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Chemical speciation

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 micro focused 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...
April 20, 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
E D Swanner, T Bayer, W Wu, L Hao, M Obst, A Sundman, J M Byrne, F M Michel, I C Kleinhanns, A Kappler, R Schoenberg
In this study, we couple iron isotope analysis to microscopic and mineralogical investigation of iron speciation during circumneutral Fe(II) oxidation and Fe(III) precipitation with photosynthetically produced oxygen. In the presence of the cyanobacterium Synechococcus PCC 7002, aqueous Fe(II) (Fe(II)aq) is oxidized and precipitated as amorphous Fe(III) oxyhydroxide minerals (iron precipitates, Feppt), with distinct isotopic fractionation (ε(56)Fe) values determined from fitting the δ(56)Fe(II)aq (1.79‰ and 2...
April 21, 2017: Environmental Science & Technology
Greta Hultqvist, Emma Åberg, Carlo Camilloni, Gustav N Sundell, Eva Andersson, Jakob Dogan, Celestine N Chi, Michele Vendruscolo, Per Jemth
Protein-protein interactions involving intrinsically disordered proteins are important for cellular function and common in all organisms. However, it is not clear how such interactions emerge and evolve on a molecular level. We performed phylogenetic reconstruction, resurrection and biophysical characterization of two interacting disordered protein domains, CID and NCBD. CID appeared after the divergence of protostomes and deuterostomes 450-600 million years ago, while NCBD was present in the protostome/deuterostome ancestor...
April 11, 2017: ELife
Robert M Hoffman
BACKGROUND: It has been known for more than 100 years that aneuploidy is an essence of cancer. The question is what keeps the genome stable, thereby preventing aneuploidy. For the past 25 years, it has been proposed that p53 is the "guardian of the genome." However, it has been shown that inactivation of p53 does not cause aneuploidy. Another essence of cancer is global DNA hypomethylation, which causes destabilization of the genome and subsequent aneupoloidy. Yet, another essence of cancer is excessive use of methionine, resulting in methionine dependence...
2017: Molecular Cytogenetics
Keila Martín-Betancor, Sonia Aguado, Ismael Rodea-Palomares, Miguel Tamayo-Belda, Francisco Leganés, Roberto Rosal, Francisca Fernández-Piñas
In the present study, the biocidal activity of three different metal organic frameworks (MOFs) based on Co (Co-SIM1), Zn (Zn-SIM1) and Ag (Ag-TAZ) has been evaluated towards one green alga and two cyanobacteria. These organisms are present in fresh- and seawater and take part in the early stages of the biofouling process. The biocidal activity of these materials was evaluated by measuring chlorophyll a concentration and by inhibition zone testing. After 24h of exposure the three different MOFs caused >50% of chlorophyll a concentration inhibition towards both cyanobacteria, however, although the green alga presented a great sensitivity for Ag-TAZ (reaching 90% of chlorophyll a concentration inhibition), it was much more resistant to the rest of MOFs...
April 7, 2017: Science of the Total Environment
Can Peng, Yuhui Ma, Yayun Ding, Xiao He, Peng Zhang, Tu Lan, Dongqi Wang, Zhaohui Zhang, Zhiyong Zhang
Thorium (Th) is a natural radioactive element present in the environment and has the potential to be used as a nuclear fuel. Relatively little is known about the influence and toxicity of Th in the environment. In the present study, the toxicity of Th to the green algae Chlorella pyrenoidosa (C. pyrenoidosa) was evaluated by algal growth inhibition, biochemical assays and morphologic observations. In the cultural medium (OECD TG 201), Th(NO₃)₄ was transformed to amorphous precipitation of Th(OH)₄ due to hydrolysis...
April 10, 2017: International Journal of Molecular Sciences
Liyakat Hamid Mujawar, Muhammad Imtiaz Rashid, Zulfiqar Ahmad Rehan, Talal Almeelbi, Jalal Mohammad Basahi, Mohammad Soror El-Shahawi
An optical assay for the rapid determination and chemical speciation of Fe(2+)/Fe(3+) species has been proposed for the first time on a polyether sulfone (PES) membrane platform. The small pore size and low wettability (θ ∼82°) of the membrane disallowed the dissipation of analyte droplets on the surface, thus localizing it onto nanoliter arrayed 1,10-phenanthroline spots. Under optimized conditions and within ∼5 min, an acceptable limit of detection (0.1 μg mL(-1)) and linear dynamic range (1 - 100 μg mL(-1)) were achieved...
2017: Analytical Sciences: the International Journal of the Japan Society for Analytical Chemistry
Zong-Ling Ren, Yann Sivry, Mickaël Tharaud, Laure Cordier, Yongtao Li, Jun Dai, Marc F Benedetti
Correct characterization of metal speciation and reactivity is a prerequisite for the risk assessment and remedial activity management of contaminated soil. To better understand the intrinsic reactivity of Pb and Zn, nine heavily and poorly contaminated soils were investigated using the combined approaches of chemical extractions, multi-element stable isotopic dilution (ID) method, and multi-surface modelling. The ID results show that 0.1-38% of total Pb and 3-45% of total Zn in the studied soils are isotopically exchangeable after a 3-day equilibration...
April 6, 2017: Environmental Pollution
Dominika Saniewska, M Bełdowska
Mercury is one of the most hazardous elements. Its transformation and transport in the environment strongly depend on its chemical form. The information about Hg form is also important for understanding the bioavailability as well as toxicity of this element. There are many methods for Hg speciation but most of them are expensive and time consuming. Therefore the aim of this research was to develop a simple thermo-desorption method for mercury fractionation in soil and sediment samples using a direct mercury analyser...
June 1, 2017: Talanta
Jun Meng, Lu Wang, Libin Zhong, Xingmei Liu, Philip C Brookes, Jianming Xu, Hongjin Chen
The intensive and unregulated application of feed additives to commercial pig foods has resulted in high levels of Cu and Zn in pig manure. The aim of this study was to assess the impacts of composting and pyrolysis processes on the bioavailability and chemical speciation of Cu and Zn in pig manure products by single and sequential extractions, and to compare metal bioavailability in composts and biochar-amended soils in incubation experiments. Composting and pyrolysis processes can convert exchangeable and carbonate-bound Cu and Zn to organic matter and residual fractions, and significantly reduce the potential availability of metals in composts and biochars...
April 3, 2017: Chemosphere
Paige Presler-Jur, Prakash Doraiswamy, Oki Hammond, Joann Rice
Black carbon (BC) or elemental carbon (EC) is a by-product of incomplete fuel combustion, and contributes adversely to human health, visibility, and climate impacts. Previous studies have examined non-destructive techniques for particle light attenuation measurements on Teflon(®) filters to estimate BC. The incorporation of an inline Magee Scientific OT21 Transmissometer into the MTL AH-225 robotic weighing system provides the opportunity to perform optical transmission measurements on Teflon(®) filters at the same time as the gravimetric mass measurement...
April 5, 2017: Journal of the Air & Waste Management Association
Safaa A Kadhum, Mohd Yusoff Ishak, Syaizwan Zahmir Zulkifli, Rohasliney Binti Hashim
The present study applied the use of sequential extraction technique and simple bioaccessibility extraction test to investigate the bioavailable fractions and the human bioaccessible concentration of metals collected from nine stations in surface sediment of the Bernam River. The concentrations of total and bioaccessible metals from different stations were in the range of 0.30-1.43 μg g(-1) and 0.04-0.14 μg g(-1) for total cadmium and bioaccessibility of cadmium, respectively, 6.20-288 μg kg(-1) and 2...
April 4, 2017: Environmental Science and Pollution Research International
Sara A Thomas, Jean-François Gaillard
The bacterial uptake of mercury(II), Hg(II), is believed to be energy-dependent and is enhanced by cysteine in diverse species of bacteria under aerobic and anaerobic conditions. To gain insight into this Hg(II) biouptake pathway, we have employed X-ray absorption spectroscopy (XAS) to investigate the relationship between exogenous cysteine, cellular metabolism, cellular localization, and Hg(II) coordination in aerobically respiring Escherichia coli (E. coli). We show that cells harvested in exponential growth phase consistently display mixtures of 2-fold and 4-fold Hg(II) coordination to sulfur (Hg-S2 and Hg-S4), with added cysteine enhancing Hg-S4 formation...
April 7, 2017: Environmental Science & Technology
T Pardo, M P Bernal, R Clemente
Phytostabilisation strategies have proven to be an efficient remediation option for mine tailings, but the adequate plant species and amendments have to be carefully selected. A remediation experiment was carried out at the semi-field level in tailings (pH 3.2, ≈1100, 4700 and 5000 mg kg(-1) of As, Pb and Zn, respectively) from the mining district of La Unión-Cartagena (SE Spain). A red mud derivative (Fe/Al oxides), its combination with compost, and hydrated lime (Ca hydroxide) were applied in field plots of 0...
March 21, 2017: Chemosphere
Muhammad Shahid, Saliha Shamshad, Marina Rafiq, Sana Khalid, Irshad Bibi, Nabeel Khan Niazi, Camille Dumat, Muhammad Imtiaz Rashid
Chromium (Cr) is a potentially toxic heavy metal which does not have any essential metabolic function in plants. Various past and recent studies highlight the biogeochemistry of Cr in the soil-plant system. This review traces a plausible link among Cr speciation, bioavailability, phytouptake, phytotoxicity and detoxification based on available data, especially published from 2010 to 2016. Chromium occurs in different chemical forms (primarily as chromite (Cr(III)) and chromate (Cr(VI)) in soil which vary markedly in term of their biogeochemical behavior...
March 24, 2017: Chemosphere
Jian Yang, Shexia Ma, Bo Gao, Xiaoying Li, Yanjun Zhang, Jing Cai, Mei Li, Ling'ai Yao, Bo Huang, Mei Zheng
In order to accurately apportion the many distinct types of individual particles observed, it is necessary to characterize fingerprints of individual particles emitted directly from known sources. In this study, single particle mass spectral signatures from vehicle exhaust particles in a tunnel were performed. These data were used to evaluate particle signatures in a real-world PM2.5 apportionment study. The dominant chemical type originating from average positive and negative mass spectra for vehicle exhaust particles are EC species...
March 24, 2017: Science of the Total Environment
Li Jian, Yan Chongling, Du Daolin, Lu Haoliang, Liu Jingchun
Avicennia marina is a high Cd tolerant species in the mangrove wetlands. A hydroponic experiment was carried out to research the accumulation and chemical form distribution of Cd in the tissues of A. marina under different concentration and time of Cd stress. It was found that the concentrations of Cd in plant tissues followed the order of root> stem>leaf. The data suggested that root activity decreased, Cd accumulation ability weakened in roots and the Translocation Factor increased in stems and leaves with the increase of stress time...
March 27, 2017: International Journal of Phytoremediation
Man Jae Kwon, Maxim I Boyanov, Jung-Seok Yang, Seunghak Lee, Yun Ho Hwang, Ju Yeon Lee, Bhoopesh Mishra, Kenneth M Kemner
Zinc contamination in near- and sub-surface environments is a serious threat to many ecosystems and to public health. Sufficient understanding of Zn speciation and transport mechanisms is therefore critical to evaluating its risk to the environment and to developing remediation strategies. The geochemical and mineralogical characteristics of contaminated soils in the vicinity of a Zn ore transportation route were thoroughly investigated using a variety of analytical techniques (sequential extraction, XRF, XRD, SEM, and XAFS)...
March 24, 2017: Environmental Pollution
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