Analysis of lead levels in deciduous teeth from children in Clark County, Nevada.

Background: Elevated blood lead levels (EBLL) are declining in the United States, although some population subgroups continue to exhibit significant health disparities. A childhood lead poisoning prevention program was recently started in Nevada, and many efforts have been made to support this program and increase the screening rates. Methods: To expand the potential pool of children screened for EBLLs, a pilot study was performed to evaluate lead concentrations in extracted deciduous teeth using Graphic Furnace Atomic Absorption Spectrometry (GFAAS), Inductively Coupled Plasma Mass Spectrometry (ICP-MS), and X-Ray Fluorescence (XRF) analysis. Results: Lead concentrations as determined by GFAAS and ICP-MS were found to be within normal ranges (0.585 ppm ± 0.022) and were similar to previous studies. Hispanic patients exhibited higher lead levels (0.580 ppm ± 0.032) than Black (0.478 ppm ± 0.051) patients, and were significantly higher than White (0.275 ppm ± 0.035) patients (p \u3c 0.05). Analysis of a small number of matched saliva samples, however, found no evidence for acute lead poisoning. Although limited by a small initial sample size (n=22), this pilot study provides evidence that teeth can be effectively used to reveal lead exposure in pediatric dentistry patients

Rapid Magnetic Dispersive solid phase extraction to preconcentration/determination of Cd and Pb in aqueous samples

A new magnetic dispersive solid phase extraction (MDSPE) method and graphite furnace atomic absorption spectrometry (GFAAS) have been combined for the analysis of Cd and Pb in environmental samples. For the preconcentration, a shell structured Fe3O4@graphene oxide nanospheres was synthetized and characterized. The material was suspended in the ionic liquid 1-n-butyl-3-metilimidazolium tetrafluoroborate [BMIM][BF4], the obtained stable colloidal suspension is named ferrofluid. GO presents excellent adsorbent properties for organic species due to the presence of the electronic π system. For this reason, the organic ligand [1,5-bis-(2-dipyridyl) methylene] thiocarbonohydrazide (DPTH) was used in order to form organic complexes of Cd and Pb. Once the DPTH ligand has been added to sample, the ferrofluid was injected and finely dispersed in the sample solution in order to extract the formed chelates. The complete adsorption of the chelates took place within few seconds then, the solid was separated from the solution with the aid of a strong magnet. Cd and Pb ions were desorbed from the material with 1 mL of acid nitric 5% solution and quantified by GFAAS. All experimental and instrumental variables were optimized. The analytical performances of the optimized method were: EF (Enrichment factor): 200 with LODs (detection limit): 0.005 and 0.004 µg L-1 and LOQs (determination limit): 0.017 and 0.013 µg L-1, for Cd and Pb, respectively. The reliability of the developed procedure was tested by relative standard deviation (% RSD), which was found to be < 5%. The accuracy of the proposed method was verified using certified reference materials (SLRS-5, SPS-SW2, and BCR-723) and by determining the analyte content in spiked aqueous samples. Sea waters and tap water samples collected from Málaga (Spain) were also analysed. The determined values were in good agreement with the certified values and the recoveries for the spiked samples were around 100% in all cases.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Cadmium in newborns

Cadmium (Cd) is a well-known nephrotoxic environmental contaminant but there are indications that the developing nervous system might be even more sensitive to Cd than the kidneys in adults. Infants are exposed to Cd from various formulas and infant diets and the gastrointestinal Cd uptake is believed to be higher in newborns than in adults. Cd levels monitored in infant foods ranged between 0.74 and 27.0 µg/kg. Cow's milk formulas had the lowest levels and cereal-based formulas had up to 21 times higher mean levels. The mean weekly Cd exposure from the recommended formula intake was calculated to vary between 0.10 and 3.05 µg/kg body weight. Rat pups received an oral dose of 109Cd in water or four different formulas. The whole-body Cd retention was higher in the pups than previously reported in adult animals and highest in the water and in the cow's milk formula groups. The small intestinal Cd retention was high, even 9 days after exposure indicating a long absorption period in the newborns. Cd levels in kidney increased still 12 days after exposure in all diet groups. Piglets received low daily doses of Cd in water or wheat/oat/milk-based follow-up formula. The formula reduced Cd uptake in comparison to water, but the distribution of Cd to the kidneys was unexpectedly higher when Cd was given in formula than in water. Simulated infant digestion of infant foods resulted in lower solubility of Cd compared to adult digestion. In a human Caco-2 cell model, cellular Cd uptake and transport from five different infant food digests was approximately one order of magnitude lower than the solubility and varied between 4-6 % and 1-2 % of the dose, respectively. Binding of Cd to dietary fibres and phytic acid reduces intestinal Cd retention and probably explains the lower Cd bioavailability from cereal-based formulas compared to water or cow's milk formula. The exposure of Cd is higher from infant formulas than from breast milk and age-specific digestion conditions as well as composition of diets affect both the Cd solubility and bioavailability. The calculated Cd intake from recommended amount of infant formulas is below the established provisional tolerable weekly intake, which however, does not include a safety factor and is based on renal effects in adults

Heavy metals and nitrogen in mosses: spatial patterns in 2010/2011 and long-term temporal trends in Europe

Naturally-occurring mosses have been sampled across Europe to monitor the deposition of heavy metals and nitrogen from the air. This survey has been repeated at five-yearly intervals since 1990 for heavy metals and since 2005 for nitrogen. In 2010/2011, mosses were collected at ca. 4,500 sites in 25 countries for heavy metals and ca. 2,400 sites in 15 countries for nitrogen. In general, the lowest concentrations in mosses were found in northern Europe for both heavy metals and nitrogen. The highest concentrations of heavy metals were often observed in south-eastern Europe, whereas the highest concentrations of nitrogen were found in parts of western and central Europe. Europe-wide the concentration of lead (77% decline), vanadium (57%), iron (52%) and cadmium (51%) has declined the most since 1990, whereas the concentration of copper has declined the least (11% decline). Since 1995, the concentration of arsenic and mercury has declined by 26% and 23% respectively. The nitrogen concentration in mosses has hardly changed since 2005

Environmental implications of phytoextraction for mercury and gold : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Earth Science

The overall objective of this study was to investigate how plants could be used to harvest gold (phytomining) and at the same time remove mercury (phytoremediation) from auriferous mercury-contaminated soils. This study was undertaken to find appropriate plants that could be used to harvest gold, residual in mine tailings or in uneconomic low-grade ore, and at the same time remove residual mercury, commonly used to extract the gold in artisanal mining areas. Different procedures involving analytical methodology, leaching of acid mine tailings and the growing of plants in both gold and mercury-bearing substrates were undertaken. The analytical methods involved in the analysis of gold in the laboratory using the modern instruments were Flame Atomic Absorption Spectrometry (FAAS) and Graphite Furnace Atomic Absorption Spectrometry (GFAAS). The determination of mercury involved using Flameless Atomic Absorption Spectrometry. To understand the induced solubility of metals in phytoextraction, Tui mine tailings were leached with several chemicals known to solubilise gold: ammonium thiocyanate, ammonium thiosulphate and urea. The pH of the tailings material was varied through amendment with lime to examine the effect of this geochemical parameter on metal solubility and thus the potential for both plant uptake and leaching. The Tui mine tailings were chosen because of their geochemistry; these are highly weathered sulphide-ore tailings that leach heavy metals into adjacent water systems. The induced-phytoextraction potential of root crops was also examined in this thesis. Five root crops were grown in an artificial substrate consisting of 3.8 mg/kg (ppm) of elemental gold dispersed in sand. The possibility of using these root crops for phytomining was determined by separately adding chelating agents ammonium thiocyanate and ammonium thiosulphate to the substrate. In most cases there was a higher gold concentration in the roots than in the shoots. The highest mean gold concentrations were found in carrot roots and in roots of two radish cultivars. It was concluded that there was some potential for the use of carrot to grow an economic crop of gold from mine tailings. Results obtained from experiments where plants were grown in Tui tailings indicated that both chicory and Brassica juncea could be used for the phytoextraction of gold and mercury in the same crop. Under acidic conditions thiocyanate induced the uptake of gold by Brassica juncea and the uptake of mercury by chicory; and thiosulphate induced the uptake of mercury by chicory, but it did not induce the uptake of gold by the same plant. Under alkaline conditions, treatment with ammonium thiosulphate induced the uptake of gold and mercury by Brassica juncea; and treatment with thiosulphate induced the uptake of mercury by chicory but it did not induce the uptake of gold. It was therefore concluded that, Brassica juncea could be used for phytoextraction of gold and mercury when ammonium thiosulphate is applied to the substrate. Results from the root-crop experiment indicate that, carrots could supersede most of the plants used due to the greater apparent metal-uptake potential. Finally, a model is proposed for field trials to examine the potential of phytoextraction for gold and mercury in Tanzania. The aim of this model is to examine how the positive results obtained from research conducted in the laboratory and greenhouse can be put into practice. The use of similar plants as well as traditional tropical species (e.g. wild cassava - a known accumulator of cyanide) is suggested along with suitable chemical amendments

Survey of sediment quality in Sabine Lake, Texas and vicinity

The toxicity of sediments in Sabine Lake, Texas, and adjoining Intracoastal Waterway canals was determined as part of bioeffects assessment studies managed by NOAA’s National Status and Trends Program. The objectives of the survey were to determine: (1) the incidence and degree of toxicity of sediments throughout the study area; (2) the spatial patterns (or gradients) in chemical contamination and toxicity, if any, throughout the study area; (3) the spatial extent of chemical contamination and toxicity; and (4) the statistical relationships between measures of toxicity and concentrations of chemicals in the sediments. Surficial sediment samples were collected during August, 1995 from 66 randomly-chosen locations. Laboratory toxicity tests were performed as indicators of potential ecotoxicological effects in sediments. A battery of tests was performed to generate information from different phases (components) of the sediments. Tests were selected to represent a range in toxicological endpoints from acute to chronic sublethal responses. Toxicological tests were conducted to measure: reduced survival of adult amphipods exposed to solid-phase sediments; impaired fertilization success and abnormal morphological development in gametes and embryos, respectively, of sea urchins exposed to pore waters; reduced metabolic activity of a marine bioluminescent bacteria exposed to organic solvent extracts; and induction of a cytochrome P-450 reporter gene system in exposures to solvent extracts of the sediments. Chemical analyses were performed on portions of each sample to quantify the concentrations of trace metals, polynuclear aromatic hydrocarbons, and chlorinated organic compounds. Correlation analyses were conducted to determine the relationships between measures of toxicity and concentrations of potentially toxic substances in the samples. Based upon the compilation of results from chemical analyses and toxicity tests, the quality of sediments in Sabine Lake and vicinity did not appear to be severely degraded. Chemical concentrations rarely exceeded effects-based numerical guidelines, suggesting that toxicant-induced effects would not be expected in most areas. None of the samples was highly toxic in acute amphipod survival tests and a minority (23%) of samples were highly toxic in sublethal urchin fertilization tests. Although toxic responses occurred frequently (94% of samples) in urchin embryo development tests performed with 100% pore waters, toxicity diminished markedly in tests done with diluted pore waters. Microbial bioluminescent activity was not reduced to a great degree (no EC50 <0.06 mg/ml) and cytochrome P-450 activity was not highly induced (6 samples exceeded 37.1 ug/g benzo[a]pyrene equivalents) in tests done with organic solvent extracts. Urchin embryological development was highly correlated with concentrations of ammonia and many trace metals. Cytochrome P450 induction was highly correlated with concentrations of a number of classes of organic compounds (including the polynuclear aromatic hydrocarbons and chlorinated compounds). (PDF contains 51 pages

Szilárdmintás spektrokémiai módszerek tanulmányozása optikai kristályok elemzésére = Study on solid sampling spectrochemical methods for the analysis of optical crystals

Szilárdmintás és oldatos grafitkemencés atomabszorpciós spektrometriai (GFAAS) módszereket tanulmányoztunk és dolgoztunk ki lítium-niobát és bizmut-tellurit optikai kristályok adalékelemeinek (Cr, Fe, Mn, Er, Nd, Tm, Zr, Pr és Yb) meghatározására. A szilárdmintás GFAAS módszereket az oldatos GFAAS módszer alapján optimáltuk, amely alkalmasnak bizonyult a szilárdmintás módszer kalibrációjára (hárompont-becsléses standard addíció). A grafitkemence hevítési ciklus (analízis) során nehezen elpárolgó minta-összetevők által keltett memóriahatás megszüntetésére egy leegyszerűsített halogénezéses módszert javasoltunk. A röntgen-abszorpciós él-közeli struktúra (X-ray absorption near-edge structure – XANES) technikával meghatároztuk a grafitkemencében a memóriahatás miatt visszamaradó mintaösszetevők kémiai formáit. A kidolgozott GFAAS módszerek egyszerűen adaptálhatók a grafitkemencés elektrotermikus párologtatós (GF-ETV) csatolt analitikai technikákhoz. A szilárdmintás módszerek validálásához oldatos GFAAS, lángatomabszorpciós spektrometriás (FAAS), induktív csatolású plazma atom emissziós spektrometriás (ICP-AES) és induktív csatolású plazma tömegspektrometriás (ICP-MS) módszereket dolgoztunk ki és alkalmaztunk. | Solid sampling and solution based graphite furnace atomic absorption spectrometry (GFAAS) methods were studied and elaborated to the determination of specific dopant elements (Cr, Fe, Mn, Er, Nd, Tm, Zr, Pr and Yb) in lithium niobate and bismuth tellurite optical crystals. The solid sampling GFAAS methods were optimized on the base of the solution based GFAAS methods, which was also proven to be applicable to the calibration of the solid sampling based method (three-point estimation standard addition). To overcome the memory-effects arising from the slow vaporization of refractory sample components during the heating of the graphite furnace (analytical cycle), a simplified halogenation method was suggested. The chemical forms of the refractory matrix components retained in the graphite furnace due to the memory-effect were determined by X-ray absorption near-edge structure (XANES). The elaborated GFAAS methods can be easily adapted to the graphite furnace electrothemal vaporization (GF-ETV) coupled analytical techniques. For the validation of the solid sampling methods, solution-based GFAAS, flame atomic absorption spectrometry (FAAS), inductively coupled plasma atomic emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS) methods were elaborated and applied

Reliability of graphite furnace atomic absorption spectrometry as alternative method for trace analysis of arsenic in natural medicinal products

Purpose: To evaluate the comparative efficiency of graphite furnace atomic absorption spectrometry (GFAAS) and hydride generation atomic absorption spectrometry (HGAAS) for trace analysis of arsenic (As) in natural herbal products (NHPs).Method: Arsenic analysis in natural herbal products and standard reference material was conducted using atomic absorption spectrometry (AAS), namely, hydride generation ASSAAS (HGAAS) and graphite furnace (GFAAS). The samples were digested with HNO3–H2O2 in a ratio of 4:1 using microwave-assisted acid digestion. The methods were validated with the aid of the standard reference material 1515 Apple Leaves (SRM) from NISTResults: Mean recovery of three different samples of NHPs, using HGAAS and GFAAS, ranged from 89.3 - 91.4 %, and 91.7 - 93.0 %, respectively. The difference between the two methods was insignificant. A (P= 0.5), B (P=0.4) and C (P=0.88) Relative standard deviation (RSD) RSD, i.e., precision was 2.5 - 6.5 % and 2.3 - 6.7 % using HGAAS and GFAAS techniques, respectively. Recovery of arsenic in SRM was 98 and 102 % by GFAAS and HGAAS, respectively.Conclusion: GFAAS demonstrates acceptable levels of precision and accuracy. Both techniques possess comparable accuracy and repeatability. Thus, the two methods are recommended as an alternative approach for trace analysis of arsenic in natural herbal products.Keywords: Arsenic, Graphite furnace atomic absorption spectrometer (GFAAS), Hydride generation atomic absorption spectrometer (HGAAS), Natural herbal product

Palladium, platinum, and gold distribution in serpentinite seamounts in the Mariana and Izu-Bonin forearcs: evidence from Leg 125 fluids and serpentinites

Palladium, platinum, and gold were analyzed for 20 interstitial water samples from Leg 125. No Pd or Pt was detected in fluids from serpentinite muds from Conical Seamount in the Mariana forearc, indicating that low-temperature seawater-peridotite interaction does not mobilize these elements into the serpentinizing fluids to levels above 0.10 parts per billion (ppb) in solution. However, Au may be mobilized in high pH solutions. In contrast, fluids from vitric-rich clays on the flanks of the Torishima Seamount in the Izu-Bonin forearc have Pd values of between 4.0 and 11.8 nmol/L, Pt values between 2.3 and 5.0 nmol/L and Au values between 126.9 and 1116.9 pmol/L. The precious metals are mobilized, and possibly adsorbed onto clay mineral surfaces, during diagenesis and burial of the volcanic-rich clays. Desorption during squeezing of the sediments may produce the enhanced precious metal concentrations in the analyzed fluids. The metals are mobilized in the fluids probably as neutral hydroxide, bisulfide, and ammonia complexes. Pt/Pd ratios are between 0.42 and 2.33, which is much lower than many of the potential sources for Pt and Pd but is consistent with the greater solubility of Pd compared with Pt in most natural low-temperature fluids

Palladium, platinum, and gold distribution in serpentinite seamounts in the Mariana and Izu-Bonin forearcs: evidence from Leg 125 fluids and serpentinites

Palladium, platinum, and gold were analyzed for 20 interstitial water samples from Leg 125. No Pd or Pt was detected in fluids from serpentinite muds from Conical Seamount in the Mariana forearc, indicating that low-temperature seawater-peridotite interaction does not mobilize these elements into the serpentinizing fluids to levels above 0.10 parts per billion (ppb) in solution. However, Au may be mobilized in high pH solutions. In contrast, fluids from vitric-rich clays on the flanks of the Torishima Seamount in the Izu-Bonin forearc have Pd values of between 4.0 and 11.8 nmol/L, Pt values between 2.3 and 5.0 nmol/L and Au values between 126.9 and 1116.9 pmol/L. The precious metals are mobilized, and possibly adsorbed onto clay mineral surfaces, during diagenesis and burial of the volcanic-rich clays. Desorption during squeezing of the sediments may produce the enhanced precious metal concentrations in the analyzed fluids. The metals are mobilized in the fluids probably as neutral hydroxide, bisulfide, and ammonia complexes. Pt/Pd ratios are between 0.42 and 2.33, which is much lower than many of the potential sources for Pt and Pd but is consistent with the greater solubility of Pd compared with Pt in most natural low-temperature fluids