.6–8.0?µg/g for Zn, 1.7–12.3?µg/g for Fe, <0.05–1.49?µg/g for Co, and 8.4–576.1µg/g for Mg. The data showed that that these metals are not present at harmful levels. Concentrations of nickel and chromium were slightly elevated but were comparable to levels reported in similar food items elsewhere in the world.  相似文献   

7.
A physiologically based extraction test, simulating sequential digestion in the stomach and intestine, has been applied to dust samples collected from various domestic and working settings to define bioaccessible concentrations of metals (Al, Ca, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sn, U, Zn) in the indoor environment. With the exception of Ca, Cd, and Zn in the stomach phase, mean bioaccessibilities (relative to respective total metal concentrations) were less than 50%. For a given metal, bioaccessibility in either phase was variable among samples but, in many cases, displayed an inverse dependence on total concentration. This suggests that, to a good approximation, variations in both metal contamination and accessibility in the indoor environment arise from variable proportions of metal-rich particulates of low digestibility. Compared with accessibility in the stomach, accessibility in the more alkaline, carbonate-rich intestine was either lower (Al, Ca, Cd, Mn, Ni, Sn, Pb, Zn), similar (Co, Cu, Fe) or greater (Cr, U). We attribute these observations to precipitation and/or readsorption in the intestine, stabilization by complexation, or anion-like adsorption of negatively charged, polyatomic species, respectively.  相似文献   

8.
Summary Ca, Cd, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Pb and Zn were determined using Atomic-Absorption Spectrophotometry (AAS) in 59 Finnish (n =10) and foreign (n = 49) wines sold in Finland. Cd and Pb were determined in a graphite furnace and the other metals with an air-acetylene flame. All wines contained only low levels of heavy metals; in all cases the concentration of Pb was under 0.3 mg/1, that of Cu was under 1.0 mg/1, that of Zn was under 5.0 mg/1 and that of Cd was under 0.1 mg/l, which are the maximum levels permitted in some countries. Finnish wines contained less Pb and Mg and more Cr and Na than the foreign wines analysed.
Die Analyse von Weinen auf Metalle mittels Atomabsorptionsspektrophotometrie
Zusammenfassung Ca, Cd, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Pb und Zn wurden unter Anwendung der Atomabsorptionsspektrophotometrie (AAS) in 59 finnischen (n =10) und ausländischen (n = 49) in Finnland zum Verkauf gelangenden Weinen analysiert. Die Bestimmung von Cd und Pb wurde im Graphitofen, die der übrigen in einer Luft-Acetylenflamme vorgenommen. Alle untersuchten Weine enthielten nur geringe Mengen von Schwermetallen; in allen Fällen blieb die Pb-Konzentration unter 0,3 mg/l, die Cu-Konzentrationunter 1,0 mg/1, die Zn-Konzentration unter 5,0 mg/1 und die Cd-Konzentration unter 0,1 mg/1. Die angegebenen Konzentrationen stellen die in einigen Ländern zugelassenen Höchstwerte dar. Die finnischen Weine enthielten weniger Pb und Mg, aber mehr Cr und Na als die zur Untersuchung gelangten ausländischen Weine.


Paper presented at the 27th IUPAC Congress, 27–31 August, 1979, Helsinki  相似文献   

9.
Short-term uptake of cadmium by a wild-type (2137) and a cell wall-less strain (CW-2) of Chlamydomonas reinhardtii was examined as a function of Cd speciation in a well-defined, aqueous medium. Internalization fluxes were determined for free cadmium concentrations ranging from 5 x 10(-10) M to 5 x 10(-4) M in the presence of ligands forming both labile and inert hydrophilic complexes. A first-order biological internalization, as predicted by the free ion activity model (FIAM), was observed for both strains. The maximum Cd internalization flux, Jmax, for the wild-type strain was 5-fold higher (1.3 x 10(-11) mol cm(-2) min(-1)) than for the CW-2 strain (2.3 x 10(-12) mol cm(-2) min(-1)) and was not influenced by the presence of competitors such as Ca in the experimental solution. The conditional stability constant for the adsorption of Cd to transport sites of the CW-2 strain was 5-fold higher (10(6.7) M(-1)) than for the wild-type strain (10(6) M(-1)). Competition experiments demonstrated that Mo, Mn, Cu, Co, Zn, Ni, Ca, and Pb inhibited, at least partially, Cd uptake, while no inhibition was observed for similar concentrations of Mg and Fe. The stability constant for the competitive binding of Ca to the Cd transport site was determined to be 10(4.5) M(-1). Cu and Zn competed with Cd uptake sites with stability constants of 10(5.6) and 10(5.2) M(-1), respectively. Protons also appeared to compete with Cd uptake sites as uptake could generally be predicted quantitatively in their presence. Finally, in the presence of low concentrations (<20 mg L(-1)) of Suwannee River fulvic acid, Cd internalization fluxes could be predicted from [Cd2+], in accordance with the FIAM.  相似文献   

10.
BACKGROUND: It is important to determine the concentrations of essential and non‐essential metals in fish for human health. The essential elements and contaminants (Pb and Cd) were determined seasonally in the muscle and liver of some pelagic fish species round herring (Etrumeus teres), chub mackerel (Scomber japonicus), golden grey mullet (Liza aurata) and Mediterranean horse mackerel (Trachurus mediterraneus) from the Iskenderun Bay, Eastern Mediterranean Sea. RESULTS: The Na, K, Ca and Mg were the most abundant elements in muscle and liver tissues. The Na, K, Ca and Mg concentrations in fish tissues were between 51.7 and 3426 mg kg?1. Muscle accumulated the lowest levels of elements. Trace element and contaminant levels in muscle were highest in spring and summer. The Cu, Zn and Cr concentrations were highest in summer. The Ni, Mn and Fe concentrations were highest in spring. The maximum Pb concentrations in the muscle and liver of fish species was 0.39 and 0.80 mg kg?1 in autumn. The maximum Cd concentration in the muscle of fish was 0.27 mg kg?1 in spring and the maximum Cd concentration in the liver was 0.78 mg kg?1 in summer. CONCLUSION: The Cr, Pb, Cd, Cu and Zn levels in muscle were found to be lower than permissible limits reported by various authorities. Estimated weekly and daily intake for Pb and Cd by consumption of fish muscle were far below the PTWI and PTDI values established by FAO/WHO. Copyright © 2009 Society of Chemical Industry  相似文献   

11.
Removal of heavy metals from mine waters by natural zeolites   总被引:1,自引:0,他引:1  
In this study, we investigated the removal of Fe, Pb, Cd, and Zn from synthetic mine waters by a natural zeolite. The emphasis was given to the zeolite's behavior toward a few cations in competition with each other. Pb was removed efficiently from neutral as well as from acidic solutions, whereas the uptake of Zn and Cd decreased with low pH and high iron concentrations. With increasing Ca concentrations in solution, elimination of Zn and Cd became poorer while removal of Pb remained virtually unchanged. The zeolite was stable in acidic solutions. Disintegration was only observed below pH 2.0. Forward- and back-titration of synthetic acidic mine water were carried out in the presence and absence of zeolite to simulate the effects of a pH increase by addition of neutralizing agents and a re-acidification which can be caused by subsequent mixing with acidic water. The pH increase during neutralization causes precipitation of hydrous ferric oxides and decreased dissolved metal concentrations. Zeolite addition further diminished Pb concentrations but did not have an effect on Zn and Cd concentrations in solution. During re-acidification of the solution, remobilization of Pb was weaker in the presence than in the absence of zeolite. No substantial differences were observed for Fe, Cd, and Zn immobilization. The immobilization of the metals during pH increase and the subsequent remobilization caused by re-acidification can be well described by a geochemical equilibrium speciation model that accounts for metal complexation at hydrous ferric oxides, for ion exchange on the zeolite surfaces, as well as for dissolution and precipitation processes.  相似文献   

12.
《Food chemistry》2005,92(2):305-309
Avocado honey samples were analyzed by inductively coupled plasma optical emission spectrometric. First, the botanical origin of the honeys was confirmed by melissopalynological analysis. Twenty-four minerals were quantified for each honey sample. The elements Al, Ba, Ca, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Ni, P, Pb, S, Se, Si and Zn were detected in all samples; seven elements were very abundant (Ca, K, Mg, Na, P, S and Si), six were not abundant (Al, Cu, Fe, Li and Zn) and 11 were trace elements (As, Ba, Cd, Co, Cr, Mo, Ni, Mo, Pb, Se, Sr and V).  相似文献   

13.
BACKGROUND: Human exposure to heavy metals is attributed to consumption of vegetables raised in polluted soil environment. We examined the concentrations of As, Cd, Co, Cr, Cu, Ni, Pb and Zn in soils and lettuce (Latuca sativa) and amaranthus (Amaranthus caudatus) in 15 garden fields under long‐term wastewater irrigation. RESULTS: The concentrations of As (0.3–2.1 mg kg?1), Cd (0.07–0.3 mg kg?1), Co (4.6–9.1 mg kg?1) and Cr (21.6–36.2 mg kg?1) in the gardens were consistent with background concentrations in soils, but Ni (12.6–25.7 mg kg?1), Cu (12.5–24.6 mg kg?1), Pb (25.7–71.6 mg kg?1) and Zn (52.3–158 mg kg?1) concentrations were double the concentrations normally encountered in arable fields in the region. The concentrations of Cd and As in the vegetables were within safe limits, but Co (0.14–0.67 mg kg?1 fresh weight (fw)) and Ni (1.0–2.7 mg kg?1 fw) concentrations in lettuce were relatively high for leaf vegetables. The concentration of Pb (0.65–4.80 mg kg?1 fw) was above safe limit of 0.3 mg kg?1 fw, while the concentrations of Cu (1.3–2.7 mg kg?1 fw and Zn (10.2–23.6 mg kg?1 fw) were close to the unsafe limits for leaf vegetables. There were no strong linear correlations between soil metal concentrations and bio‐concentrations in the vegetable crops. CONCLUSION: We surmise that leaf vegetables can accumulate metals in their tissues to unsafe levels even when total metal concentrations in these soils are below the allowable concentrations in agricultural soils. Copyright © 2008 Society of Chemical Industry  相似文献   

14.
In the United Arab Emirates (UAE), overall diabetes prevalence in adult population is around 20%. Along with, or instead of oral hypoglycemic drugs and insulin, some patients use bitter gourd (Momrodica charantia) because of its hypoglycemic properties. The aim of this study was to assess the essential (Ca, Mg, V, Cr, Mn, Co, Cu, Zn, and Mo) and toxic (As, Cd, Hg, and Pb) trace elements of bitter gourd using inductively coupled plasma-mass spectrometry (ICP-MS). Mean concentrations of each essential element were compared with literature data. Toxic As and Cd could not be detected, while Hg and Pb concentrations in our samples were much lower compared to values reported previously from contaminated areas. Results obtained in our study after ICP-MS/MW analysis, indicate that bitter gourd can be a good source of essential elements.  相似文献   

15.
Modeling metal binding to soils: the role of natural organic matter   总被引:4,自引:0,他引:4  
The use of mechanistically based models to simulate the solution concentrations of heavy metals in soils is complicated by the presence of different sorbents that may bind metals. In this study, the binding of Zn, Pb, Cu, and Cd by 14 different Swedish soil samples was investigated. For 10 of the soils, it was found that the Stockholm Humic Model (SHM) was able to describe the acid-base characteristics, when using the concentrations of "active" humic substances and Al as fitting parameters. Two additional soils could be modeled when ion exchange to clay was also considered, using a component additivity approach. For dissolved Zn, Cd, Ca, and Mg reasonable model fits were produced when the metal-humic complexation parameters were identical for the 12 soils modeled. However, poor fits were obtained for Pb and Cu in Aquept B horizons. In two of the soil suspensions, the Lund A and Romfartuna Bhs, the calculated speciation agreed well with results obtained by using cation-exchange membranes. The results suggest that organic matter is an important sorbent for metals in many surface horizons of soils in temperate and boreal climates, and the necessity of properly accounting for the competition from Al in simulations of dissolved metal concentrations is stressed.  相似文献   

16.
The concentrations of 23 chemical elements (Al, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Na, Ni, Pb, Sb, Se, Sr, Th, Tl, U, Zn) were determined in 51 honey samples of different botanical origin produced in Siena County (Italy). K, Ca, Na and Mg were the most abundant elements, with mean contents of 1195, 257, 96.6 and 56.7 mg/kg, respectively. The Fe, Zn and Sr contents generally ranged from 1 to 5 mg/kg. Except for Ba, Cu, Mn and Ni, the trace element contents were below 100 μg/kg. The analytical data indicated a good level of quality of the honeys, especially with regard to the concentrations of toxic trace elements, such as As, Cd, Pb and Sb, and suggested a significant influence of the botanical origin on the element composition. Some local geological and geochemical features also seemed to affect the chemistry of the honey.  相似文献   

17.
Ninety-two black and green table olive samples from the Bursa, Turkey were analyzed. The olives were sampled from 56 brands, four processing methods and three packing types. The concentration of Mg, Cr, Co, Ni, Fe, Cu, Zn, Sn, Cd and Pb were measured by inductively coupled plasma mass spectrometry (ICP-MS). While the most concentrated element was Mg (125.11 ± 5.02), Co (0.09 ± 0.01) had the lowest concentration in tested olive samples. The levels of the ten metals studied are within safe limits. The data here obtained will be valuable in complementing available food composition data, and estimating dietary intakes of heavy metals in Turkey. The metals Mg, Fe, Zn, Sn and Pb presented significant differences (p < 0.05) in content between two types, hence processing method, brand and packing material must influence their content.  相似文献   

18.
Recent spectroscopic studies have demonstrated the formation of layered double hydroxides (LDH) and phyllosilicates upon sorption of Zn2+, Ni2+, and Co2+ to clay minerals and aluminum oxides at neutral to alkaline pH and at relatively high initial metal concentrations (>1 mM). The intention of the present study was to investigate whether such phases also form in soil under slightly acidic conditions and at lower metal concentrations. Columns packed with a loamy soil were percolated with aqueous solutions containing 0.1 or 0.2 mM Zn, Ni, Co, and Cd in a 10 mM CaCl2 background at pH 6.5. Metal breakthrough curves indicated a rapid initial sorption step, resulting in retarded breakthrough fronts, followed by further slow metal retention during the entire loading period of 42 days (7000 pore volumes). Total metal sorption and the contribution of slow sorption processes decreased in the order Zn > Ni > Co > Cd. Leaching the reacted soil with 10 mM CaCl2 at pH 6.5 remobilized 8% of the total retained Zn, 15% of Ni, 21% of Co, and 77% of Cd. Subsequent leaching with acidified influent (pH 3.0) remobilized most of the remaining metals. X-ray absorption fine-structure (XAFS) spectroscopy revealed that slow Zn sorption was due to the formation of a Zn-Al LDH precipitate. Although Ni, Co, and Cd concentrations were too low for XAFS analysis, their leaching patterns suggest that part of Ni and Co were also incorporated in solid phases, while most sorbed Cd was still present as exchangeable sorption complex after 42 days. A small but significant percentage of the sorbed metals (2-5%) remained in the soil, even after leaching with more than 3000 pore volumes at pH 3.0, which may suggest micropore diffusion or incorporation into more stable mineral phases.  相似文献   

19.
The concentrations of metals (Cd, Pb, Ni, Cr, Cu, Co, Fe, Mn and Zn) were examined in some popular brands of wine in the Nigerian market after HNO3/H2O2 digestion by atomic absorption spectrophotometry. The mean concentrations (mg/L) of metals in these categories of wines ranged from 0.01 to 0.02, 0.27 to 0.35, 0.10 to 0.12, 0.02 to 0.02, 0.15 to 0.21, 0.09 to 0.10, 3.47 to 4.55, 0.79 to 0.86 and 0.78 to 1.10 for Cd, Pb, Ni, Cr, Cu, Co, Fe, Mn and Zn, respectively. The estimated dietary intakes of metals based on the ingestion of 250?mL/day of these brands of wine were below the specified provisional tolerable daily intake (PTDI) value for each metal. However, only Pb intake from the consumption of these wines constituted 31–41% of its PTDI value as a single source. The estimated target hazard quotients (THQ) for the metals (except for Pb and Cr) are of concern in that they were above the safe level of THQ?相似文献   

20.
Two varieties of peanut (Arachis hypogeaea), which grow in two different areas of Greece, were analysed for essential and toxic elements by atomic absorption spectroscopy (AAS).Differences in concentrations, probably depending on the growing area, were observed for seven elements (Ca, Mg, Cu, Fe, Zn, Co and Pb).Higher concentrations of Ca, Mg, Co and Pb were found in the oil-free material of the Serron variety (continental area), while the Kalamon variety (coastal area) showed higher concentrations of Cu, Fe and Zn.The contents of these elements in the peanut oil are significantly different in the two varieties.Significant variations also appear in the concentrations of the water-and fat-soluble salts of the elements studied. Discussion of the results is based on statistical treatment of the data.  相似文献   

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