خيارات البحث
النتائج 1 - 5 من 5
Maternal exposure to alkali, alkali earth, transition and other metals: Concentrations and predictors of exposure النص الكامل
2015
Hinwood, A.L. | Stasinska, A. | Callan, A.C. | Heyworth, J. | Ramalingam, M. | Boyce, M. | McCafferty, P. | Odland, J.Ø
Most studies of metals exposure focus on the heavy metals. There are many other metals (the transition, alkali and alkaline earth metals in particular) in common use in electronics, defense industries, emitted via combustion and which are naturally present in the environment, that have received limited attention in terms of human exposure. We analysed samples of whole blood (172), urine (173) and drinking water (172) for antimony, beryllium, bismuth, cesium, gallium, rubidium, silver, strontium, thallium, thorium and vanadium using ICPMS. In general most metals concentrations were low and below the analytical limit of detection with some high concentrations observed. Few factors examined in regression models were shown to influence biological metals concentrations and explained little of the variation. Further study is required to establish the source of metals exposures at the high end of the ranges of concentrations measured and the potential for any adverse health impacts in children.
اظهر المزيد [+] اقل [-]Seasonal distribution of metals in vertical and horizontal profiles of sheltered and exposed beaches on Polish coast النص الكامل
2016
Bigus, Katarzyna | Astel, Aleksander | Niedzielski, Przemysław
The distribution of alkali and heavy metals in coastal sediments of three Polish beaches was assessed. In all locations there are sandy beaches of different characteristics according to the anthropogenic impact and degree of sheltering. Core sediments collected in Czołpino and Ustka were characterized by the highest concentration of Cd, Ag, Ba, and Al, Cu, Cr, Bi, Na, respectively. Among the alkaline metals core sediments were the most abundant with Ca, Bi, Mg and Na, presenting almost stable decreasing order in all beaches. The majority of dredge material collected can be classified as light or trace contaminated by Cr, Cu, Zn, Cd and Hg. An abundance of mineralogical components in core sediments in Ustka increases in Summer and Autumn, while in Puck is stable throughout the year. The content of studied metals in core sediments collected in three Polish beaches changes both in the vertical and horizontal profiles of the beach.
اظهر المزيد [+] اقل [-]The chemistry and toxicity of discharge waters from copper mine tailing impoundment in the valley of the Apuseni Mountains in Romania النص الكامل
2017
Rzymski, Piotr | Klimaszyk, Piotr | Marszelewski, Włodzimierz | Borowiak, Dariusz | Mleczek, Mirosław | Nowiński, Kamil | Pius, Bożena | Niedzielski, Przemysław | Poniedziałek, Barbara
Copper mining generates large quantities of waste, tailings, and acid outflows causing long-term environmental impacts and potential threats to human health. Valea Şesei is the largest tailing impoundment in Romania, created by flooding the valley (known as Valea Şesei) of the Metalliferous Mountains (a division of the Apuseni Mountains) with copper mining waste. The present study (i) estimated the total volume of tailings in this area; (ii) screened the concentration of 65 elements (rare earth and platinum group elements, alkali metals and alkali earth metals, transition and post-transition metals and metalloids) and cyanide concentrations in wastewater samples collected from tailing impoundment; (iii) evaluated the toxicity of these water samples using five in vitro bioassays employing human cells isolated from healthy donors and a short-term (1 h) exposure model. The sampled waters were highly acidic (pH 2.1–4.9) and had high electrical conductivity (280–1561 mS cm⁻¹). No cyanides were detected in any sample. Water samples collected from the stream (AMD) inflowing to the tailing impoundment were characterized by the greatest concentrations of alkali metals, alkaline earth metals, transition and post-transition metals, metalloids, rare earth elements, and noble metal group. At other sites, the elemental concentrations were lower but remained high enough to pose a relevant risk. The greatest magnitude of in vitro toxic effects was induced by AMD. Observed alterations included redox imbalance in human neutrophils followed by lipid peroxidation and decreased cell survival, significant aggregation of red blood cells, and increased prothrombin time. The study highlights that Valea Şesei is a large sink for toxic elements, posing environmental and health risks, and requiring action to prevent further release of chemicals and to initiate restoration of the area.
اظهر المزيد [+] اقل [-]The enhanced SO3 formation by alkali-metal sulfates from ash in the post-flame region during the combustion of high-alkali coal النص الكامل
2020
Xiao, Haiping | Cheng, Qiyong | Shi, Hao | Li, Jian | Ru, Yu
High alkali-metal sulfate contents in ash from high-alkali coal are a result of the alkali metals’ strong sulfur-capturing capacity. In this work, the effects of sulfates in ash on SO₃ formation were investigated by adding alkali-metal sulfates (Na₂SO₄ and K₂SO₄) to ash and performing experiments to simulate SO₃ formation. The results show that Na₂SO₄ and K₂SO₄ addition significantly increased SO₃ formation and the formation rate increased with increasing temperature. The formed SO₃ concentration increased by 6.8 ppm (adding Na₂SO₄) and 6.3 ppm (adding K₂SO₄) at 1000 °C. These increases are the result of SO₃ release from sulfate during the formation of aluminosilicates such as NaAlSi₃O₈ (albite), NaAlSiO₄ (nepheline), KAlSiO₄ (kalsilite), and KAlSi₃O₈ (feldspar) with the SiO₂ and Al₂O₃ in the ash. This was confirmed by X-ray diffraction (XRD) and thermodynamic calculation. In addition, increasing the SO₂ concentration increased the SO₃ concentration and decreased the SO₃ conversion ratio. Graphical abstract Note: This data is mandatory.
اظهر المزيد [+] اقل [-]Environmental monitoring of water resources around a municipal landfill of the Rio Grande do Sul state, Brazil النص الكامل
2017
de Medeiros Engelmann, Pâmela | dos Santos, VictorHugo Jacks Mendes | Moser, LetíciaIsabela | do Canto Bruzza, Eduardo | Barbieri, CristinaBarazzetti | Barela, PâmelaSusin | de Moraes, DiogoPompéu | Augustin, AdolphoHerbert | Goudinho, FlávioSoares | Melo, ClarissaLovato | Ketzer, JoãoMarcelo Medina | Rodrigues, LuizFrederico
In Brazil, landfills are commonly used as a method for the final disposal of waste that is compliant with the legislation. This technique, however, presents a risk to surface water and groundwater resources, owing to the leakage of metals, anions, and organic compounds. The geochemical monitoring of water resources is therefore extremely important, since the leachate can compromise the quality and use of surface water and groundwater close to landfills. In this paper, the results of analyses of metals, anions, ammonia, and physicochemical parameters were used to identify possible contamination of surface water and groundwater in a landfill area. A statistical multivariate approach was used. The values found for alkali metals, nitrate, and chloride indicate contamination in the regional groundwater and, moreover, surface waters also show variation when compared to the other background points, mainly for ammonia. Thus, the results of this study evidence the landfill leachate influence on the quality of groundwater and surface water in the study area.
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