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Chemical speciation

Juan Lin, Yufang Zhong, Hua Fan, Chaofeng Song, Chao Yu, Yue Gao, Xiong Xiong, Chenxi Wu, Jiantong Liu
In this work, sediments were treated with calcium nitrate, aluminum sulfate, ferric sulfate, and Phoslock®, respectively. The impact of treatments on internal phosphorus release, the abundance of nitrogen cycle-related functional genes, and the growth of submerged macrophytes were investigated. All treatments reduced total phosphorus (TP) and soluble reactive phosphorus (SRP) in interstitial water, and aluminum sulfate was most efficient. Aluminum sulfate also decreased TP and SRP in overlying water. Treatments significantly changed P speciations in the sediment...
October 20, 2016: Environmental Science and Pollution Research International
Haomiao Xu, Yongpeng Ma, Wenjun Huang, Jian Mei, Songjian Zhao, Zan Qu, Naiqiang Yan
Mercury temperature-programmed desorption (Hg-TPD) method was employed to clarify mercury species over Mn-based oxides. The elemental mercury (Hg(0)) removal mechanism over MnOx was ascribed to chemical-adsorption. HgO was the primary mercury chemical compound adsorbed on the surface of MnOx. Rare earth element (Ce), main group element (Sn) and transition metal elements (Zr and Fe) were chosen for the modification of MnOx. Hg-TPD results indicated that the binding strength of mercury on these binary oxides followed the order of Sn-MnOx<Ce-MnOx∼MnOx<Fe-MnOx<Zr-MnOx...
September 14, 2016: Journal of Hazardous Materials
Reijiro Nogami, Haruo Nishida, Dang Diem Hong, Minato Wakisaka
A solubility diagram was employed to understand growth promotion of Arthrospira (Spirulina) platensis by steelmaking slag (SMS). The growth promotion effect of 112 % of freshwater microalga A. platensis was obtained using 5 g/L SMS. However, metabolites, such as pigments, and protein content of A. platensis were not significantly affected. Several metals dissolved in Spirulina-Ogawa-Terui medium were detected by inductively coupled plasma atomic emission spectrometry just after the addition of SMS. The solubility diagram provides information on the chemical speciation of metal elements based on pH and concentration...
December 2016: AMB Express
Raewyn M Town, Herman P Van Leeuwen
The Counterion Condensation-Donnan (CCD) model for the electrostatic features of soft, charged nanoparticles (NPs) is applied to the determination of the intrinsic stability constants, <i>K</i><sub>int</sub>, for inner-sphere Cd(II) and Cu(II) complexes with humic acid NPs. The novel CCD model accounts for the strong ion condensation potential for higher valency counterions within the intraparticulate double layer zone of the soft NP. The approach offers new insights into the intrinsic heterogeneity of the HA complexes, as revealed by the intraparticulate speciation as a function of the true degree of inner-sphere complexation, <i>θ<sub></i>M<i></sub></i>...
October 10, 2016: Journal of Physical Chemistry. A
Aysha Masood Khan, Nor Kartini Abu Bakar, Ahmad Farid Abu Bakar, Muhammad Aqeel Ashraf
Rare earths (RE), chemically uniform group of elements due to similar physicochemical behavior, are termed as lanthanides. Natural occurrence depends on the geological circumstances and has been of long interest for geologist as tools for further scientific research into the region of ores, rocks, and oceanic water. The review paper mainly focuses to provide scientific literature about rare earth elements (REEs) with potential environmental and health effects in understanding the research. This is the initial review of RE speciation and bioavailability with current initiative toward development needs and research perceptive...
October 10, 2016: Environmental Science and Pollution Research International
Elizabeth S Gilchrist, David A Healy, Virginia N Morris, Jeremy D Glennon
This paper is a review of ion chromatographic (IC) separations of inorganic oxyhalide disinfection by-products (DBPs) in water and beverages. The review outlines the chemical mechanisms of formation, regulation of maximum allowable levels, chromatographic column selection and speciation. In addition, this review highlights the application of IC coupled to mass spectrometry (MS) for trace and elemental composition analysis of oxyhalides, along with the analytical considerations associated to enable sensitive analysis...
October 26, 2016: Analytica Chimica Acta
Emeline Boni Campanini, Reinaldo Alves de Brito
BACKGROUND: Odorant-binding proteins (OBPs) are of great importance for survival and reproduction since they participate in initial steps of the olfactory signal transduction cascade, solubilizing and transporting chemical signals to the olfactory receptors. A comparative analysis of OBPs between closely related species may help explain how these genes evolve and are maintained under natural selection and how differences in these proteins can affect olfactory responses. We studied OBP genes in the closely related species Anastrepha fraterculus and A...
October 7, 2016: BMC Evolutionary Biology
Yu-Ling Wei, Hsi-Chih Wang, Yen-Shiun Peng
Cr speciation in Cr-sorbing washed incinerator fly ash after heating up to 1100°C is temperature dependent. Higher temperature leads to greater level of chemical reduction of Cr(VI) that is considerably more toxic than Cr(III). Most Cr(VI) sorbed washed incinerator fly ash is effectively transformed into Cr(III) after heating to 1100°C for 2 hr, as indicated by the disappearance of hexavalent pre-edge peak of Cr K-edge XANES spectrum. After heating the Cr-sorbing incinerator fly ash to 100(o)C and 500(o)C for 2 hr, water soluble CaCrO4 is determined to be the principal Cr species due to the chemical reaction between the sorbed Cr(VI) and CaO component of washed fly ash, based on the comparison between sample and reference XANES spectra...
October 6, 2016: Environmental Technology
Michael F Tweedle
The methodology and published work aimed at speciation of gadolinium based contrast agents in tissues is reviewed. The discussion focusses on the context of Gd deposited long term in tissue following administration of the contrast agents. Detection of Gd without identification of the chemical form detected is simple and straight forward using a variety of methods. Determination of the chemical form of Gd detected is far more complex and most method require inherently imperfect extraction steps that can alter the Gd chemical species detected...
September 30, 2016: Magnetic Resonance Imaging
Bingdi Cao, Weijun Zhang, Qiandi Wang, Yangrui Huang, Chenrui Meng, Dongsheng Wang
Chemical conditioning is one of the most important processes for improve the performance of sludge dewatering device. Aluminum salt coagulant has been widely used in wastewater and sludge treatment. It is generally accepted that pre-formed speciation of aluminum salt coagulants (ASC) has an important influence on coagulation/flocculation performance. In this study, the interaction mechanisms between sludge particles and aluminum salt coagulants with different speciation of hydroxy aluminum were investigated by characterizing the changes in morphological and EPS properties...
November 15, 2016: Water Research
Elżbieta Malinowska
The paper deals with effects of liming and different doses of municipal sewage sludge (5, 10, and 15 % of soil mass) on copper speciation in soil. In all samples, pH was determined together with total copper concentration, which was measured with the ICP-AES method. Concentration of copper chemical fractions was determined using the seven-step procedure of Zeien and Brümmer. In the soil treated with the highest dose of sludge (15 %), there was, compared to the control, a twofold increase in the concentration of copper and a threefold increase in the concentration of nitrogen...
October 2016: Environmental Monitoring and Assessment
Tatiane Morais Ferreira, Maria Cristina Forti, Clarice Umbelino de Freitas, Felipe Parra Nascimento, Washington Leite Junger, Nelson Gouveia
Various fractions of particulate matter have been associated with increased mortality and morbidity. The purpose of our study is to analyze the associations between concentrations of PM2.5, PM2.5-10, PM10 and their chemical constituents (soluble ions) with hospital admissions due to circulatory and respiratory diseases among the elderly in a medium-sized city in Brazil. A time series study was conducted using Poisson regression with generalized additive models adjusted for confounders. Statistically significant associations were identified between PM10 and PM2...
2016: International Journal of Environmental Research and Public Health
Xiongfei Xie, Daniel E Giammar, Zimeng Wang
Deterpmination of equilibrium constants describing chemical reactions in the aqueous phase and at solid-water interface relies on inverse modeling and parameter estimation. Although there are existing tools available, the steep learning curve prevents the wider community of environmental engineers and chemists to adopt those tools. Stemming from classical chemical equilibrium codes, MINEQL+ has been one of the most widely used chemical equilibrium software programs. We developed a spreadsheet-based tool, which we are calling MINFIT, that interacts with MINEQL+ to perform parameter estimations that optimize model fits to experimental data sets...
October 7, 2016: Environmental Science & Technology
Raphaël Bondu, Vincent Cloutier, Eric Rosa, Mostafa Benzaazoua
High arsenic concentrations occur in groundwater collected from a fractured crystalline bedrock aquifer in western Quebec (Canada). Sampling and analysis of water from 59 private wells reveal that more than half of the bedrock wells exceed the Canadian guideline value of 10μg/l for arsenic, whereas shallow wells in unconsolidated surficial deposits are not affected by the contamination. The weathering of arsenic-bearing sulfides present along the mineralized fault zone is considered to be the primary source of arsenic in groundwater...
September 17, 2016: Science of the Total Environment
Alan Lock, Dirk Wallschläger, Colin McMurdo, Laura Tyler, Nelson Belzile, Graeme Spiers
A sequential extraction procedure (SEP) for the speciation analysis of As(III) and As(V) in oxic and suboxic soils and sediments was validated using a natural lake sediment and three certified reference materials, as well as spike recoveries of As(III) and As(V). Many of the extraction steps have been previously validated making the procedure useful for comparisons to similar previous SEP studies. The novel aspect of this research is the validation for the SEP to maintain As(III) and As(V) species. The proposed five step extraction procedure includes the extraction agents (NH4)2SO4, NH4H2PO4, H3PO4 + NH2OH·HCl, oxalate + ascorbic acid (heated), and HNO3 + HCl + HF, targeting operationally defined easily exchangeable, strongly sorbed, amorphous Fe oxide bound, crystalline Fe oxide bound, and residual As fractions, respectively...
September 15, 2016: Environmental Pollution
Christian E Schlekat, Emily R Garman, Marnix Lu Vangheluwe, G Allen Burton
To assess nickel (Ni) toxicity and behavior in freshwater sediments, a large-scale laboratory and field sediment testing program was conducted. The program used an integrative testing strategy to generate scientifically based threshold values for Ni in sediments and to develop integrated equilibrium partitioning-based bioavailability models for assessing risks of Ni to benthic ecosystems. The sediment testing program was a multi-institutional collaboration that involved extensive laboratory testing, field validation of laboratory findings, characterization of Ni behavior in natural and laboratory conditions, and examination of solid phase Ni speciation in sediments...
October 2016: Integrated Environmental Assessment and Management
Xinshu Jiang, Zhe Wang, Yiyue Zhang, Fei Wang, Mijia Zhu, Jun Yao
Specific industrial application of dimethyl o-phthalate (DMP) in ore flotation has led to DMP-heavy metals combined pollution, which causes the abiotic degradation of DMP in the environment more complex. This study focused on the effect of Cu and Pb on photodegradation of DMP. The major mechanism of inhibiting effect of Cu and Pb on degradation of DMP involved their speciation and combination. It was found that the Cu (5 mg/L, I = 95.4%) and Pb (5 mg/L, I = 100%) could inhibit the photodegradation of DMP...
December 2016: Chemosphere
S Stiernström, O Wik, D Bendz
A new harmonized EU regulation for the classification of waste came into effect on 1st June 2015, in which the criteria and assessment methods for the classification of hazardous waste are harmonized with other internationally agreed-upon systems for hazard classification of chemicals (CLP). However, criteria and guidance for the assessment of ecotoxicological hazard (Hazard Property 14, HP14) are still lacking for waste classification. This paper have evaluated and compared two HP14 classification frameworks: (i) a calculation method (summation) for mixtures, and (ii) leaching tests...
September 14, 2016: Waste Management
Yuhui Ma, Jingkun Wang, Can Peng, Yayun Ding, Xiao He, Peng Zhang, Na Li, Tu Lan, Dongqi Wang, Zhaohui Zhang, Fuhong Sun, Haiqing Liao, Zhiyong Zhang
Cerium (Ce) and thorium (Th) are always thought to be chemically similar and have comparable toxic properties on living organisms. In the present study, the acute and chronic toxicity of these two elements to freshwater crustacean Daphnia magna were investigated in the modified reconstituted water (6mg/L KCl, 123mg/L MgSO4·7H2O, and 294mg/L CaCl2·2H2O in Milli-Q water, pH 7.8). It seemed that Ce and Th had comparable acute toxicity on Daphnia: 24/48h EC50 for Th and Ce were 7.3/4.7μM and 16.4/10.7μM, respectively...
September 14, 2016: Ecotoxicology and Environmental Safety
Simone M Pieber, Imad El Haddad, Jay G Slowik, Manjula R Canagaratna, John T Jayne, Stephen M Platt, Carlo Bozzetti, Kaspar R Daellenbach, Roman Fröhlich, Athanasia Vlachou, Felix Klein, Josef Dommen, Branka Miljevic, José L Jiménez, Douglas R Worsnop, Urs Baltensperger, André S H Prévôt
Aerodyne aerosol mass spectrometer (AMS) and Aerodyne aerosol chemical speciation monitor (ACSM) mass spectra are widely used to quantify organic aerosol (OA) elemental composition, oxidation state, and major environmental sources. The OA CO2(+) fragment is among the most important measurements for such analyses. Here, we show that a non-OA CO2(+) signal can arise from reactions on the particle vaporizer, ion chamber, or both, induced by thermal decomposition products of inorganic salts. In our tests (eight instruments, n = 29), ammonium nitrate (NH4NO3) causes a median CO2(+) interference signal of +3...
October 4, 2016: Environmental Science & Technology
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