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Chemical speciation

Yang Hua, Shuxiao Wang, Jingkun Jiang, Wei Zhou, Qingcheng Xu, Xiaoxiao Li, Baoxian Liu, Dawei Zhang, Mei Zheng
Annual average PM2.5 concentration in south Beijing was 30% and 40% higher than the whole Beijing city in 2015 and 2016, respectively. Few studies have been conducted to investigate what leads to the characteristics and sources of heavy pollution in the south rural area of Beijing. This study conducted an observation with Aerosol Chemical Speciation Monitor (ACSM) at a southwest rural site (Liulihe) in Beijing during 2014-2016, to investigate the seasonal aerosol characteristics and their sources. Positive matrix factorization (PMF) algorithm was used to distinguish different components of organic aerosol measured by ACSM...
January 17, 2018: Science of the Total Environment
Riccardo Fornaroli, Alessio Ippolito, Mari J Tolkkinen, Heikki Mykrä, Timo Muotka, Laurie S Balistrieri, Travis S Schmidt
One of the primary goals of biological assessment of streams is to identify which of a suite of chemical stressors is limiting their ecological potential. Elevated metal concentrations in streams are often associated with low pH, yet the effects of these two potentially limiting factors of freshwater biodiversity are rarely considered to interact beyond the effects of pH on metal speciation. Using a dataset from two continents, a biogeochemical model of the toxicity of metal mixtures (Al, Cd, Cu, Pb, Zn) and quantile regression, we addressed the relative importance of both pH and metals as limiting factors for macroinvertebrate communities...
January 16, 2018: Environmental Pollution
Eshani Hettiarachchi, Omar Hurab, Gayan Rubasinghege
Over the last several decades, iron has been identified as a limiting nutrient in about half of the world's oceans. Its most significant source is identified as deposited iron-containing mineral dust that has been processed during atmospheric transportation. The current work focuses on chemical and photochemical processing of iron-containing mineral dust particles in the presence of nitric acid, and an organic pollutant dimethyl sulfide under atmospherically relevant conditions. More importantly, ilmenite (FeTiO3) is evaluated as a proxy for the iron-containing mineral dust...
January 16, 2018: Journal of Physical Chemistry. A
Rixiang Huang, Bei Zhang, Emily M Saad, Ellery D Ingall, Yuanzhi Tang
Thermal and hydrothermal treatments are promising techniques for sewage sludge management that can potentially facilitate safe waste disposal, energy recovery, and nutrient recovery/recycling. Content and speciation of heavy metals in the treatment products affect the potential environmental risks upon sludge disposal and/or application of the treatment products. Therefore, it is important to study the speciation transformation of heavy metals and the effects of treatment conditions. By combining synchrotron X-ray spectroscopy/microscopy analysis and sequential chemical extraction, this study systematically characterized the speciation of Zn and Cu in municipal sewage sludges and their chars derived from pyrolysis (a representative thermal treatment technique) and hydrothermal carbonization (HTC; a representative hydrothermal treatment technique)...
January 4, 2018: Water Research
Elizabeth K Coward, Tsutomu Ohno, Alain F Plante
Iron (Fe)-bearing mineral phases contribute disproportionately to adsorption of soil organic matter (SOM), due to their elevated chemical reactivity and specific surface area (SSA). However, the spectrum of Fe solid-phase speciation present in oxidation-reduction-active soils challenges analysis of SOM-mineral interactions and may induce differential molecular fractionation of dissolved organic matter (DOM). This work used paired selective dissolution experiments and batch sorption of post-extraction residues to 1) quantify the contributions of Fe-bearing minerals of varying crystallinity to DOM sorption, and 2) characterize molecular fractionation using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS)...
January 12, 2018: Environmental Science & Technology
Jiao-Feng Gu, Hang Zhou, Wen-Tao Yang, Pei-Qin Peng, Ping Zhang, Min Zeng, Bo-Han Liao
A pot experiment was carried out to investigate the remediation of paddy soils contaminated with both Cd and As. The effects of a soil additive (HZB: hydroxyapatite + zeolite + biochar) on the chemical speciation of Cd and As in the soil and on the accumulation and translocation of these two elements in rice plants were studied. The application of HZB decreased the concentration of acid-extractable Cd in the soil by 7.3-32.6% by promoting the transformation of soil Cd from soluble to insoluble species; as a result, the concentration of organically bound Cd in the soil increased by 6...
January 9, 2018: Environmental Science and Pollution Research International
Jordan G Hamilton, Jay Grosskleg, David Hilger, Kris Bradshaw, Trevor Carlson, Steven D Siciliano, Derek Peak
Adsorption and precipitation reactions often dictate the availability of phosphorus in soil environments. Tripolyphosphate (TPP) is considered a form of slow release P fertilizer in P limited soils, however, investigations of the chemical fate of TPP in soils are limited. It has been proposed that TPP rapidly hydrolyzes in the soil solution before adsorbing or precipitating with soil surfaces, but in model systems, TPP also adsorbs rapidly onto mineral surfaces. To study the adsorption behavior of TPP in calcareous soils, a short-term (48 h) TPP spike was performed under laboratory conditions...
January 8, 2018: Geochemical Transactions
Khosro Ashrafi, Reza Fallah, Mostafa Hadei, Marayam Yarahmadi, Abbas Shahsavani
There is a compelling need for apportionment of pollutants' sources to facilitate their reduction through proper management plans. The present study was designed to determine the contribution of each possible source of total suspended particles in Ahvaz's ambient air using positive matrix factorization (PMF), chemical mass balance (CMB), and the SPECIATE database. The sampling program undertaken followed EPA's guidelines and finally resulted in 74 samples. The concentration of 33 elemental and 10 ionic species were measured during a whole year...
January 8, 2018: Archives of Environmental Contamination and Toxicology
Mingwei Yang, Yuzhen Sun, Xiaobin Zhang, Bruce McCord, Anthony J McGoron, Alexander Mebel, Yong Cai
Surface enhanced Raman scattering (SERS) has great potential as an alternative tool for arsenic speciation in biological matrices. SERS measurements have advantages over other techniques due to its ability to maintain the integrity of arsenic species and its minimal requirements for sample preparation. Up to now, very few Raman spectra of arsenic compounds have been reported. This is particularly true for thiolated arsenicals, which have recently been found to be widely present in humans. The lack of data for Raman spectra in arsenic speciation hampers the development of new tools using SERS...
March 1, 2018: Talanta
Gabrijel Ondrasek, Zed Rengel, Davor Romic
Naturally-occurring highly-complexed and polymerised organics such as humic acids (HA), due to their large negative charge, play a crucial role in biogeochemistry of trace metals (TM). Toxic (Cd) as well as essential (Zn, Cu, Mn) TM bind strongly to HA, but how these organo-metalic forms influence metal uptake by plants is poorly understood. A solution culture study was conducted to characterize the effects of different concentrations of HA (0-225mg/L) on the growth and element uptake/distribution in roots, shoots and hypocotyls of radish (Raphanus sativus L...
January 3, 2018: Ecotoxicology and Environmental Safety
Maja Arsic, Peter R Teasdale, David Thomas Welsh, Scott G Johnston, Edward D Burton, Kerstin Hockmann, William Walpole Bennett
Antimony (Sb) and arsenic (As) are priority environmental contaminants that often co-occur at mining-impacted sites. Despite their chemical similarities, Sb mobility in waterlogged sediments is poorly understood in comparison to As, particularly across the sediment-water interface (SWI) where changes can occur at the millimetre scale. Combined diffusive gradients in thin films (DGT) and diffusive equilibration in thin films (DET) techniques provided a high resolution, in situ comparison between Sb, As and iron (Fe) speciation and mobility across the SWI in contaminated freshwater wetland sediment mesocosms under an oxic-anoxic-oxic transition...
January 5, 2018: Environmental Science & Technology
Shrutika L Wadgaonkar, Yarlagadda V Nancharaiah, Giovanni Esposito, Piet N L Lens
Selenium concentrations in the soil environment are directly linked to its transfer in the food chain, eventually causing either deficiency or toxicity associated with several physiological dysfunctions in animals and humans. Selenium bioavailability depends on its speciation in the soil environment, which is mainly influenced by the prevailing pH, redox potential, and organic matter content of the soil. The selenium cycle in the environment is primarily mediated through chemical and biological selenium transformations...
January 5, 2018: Critical Reviews in Biotechnology
Cerovac Andrea, Covelli Stefano, Emili Andrea, Pavoni Elena, Petranich Elisa, Gregorič Asta, Urbanc Janko, Zavagno Enrico, Zini Luca
This work aims at evaluating mercury (Hg) occurrence, spatial distribution and speciation in groundwater of the Isonzo/Soča River upper alluvial plain downstream from the Idrija Hg mine (Western Slovenia). Several wells and piezometers were sampled both in static and dynamic mode. Total (THg) and filtered (FHg) concentrations were generally higher in static (THg, 1.87-855 ng L-1; FHg, 0.20-13.61 ng L-1) than in dynamic mode (THg, 0.08-78.77 ng L-1; FHg, 0.28-6.65 ng L-1). The estimated background value accounts for 2-3 ng L-1...
December 19, 2017: Chemosphere
Jennifer Hellal, André Burnol, Aude Locatelli, Fabienne Battaglia-Brunet
Fate and speciation of trace elements (TEs), such as arsenic (As) and mercury (Hg), in aquifers are closely related to physio-chemical conditions, such as redox potential (Eh) and pH, but also to microbial activities that can play a direct or indirect role on speciation and/or mobility. Indeed, some bacteria can directly oxidize As(III) to As(V) or reduce As(V) to As(III). Likewise, bacteria are strongly involved in Hg cycling, either through its methylation, forming the neurotoxin monomethyl mercury, or through its reduction to elemental Hg°...
December 19, 2017: Journal of Visualized Experiments: JoVE
Pierre-Jean Superville, Anastasia Ivanovsky, Pratima Bhurtun, Jean Prygiel, Gabriel Billon
Electrolabile reduced manganese (II) has been monitored by voltammetry during two periods of one month in summer 2014 and at the end of winter 2015 in a small river (the Marque River) located in northern France and going through a suburban area with agricultural activities. Diel variations, evolution within the one-month periods and seasonal differences have been observed. Taking into consideration the multiple physical, biological and chemical reactions regulating manganese speciation in aquatic systems, it has been demonstrated that manganese speciation is probably controlled by the competition of two antagonist reactions: the photoreduction of manganese oxides (in broad sense and represented thereafter by MnOx) and the biotic oxidation of Mn(II)...
December 21, 2017: Science of the Total Environment
I M Ogunade, Y Jiang, A A Pech Cervantes, D H Kim, A S Oliveira, D Vyas, Z G Weinberg, K C Jeong, A T Adesogan
The first objective of this study was to examine effects of adding Escherichia coli O157:H7 with or without chemical or microbial additives on the bacterial diversity and composition of alfalfa silage. The second objective was to examine associations between the relative abundance of known and unknown bacterial species and indices of silage fermentation quality. Alfalfa forage was harvested at 54% dry matter, chopped to a theoretical length of cut of 19 mm, and ensiled in quadruplicate in laboratory silos for 100 d after the following treatments were applied: (1) distilled water (control); (2) 1 × 105 cfu/g of E...
December 20, 2017: Journal of Dairy Science
Tara N Tait, James C McGeer, D Scott Smith
Speciation of copper in marine systems strongly influences the ability of copper to cause toxicity. Natural organic matter (NOM) contains many binding sites which provides a protective effect on copper toxicity. The purpose of this study was to characterize copper binding with NOM using fluorescence quenching techniques. Fluorescence quenching of NOM with copper was performed on nine sea water samples. The resulting stability constants and binding capacities were consistent with literature values of marine NOM, showing strong binding with [Formula: see text] values from 7...
December 23, 2017: Bulletin of Environmental Contamination and Toxicology
Sarah E Crawford, Stephen Lofts, Karsten Liber
Assessment of uranium (U)-contaminated sediment is often hindered by the inability to accurately account for the physicochemical properties of sediment that modify U bioavailability. The goal of this research was to determine whether sediment-associated U bioavailability could be predicted over a wide range of conditions and sediment properties using simple regressions and a geochemical speciation model, the Windermere Humic Aqueous Model (WHAM7). Data from U-contaminated field sediment bioaccumulation tests, along with previously published bioaccumulation studies with U-spiked field and formulated sediments were used to examine the models...
December 13, 2017: Environmental Toxicology and Chemistry
Andreas Johannes, Damien Salomon, Gema Martinez-Criado, Markus Glaser, Alois Lugstein, Carsten Ronning
We introduce a method for directly imaging depletion layers in operando with elemental specificity and chemical speciation at sub-100 nm spatial resolution applicable to today's three-dimensional electronic architectures. These typically contain complex, multicomponent designs consisting of epitaxial heterostructures, buried domains, or nanostructures with different shapes and sizes. Although the variety of devices is immense, they commonly rely on carrier separation in a built-in potential induced by composition or strain gradients...
December 2017: Science Advances
Astrid Avellan, John Stegemeier, Ke Gai, James G Dale, Heileen Hsu-Kim, Clément Levard, Dennis O'Rear, Thomas P Hoelen, Gregory V Lowry
Petroleum, natural gas, and natural gas condensate can contain low levels of mercury (Hg). The speciation of Hg can affect its behavior during processing, transport, and storage so efficient and safe management of Hg requires an understanding of its chemical form in oil, gas and byproducts. Here, X-ray absorption spectroscopy was used to determine the Hg speciation in samples of solid residues collected throughout the petroleum value chain including stabilized crude oil residues, sediments from separation tanks and condensate glycol dehydrators, distillation column pipe scale, and biosludge from wastewater treatment...
December 11, 2017: Environmental Science & Technology
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