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Chemical speciation

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https://www.readbyqxmd.com/read/28314620/selenium-speciation-in-seleniferous-agricultural-soils-under-different-cropping-systems-using-sequential-extraction-and-x-ray-absorption-spectroscopy
#1
Hai-Bo Qin, Jian-Ming Zhu, Zhi-Qing Lin, Wen-Po Xu, De-Can Tan, Li-Rong Zheng, Yoshio Takahashi
Selenium (Se) speciation in soil is critically important for understanding the solubility, mobility, bioavailability, and toxicity of Se in the environment. In this study, Se fractionation and chemical speciation in agricultural soils from seleniferous areas were investigated using the elaborate sequential extraction and X-ray absorption near-edge structure (XANES) spectroscopy. The speciation results quantified by XANES technique generally agreed with those obtained by sequential extraction, and the combination of both approaches can reliably characterize Se speciation in soils...
March 14, 2017: Environmental Pollution
https://www.readbyqxmd.com/read/28306235/gcib-tof-sims-high-resolution-imaging-of-cardiolipin-speciation-in-the-brain-identification-of-molecular-losses-after-traumatic-injury
#2
Hua Tian, Louis J Sparvero, Andrew A Amoscato, Anna Bloom, Hulya Bayir, Valerian E Kagan, Nicholas Winograd
Gas cluster ion beam secondary ion mass spectrometry (GCIB-SIMS) has shown the full potential of mapping intact lipids in biological systems with better than 10 µm lateral resolution. This study investigated further the capability of GCIB-SIMS in imaging high-mass signals from intact cardiolipin (CL) and gangliosides in normal brain and the effect of a controlled cortical impact model (CCI) of traumatic brain injury (TBI) on their distribution. A combination of enzymatic and chemical treatments was employed to suppress the signals from the most abundant phospholipids (phosphatidylcholine (PC) and phosphatidylethanolamine (PE)) and enhance the signals from the low abundance CLs and gangliosides to allow their GCIB-SIMS detection at 8 and 16 µm spatial resolution...
March 17, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28303197/heterogeneous-tempo-and-mode-of-evolutionary-diversification-of-compounds-in-lizard-chemical-signals
#3
Roberto García-Roa, Manuel Jara, Pilar López, José Martín, Daniel Pincheira-Donoso
Important part of the multivariate selection shaping social and interspecific interactions among and within animal species emerges from communication. Therefore, understanding the diversification of signals for animal communication is a central endeavor in evolutionary biology. Over the last decade, the rapid development of phylogenetic approaches has promoted a stream of studies investigating evolution of communication signals. However, comparative research has primarily focused on visual and acoustic signals, while the evolution of chemical signals remains largely unstudied...
February 2017: Ecology and Evolution
https://www.readbyqxmd.com/read/28286302/recent-advances-in-the-detection-of-specific-natural-organic-compounds-as-carriers-for-radionuclides-in-soil-and-water-environments-with-examples-of-radioiodine-and-plutonium
#4
REVIEW
P H Santschi, C Xu, S Zhang, K A Schwehr, P Lin, C M Yeager, D I Kaplan
Among the key environmental factors influencing the fate and transport of radionuclides in the environment is natural organic matter (NOM). While this has been known for decades, there still remains great uncertainty in predicting NOM-radionuclide interactions because of lack of understanding of radionuclide interactions with the specific organic moieties within NOM. Furthermore, radionuclide-NOM studies conducted using modelled organic compounds or elevated radionuclide concentrations provide compromised information related to true environmental conditions...
March 9, 2017: Journal of Environmental Radioactivity
https://www.readbyqxmd.com/read/28281067/changes-in-structural-characteristics-and-metal-speciation-for-biochar-exposure-in-typic-udic-ferrisols
#5
Qi Lin, Xin Xu, Qian Chen, Jing Fang, Xiaodong Shen, Lijuan Zhang
Recent studies on biochars confirmed their potential benefits in improving soil fertility and sequestrating contaminants. However, little information on the changes in structural characteristics and metal speciation of biochars after exposure to soils is currently available. The aim of this study was to use double experimental bags to study the transformation of ozonized biochars derived from poultry manure and drying sludge (denoted PB and SB, respectively) in typic udic ferrisols. The carbon and sulfur functional groups and chemical characteristics of the biochars were determined using spectroscopic techniques, such as Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and near-edge X-ray absorption fine structure spectroscopy spectroscopy, combined with chemical extractions...
March 9, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28278094/citric-acid-preacidification-enhanced-electrokinetic-remediation-for-removal-chromium-from-chromium-residue-contaminated-soil
#6
Fansheng Meng, Hao Xue, Yeyao Wang, Binghui Zheng, Juling Wang
Electrokinetic experiments were conducted on chromium residue contaminated soils collected from a chemical plant in China. Acidification-electrokinetic remediation technology was proposed in order to solve the problem of removing inefficient with ordinary electrokinetic. In present study, the effects of acidification time, concentrations of citric acid on removal of chromium from soils were studied by changing the acidification pretreatment conditions, and then speciation analysis of chromium was also conducted to study the regularity of Cr in different forms...
March 1, 2017: Environmental Technology
https://www.readbyqxmd.com/read/28273539/nanoscale-zero-valent-iron-for-metal-metalloid-removal-from-model-hydraulic-fracturing-wastewater
#7
Yuqing Sun, Cheng Lei, Eakalak Khan, Season S Chen, Daniel C W Tsang, Yong Sik Ok, Daohui Lin, Yujie Feng, Xiang-Dong Li
Nanoscale zero-valent iron (nZVI) was tested for the removal of Cu(II), Zn(II), Cr(VI), and As(V) in model saline wastewaters from hydraulic fracturing. Increasing ionic strength (I) from 0.35 to 4.10 M (Day-1 to Day-90 wastewaters) increased Cu(II) removal (25.4-80.0%), inhibited Zn(II) removal (58.7-42.9%), slightly increased and then reduced Cr(VI) removal (65.7-44.1%), and almost unaffected As(V) removal (66.7-75.1%) by 8-h reaction with nZVI at 1-2 g L(-1). The removal kinetics conformed to pseudo-second-order model, and increasing I decreased the surface area-normalized rate coefficient (ksa) of Cu(II) and Cr(VI), probably because agglomeration of nZVI in saline wastewaters restricted diffusion of metal(loid)s to active surface sites...
February 27, 2017: Chemosphere
https://www.readbyqxmd.com/read/28255608/solubility-of-tin-in-aqueous-media-implications-for-regulatory-ecotoxicity-testing
#8
Iain Wilson, Adam Peters, Graham Merrington, Jeremy Pearce, Jonathan Rickwood, Paul Cusack, Kay Nimmo
Effects caused in ecotoxicity tests by physical factors due to precipitated particles cannot be used for classification in Europe under the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH). For tin (Sn), results from ecotoxicity tests have been observed to be difficult to interpret in regard to exposures of dissolved Sn. Experiments were undertaken with Sn(IV) chloride at 2-2000 µg L(-1) in aquatic test media of differing pHs and hardness. A predictive Sn precipitation model was derived using these data and speciation modelling...
March 2, 2017: Bulletin of Environmental Contamination and Toxicology
https://www.readbyqxmd.com/read/28254036/metal-distribution-characteristic-of-mswi-bottom-ash-in-view-of-metal-recovery
#9
Yi Xia, Pinjing He, Liming Shao, Hua Zhang
Bottom ash is the major by-product of municipal solid waste incineration (MSWI), and is often reused as an engineering material, such as road-base aggregate. However, some metals (especially aluminum) in bottom ash can react with water and generate gas that could cause expansion and failure of products containing the ash; these metals must be removed before the ash is utilized. The size distribution and the chemical speciation of metals in the bottom ash from two Chinese MSWI plants were examined in this study, and the recovery potential of metals from the ash was evaluated...
February 2017: Journal of Environmental Sciences (China)
https://www.readbyqxmd.com/read/28248107/thermodynamic-modelling-of-the-solubility-and-chemical-speciation-of-mercury-and-methylmercury-driven-by-organic-thiols-and-micromolar-sulfide-concentrations-in-boreal-wetlands
#10
Van Liem-Nguyen, Ulf Skyllberg, Erik Björn
Boreal wetlands have been identified as environments in which inorganic divalent mercury (HgII) is transformed to methylmercury (MeHg) by anaerobic microbes. In order to understand this transformation and the mobility and transport of HgII and MeHg, factors and conditions in control of the solubility and chemical speciation of HgII and MeHg need to be clarified. Here we explore the ability of thermodynamic models to simulate measured solubility of HgII and MeHg in different types of boreal wetland soils. With the input of measured concentrations of MeHg, sulfide, eight low molecular mass thiols and thiol groups associated with natural organic matter (NOM), as determined by sulfur K-edge X-ray absorption near-edge structure (XANES) spectroscopy and Hg LIII-edge extended X-ray absorption fine structure spectroscopy (EXAFS), the model could accurately predict porewater concentrations of MeHg in the wetlands...
March 1, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28245633/bioavailability-comparison-of-nine-bioselenocompounds-in-vitro-and-in-vivo
#11
Kazuaki Takahashi, Noriyuki Suzuki, Yasumitsu Ogra
Selenium (Se) shows biologically ambivalent characteristics in animals. It is an essential element but becomes severely toxic when the amount ingested exceeds the adequate intake level. Its biological, nutritional, and toxicological effects are strongly dependent on its chemical form. In this study, we evaluated the toxicity and bioavailability of nine naturally occurring Se compounds, or the so-called bioselenocompounds, in vivo and in vitro. Selenite and selenocystine showed higher toxicity than the other bioselenocompounds in vitro...
February 26, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/28244747/rapid-iron-reduction-rates-are-stimulated-by-high-amplitude-redox-fluctuations-in-a-tropical-forest-soil
#12
Brian Ginn, Christof Meile, Jared Wilmoth, Yuanzhi Tang, Aaron Thompson
Iron oxides are important structural and biogeochemical components of soils that can be strongly altered by redox-driven processes. This study examined the influence of temporal oxygen variations on Fe speciation in soils from the Luquillo Critical Zone Observatory (Puerto Rico). We incubated soils under cycles of oxic-anoxic conditions (τoxic:τanoxic = 1:6) at three frequencies with and without phosphate addition. Fe(II) production, P availability, and Fe mineral composition were monitored using batch analytical and spectroscopic techniques...
February 28, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28242686/previously-unknown-class-of-metalorganic-compounds-revealed-in-meteorites
#13
Alexander Ruf, Basem Kanawati, Norbert Hertkorn, Qing-Zhu Yin, Franco Moritz, Mourad Harir, Marianna Lucio, Bernhard Michalke, Joshua Wimpenny, Svetlana Shilobreeva, Basil Bronsky, Vladimir Saraykin, Zelimir Gabelica, Régis D Gougeon, Eric Quirico, Stefan Ralew, Tomasz Jakubowski, Henning Haack, Michael Gonsior, Peter Jenniskens, Nancy W Hinman, Philippe Schmitt-Kopplin
The rich diversity and complexity of organic matter found in meteorites is rapidly expanding our knowledge and understanding of extreme environments from which the early solar system emerged and evolved. Here, we report the discovery of a hitherto unknown chemical class, dihydroxymagnesium carboxylates [(OH)2MgO2CR](-), in meteoritic soluble organic matter. High collision energies, which are required for fragmentation, suggest substantial thermal stability of these Mg-metalorganics (CHOMg compounds). This was corroborated by their higher abundance in thermally processed meteorites...
February 27, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28242174/effect-of-various-types-of-thermochemical-processing-of-sewage-sludges-on-phosphorus-speciation-solubility-and-fertilization-performance
#14
Daniel Steckenmesser, Christian Vogel, Christian Adam, Diedrich Steffens
Sewage sludge has one of the highest phosphorus (P) recovery potentials of all waste materials. Therefore, P-recycling from sewage sludge could contribute to closing the P-cycle. Recently, various thermal processes for P-recovery have been developed, but there is still a demand for information on the effect of different process parameters (e.g. additives and temperature) on P-speciation and especially on the fertilization performance. In the present study, two common methods (low-temperature conversion at 400-500°C and thermochemical treatment at 950°C) were investigated and combined to produce highly bioavailable P-fertilizers from two different types of sewage sludge based on chemical phosphorus precipitation (Chem-P) and enhanced biological phosphorus removal (Bio-P)...
February 24, 2017: Waste Management
https://www.readbyqxmd.com/read/28237464/review-of-receptor-based-source-apportionment-research-of-fine-particulate-matter-and-its-challenges-in-china
#15
REVIEW
Yanjun Zhang, Jing Cai, Shuxiao Wang, Kebin He, Mei Zheng
As the key for haze control, atmospheric fine particulate matter with aerodynamic diameter <2.5μm (or PM2.5) is of great concern lately in China. It is closely linked to fast pace of urbanization, industrialization and economic development, especially in eastern China. A good understanding of its sources is required for effective pollution abatement. Receptor models are one of the major methods for source apportionment used in China. The major objective of this study is to understand sources that contribute to fine particulate matter in China and key challenges in this area...
May 15, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28236461/gas-chromatography-vacuum-ultraviolet-detection-for-classification-and-speciation-of-polychlorinated-biphenyls-in-industrial-mixtures
#16
Changling Qiu, Jack Cochran, Jonathan Smuts, Phillip Walsh, Kevin A Schug
Polychlorinated biphenyls (PCBs) are a group of synthetic chlorinated compounds that have been widely used as dielectric fluids in capacitors and transformers. Due to their toxicity, persistence, and bioaccumulation in the food chain, PCBs are an environmental concern and among the most analyzed compounds in environmental analysis. The most common analytical methods for analysis of PCBs are based on gas chromatography-electron capture detection (GC-ECD) and gas chromatography-mass spectrometry (GC-MS). However, the number of possible congeners (209), similarities of physical and chemical properties, and complexity of sample matrices make it difficult to distinguish and accurately speciate PCB congeners using existing methods...
February 16, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28235745/spatial-imaging-and-speciation-of-cu-in-rice-oryza-sativa-l-roots-using-synchrotron-based-x-ray-microfluorescence-and-x-ray-absorption-spectroscopy
#17
Lingli Lu, Ruohan Xie, Ting Liu, Haixing Wang, Dandi Hou, Yonghua Du, Zhenli He, Xiaoe Yang, Hui Sun, Shengke Tian
Knowledge of elemental localization and speciation in rice (Oryza sativa L.) roots is crucial for elucidating the mechanisms of Cu accumulation so as to facilitate the development of strategies to inhibit Cu accumulation in rice grain grown in contaminated soils. Using synchrotron-based X-ray microfluorescence and X-ray absorption spectroscopy, we investigated the distribution patterns and speciation of Cu in rice roots treated with 50 μM Cu for 7 days. A clear preferential localization of Cu in the meristematic zone was observed in root tips as compared with the elongation zone...
May 2017: Chemosphere
https://www.readbyqxmd.com/read/28225906/the-current-status-of-the-lutzomyia-longipalpis-diptera-psychodidae-phlebotominae-species-complex
#18
Nataly A Souza, Reginaldo P Brazil, Alejandra S Araki
Lutzomyia longipalpis s.l. is a complex of sibling species and is the principal vector of American visceral leishmaniasis. The present review summarises the diversity of efforts that have been undertaken to elucidate the number of unnamed species in this species complex and the phylogenetic relationships among them. A wide variety of evidence, including chemical, behavioral and molecular traits, suggests very recent speciation events and complex population structure in this group. Although significant advances have been achieved to date, differential vector capacity and the correlation between structure of parasite and vector populations have yet to be elucidated...
March 2017: Memórias do Instituto Oswaldo Cruz
https://www.readbyqxmd.com/read/28225102/stability-of-reverse-micelles-in-rare-earth-separation-a-chemical-model-based-on-a-molecular-approach
#19
Yushu Chen, Magali Duvail, Philippe Guilbaud, Jean-François Dufrêche
Molecular complexes formed in the organic phase during solvent extraction may self-assemble as reverse micelles, and therefore induce a supramolecular organization of this phase. In most of the cases, water molecules play an essential role in the organization of this non polar medium. The aim of this work is to investigate the speciation of the aggregates formed in the organic phase during solvent extraction, and especially to assess their stability as a function of the number of water molecules included in their polar core...
February 22, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28224666/refinement-and-cross-validation-of-nickel-bioavailability-in-pnec-pro-a-regulatory-tool-for-site-specific-risk-assessment-of-metals-in-surface-water
#20
Anja J Verschoor, Martina G Vijver, Jos P M Vink
The European Water Framework Directive prescribes that the environmental quality standards for nickel in surface waters should be based on bioavailable concentrations. Biotic ligand models (BLMs) are powerful tools to account for site-specific bioavailability within risk assessments. Several BLMs and simplified tools are available. For nickel, most of them are based on the same toxicity dataset and chemical speciation methodology as laid down in the 2008 European Union Environmental-Risk Assessment Report (RAR)...
February 22, 2017: Environmental Toxicology and Chemistry
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