Μg Of Hg Research Articles

Mercury Uptake and Translocation in Impatiens walleriana Plants Grown in the Contaminated Soil from Oak Ridge

Mercury (Hg) contaminated soils from Oak Ridge, Tennessee were investigated for phytoavailability of mercury as measured by degree of Hg translocation in aboveground biomass of Impatiens walleriana plants grown in the soils. After 90 days of incubation, results revealed a higher concentration of total Hg in the leaves than in the flowers or the stems. Plants that were grown in the soils with higher Hg concentrations showed significantly higher Hg uptake and translocation in the aboveground plant-biomass, and the correlation with the initial soil-Hg was significant for the leaves and the stems in the plants that were tested. On an average, only 4.06 μg of Hg could be found in the above ground plant biomass of all the plants, compared to an average 3673.50 μg of initial total Hg concentrations in these soils. Statistical analysis revealed a greater affinity of Hg for the soil carbon, which supported the finding of this study on low soil Hg bioavailability.

Effect of age upon retention of mercury in chickens with a different growth rate

Retention of total mercury was examined in groups of 95 slowly-growing laying type chickens and 52 fast-growing broiler hybrids in 47 subsequent balance periods from 1 to 100 days of age. Chickens were fed <I>ad libitum</I> on a diet containing 5.41 µg of Hg per kilogram. Until Day 4 the values of coefficients of apparent retention of Hg were negative or very low. They were influenced by excretion of endogenous nutrients originating primarily from the yolk sac. When evaluating the period of 4 to 100 days of age, the dependence of Hg retention coefficients upon age was highly significant (<I>P</I> < 0.01). The course of this dependence was expressed by parabolas for laying type chickens with the maximum value at Day 61 of age and for broilers with the minimum value at Day 53. In fast growing chickens, Hg content in body gain decreased until Day 14 and then increased while in slow growing chickens it was linearly increasing for the whole experimental period. The average coefficients of Hg retention from the feed mixture were 48.18 ± 0.719 (mean ± SEM) and 47.90 ± 1.057% and Hg retained per g of live body gain were 7.494 ± 0.4682 and 6.775 ± 0.6233 ng in laying and meat type cockerels, respectively. The difference between hybrids was insignificant (<I>P</I> > 0.05). The growth rate of total amount of Hg in the body was lower (<I>P</I> < 0.01) than that of body weight of chickens, allometric coefficients were 0.706 and 0.747 for slow and fast growing chickens, respectively.

Toxic heavy metal biosorption by some marine bacteria isolated from the sediments of industrial effluents of Iligan Bay

Heavy metal-resistant marine bacteria were isolated from the sediments of Iligan Bay near the effluents outlets of certain factories. Isolation was done using marine agar fortified with corresponding different heavy metal concentrations. Isolates were grouped using their morphological and colonial growth characteristics. Among the purified isolates(61), 19 were cadmium-resistant, 29 were lead-resistant and 13 were mercury-resistant. These isolates were tested for their absorptive capability using marine broth added with metal ions: 23.20 µg of Cd, 250.24 µg of Pb and 495.66 µg of Hg, and consequently analyzed using Atomic Absorption Spectrophotometric(AAS) method. From these isolates, 10 heavy metal-resistant species with relatively high absorptive efficiency were identified using conventional method and API 20E Test Kit. Out of ten isolates, 3 were Gram-positive and 7 were Gram-negative rods. All Gram-positive bacteria belong to the genus Bacillus and were found to absorb lead metals at 94% absorptive efficiency. However, Enterobacter sp. 2 had the highest absorptive efficiency for Cd at 99% among Gram negative bacteria followed by Chryseomonas sp. 2 with 96% biosorption. Furthermore, among the mercury resistant isolates, Pseudomonas sp. had the highest absorptive efficiency at 79%. Only those heavy metal-resistant isolates which exhibited the highest absorptive efficiency were able to form a zone of growth promotion around a heavy metal-containing filter paper disk which suggests that these bacteria have accumulated heavy metals in their cells. The presence of heavy metal-resistant bacteria is helpful in cleaning up or remediating metal contaminated environments released from industrial effluents.

Selective Determination of Trace Mercury (II) after Preconcentration with 4-(2-Pyridylazo)-Resorcinol-Modified Nanometer-Sized SiO2 Particles from Sample Solutions

A rapid, selective method that utilize 4-(2-Pyridylazo)-resorcinol (PAR)-modified nanometer SiO2 (nanometer SiO2–PAR) as a new solid-phase extractant for preconcentration of trace mercury (II) has been developed. The adsorption property of nanometer SiO2–PAR for metal ions was studied by selectively extracting different metal ions from aqueous solutions. The results revealed an excellent affinity of the nanometer SiO2–PAR for mercury (II) in presence of interfering metal ions at pH 4. The main parameters of solid-phase extraction such as shaking time, elution and sample dilution effect were studied. The extractant shows rapid kinetic sorption, and the adsorption equilibrium of mercury (II) on nanometer SiO2–PAR was achieved in less than 2 min. The adsorbed mercury (II) was easily eluted by 4 mL of 6 mol L−1 HCl. The maximum preconcentration factor was 50. The maximum static adsorption capacity was 276 µmol g−1 at pH 4. The detection limit (3σ) was 0.43 µg L−1 for cold vapor atomic absorption spectrometry (CVAAS), and the relative standard deviation of the eight replicate determinations was 2.4% for the determination of 2.0 µg of Hg(II) in 100 mL water sample. The method was applied to the determination of trace mercury (II) in sample solutions with satisfactory results.

Highly selective determination of inorganic mercury(II) after preconcentration with Hg(II)-imprinted diazoaminobenzene–vinylpyridine copolymers

Hg(II) imprinted and non-imprinted copolymers were prepared by metal ion imprinted polymer (MIIP) technique. The copolymers were obtained by copolymerizing mercury chloride (or without it), diazoaminobenzene (DAAB) and vinylpyridine (VP) using ethyleneglycoldimethacrylate (EGDMA) as cross-linker in the presence of 2,2′-azobisisobutryonitrile as initiator. The separation and preconcentration characteristics of the copolymers for Hg(II) were investigated by batch and column procedures. The results demonstrated that the Hg(II) imprinted copolymers had higher adsorption capacity with the value of 205 μmol g −1 of dry copolymer, about 3.5 times of and good selectivity for Hg(II) compare to non-imprinted copolymers (58.6 μmol g −1 of dry copolymer). The distribution ratio ( D) values of the Hg(II) imprinted copolymers increased for Hg(II) with respect to both D values of Zn(II), Cu(II), Cd(II), CH 3HgCl, CH 3CH 2HgCl and non-imprinted copolymer. The relatively selective factor ( α r) values of Hg(II)/Cu(II), Hg(II)/Zn(II), Hg(II)/Cd(II), Hg(II)/CH 3HgCl and Hg(II)/CH 3CH 2HgCl are 45.5, 63.5, 55.1, 49.6 and 84.0, respectively. The tolerance limit for other electrolytes such as NaCl, KBr, KI, NaNO 3, Na 3PO 4, Na 2SO 4 and Mg(NO 3) 2 is also greatly improved with the values of 10–100-fold of the non-imprinted copolymer. The Hg(II) imprinted copolymers can be used at least 20 times with recoveries no less than 95%. Based on the packed columns with Hg(II) imprinted copolymers, a highly selective solid-phase extraction (SPE) and preconcentration method for Hg(II) from dilute aqueous solution was developed. The MIIP-SPE preconcentration procedure showed a linear calibration curve within concentration range from 0.13 to 25 μg l −1. The detection limit and quantification limit were 0.05 and 0.13 μg l −1 (3 σ) for cold vapor atomic absorption spectrometry (CVAAS). The relative standard deviation of the eleven replicate determinations was 2.4% for the determination of 1.0 μg of Hg(II) in 100 ml water sample. Determination of Hg(II) in certified river sediment sample (GBW 08603) demonstrated that the column was good enough for Hg(II) determination in matrixes containing components with similar chemical property such as Cu(II), Zn(II), Cd(II), CH 3HgCl and CH 3CH 2HgCl.

A validated cold vapour-AAS method for determining mercury in human red blood cells

A cold vapour-atomic absorption spectrometry (CV-AAS) method for determining mercury in dental students and clinical teaching staff red blood cells at a dental school using amalgam as a restorative material has been validated. A number of blood samples ( n = 122) from dental students in years I to V, clinical teachers in restorative dentistry and controls were collected and analysed. Accuracy, linearity, precision (repeatability and reproducibility) and robustness of the method have been determined, and detection and quantification limits have been calculated. Linearity of response was verified for concentrations ranging from 5 to 40 μg L −1 of mercury. Correlation coefficient of the calibration straight lines was always ≥0.99. Intra-day precision of the method gave coefficient of variation (CV) of 5.51%. Inter-day precision of the method calculated after analysis of five different concentrations of mercury standard solutions by the same analyst in different days and by two different analysts in different days gave coefficient of variation 4.89 and 5.44%, respectively. The accuracy of the method was calculated a CRM NIST 966 (toxic metals in bovine blood) total amount of mercury was found a concentration of 28.83 ± 2.2 μg L −1. Recovery was 89.27%. Robustness of the method evaluated by changing different experimental conditions under which analyses performed, fractional factorial design was done for assessing robustness of the method. Root mean square error was found out as 1.56. Limits of detection and quantification were 1.84 and 4.03 μg of Hg per litre of sample, respectively. Results show the suitability of the method for direct measurement of mercury in red blood cells and the importance of the working conditions for people dealing with amalgam at a dental school.

Total mercury in the night shark, Carcharhinus signatus in the western equatorial Atlantic Ocean

Mercury is the only element capable to biomagnificate along the food chain, and carnivorous fish tend to accumulate high concentrations of this element. Total mercury in muscle tissue of Carcharhinus signatus sampled along the western equatorial Atlantic Ocean was measured by atomic emission spectrophotometry with ICP/AES. The average total mercury concentrations were consistently greater than the maximum limit for human consumption established by the Brazilian Health Ministry for carnivorous fishes (1000 µg. kg-1 w.w.). Therefore, an average consumption of 0.1 kg/day of C. signatus would result in an average daily ingestion of 174.2 µg of Hg, more than five times the 30 µg/day intake established by the World Health Organization. In the range of lengths studied, body length could not be used as an indicator of the Hg contamination degree for C. signatus. Also, sex cannot be considered a determining factor in the total mercury accumulation in C. signatus.

A rapid spectrophotometric method for the determination of mercury in environmental, biological, soil and plant samples using diphenylthiocarbazone

A simple, sensitive and highly selective direct spectrophotometric method for the determination of trace levels of mercury(II) in various samples is described. Diphenylthiocarbazone (dithizone) reacts in slightly acidic 50% aqueous 1,4‐dioxane media (0.18–1.80 M sulphuric acid) with mercury(II) to give an orange chelate which has an absorption maximum at 488 nm. The average molar absorption co‐efficient and Sandell′s sensitivity were found to be 2.5×104l mol−1 cm−1 and 0.015 μg of Hg(II) cm−2, respectively. The reaction is immediate and absorbance remains stable for over 24 h. Beer′s law is obeyed for concentration range of mercury(II) between 0.1 μg ml−1 and 25 μg ml−1; the stoichiometric composition of the chelate is 1 :2 (mercury : dithizone). The various analytical parameters, such as effect of time, acidity, reagent concentration and foreign species, were studied. The method was applied successfully to a number of environmental waters (portable and polluted), biological samples (human blood, urine and fish), soils, plant samples (potato, cabbage, lettuce, carrot and tomato), solutions containing both mercury(I) and mercury(II) and complex synthetic mixtures. The method is very simple and requires no solvent extraction or pre‐concentration steps.

Nuclear moments and isotope and isomer shifts of neutron-deficient mercury isotopes 195, 195 m, 194, 193, 193 m and 192

Nuclear spins I, magnetic-dipole μ and electro-quadropole Q moments, and optical spectroscopic isotope and isomer shifts (I.S.) have been obtained for the neutron-deficient mercury isotopes and isomers with mass numbers from 192 to 195. The isotopes were produced by p, yn reactions on Au 197. Approximately 0.01μg of Hg was transferred into the rf-excited electrodeless light sources. A well-blazed plane diffraction grating, 25 cm wide, was used in the multiple wavelength monochromator of 11 m focal length for these high-resolution optical hfs measurements. These lead to the results I = 1 2 for Hg 195, I = 13 2 for Hg 195m and Hg 193m; μ = −1.05, 0.53, −1.04 nm for Hg 193m, Hg 195, Hg 195m; Q = 1.37, 1.41 b for Hg 193m, Hg 195m; with respect to Hg 198, I.S. = 0.441±0.020, 0.368 ±0.006, 0.284±0.007, 0.214±0.008, 0.220±0.005 cm−1 for Hg 192, Hg 193m, Hg 194, Hg 195 and Hg 195m. For Hg 193 the tentative results are I = 1 2 , μ = 0.56 nm, and I.S. = 0.350±0.027 cm −1; the last result was obtained by Walter and Stroke in a magnetic-scanning experiment. The isotope- and isomer-shift results, which have led to a hypothesis of the cause of odd-even staggering in isotope shift, are discussed qualitatively in the light of the polarizability of nuclei by nucleons (coupling of core-excited states with odd particle).