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Metal Contaminants (metal + contaminant)
Selected AbstractsOn the Role of Metal Contaminants in Catalyses with FeCl3,ANGEWANDTE CHEMIE, Issue 31 2009Stephen Warnung: Katalytische N-, O- und C-Arylierungen, die der Wirkung von FeCl3 zugeschrieben wurden, könnten stattdessen durch Spuren von Kupfersalzen katalysiert sein. [source] Isolation of highly copper-tolerant fungi from the smelter of the Naganobori copper mine, an historic mine in JapanJOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2008K. Fujii Abstract Aims:, Copper is a critical metal of modern industry, and is the most widespread heavy metal contaminant in wastewater. Therefore, isolation of copper-tolerant microbes having the potential as biosorbent is fascinating not only from an environmental microbiology, but also from a biotechnology view point. In this study, we attempted to isolate highly copper-tolerant microbes from soil samples of the Nabanobori copper mine, the oldest mine in Japan. Methods and Results:, As a result of an enrichment culture, two fungal strains were isolated from soil of the smelter remains. The isolates could grow in a maximum of 200 mmol l,l Cu2+, and grew under a wide pH range. The Cu2+ -binding capacity of nontreated biomass of the isolates was around 35 mg Cu2+ g,1 -biomass. Analysis of 18S rDNA suggested that the isolates belong to the Aspergillus/Penicillium clade, but they represented a distinct lineage against known neighbours. Conclusion:, The isolates were highly copper-tolerant, and their Cu2+ -binding capacity was comparable to well-studied fungal sorbents. The isolates were implied as novel species. Soil of the historic old mine under weather-beaten conditions might be a suitable source for metal-tolerant microbes. Significance and Impact of the Study:, The present results advance our understanding of metal-tolerant microbes, and offer a new tool for both environmental control and metal recovery operations. [source] Evaluation of sorbent amendments for in situ remediation of metal-contaminated sedimentsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2010Seokjoon Kwon Abstract The present study evaluated sorbent amendments for in situ remediation of sediments contaminated with two divalent metals. A literature review screening was performed to identify low-cost natural mineral-based metal sorbents and high-performance commercial sorbents that were carried forward into laboratory experiments. Aqueous phase metal sorptivity of the selected sorbents was evaluated because dissolved metals in sediment porewater constitute an important route of exposure to benthic organisms. Based on pH-edge sorption test results, natural sorbents were eliminated due to inferior performance. The potential as in situ sediment amendment was explored by comparing the sorption properties of the engineered amendments in freshwater and saltwater (10 PPT salinity estuarine water) matrices. Self-assembled monolayers on mesoporous supports with thiols (Thiol-SAMMSÔ) and a titanosilicate mineral (ATSÔ) demonstrated the highest sorption capacity for cadmium (Cd) and lead (Pb), respectively. Sequential extraction tests conducted after mixing engineered sorbents with contaminated sediment demonstrated transfer of metal contaminants from a weakly bound state to a more strongly bound state. Biouptake of Cd in a freshwater oligochaete was reduced by 98% after 5-d contact of sediment with 4% Thiol-SAMMS and sorbed Cd was not bioavailable. While treatment with ATS reduced the small easily extractable portion of Pb in the sediment, the change in biouptake of Pb was not significant because most of the native lead was strongly bound. The selected sorbents added to sediments at a dose of 5% were mostly nontoxic to a range of sensitive freshwater and estuarine benthic organisms. Metal sorbent amendments in conjunction with activated carbon have the potential to simultaneously reduce metal and hydrophobic contaminant bioavailability in sediments. Environ. Toxicol. Chem. 2010;29:1883,1892. © 2010 SETAC [source] Determination of lead content in medicinal plants by pre-concentration flow injection analysis,flame atomic absorption spectrometryPHYTOCHEMICAL ANALYSIS, Issue 6 2009Marina M. A. Campos Abstract Introduction , Although medicinal plants are widely used throughout the world, few studies have been carried out concerning the levels of heavy metal contaminants present. Such metals are highly toxic to living organisms even in low concentrations owing to their cumulative effect. The present paper describes the the development of a pre-concentration flow injection analysis-flame atomic absorption spectrometric system to determine the lead content in medicinal plants at the ppb level. Objective , To develop a pre-concentration flow injection analysis-flame atomic absorption spectrometric system to determine the lead content in medicinal plants at the ppb level. Methodology , A pre-concentration flow system was coupled to a flame atomic absorption spectrometer. The plant samples were analysed after nitroperchloric digestion. The proposed system was optimised by evaluating the following parameters: nature, concentration and volume of the eluent solution, elution flow rate, elution efficiency, pre-concentration flow rate and pre-concentration time. Results , The proposed system exhibited good performance with high precision and repeatability (RSD , 2.36%), excellent linearity (r = 0.9999), low sample consumption (10.5 mL per determination) and an analytical throughput of 55 samples/h. Lead concentrations ranged from 3.37 ± 0.25 to 7.03 ± 0.51 ,g/g in dry material. This concentration interval is greater than that previously published in the literature. Conclusion , The inclusion of a pre-concentration column in the flow manifold improved the sensitivity of the spectrometer. Thus, it was possible to determine the analyte at the ng/mL level in sample solutions of medicinal plants. This is a very important accomplishment, especially when the cumulative effect of heavy metals in living organisms is considered. Copyright © 2009 John Wiley & Sons, Ltd. [source] | |||||||||||||