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Environmental context: Cobalt is a technologically critical element due to its uses in the green energy transition, but its cycling is poorly constrained in surface environments. We determined the form of cobalt in naturally enriched soils and found that it is commonly associated with manganese as mixed oxide nanoparticles. These findings demonstrate that the behaviour of critical elements such as cobalt in the environment is in part governed at the nanoscale. Rationale: Cobalt (Co) faces increasing demand for use in batteries and alloys, but its environmental behaviour in terrestrial surface environments is poorly constrained. This study analyses cobalt regolith mineralogy and nanoparticulate phase transitions to address this knowledge gap. Methodology: We studied Co-enriched environments across six localities and four distinct deposit types in arid and semi-arid Australian regolith environments to analyse its environmental behaviour. We used a combination of single particle inductively coupled plasma–mass spectrometry (SP ICP-MS) and synchrotron X-ray techniques (fluorescence microscopy, X-ray flouresence microscopy and X-ray absorption spectroscopy). Results: We discovered the presence of Co oxide-based nanoparticles in soils surrounding cobalt-rich rocks at all of our studied locations, to our knowledge the first detection of terrestrial Co oxide-based nanoparticles. The extractable concentration of Co in the nanoparticles varied from 0.7 ng of nanoparticulate Co per gram of soil (ng Co g–1), up to 1390 ng Co g–1, the latter soil containing 1 × 109 extractable Co-based nanoparticles per gram of soil. Discussion: Nanoparticulate cobalt was typically closely associated with manganese (Mn) in the form of natural Co–Mn oxide phases, with only two of the studied locations not showing a close Co–Mn association. We discuss the environmental drivers that may facilitate formation of Co–Mn oxide nanoparticles. Our study suggests that Co may be more mobile in surface environments than previously thought, with Co–Mn oxide nanoparticles found around all four analysed types of Co-rich outcrops. Environmental context.  Cobalt is a technologically critical element due to its uses in the green energy transition, but its cycling is poorly constrained in surface environments. We determined the form of cobalt in naturally enriched soils and found that it is commonly associated with manganese as mixed oxide nanoparticles. These findings demonstrate that the behaviour of critical elements such as cobalt in the environment is in part governed at the nanoscale. (Photograph by O. P. Missen, 11 July 2022.) [ABSTRACT FROM AUTHOR]

A free energy-based conceptual theoretical framework from which the conditional equilibrium constant can be comprehensibly understood is presented. This constant is found to be a weighted geometric mean of the equilibrium constants of the reactions of all forms of the conditioned species under buffering conditions, where the weight is given by a function of their predominance in terms of their mole fractions. Once it is shown that this type of equilibrium constant can be easily deduced form free energy functions, it is shown how corrections for activity coefficient can be incorporated as well. The framework additionally permits to interpret side-reactions coefficients as free energy terms related to the chemical speciation of the system, allowing the use of the generalization of Hess' law to obtain conditional constants and a straightforward deduction of multiconditional equilibrium constants. Furthermore, different uses of the conditional constants along the actual literature are reviewed as well allowing to have a complete and updated panorama of the employment of this important concept in chemical and speciation analysis in many areas of research. [ABSTRACT FROM AUTHOR]

The interest of researchers on quantification of Pt, Pd and Rh in the environmental and food matrices is the consequence of the production of catalytic converters for car engines. Sensitization, mutagenic effects in bacterial and mammalian cells, and increased tumour incidence are the effects of Pt, Pd and Rh at high concentrations reported in medical and occupational researches while their effects at the low environmental concentrations have not been determined. Voltammetric techniques are very advantageous to quantify PGEs in environmental and food matrices due to their intrinsic sensitivity derived from the electrochemical pre‐concentration of the analyte at the electrode surface, the capability to distinguish between different redox species and/or labile from non‐labile metal complexes, with applications for metal speciation studies. The analysis of PGEs by spectrophotometric methods (atomic absorption, ICP‐MS, ICP‐OES, etc.) suffers from several practical problems. In this article we take into consideration the research concerning environmental and food matrices from 1996 to 2022. [ABSTRACT FROM AUTHOR]

In this article, we demonstrate the viability of highly monochromatic full-field X-ray absorption near edge structure based tomography using a laboratory-scale Johann-type X-ray absorption spectrometer utilising a conventional X-ray tube source. In this proof-of-concept, by using a phantom embedded with elemental Se, Na 2 SeO 3 , and Na 2 SeO 4 , we show that the three-dimensional distributions of Se in different oxidation states can be mapped and distinguished from the phantom matrix and each other with absorption edge contrast tomography. The presented method allows for volumetric analyses of chemical speciation in mm-scale samples using low-brilliance X-ray sources, and represents a new analytic tool for materials engineering and research in many fields including biology and chemistry. [ABSTRACT FROM AUTHOR]

Particulate matter (PM) pollution from coal combustion is a leading contributor to the influence of atmospheric visibility, photochemical smog, and even global climate. A drop tube furnace was employed to explore the effects of temperature and chemical speciation of mineral elements on PM formation during the combustion of Zhundong coal. Chemical fractionation analysis (CFA), X-ray fluorescence (XRF), and inductively coupled plasma-atomic emission spectrometry (ICP-AES) were used to investigate the chemical and physical characteristics of the solid samples. It can be indicated that the combustion of similarly sized coal particles yielded more PM10 when the combustion temperature was increased from 1000 to 1400 °C. Zhundong coal is fractionated with deionized water, ammonium acetate, and hydrochloric acid, and pulverized coal, after fractionation, is burned to study the influence of mineral elements with different occurrence forms, such as water-soluble mineral elements, exchangeable ion elements, hydrochloric acid soluble elements and acid-insoluble elements, on the formation of particles. The results show that water-soluble salts play an important role in forming ultrafine particles (PM0.2); Fe, Ca, and other elements in organic form are distributed in flue gas through evaporation during pulverized coal combustion. When the flue gas temperature decreases, PM1 is formed through homogeneous nucleation and heterogeneous condensation, resulting in the distribution of these two elements on PM1. Different fractionation methods do not significantly affect the distribution of Si and Al in the PM1–10 combustion process. [ABSTRACT FROM AUTHOR]

This review considers the use of filters to sample air in mining workplace environments for dust concentration measurement and subsequent analysis of hazardous contaminants, especially respirable crystalline silica (RCS) on filters compatible with wearable personal dust monitors (PDM). The review summarizes filter vendors, sizes, costs, chemical and physical properties, and information available on filter modeling, laboratory testing, and field performance. Filter media testing and selection should consider the characteristics required for mass by gravimetry in addition to RCS quantification by Fourier-transform infrared (FTIR) or Raman spectroscopic analysis. For mass determination, the filters need to have high filtration efficiency (≥99% for the most penetrable particle sizes) and a reasonable pressure drop (up to 16.7 kPa) to accommodate high dust loading. Additional requirements include: negligible uptake of water vapor and gaseous volatile compounds; adequate particle adhesion as a function of particle loading; sufficient particle loading capacity to form a stable particle deposit layer during sampling in wet and dusty environments; mechanical strength to withstand vibrations and pressure drops across the filter; and appropriate filter mass compatible with the tapered element oscillating microbalance. FTIR and Raman measurements require filters to be free of spectral interference. Furthermore, because the irradiated area does not completely cover the sample deposit, particles should be uniformly deposited on the filter. [ABSTRACT FROM AUTHOR]

A unique combination of real-time and conventional optical spectroscopy, off-line chemical analyses, and equilibrium solvent extraction measurements were employed to monitor progressive changes in the speciation of the organic-phase complexes of neodymium or americium in the biphasic scrub stage of the Actinide-Lanthanide Separation (ALSEP) solvent extraction process proposed for trivalent actinide/lanthanide separations. Consistent with the findings of other researchers, four unique organic-phase species are identified by three separate methods of multivariate analysis. The organic phase initially contains M(TEHDGA)2(HEH[EHP])2(NO3)3 complexes. As the ALSEP organic phase is scrubbed with an aqueous malonate buffer, the complex loses HNO3 to form M(TEHDGA)2(H(EH[EHP])2)(NO3)2 as the first organic-phase intermediate species. Further contact with the scrub aqueous phase forms a second intermediate species, M(TEHDGA)(H(EH[EHP])2)2(NO3), and eventually a complex containing only HEH[EHP], M{H(EH[EHP])2}3 (where TEHDGA = N,N,N',N'-tetra(2-ethylhexyl)diglycolamide and HEH[EHP] = 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester). Similar intermediate species were also observed in equilibrium ALSEP organic phases when lower aqueous concentrations of nitric acid (e.g., 0.5 M HNO3) were used to extract actinides or lanthanides. [ABSTRACT FROM AUTHOR]

The excessive input of heavy metals such as vanadium (V) into the environment has been one of the consequences of global industrial development. Excessive exposure to V can pose a potential threat to ecological safety and human health. Due to the heterogeneous composition and reactivity of the various elements in soils and sediments, quantitative analysis of the chemical speciation of V in different environmental samples is very complicated. The analysis of V chemical speciation can further reveal the bioavailability of V and accurately quantify its ecotoxicity. This is essential for assessing for exposure and for controlling ecological risks of V. Although the current investigation technologies for the chemical speciation of V have grown rapidly, the lack of comprehensive comparisons and systematic analyses of these types of technologies impedes a more comprehensive understanding of ecosystem safety and human health risks. In this review, we studied the chemical and physical extraction methods for V from multiple perspectives, such as technological, principle-based, and efficiency-based, and their application to the evaluation of V bioavailability. By sorting out the advantages and disadvantages of the current technologies, the future demand for the in situ detection of trace heavy metals such as V can be met and the accuracy of heavy metal bioavailability prediction can be improved, which will be conducive to development in the fields of environmental protection policy and risk management. [ABSTRACT FROM AUTHOR]

The presence of toxic trace metals and high concentrations of essential elements in the environment presents a serious threat to living organism. Various methods have been used for the detection, preconcentration and remediation of these metals from biological, environmental and food matrices. Owing to the complexicity of samples, methods with high selectivity have been used for detection, preconcentration and remediation of these trace metals. These methods are achieved by the use of ion-imprinted polymers (IIPs) due to their impressive properties such as selectivity, high extraction efficiency, speciation capability and reusability. Because of the increase of toxic trace and essential metals in the environment, IIPs have attracted great use in analytical chemistry. This review, provide a brief background on IIPs and polymerization method that are used for their preparation. Recent applications of IIPs as adsorbents for preconcentration, removal, speciation and electrochemical detection of trace and essential metal is also discussed. [ABSTRACT FROM AUTHOR]

The organic mass fraction from sea spray aerosol (SSA) is currently a subject of intense research. The majority of this research is dedicated to measurements in ambient air. However a number of studies have recently started to focus on nascent sea spray aerosol. This work presents measurements collected during a 5-week cruise in May and June 2017 in the central and western Mediterranean Sea, an oligotrophic marine region with low phytoplankton biomass. Surface seawater was continuously pumped into a bubble-bursting apparatus to generate nascent sea spray aerosol. Size distributions were measured with a differential mobility particle sizer (DMPS). Chemical characterization of the submicron aerosol was performed with a time-of-flight aerosol chemical speciation monitor (ToF-ACSM) operating with 10 min time resolution and with filter-based chemical analysis on a daily basis. Using positive matrix factorization analysis, the ToF-ACSM non-refractory organic matter (OM NR) was separated into four different organic aerosol types, identified as primary OA (POA NR), oxidized OA (OOA NR), methanesulfonic acid type OA (MSA-OA NR), and mixed OA (MOA NR). In parallel, surface seawater biogeochemical properties were monitored providing information on phytoplankton cell abundance and seawater particulate organic carbon (1 h time resolution) and seawater surface microlayer (SML) dissolved organic carbon (DOC) (on a daily basis). Statistically robust correlations (for n>500) were found between MOA NR and nanophytoplankton cell abundance, as well as between POA NR , OOA NR , and particulate organic carbon (POC). Parameterizations of the contributions of different types of organics to the submicron nascent sea spray aerosol are proposed as a function of the seawater biogeochemical properties for use in models. [ABSTRACT FROM AUTHOR]

The proton induced K X-ray emission spectra of several different phosphorus and sulfur compounds were recorded with the new parallel-beam wavelength dispersive X-ray emission spectrometer. The spectrometer was installed recently at the external proton microbeam at the J. Stefan Institute to perform high energy resolution in-air micro-PIXE analysis in the tender X-ray range. Reported measurements are used to probe the capabilities of the spectrometer to perform also chemical state analysis. For phosphorus measurements, where the energy resolution of the spectrometer is the highest, a clear correlation between measured energy position of the Kα emission line and the phosphorus formal oxidation state is obtained. Chemical contrast is increased further in the Kβ emission spectra reflecting the structure of occupied valence molecular orbitals defined by the first coordination shell around the central phosphorus atom. A reasonable chemical contrast is maintained also in the sulfur Kβ emission spectra, despite the fact that the energy resolution of the spectrometer declines with increasing X-ray energy. Finally, an example of phosphorus speciation in reference biological material is presented, demonstrating the feasibility of the new setup to extend the capabilities of in-air micro-PIXE analysis towards chemical speciation. [Display omitted] • The PB-WDS X-ray emission spectrometer was used to perform chemical state analysis of P and S. • Measured phosphorus Kα emission spectra exhibit energy shifts correlated with the formal oxidation state. • Kβ emission spectra of P and S reflect the coordination of neighboring atoms bound to the central phosphorus or sulfur atom. • The phosphorus spectra collected from standard reference biological material was used to specify its chemical state as a phosphate. [ABSTRACT FROM AUTHOR]

Hexavalent chromium is much more toxic than trivalent chromium and is severe environmental pollution caused by human activity. The presence of Cr(VI) ions in waters comes from anthropogenic sources, mainly from industries, and poses an enormous danger. Because of the health effects of Cr(VI) ions on humans, even at very low concentrations, it is necessary to control its levels in the water. However, the determination and speciation of Cr(VI) in water samples remains a sophisticated subject, and according to the WHO recommendation, further studies on reliable and validated methods should be continued. In this study, graphene oxide (GO) was modified with tetraethylenepentamine (TEPA) for the highly effective adsorption and determination of Cr(VI) ions by energy-dispersive X-ray fluorescence (EDXRF) and total-reflection X-ray fluorescence spectrometry (TXRF). The experiment shows that Cr(VI) ions can be adsorbed from aqueous solutions at pH 3.5 with a maximum adsorption capacity of 102 mg g−1 using minimal adsorbent doses, 10–50 μg mL−1, much lower than those of the currently reported adsorbents. These adsorptive properties of GO-TEPA and selectivity toward Cr(VI) in the presence of Cr(III) indicate its potential use as a micro-adsorbent in the determination and speciation of chromium. Due to the high preconcentration factors of 865 and 100, for EDXRF and TXRF, respectively, and high recovery of 98.5–100%, the method based on dispersive micro-solid phase extraction allows obtaining extremely low detection limits of 53 and 3.5 pg mL−1 for EDXRF and TXRF. The exceptional adsorptive properties of GO-TEPA, including the possibility of application in micro-quantities, allow for the development of the ultra-trace method according to the fundamental principles of green analytical chemistry. It significantly expands the possibilities of using the EDXRF, as well as the TXRF technique in water analysis. [Display omitted] • Very low detection limit of 3.5 and 53 pg mL−1 Cr(VI) using TXRF and EDXRF instruments. • Simple and accurate speciation of chromium. • Superior nanoadsorbent for highly effective separation of hexavalent chromium. • Extremely small adsorbent dosage (0.5 mg). • High adsorption capacity (102 mg g−1) and selectivity of the adsorbent toward Cr(VI). [ABSTRACT FROM AUTHOR]

The distribution and origins of Ni and V were assigned in the surficial sediments from 160 stations in Shadegan international wetlands with 537,700 ha. The findings showed that the mean total content of Ni and V in the surface sediments were 45.08 ± 12.09 and 25.25 ± 20.8 μg g−1 dw, respectively. According to the analysis chemical speciation, the Ni and V residual fraction in the surface sediments were calculated for > 80% of the total level of metals, indicating that the metals may be an indicator for the input of natural resources. The analysis of the interpolation maps according to their chemical fractionation manifested that the Ni and V pollution hotspots have been happened in the northern, southern, and western points. Interpolation maps also highlighted that Ni and V are often controlled by natural factors like parent material; however, anthropogenic inputs have also caused the accumulation of these metals in the sediment. [ABSTRACT FROM AUTHOR]

Positive Matrix Factorization analysis of PM2.5 chemical speciation data collected from 2015–2017 at Washington State Department of Ecology's urban NCore (Beacon Hill) and near-road (10th and Weller) sites found similar PM2.5 sources at both sites. Identified factors were associated with gasoline exhaust, diesel exhaust, aged and fresh sea salt, crustal, nitrate-rich, sulfur-rich, unidentified urban, zinc-rich, residual fuel oil, and wood smoke. Factors associated with vehicle emissions were the highest contributing sources at both sites. Gasoline exhaust emissions comprised 26% and 21% of identified sources at Beacon Hill and 10th and Weller, respectively. Diesel exhaust emissions comprised 29% of identified sources at 10th and Weller but only 3% of identified sources at Beacon Hill. Correlation of the diesel exhaust factor with measured concentrations of black carbon and nitrogen oxides at 10th and Weller suggests a method to predict PM2.5 from diesel exhaust without a full chemical speciation analysis. While most PM2.5 sources exhibit minimal change over time, primary PM2.5 from gasoline emissions is increasing on average 0.18 µg m−3 per year in Seattle. This study utilizes Positive Matrix Factorization to determine PM2.5 sources from chemical speciation measurements at two urban Seattle sites from 2015-2017. The paper reports PM2.5 source trends, and extends previous source apportionment analyses in Seattle to the present day. The study also quantifies diesel PM2.5 at a near-road site, and describes a predictive model that allows estimation of the contribution of diesel PM2.5 to the total measured PM2.5 at near-road sites across the country without a full chemical speciation analysis. [ABSTRACT FROM AUTHOR]

The chemical speciation of nanoparticles is technically challenging because of the minute mass of the particles. There is a constant need for more sensitive collection methods and chemical analyses. In this study, we demonstrated the applicability of a surface enhanced Raman scattering (SERS) technique on the rapid and sensitive chemical analysis of individual nanoparticles. SERS technique provides a significant enhancement of the scattering efficiency over traditional Raman spectroscopy. The novelty of the proposed technique is that the SERS substrate is used directly as the sampling substrate of a condensational growth tube (CGT) sampler, which can activate nanoparticles into water droplets and ensure simultaneous inertial sampling and SERS pretreatment. First, we investigated applicability of the method on mono-dispersed (20 nm, 50 nm, or 100 nm) ammonium sulfate (AS) and levoglucosan (LG) particles as model aerosols. The method was then applied to ambient nanoparticles. The successful detection of peaks corresponding to sulfate ν(SO42-) and organics ν(C-H) indicates that our proposed method to combine a CGT sampler and SERS showed a sensitivity high enough to provide deep insights into the chemical speciation of atmospheric nanoparticles as small as 20 nm in diameter. [ABSTRACT FROM AUTHOR]

In this work, a methodology for chemical speciation analysis of inorganic As and Sb in urban dust using slurry sampling and detection by fast sequential hydride generation atomic absorption spectrometry is proposed. Doehlert design and desirability function were used to find the optimum conditions for hydride generation (1.0 mol L−1 HCl and 0.9% m v−1 NaBH4). The accuracy of the analytical method was evaluated by analysis of reference material fly ash (BCR 176R), addition and recovery tests for inorganic As species, and comparison of independent methods for Sb determination in urban dust samples. The determination of the total concentrations of As and Sb and their inorganic species presented good accuracy, between 80 ± 1 and 101 ± 6%. Precision was expressed as the relative standard deviation and was better than 4.7% (n = 3). The limit-of-quantification values were 0.23 and 1.03 mg kg−1 for As and Sb, respectively. The methodology was applied to eight samples of dust collected in an urban area of Salvador and Jaguaquara cities, Bahia, Northeast, Brazil, with an aerodynamic size lower than 38 μm. Concentrations of pentavalent inorganic species (iAs5+ and iSb5+) in relation to trivalent species (iAs3+ and iSb3+) were found in urban dust collected in the city of Salvador, which are regarded as more toxic for both elements. The enrichment factor and geoaccumulation index (Igeo) values showed that for some samples, the concentrations of iAs and iSb presented strong enrichment and, and regarding environment, strong to moderately polluted by iAs and iSb, with an indication of anthropogenic contributions. The occurrence of these inorganic constituents in the urban area of Salvador can be related with intense industrial activities and vehicular traffic. [ABSTRACT FROM AUTHOR]

The Eleventh Aegean Analytical Chemistry Days (AACD2018) was held in Chania, Crete, Greece during the period from 25 to 29 September 2018. The scientific framework consisted of 13 oral sessions and 2 poster sessions. Papers in fields such as atomic and molecular spectrometry, mass spectrometry, bioanalytical and clinical analysis, chromatography and separation techniques, electroanalytical methods and biosensors, speciation analysis, sample preparation, chemometrics, quality control/quality assurance and chemical metrology, environmental analysis, food analysis and pharmaceutical analysis were presented during this five-day conference. The social program included a visit to the Botanical Park of Chania and dinner with Cretan dishes and a post-conference one-day excursion to Knossos and Herakleio. During the closing ceremony, it was announced that the next AACD will be organized in Turkey by Professor Sezgin Bakirdere at Yildiz Technical University, Istanbul. [ABSTRACT FROM AUTHOR]

In this work, fast sequential determination and chemical speciation analysis of inorganic arsenic and antimony in airborne particulate matter collected in outdoor and indoor environments using slurry sampling and detection by hydride generation atomic absorption spectrometry (HG-AAS) is proposed. A Doehlert design was applied to optimise the hydride generation conditions of As and Sb for fast sequential determination in the same aliquot of particulate matter samples after preparation of the slurry. The limits of quantification (LoQ) obtained for As and Sb were 0.3 and 0.9 ng m−3, respectively. The accuracy of the analytical method was confirmed by analysis of the certified reference material of urban particulate matter (SRM NIST 1648a), presenting concordance with certified values of 92.7±7.7% for As and 91.2±9.5% for Sb. Precision was expressed as relative standard deviation (% RSD, n=3), with our results presenting values better than 3.4% and 4.2% for total inorganic As and Sb, respectively. For all analysed samples, total As concentrations and its inorganic species were below the LoQ of the analytical method (<0.3 ng m−3). However, the averages of total inorganic Sb concentrations in airborne particulate matter, collected as total suspended outdoor particles (TSPoutdoor), inhalable particulate matter (PM10), and total suspended indoor particles (TSPindoor), were 3.1±0.5, 2.4±0.6, and 2.6±0.4 ng m−3, respectively. Trivalent Sb (Sb3+) was the predominant inorganic species in all samples investigated, with mean percentages of 76%, 72%, and 73% in TSPoutdoor, PM10, and TSPindoor, respectively. The presence of Sb and its predominant inorganic form (Sb3+) can be attributed to vehicular traffic close to the sampled urban areas. Therefore, fast sequential determination of As and Sb and their inorganic species in particulate matter samples prepared as slurry by FS-HG-AAS is an efficient, accurate, and precise method and can be successfully applied to routine analysis. [ABSTRACT FROM AUTHOR]

Abstract A low temperature plasma integrating the merits of small size, simple operation and rich active particles has good performance in analytical chemistry. In this work, a point discharge microplasma was used as a reactor to facilitate the gaseous conversion reaction from H 2 S to SO 2 with an excellent efficiency as high as 95%. By coupling this reactor with a fluorescence spectrometer, the speciation analysis of sulfide and sulfite was achieved in a simple, chromatographic separation-free, time-saving and practical way. Specifically, with the discharge off, only sulfite was quantified; with discharge on, both sulfide and sulfite were quantified; and with a simple subtraction, the speciation analysis could be easily attained. By the acidification process, a limit of detection of 7.7 μM by the proposed method was obtained for both sulfide and sulfite in aqueous medium, and this method was successfully utilized to analysis of real samples. Graphical abstract The speciation analysis of H 2 S and SO 2 can be easily achieved with a point discharge on/off for sampling into a fluorescence spectrometer. Image 1 Highlights • A compact and efficient gas reactor based on a point discharge microplasma (PD). • Gaseous oxidation reaction from H 2 S to SO 2 with a high efficiency of 95%. • Chromatography-free and rapid speciation analysis for sulfide and sulfite. • Simple operation with PD on/off for sampling into a fluorescence spectrometer. [ABSTRACT FROM AUTHOR]

The replacement of the Desert Research Institute (DRI) model 2001 with model 2015 thermal/optical analyzers (TOAs) results in continuity of the long-term organic carbon (OC) and elemental carbon (EC) database, and it adds optical information with no additional carbon analysis effort. The value of multiwavelength light attenuation is that light absorption due to black carbon (BC) can be separated from that of brown carbon (BrC), with subsequent attribution to known sources such as biomass burning and secondary organic aerosols. There is evidence of filter loading effects for the 25% of all samples with the highest EC concentrations based on the ratio of light attenuation to EC. Loading corrections similar to those used for the seven-wavelength aethalometer need to be investigated. On average, nonurban Interagency Monitoring of PROtected Visual Environments (IMPROVE) samples show higher BrC fractions of short-wavelength absorption than urban Chemical Speciation Network (CSN) samples, owing to greater influence from biomass burning and aged aerosols, as well as to higher primary BC contributions from engine exhaust at urban sites. Sequential samples taken during an Everglades National Park wildfire demonstrate the evolution from flaming to smoldering combustion, with the BrC fraction increasing as smoldering begins to dominate the fire event. Implications: The inclusion of seven wavelengths in thermal/optical carbon analysis of speciated PM2.5 (particulate matter with an aerodynamic diameter ≤2.5 μm) samples allows contributions from biomass burning and secondary organic aerosols to be estimated. This separation is useful for evaluating control strategy effectiveness, identifying exceptional events, and determining natural visibility conditions. [ABSTRACT FROM AUTHOR]

Abstract: Recent recognition that mobile pools of Zn2+ and Cu2+ are involved in the regulation of neuronal, endocrine and other cells has stimulated the development of tools to visualize and quantify the level of free trace metal ions. Most of the methods used to measure or control loosely bound metals require reference media that contain exactly defined free concentrations of the target ions. Despite the central importance of proper metal ion buffering, there is still a lack of international standards and beginners in the field may have difficulties finding a coherent description of how to prepare trace metal ion buffers, especially when experiments are to be performed in multimetal systems. To close this gap, we provide a guide for the design, preparation and use of metal ion‐buffered systems that facilitate immediate application under physiologically relevant ionic conditions. Thermodynamic and kinetic concepts of chemical speciation as well as general protocols and specific examples are outlined for the accurate preparation of single‐ and dual‐metal ion buffers. In addition, experiments have been performed with FluoZin‐3 to illustrate that metal ion‐buffered systems are required for reliable preparation of nanomolar Zn2+ solutions and that dual‐metal ion buffers can be used to calibrate suitable fluorescent Zn2+ sensors in the presence of millimolar Ca2+ concentrations. Together, the information provided should sensitize readers to the many potential pitfalls and uncertainties that exist when working with physiologically relevant concentrations of trace metal ions and enable them to formulate their own metal ion buffers for most in vitro applications. [ABSTRACT FROM AUTHOR]

The objective of this study was to assess total concentration and chemical fractionation of trace metals in the industrial wastewater and sludge collected from seven different types of industries in Dhaka City, Bangladesh. The sludge from industries is either dumped on landfills or reused as secondary resources in order to preserve natural resources. Metals were analyzed using inductively coupled plasma mass spectrometry (ICP-MS). The ranges of Cr, Ni, Cu, As, Cd, and Pb in the sludges were 1.4-9,470, 4.8-994, 12.8-444, 2.2-224, 1.9-46.0 and 1.3-87.0 mg/kg, respectively. As a whole, the average concentrations of trace metals in samples were in the decreasing order of Cr> Ni> Cu >As>Pb >Cd. The results of the Community Bureau of Reference (BCR) sequential extraction showed that the studied metals were predominantly associated with the residual fraction followed by the oxidizable fraction. The study revealed that the mobile fractions of trace metals are poorly predictable from the total content, and bioavailability of all fractions of elements tends to decrease. [ABSTRACT FROM AUTHOR]

Site-specific functionalizations are the emergent attention for the enhancement of sorption latent of heavy metals. Limited chemistry has been applied for the fabrication of diafunctionalized materials having potential to tether both environmentally stable oxidation states of chromium (Cr(III) and Cr(VI). Polyaniline impregnated nanocellulose composite (PANI-NCC) has been fabricated using click chemistry and explored for the removal of Cr(III) and Cr(VI) from hydrological environment. The structure, stability, morphology, particle size, surface area, hydrophilicity, and porosity of fabricated PANI-NCC were characterized comprehensively using analytical techniques and mathematical tools. The maximum sorption performance of PANI-NCC was procured for (Cr(III): 47.06 mg g; 94.12 %) and (Cr(VI): 48.92 mg g; 97.84 %) by equilibrating 0.5 g sorbent dose with 1000 mL of 25 mg L chromium conc. at pH 6.5 and 2.5 for Cr(III) and Cr(VI), respectively. The sorption data showed a best fit to the Langmuir isotherm and pseudo-second-order kinetic model. The negative value of ∆ G° (-8.59 and -11.16 kJ mol) and ∆ H° (66.46 × 10 and 17.84 × 10 kJ mol), and positive value of ∆ S° (26.66 and 31.46 J molK) for Cr(III) and Cr(VI), respectively, reflect the spontaneous, feasibility, and exothermic nature of the sorption process. The application of fabricated PANI-NCC for removing both the forms of chromium in the presence of other heavy metals was also tested at laboratory and industrial waste water regime. These findings open up new avenues in the row of high performance, scalable, and economic nanobiomaterial for the remediation of both forms of chromium from water streams. [ABSTRACT FROM AUTHOR]

Chemical speciation, reactivity, and bioavailability of trace metals in aqueous systems arestrongly influenced by dissolved organic matter (DOM). DOM is a mixture of diverse components, so a range of organic molecules potentially participates in the occurrence of dissolved trace metals. In this study, we investigated water quality variables that influence dissolved trace metal concentrations in natural and effluent water systems with a particular attention given to the relationship between DOM optical properties and dissolved copper and iron concentrations. We found that specific UV absorbance (SUVA 254 : an indicator of DOM aromaticity) has a significant correlation with dissolved trace metal to dissolved organic carbon concentration ratios ([Me] T /[DOC]) for copper and iron in natural freshwaters and treated municipal wastewater in the Sagami River basin, Japan. This trend was also prevalent for other freshwaters in temperate climates except for Fe-rich waters. Our findings indicate that the concentrations of dissolved copper and iron in natural and effluent waters are significantly influenced not only by DOM concentration, but also by aromaticity of DOM, and that this DOM property can be inferred from spectrophotometric measurements. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine the valence state of chromium (Cr) in the blood of individuals with Cr-containing metal hip implants. Serum and red blood cell (RBC) Cr concentrations from 52 patients with Cr-containing total hip arthroplasties were measured preoperatively and at 3, 12, and 24 months postoperatively. Geometric mean and median pre-surgery serum Cr concentrations were consistently below 0.2 µg/L, while geometric mean and median pre-op RBC Cr concentrations were typically about four- to six-fold higher than the serum values. A significant 5- to 13-fold increase was found in the mean and median serum Cr concentrations three months post-surgery, with an 8- to 18-fold rise at 12 and 24 months, respectively. Steady-state serum concentrations were reached between 3 and 12 months. In contrast, there were no marked differences in mean and median RBC Cr concentrations pre- and post-surgery. Slope regression analysis for our data was similar to those reported for Cr(III) in spiked blood samples. The analysis showed that Cr released from hip implants preferentially distributed into serum and not RBC, indicating that the form of Cr present in blood of hip implant patients was in the form of non-toxic Cr(III). Our findings indicate that blood Cr concentrations Cr(III) associated with metal implants do not pose an adverse health risk to patients, which is in agreement with findings published by most investigators. [ABSTRACT FROM PUBLISHER]

• Photooxidation of sulfite by UV irradiation produces e aq −and SO 3 •−. • e aq −and SO 3 •− trigger ferrihydrite transformation to more crystalline minerals. • The sulfite content is key in influencing the ferrihydrite transformation product. • The surface-bound Fe(II) concentration distinctly affects the transformation rate. • Cd is incorporated into the structure of goethite at a high sulfite concentration. The photoinduced transformation of ferrihydrite is an important process that can predict the geochemical cycle of Fe in anoxic environments as well as the fate of trace elements bonded to Fe minerals. We report that the photooxidation of sulfite by UV irradiation produces hydrated electrons (super-reductants), which significantly promote ferrihydrite reduction to Fe(II), and SO 3 •− (a moderate oxidant), enabling its further oxidation to more crystalline Fe(III) products. The experimental results show that the concentration of sulfite was key in influencing the rate and extent of surface-bound Fe(II) formation, which ultimately determined the distribution of individual products. For example, fitting of the Mössbauer spectroscopy data revealed that the relative abundances of mineral species after 8 h of treatment in the UV/sulfite systems were 41.9% lepidocrocite and 58.1% ferrihydrite at 2 mM SO 3 2−; 41.8% goethite, 28.2% lepidocrocite, and 29.1% ferrihydrite at 5 mM SO 3 2−; and 100% goethite at 10 mM SO 3 2−. The combined results of the chemical speciation analysis and the Cd K-edge EXAFS characterization provided compelling evidence that Cd was firmly incorporated into the structure of newly formed minerals, particularly at high sulfite concentrations. These findings provide an understanding of the role of UV/sulfite in facilitating ferrihydrite transformation and promoting Cd stabilization in oxygen-deficit soils and aquatic environments. [Display omitted] [ABSTRACT FROM AUTHOR]

Net formation of methylmercury (MeHg) in sediments is known to be affected by the availability of inorganic divalent mercury (HgII) and by the activities of HgII methylating and MeHg demethylating bacteria. Enhanced autochthonous organic matter deposition to the benthic zone, following increased loading of nutrients to the pelagic zone, has been suggested to increase the activity of HgII methylating bacteria and thus the rate of net methylation. However, the impact of increased nutrient loading on the biogeochemistry of mercury (Hg) is challenging to predict as different geochemical pools of Hg may respond differently to enhanced bacterial activities. Here, we investigate the combined effects of nutrient (N and P) supply to the pelagic zone and the chemical speciation of HgII and of MeHg on MeHg formation and degradation in a brackish sediment-water mesocosm model ecosystem. By use of Hg isotope tracers added in situ to the mesocosms or ex situ in incubation experiments, we show that the MeHg formation rate increased with nutrient loading only for HgII tracers with a high availability for methylation. Tracers with low availability did not respond significantly to nutrient loading. Thus, both microbial activity (stimulated indirectly through plankton biomass production by nutrient loading) and HgII chemical speciation were found to control the MeHg formation rate in marine sediments [ABSTRACT FROM AUTHOR]

The concentration and chemical speciation of arsenic (As) in different environmental matrixes (water, sediment, agricultural soils, and non-agricultural soils) were investigated in the Nanpan River area, the upstream of Pearl River, China. The results did not show any obvious transport of As along the flow direction of the river (from upstream to downstream). Total As concentrations in sediment were significantly different from those in agricultural soil. According to the comparison to quality standards, the As in sediments of the studied area have potential ecological risks and a minority of the sampling sites of agricultural soils in the studied area were polluted with As. As speciations were analyzed using sequential extraction and the percentage of non-residual fraction in sediment predominated over residual fraction. We thus believe that As in the studied area was with low mobility and bioavailability in sediment, agricultural soils, and non-agricultural soils. However, the bioavailability and mobility of As in sediment were higher than in both agricultural and non-agricultural soils, and thus, special attention should be paid for the risk assessment of As in the river in future studies. [ABSTRACT FROM AUTHOR]

The distributions of various forms of phosphorus (P) and their relation with sediment geochemistry in two core sediments near Karwar and Mangalore offshore have been studied through the modified SEDEX procedure ( Ruttenberg et al., 2009 ) and bulk chemical analysis. The present study provides the first quantitative analysis of complete phosphorus speciation in the core sediments of the Eastern Arabian shelf. The chemical index of alteration (CIA), chemical Index of Weathering (CIW) and Al–Ti–Zr ternary diagram suggest low to moderate source area weathering of granodioritic to tonalitic source rock composition, despite the intense orographic rainfall in the source area. Due to the presence of same source rock and identical oxic depositional environment, the studied sediments show the same range of variation of total phosphorus (24 to 83 µmol/g) with a down-depth depleting trend. Organic bound P and detrital P are the two major chemical forms followed by iron-bound P, exchangeable/loosely bound P and authigenic P. The authigenic P content in the sediments near Mangalore coast varies linearly with calcium ( r =0.88) unlike that of Karwar coast. The different reactive-phosphorus pools exhibit identical depleting trend with depth. This indicates that the phosphorus released from the organic matter and Fe bound fractions are prevented from precipitating as authigenic phosphates in the deeper parts of the sediment column. The low concentration of total P, dominance of detrital non-reactive fraction of P and inhibition of formation of authigenic phosphate result in the absence of active phosphatization in the Eastern Arabian Shelf in the studied region. High sedimentation rate (35–58 cm/kyr) and absence of winnowing effect appear to be the dominant factor controlling the P-speciation in the studied sediments. [ABSTRACT FROM AUTHOR]

ABG black holes are charged regular black holes based on Einstein gravity and nonlinear electrodynamics, proposed by Ayón-Beato and García. In 2005, they generalized the ABG black holes to a new class of regular black holes which have four characteristic parameters: the mass m, the electric charge q and the rest two parameters $$\alpha $$ and $$\beta $$ related with the dipole and quadrupole moment of the nonlinear electromagnetic field, respectively. In this paper, we study the quasinormal modes (QNMs) of these generalized ABG black holes for scalar and gravitational perturbations by the sixth-order WKB method. The numerical results show the generalized ABG black holes are stable and the relations between QNMs and the parameter of the perturbation fields and the parameters of the black holes are discussed. The real part and the imaginary part of the generalized ABG black holes increase as the charge increasing. Furthermore, the dependence of the QNMs on the other parameters is also illustrated and the analytical expression of the quasinormal frequency for the large multipole index is obtained. [ABSTRACT FROM AUTHOR]

This review describes the different steps involved in the determination of arsenic in air, considering the particulate matter (PM) and the gaseous phase. The review focuses on sampling, sample preparation and instrumental analytical techniques for both total arsenic determination and speciation analysis. The origin, concentration and legislation concerning arsenic in ambient air are also considered. The review intends to describe the procedures for sample collection of total suspended particles (TSP) or particles with a certain diameter expressed in microns (e.g. PM10 and PM2.5), or the collection of the gaseous phase containing gaseous arsenic species. Sample digestion of the collecting media for PM is described, indicating proposed and established procedures that use acids or mixtures of acids aided with different heating procedures. The detection techniques are summarized and compared (ICP-MS, ICP-OES and ET-AAS), as well those techniques capable of direct analysis of the solid sample (PIXE, INAA and XRF). The studies about speciation in PM are also discussed, considering the initial works that employed a cold trap in combination with atomic spectroscopy detectors, or the more recent studies based on chromatography (GC or HPLC) combined with atomic or mass detectors (AFS, ICP-MS and MS). Further trends and challenges about determination of As in air are also addressed. [ABSTRACT FROM AUTHOR]

This work presents the development of a new probe (ISIDORE probe) based on the hyphenation of a Donnan Membrane Technique device (DMT) to a screen-printed electrode through a flow-cell to determine the free zinc, cadmium and lead ion concentration in natural samples, such as a freshwater river. The probe displays many advantages namely: (i) the detection can be performed on-site, which avoids all problems inherent to sampling, transport and storage; (ii) the low volume of the acceptor solution implies shorter equilibration times; (ii) the electrochemical detection system allows monitoring the free ion concentration in the acceptor solution without sampling. [ABSTRACT FROM AUTHOR]

Santiago is one of the largest cities in South America and has experienced high fine particulate matter (PM 2.5 ) concentrations in fall and winter months for decades. To better understand the sources of fall and wintertime pollution in Santiago, PM 2.5 samples were collected for 24 h every weekday from March to October 2013 for chemical analysis. Samples were analyzed for mass, elemental carbon (EC), organic carbon (OC), water soluble organic carbon (WSOC), water soluble nitrogen (WSTN), secondary inorganic ions, and particle-phase organic tracers for source apportionment. Selected samples were analyzed as monthly composites for organic tracers. PM 2.5 concentrations were considerably higher in the coldest months (June–July), averaging (mean ± standard deviation) 62 ± 15 μg/m 3 in these two months. Average fine particle mass concentration during the study period was 40 ± 20 μg/m 3 . Organic matter during the peak winter months was the major component of fine particles comprising around 70% of the particle mass. Source contributions to OC were calculated using organic molecular markers and a chemical mass balance (CMB) receptor model. The four combustion sources identified were wood smoke, diesel engine emission, gasoline vehicles, and natural gas. Wood smoke was the predominant source of OC, accounting for 58 ± 42% of OC in fall and winter. Wood smoke and nitrate were the major contributors to PM 2.5 . In fall and winter, wood smoke accounted for 9.8 ± 7.1 μg/m 3 (21 ± 15%) and nitrate accounted for 9.1 ± 4.8 μg/m 3 (20 ± 10%) of fine PM. The sum of secondary inorganic ions (sulfate, nitrate, and ammonium) represented about 30% of PM 2.5 mass. Secondary organic aerosols contributed only in warm months, accounting for about 30% of fine PM during this time. [ABSTRACT FROM AUTHOR]

Rice ( Oryza sativa L.) is a bio-accumulative plant for arsenic (As), particularly the most toxic inorganic As species (i-As), and the main contributor to i-As intake among agricultural products. The analytical process for determination and speciation of As in rice is complex. Different aspects have to be considered, including detection method, calibration strategy, sample-treatment and preparation procedures, and quality assurance and quality control of results. It is well known that sample preparation is a critical step in the whole analytical chain, so this review surveys achievements in analysis of rice for the content of total As and the species of As reported in the past 15 years using spectrochemical techniques. We discuss different sample-preparation procedures, with their advantages and drawbacks. We highlight common strategies and alternative approaches to speciation analysis of As. [ABSTRACT FROM AUTHOR]

Chromium holds a special position among living organisms because depending on its species it can be either essential or toxic. Cr(VI) even at very low concentrations is harmful and carcinogenic, while Cr(III) is a necessary microelement for cellular metabolism. Therefore, a simple analysis of Cr concentration in collected samples will not be able to distinguish these differences effectively: for a proper chemical analysis we need to perform a reliable detection and quantification of Cr species. Separation and detection of chromium can be accomplished with high performance liquid chromatography hyphenated to inductively coupled plasma mass spectrometry (HPLC/ICP-MS) in a one-step. Our review assembles articles published since 2000 regarding chromium speciation in water samples with the use of HPLC/ICP-MS. It addresses the following issues: chromium chemistry, the possibilities of dealing with interferences, metrological aspects, analytical performance and speciated isotope dilution mass spectrometry (SIDMS) which is a definitive measurement method. The authors would like to advocate this hyphenated advanced technique as well as the metrological approach in speciation analysis of chromium. [ABSTRACT FROM AUTHOR]

The U.S. Environmental Protection Agency (EPA) initiated the national PM2.5Chemical Speciation Monitoring Network (CSN) in 2000 to support evaluation of long-term trends and to better quantify the impact of sources on particulate matter (PM) concentrations in the size range below 2.5 μm aerodynamic diameter (PM2.5; fine particles). The network peaked at more than 260 sites in 2005. In response to the 1999 Regional Haze Rule and the need to better understand the regional transport of PM, EPA also augmented the long-existing Interagency Monitoring of Protected Visual Environments (IMPROVE) visibility monitoring network in 2000, adding nearly 100 additional IMPROVE sites in rural Class 1 Areas across the country. Both networks measure the major chemical components of PM2.5using historically accepted filter-based methods. Components measured by both networks include major anions, carbonaceous material, and a series of trace elements. CSN also measures ammonium and other cations directly, whereas IMPROVE estimates ammonium assuming complete neutralization of the measured sulfate and nitrate. IMPROVE also measures chloride and nitrite. In general, the field and laboratory approaches used in the two networks are similar; however, there are numerous, often subtle differences in sampling and chemical analysis methods, shipping, and quality control practices. These could potentially affect merging the two data sets when used to understand better the impact of sources on PM concentrations and the regional nature and long-range transport of PM2.5. This paper describes, for the first time in the peer-reviewed literature, these networks as they have existed since 2000, outlines differences in field and laboratory approaches, provides a summary of the analytical parameters that address data uncertainty, and summarizes major network changes since the inception of CSN.ImplicationsTwo long-term chemical speciation particle monitoring networks have operated simultaneously in the United States since 2001, when the EPA began regular operations of its PM2.5 Chemical Speciation Monitoring Network (IMPROVE began in 1988). These networks use similar field sampling and analytical methods, but there are numerous, often subtle differences in equipment and methodologies that can affect the results. This paper describes these networks since 2000 (inception of CSN) and their differences, and summarizes the analytical parameters that address data uncertainty, providing researchers and policymakers with background information they may need (e.g., for 2018 PM2.5 designation and State Implementation Plan process; McCarthy, 2013) to assess results from each network and decide how these data sets can be mutually employed for enhanced analyses. Changes in CSN and IMPROVE that have occurred over the years also are described. [ABSTRACT FROM AUTHOR]

To evaluate biogeochemical characteristics, eco-environmental risks and sources of trace elements (TEs: As, Hg, Se, Sb, Te, Sn, Bi and Ge), their total concentrations and chemical speciation in surface sediments collected from the Changjiang Estuary were determined. Total concentrations for As, Hg, Se, Sb, Te, Sn, Bi and Ge were 4.57-30.20, 0.01-0.40, 0.04-0.38, 0.36-1.48, 0.02-0.10, 0.48-6.58, 0.13-0.64 and 0.83-2.43 μg/g, respectively, with higher values at the estuary. This distribution pattern was attributed to the riverine input and high clay and total organic carbon contents. The sequential extraction suggested that TEs mainly occurred in residual fractions. The risk assessment code suggested that As, Hg and Sn were at low risk, whereas Bi, Se, Sb, Te and Ge were at medium risk. The geoaccumulation index ( I) and principal component analysis indicated that Se and Sn mainly came from the natural input (crustal and biological inputs), whereas As, Sb, Hg, Bi and Te came from both of the crustal and anthropogenic inputs via atmosphere and rivers. In addition, Ge possibly came from the natural (crustal and biological inputs) and anthropogenic inputs. [ABSTRACT FROM AUTHOR]