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Arsenic migration to deep groundwater in Bangladesh influenced by adsorption and water demand

Arsenic migration to deep groundwater in Bangladesh influenced by adsorption and water demand

Nature Geoscience 4, 793 (2011).
doi:10.1038/ngeo1283

Authors: K. A. Radloff, Y. Zheng, H. A. Michael, M. Stute, B. C. Bostick, I. Mihajlov, M. Bounds, M. R. Huq, I. Choudhury, M. W. Rahman, P. Schlosser, K. M. Ahmed & A. van Geen

from Nature Geoscience – Issue – nature.com science feeds http://www.nature.com/ngeo/journal/v4/n11/full/ngeo1283.html

Conformation and internal motions of dimethyl sulfate: a microwave spectroscopy study

Publication year: 2011
Source: Chemical Physics Letters, Available online 15 October 2011
Laura B. Favero, Luca Evangelisti, Gang Feng, Lorenzo Spada, Walther Caminati
The rotational spectra of five isotopologues of dimethyl sulfate have been assigned by pulsed-jet Fourier-transform microwave spectroscopy. The global minimum configuration has aC2symmetry, with the two methyl groups nearly trans with respect to the two sulphonic oxygen atoms. The internal rotations of the two methyl groups split each transition into several components line, allowing for the determination of accurate values of theV3barrier height to internal rotation and of the orientation of the methyl groups with respect to the principal axis system. The geometry of the molecular skeleton is fully determined.

Graphical abstract

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Highlights

► The global minimum configuration of dimethylsulfate has aC2symmetry. ► The internal rotations of the two methyl groups split each transition into quartets. ► The internal rotations split each transition into quintets for asymmetrically substituted species. ► The structure of the heavy atoms skeleton is fully determined.

from ScienceDirect Publication: Chemical Physics Letters http://www.sciencedirect.com/science?_ob=GatewayURL&_origin=IRSSCONTENT&_method=citationSearch&_piikey=S0009261411012747&_version=1&md5=d17f77957c74a5cfaf1598a7c26e1368

Computational characterization of the HOMO-2 photoemission intensity oscillations in C60

Publication year: 2011
Source: Chemical Physics Letters, Available online 10 October 2011
Daniele Toffoli, Mauro Stener, Giovanna Fronzoni, Piero Decleva
We have calculated the photoionization cross section of the HOMO, HOMO-1 and HOMO-2 photoemission bands of C60from threshold up to 250 eV of photon energy. The calculated HOMO-2/HOMO-1 intensity ratio is in excellent agreement with recent experimental data. The computational method uses a multicentric expansion of the scattering wave function and a density functional theory (DFT) Hamiltonian. Time dependent DFT calculations suggest that the oscillatory phenomenon is essentially of single particle nature. An interpretation of the experimental findings in terms of the σ-πsymmetries of the ionized orbitals is provided.

Graphical abstract

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Highlights

► Computational study of the HOMO-2 photoemission intensity oscillations in C60. ► DFT and TDDFT results are in excellent agreement with recent experimental data. ► An interpretation of the oscillations in the HOMO-2 cross section is provided.

from ScienceDirect Publication: Chemical Physics Letters http://www.sciencedirect.com/science?_ob=GatewayURL&_origin=IRSSCONTENT&_method=citationSearch&_piikey=S0009261411012589&_version=1&md5=badb8b0f4dce56f947091b8e49905fb7

Comparative survey of potential nitrate and sulfate reduction rates in aquatic sediments

Publication year: 2011
Source: Geochimica et Cosmochimica Acta, Available online 28 October 2011
Anniet Laverman, Céline Pallud, Jeffrey Abell, Philippe Van Cappellen
Nitrate and sulfate are two major terminal electron acceptors of anaerobic respiration in nearshore sediments. Potential nitrate and sulfate reduction rates (NRR and SRR) were determined on surficial sediments sampled at 14 sites representing a wide range of shallow-water depositional environments. The rates were obtained by supplying undisturbed slices of sediments with nitrate, sulfate or both using a flow-through reactor technique. No external electron donor was added to the sediments. The results indicate that all studied sediments harbored viable and coexisting nitrate- and sulfate-reducing communities, which were able to instantaneously consume the electron acceptors supplied to the reactors. On average, NRR exceeded SRR by about one order of magnitude (309 ± 180 nmol NO3cmhversus 37 ± 29 nmol SO4cmh). The NRR:SRR molar ratio, however, varied significantly from site to site, with values ranging from 1.7 to 59. Nitrite production, indicative of incomplete nitrate reduction, was observed in all studied sediments and, on average, accounted for 45% of NRR (range 3–80%). Production of sulfate under nitrate-reducing conditions was observed in 10 out of 14 of the studied sediments, suggesting a common occurrence of sulfide oxidation coupled to nitrate reduction. Oxidation of sulfide accounted for 0 to 40% of NRR in the nitrate-only experiments. When both electron acceptors were supplied simultaneously, net sulfate consumption decreased on average by 45%. The effect of nitrate on SRR was highly variable, however, ranging from near complete inhibition to a 25% enhancement of SRR. Overall, the results of this study point to the need to critically reassess the model formulations used to represent anaerobic respiration processes and their interactions in early diagenetic models.

from ScienceDirect Publication: Geochimica et Cosmochimica Acta http://www.sciencedirect.com/science?_ob=GatewayURL&_origin=IRSSCONTENT&_method=citationSearch&_piikey=S001670371100620X&_version=1&md5=8ea2a40b2b6449690d6e3d7d7e60a424

Correlation Equation for Predicting Attachment Efficiency (α) of Organic Matter-Colloid Complexes in Unsaturated Porous Media

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Environmental Science & Technology
DOI: 10.1021/es2023829

from Environmental Science & Technology: Latest Articles (ACS Publications) http://pubs.acs.org/doi/abs/10.1021/es2023829

Trace metal pollution in China

Publication year: 2011
Source: Science of The Total Environment, Available online 26 October 2011
Xiang-dong Li, Wen-xiong Wang, Yong-guan Zhu

from ScienceDirect Publication: Science of The Total Environment http://www.sciencedirect.com/science?_ob=GatewayURL&_origin=IRSSCONTENT&_method=citationSearch&_piikey=S0048969711011582&_version=1&md5=e2f28812a2f2f9cc68ac93642202bab2

Characterization of main sulfur source of wood-degrading basidiomycetes by S K-edge X-ray absorption near edge spectroscopy (XANES)

Publication year: 2011
Source: International Biodeterioration & Biodegradation, Volume 65, Issue 8, December 2011, Pages 1215-1223
Achim Schmalenberger, Wolfgang Pritzkow, Jesus J. Ojeda, Matthias Noll
The main wood degraders in aerobic terrestrial ecosystems belong to the white- and brown-rot fungi, where their biomass can be created on wood decay only. However, total sulfur (S) concentration in wood is very low and only little is known about the different sulfur compounds in wood today. Sulfur-starved brown-rot fungiGloeophyllum trabeumandOligoporus placentawere incubated on sterilized pine wood blocks whereasLentinus cyathiformisand the white-rot fungiTrametes versicolorwere incubated on sterilized beech wood blocks. After 19 weeks of incubation, the S oxidation status was analyzed in wood, in degraded wood, and in biomass of wood-degrading fungi by synchrotron based S K-edge XANES, and total S and sulfate were quantified. Total sulfur and sulfate content in pine wood blocks were approximately 50 and 1 μg g, respectively, while in beech wood approximately 100 and 20 μg gwere found, respectively. Sulfur in beech was dominated by sulfate-esters. In contrast, pine wood also contained larger amounts of reduced S. Three out of four selected fungi caused a reduction of the S oxidation state in wood from oxidized S (sulfate-ester, sulfate) to intermediate S (sulfonate, sulfoxide) or reduced S (thiols, e.g., proteins, peptides, enzyme cofactors). OnlyO. placentashifted thiol to sulfonate. Growth experiments of these fungi on selective minimal media showed that in particular cysteine (thiol), sulfonates, and sulfate enhanced total mycelium growth. Consequently, wood-degrading fungi were able to utilize a large variety of different wood S sources for growth but preferentially transformed in vivo sulfate-esters and thiol into biomass structures.

Highlights

► Sulfur utilization of brown- and white-rot fungi were investigated. ► Changes in the S oxidation state were examined by S K-edge XANES. ► Three out of four fungi caused a reduction of the S oxidation state in wood. ► Wood-degrading fungi transformed wood S sourcesin vivoto sulfate-esters and thiol.

from ScienceDirect Publication: Chemical Geology http://www.sciencedirect.com/science?_ob=GatewayURL&_origin=IRSSCONTENT&_method=citationSearch&_piikey=S0964830511002010&_version=1&md5=2a29a1e525fb7f74bb5b776306b40bea

Electrochemical Carbon Nanotube Filter Oxidative Performance as a Function of Surface Chemistry

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Environmental Science & Technology
DOI: 10.1021/es202271z

from Environmental Science & Technology: Latest Articles (ACS Publications) http://pubs.acs.org/doi/abs/10.1021/es202271z