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Chemical speciation

Youyuan Chen, Bingbing Dong, Jia Xin
This study investigated the chromium (Cr) occurrence and distribution along the Loushan River adjacent to a chromium slag heap. The speciation and chemical fractionation of Cr in different environmental media were determined. The potential ecological risks for the surrounding environment were assessed on the basis of both potential ecological risk index (RI) and risk assessment code (RAC). The results show that the surface soil experienced severe Cr contamination with Cr(T) and Cr(VI) values of 3220 ± 6266 and 64 ± 94 mg/kg, respectively, even though the chromium slag heap had already been removed...
May 18, 2017: Environmental Science and Pollution Research International
Wenling Ye, Jingjing Zhang, Ting Fan, Hongjuan Lu, Haiyan Chen, Xuede Li, Rimao Hua
Arsenic (As) speciation in the phloem sap of rice plants and its role in As accumulation in rice grains remain largely uncharacterized. In the present study, we tested As chemical species in the phloem exudates of rice treated with arsenate [As(V)], arsenite [As(III)], monomethylarsonic acid [MMA(V)], or dimethylarsinic acid [DMA(V)]. As(V) was the main species (58%) in the phloem exudates of As(V)-exposed rice, whereas As(III) predominated (69%) in As(III)-exposed rice. A large proportion of As(V) (41-45%) was observed in the phloem exudates when rice was treated with methylated As species...
May 12, 2017: Ecotoxicology and Environmental Safety
Junxia Li, Hailing Zhou, Yanxin Wang, Xianjun Xie, Kun Qian
Characterizing the properties of main host of iodine in soil/sediment and the geochemical behaviors of iodine species are critical to understand the mechanisms of iodine mobilization in groundwater systems. Four surface soil and six subsurface sediment samples were collected from the iodine-affected area of Datong basin in northern China to conduct batch experiments and to evaluate the effects of NOM and/or organic-mineral complexes on iodide/iodate geochemical behaviors. The results showed that both iodine contents and kf-iodate values had positive correlations with solid TOC contents, implying the potential host of NOM for iodine in soil/sediment samples...
April 24, 2017: Journal of Contaminant Hydrology
Thomas L Sheppard, Stephen W T Price, Federico Benzi, Sina Baier, Michael Klumpp, Roland Dittmeyer, Wilhelm Schwieger, Jan-Dierk Grunwaldt
A Cu/ZnO/Al2O3@ZSM-5 core@shell catalyst active for one-step conversion of synthesis gas to dimethyl ether was imaged simultaneously and in situ using synchrotron-based X-ray Fluorescence (μ-XRF), X-ray Diffraction (μ-XRD) and Scanning Transmission X-ray Microscopy (STXM) Computed Tomography (CT) with micrometer spatial reso-lution. An identical sample volume was imaged stepwise, first under oxidizing and reducing atmospheres (imitating calcination and activation processes), and then under model reaction conditions for DME synthesis (H2:CO:CO2 ratio of 16:8:1, up to 250 °C)...
May 12, 2017: Journal of the American Chemical Society
Jingzi Beiyuan, Jiang-Shan Li, Daniel C W Tsang, Lei Wang, Chi Sun Poon, Xiang-Dong Li, Scott Fendorf
This study evaluated the feasibility of 2-h chemical-enhanced washing of As-containing soil resulting from geogenic sources in Hong Kong and the fate of As before and after remediation. The soil morphology and As speciation in soil was elucidated by scanning electron microscopy with energy dispersive X-ray spectroscopy, X-ray diffractometer, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy. Integrated analysis of the results suggests that the As (>90%) resides predominantly as arsenate bound to ferric iron oxides, with a minor contribution (<10%) from an As(III)-sulphide phase...
May 8, 2017: Science of the Total Environment
Myrtille O J Y Hunault, Claudine Loisel, Fanny Bauchau, Quentin Lemasson, Claire Pacheco, Laurent Pichon, Brice Moignard, Karine Boulanger, Michel Hérold, Georges Calas, Isabelle Pallot-Frossard
The sophisticated colors of medieval glasses arise from their transition metal (TM) impurities, and capture information on the ancient glassmaking techniques. Beyond the glass chemical composition, the TM redox is also a key factor of the glass color but its quantification without any sampling is a challenge. We report the combination of non-destructive and non-invasive quantitative analyses of the chemical composition by PIXE-PIGE mappings and of the color and TM element speciation by optical absorption spectroscopy performed on a red-blue-purple striped glass from the stained glass windows of the Sainte-Chapelle in Paris (France) during its restoration...
May 11, 2017: Analytical Chemistry
Huajing Teng, Yaohua Zhang, Chengmin Shi, Fengbiao Mao, Wanshi Cai, Liang Lu, Fangqing Zhao, Zhongsheng Sun, Jianxu Zhang
Murine rodents are excellent models for study of adaptive radiations and speciation. Brown Norway rats (Rattus norvegicus) are successful global colonizers and the contributions of their domesticated laboratory strains to biomedical research are well established. To identify nucleotide-based speciation timing of the rat and genomic information contributing to its colonization capabilities, we analyzed 51 whole-genome sequences of wild-derived Brown Norway rats and their sibling species, R. nitidus, and identified over 20 million genetic variants in the wild Brown Norway rats that were absent in the laboratory strains, which substantially expand the reservoir of rat genetic diversity...
May 8, 2017: Molecular Biology and Evolution
Sohei Sukenaga, Pierre Florian, Koji Kanehashi, Hiroyuki Shibata, Noritaka Saito, Kunihiko Nakashima, Dominique Massiot
The description of the structure of aluminosilicate glasses is more often centered on its cationic constituents, and oxygen ions determine their connectivity, directly impacting the physical properties of those disordered materials. A very powerful approach to ascertain this short- to medium-range order is to use (17)O NMR, but up to now the speciation of the chemical bonds was only ambiguously achieved for multicomponent glasses. Here, we propose to directly probe the very scarcely explored through-bond correlations using (17)O{(27)Al} and (17)O{(23)Na} solid-state nuclear magnetic resonance (NMR) double-resonance experiments...
May 8, 2017: Journal of Physical Chemistry Letters
Julien Alleon, Sylvain Bernard, Corentin Le Guillou, Damien Daval, Feriel Skouri-Panet, Maïa Kuga, François Robert
Reconstructing the original biogeochemistry of organic fossils requires quantifying the extent of the chemical transformations that they underwent during burial-induced maturation processes. Here, we performed laboratory experiments on chemically different organic materials in order to simulate the thermal maturation processes that occur during diagenesis. Starting organic materials were microorganisms and organic aerosols. Scanning transmission X-ray microscopy (STXM) was used to collect X-ray absorption near edge spectroscopy (XANES) data of the organic residues...
May 4, 2017: Scientific Reports
Laura Chiarantini, Valentina Rimondi, Fabrizio Bardelli, Marco Benvenuti, Claudia Cosio, Pilario Costagliola, Francesco Di Benedetto, Pierfranco Lattanzi, Géraldine Sarret
This study determined, by means of X-ray absorption near-edge structure (XANES) spectroscopy, the speciation of mercury (Hg) in black pine (Pinus nigra) barks from Monte Amiata, that were previously shown to contain exceptionally high (up to some mg kg(-1)) Hg contents because of the proximity to the former Hg mines and roasting plants. Linear fit combination (LCF) analysis of the experimental spectra compared to a large set of reference compounds showed that all spectra can be fitted by only four species: β-HgS (metacinnabar), Hg-cysteine, Hg bound to tannic acid, and Hg(0)...
April 27, 2017: Environmental Pollution
Jos P M Vink, Andre van Zomeren, Joris J Dijkstra, Rob N J Comans
Simulating the storage of aerobic soils under water, the chemical speciation of heavy metals and arsenic was studied over a long-term reduction period. Time-dynamic and redox-discrete measurements in reactors were used to study geochemical changes. Large kinetic differences in the net-complexation quantities of heavy metals with sulfides was observed, and elevated pore water concentrations remained for a prolonged period (>1 year) specifically for As, B, Ba, Co, Mo, and Ni. Arsenic is associated to the iron phases as a co-precipitate or sorbed fraction to Fe-(hydr)oxides, and it is being released into solution as a consequence of the reduction of iron...
April 27, 2017: Environmental Pollution
R M Fisher, J P Alvarez-Gaitan, R M Stuetz, S J Moore
High flows of sulfur through wastewater treatment plants (WWTPs) may cause noxious gaseous emissions, corrosion of infrastructure, inhibit wastewater microbial communities, or contribute to acid rain if the biosolids or biogas is combusted. Yet, sulfur is an important agricultural nutrient and the direct application of biosolids to soils enables its beneficial re-use. Flows of sulfur throughout the biosolids processing of six WWTPs were investigated to identify how they were affected by biosolids processing configurations...
April 27, 2017: Journal of Environmental Management
Wakana Oishi, Daisuke Sano, Loic Decrey, Syunsuke Kadoya, Tamar Kohn, Naoyuki Funamizu
Volume reduction (condensation) is a key for the practical usage of human urine as a fertilizer because it enables the saving of storage space and the reduction of transportation cost. However, concentrated urine may carry infectious disease risks resulting from human pathogens frequently present in excreta, though the survival of pathogens in concentrated urine is not well understood. In this study, the inactivation of MS2 coliphage, a surrogate for single-stranded RNA human enteric viruses, in concentrated synthetic urine was investigated...
April 23, 2017: Science of the Total Environment
Ana E Pradas Del Real, Vladimir Vidal, Marie Carrière, Hiram Castillo-Michel, Clément Levard, Perrine Chaurand, Géraldine Sarret
Agricultural soils are major sinks of silver nanoparticles in the environment, and crops are directly exposed to these emerging contaminants. A clear picture of their chemical transformations, uptake and transport mechanisms, and phytotoxic impacts is still lacking. In this work, wheat plants were exposed to pristine metallic (Ag-NPs) and sulfidized (Ag2S-NPs) silver nanoparticles and ionic Ag. Data on Ag distribution and speciation, phytotoxicity markers, and gene expression were studied. A multi-technique and multi-scale approach was applied, combining innovating tools at both the laboratory and synchrotron...
May 5, 2017: Environmental Science & Technology
M Dowdall, Y Bondar, L Skipperud, V Zabrotski, M Nandrup Pettersen, Ø G Selnæs, J E Brown
The effects of fire events on contaminant radionuclides within soils of the Belarusian Exclusion Zone were investigated. A number of cores were taken from locations known to have been subject to fire events in the past as well as a series of cores from nearby unburnt locations. Both burnt and unburnt cores were analyzed for contaminant radionuclides as well as a range of relevant soil parameters. The distribution of (137)Cs between various fractions (reversibly bound, irreversibly bound and insoluble) was analyzed...
April 22, 2017: Journal of Environmental Radioactivity
Iris K M Yu, Daniel C W Tsang
Conversion of biomass waste to hydroxymethylfurfural (HMF), a value-added platform chemical, has captured great research interests driven by the economic and environmental incentives. This review evaluates the recent development of biomass conversion systems for high HMF yield and selectivity, with a focus on the performance of emerging catalysts and solvents from a mechanistic view. We highlight that the ratio and strength of Brønsted and Lewis acid in bifunctional catalyst are critical for maximizing HMF production by selective improvement in the kinetics of desirable reactions (hydrolysis, isomerization, and dehydration) over undesirable reactions (rehydration, polymerization)...
April 9, 2017: Bioresource Technology
Évila Pinheiro Damasceno, Lívia Pitombeira de Figuerêdo, Marcionília Fernandes Pimentel, Susana Loureiro, Letícia Veras Costa-Lotufo
Few studies have examined the toxicity of metal mixtures to marine organisms exposed to different salinities. The aim of the present study was to investigate the acute toxicity of zinc and nickel exposures singly and in combination to Artemia sp. under salinities of 10, 17, and 35 psu. The mixture concentrations were determined according to individual toxic units (TUs) to follow a fixed ratio design. Zinc was more toxic than nickel, and both their individual toxicities were higher at lower salinities. These changes in toxicity can be attributed to the Biotic Ligand Model (BLM) rather than to metal speciation...
April 20, 2017: Ecotoxicology and Environmental Safety
Hai-Bo Qin, Yasuo Takeichi, Hiroaki Nitani, Yasuko Terada, Yoshio Takahashi
The distribution and chemical species of tellurium (Te) in contaminated soil were determined by a combination of microfocused X-ray fluorescence (μ-XRF), X-ray diffraction (μ-XRD), and X-ray absorption fine structure (μ-XAFS) techniques. Results showed that Te was present as a mixture of Te(VI) and Te(IV) species, while selenium (Se) was predominantly present in the form of Se(IV) in the soil contaminated by abandoned mine tailings. In the contaminated soil, Fe(III) hydroxides were the host phases for Se(IV), Te(IV), and Te(VI), but Te(IV) could be also retained by illite...
May 10, 2017: Environmental Science & Technology
Lidia Kozak, Przemyslaw Niedzielski
The article describes the unique studies of the chemical composition changes of new geological object (tsunami deposits in south Thailand - Andaman Sea Coast) during four years (2005-2008) from the beginning of formation of it (deposition of tsunami transported material, 26 December 2004). The chemical composition of the acid leachable fraction of the tsunami deposits has been studied in the scope of concentration macrocompounds - concentration of calcium, magnesium, iron, manganese and iron speciation - the occurrence of Fe(II), Fe(III) and non-ionic iron species described as complexed iron (Fe complex)...
April 15, 2017: Chemosphere
Kelly Peeters, Tea Zuliani, Dušan Žigon, Radmila Milačič, Janez Ščančar
Nickel (Ni) is considered to be a potentially harmful element for humans. Its levels in foodstuffs are normally low (below 0.2mgkg(-1)), but sensitive individuals may develop allergy to Ni as a result of dietary consumption. Cocoa contains relatively high Ni concentrations (around 3mgkg(-1)). Ni bioavailability, its role in the flavour of food and its potential impact on human health depends primarily on its chemical species. However, there is a lack of information about Ni speciation in cocoa. In this work Ni species were separated on a weak convective interaction media diethylamine (CIM DEAE) monolithic chromatographic column and quantified by the post-column isotope dilution inductively coupled plasma mass spectrometry (ID-ICP-MS)...
September 1, 2017: Food Chemistry
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