Trace Ions Research Articles

Field‐Aligned Low‐Energy O+ Flux Enhancements in the Inner Magnetosphere Observed by Arase

AbstractThe present study examines the low‐energy ion flux variations observed by the Arase satellite in the inner magnetosphere. From the magnetic field and ion flux data obtained by the fluxgate magnetometer and the low‐energy particle experiments–ion mass analyzer onboard Arase, we find 55 events of the low‐energy O+ flux enhancement accompanied with magnetic field dipolarization in the periods of April 1–October 31, 2017 and July 1, 2018–January 31, 2019. The low‐energy O+ flux enhancements (a) start a few minutes after the dipolarization onset, (b) have energy‐dispersed signatures with decreasing energy from a few keV down to ∼10 eV, (c) are observed in both storm and non‐storm periods, (d) have a field‐aligned distribution (α ∼ 0° in the southern hemisphere and α ∼ 180° in the northern hemisphere), (e) are accompanied by the low‐energy H+ flux enhancements that have lower energies than O+ by a factor of 3–10, and (f) increase the O+ density and the O+/H+ density ratio by ∼10 times and 4–5 times, respectively. We perform a numerical simulation to trace ion trajectories forward in time from the Arase positions. It is revealed that both H+ and O+ ions drift eastward and reach the dawn‐to‐morning sector without being lost in the ionosphere, if the pitch angle scattering effect is considered near the equatorial plane. This result suggests that these low‐energy field‐aligned ions can contribute to formation of the warm plasma cloak.

Hydrogeochemistry and geothermometry of thermal springs in the eastern Trans-Mexican Volcanic Belt

This study was aimed at investigating the hydrogeochemical and isotopic characteristics of low-temperature hydrothermal springs in six study sites located in the eastern portion of the Trans-Mexican Volcanic Belt, in order to evaluate the source of the thermal water, rock-water interactions, and reservoir temperature. In addition, based on this, possible similarities and differences among these thermal springs were explored. Samples of thermal waters (12 samples) and non-thermal waters (6 samples) were collected during dry and rainy seasons. Stable isotopes (18O, 2H) as well as major, minor, and trace ions were analyzed for, and saturation indices and reservoir temperatures were estimated. Thermal water temperatures ranged from 33 to 55°C and the pH was slightly acid (and slightly basic in only one case). The electrical conductivity ranged widely, from 0.2 to 27 mS/cm, although most samples had > 8 mS/cm. Using a Piper diagram, three hydrochemical facies were identified: Na-Cl, Na-Ca-SO4-HCO3, and Na-HCO3. The notable minor and trace elements and ions were B, Li, As, and F− . δ18O and δ2H values plot very close to the meteoric water line, although samples from three of the study sites showed a possible isotope exchange between water and minerals at high temperatures. By estimating reservoir temperatures using solute geothermometers and saturation indices, it was possible to determine similarity among the values obtained (90 to 190°C). These data indicate that the hydrochemistry of the thermal waters reflects a water source that is related to geothermal brines in some cases, and with the mixing of a thermal fluid and a recently infiltrated water in other cases, as well as water-rock interactions (mostly with silicates) and carbonate precipitation.

Cross talk of serum elements, cardiac and liver enzymes in patients with HCV chronic hepatitis and hepatocellular carcinoma in Pakistani population

HCV-associated hepatic pathologies are now the frequent inducer of cardiac abnormalities because of cardio-hepatic interaction. Studies are going on to elucidate and highlight the possible factors involved in this complex interaction, but this paradigm is still unclear. Here, we aimed to explore the interrelationship among electrolytes, cardiac, and liver enzymes in HCV-associated hepatic abnormalities, including chronic hepatitis and hepatocellular carcinoma in the Pakistani population. 100 Hepatitis C virus (HCV) infected patients with liver disorders and 50 healthy individuals were recruited in the present analysis. Trace elements, ions, and enzyme concentrations were quantified via an automatic analyzer, while HCV was confirmed by enzyme-linked immunosorbent assay (ELISA). Our results demonstrated that serum Ca++, Mg++, Fe++, Cl-, and PO4- levels were significantly increased in HCV patients with hepatic pathologies, including cirrhosis and carcinoma. Cardiac enzymes, including aspartate aminotransferase (AST), creatine kinase (CK2), and lactate dehydrogenase (LDH) concentration, were also elevated in HCV patients. Furthermore, serum cholesterol and triglyceride levels significantly differed in HCV patients than in normal individuals. Impaired alkaline transaminase (ALT) and alkaline phosphatase levels in HCV patients further validate the HCV patients' hepatic pathologies. Interestingly, all these impaired factors were positively correlated with the progression of hepatic disorders. In conclusion, altered ionic concentrations, cardiac enzymes, and liver dysfunction markers suggest their significant relationship to HCV leading liver pathologies in the Pakistani population.

Nanofiltration of Multi-Ion Solutions: Quantitative Control of Concentration Polarization and Interpretation by Solution-Diffusion-Electro-Migration Model.

For effective use of advanced engineering models of nanofiltration quality of experimental input is crucial, especially in electrolyte mixtures where simultaneous rejections of various ions may be very different. In particular, this concerns the quantitative control of concentration polarization (CP). This work used a rotating disklike membrane test cell with equally accessible membrane surface, so the CP extent was the same over the membrane surface. This condition, which is not satisfied in the conventional membrane test cell, made possible correcting for CP easily even in multi-ion systems. Ion rejections were studied experimentally for several dominant salts (NaCl, MgCl2, Na2SO4 and MgSO4) and trace ions (Na+, NH4+, Cl− and NO3−) using NF270 membrane. The solution–diffusion–electro–migration model was used to obtain ion permeances from the experimental measurements. The model could well fit the experimental data except in the case of NH4+. The correlations between the ion permeances and type of dominant salt are discussed in the context of the established mechanisms of NF such as Donnan and dielectric exclusion. The obtained information contributes to the systematic transport characterization of NF membranes and may be ultimately useful for computational fluid dynamics simulations of the performance of the membranes in various applications.

The Pulse of the Amazon: Fluxes of Dissolved Organic Carbon, Nutrients, and Ions From the World's Largest River

AbstractThe Amazon River drains a diverse tropical landscape greater than 6 million km2, culminating in the world's largest export of freshwater and dissolved constituents to the ocean. Here, we present dissolved organic carbon (DOC), organic and inorganic nitrogen (DON, DIN), orthophosphate (PO43−), and major and trace ion concentrations and fluxes from the Amazon River using 26 samples collected over three annual hydrographs. Concentrations and fluxes were predominantly controlled by the annual wet season flood pulse. Average DOC, DON, DIN, and PO43− fluxes (±1 s.d.) were 25.5 (±1.0), 1.14 (±0.05), 0.82 (±0.03), and 0.063 (±0.003) Tg yr−1, respectively. Chromophoric dissolved organic matter absorption (at 350 nm) was strongly correlated with DOC concentrations, resulting in a flux of 74.8 × 106 m−2 yr−1. DOC and DON concentrations positively correlated with discharge while nitrate + nitrite concentrations negatively correlated, suggesting mobilization and dilution responses, respectively. Ammonium, PO43−, and silica concentrations displayed chemostatic responses to discharge. Major and trace ion concentrations displayed clockwise hysteresis (except for chloride, sodium, and rubidium) and exhibited either dilution or chemostatic responses. The sources of weathered cations also displayed seasonality, with the highest proportion of carbonate‐ and silicate‐derived cations occurring during peak and baseflow, respectively. Finally, our seasonally resolved weathering model resulted in an average CO2 consumption yield of (3.55 ± 0.11) × 105 mol CO2 km−2 yr−1. These results represent an updated and temporally refined quantification of dissolved fluxes that highlight the strong seasonality of export from the world's largest river and set a robust baseline against which to gauge future change.

Geochemical evidence for fugitive gas contamination and associated water quality changes in drinking-water wells from Parker County, Texas.

Extensive development of horizontal drilling and hydraulic fracturing enhanced energy production but raised concerns about drinking-water quality in areas of shale-gas development. One particularly controversial case that has received significant public and scientific attention involves possible contamination of groundwater in the Trinity Aquifer in Parker County, Texas. Despite extensive work, the origin of natural gas in the Trinity Aquifer within this study area is an ongoing debate. Here, we present a comprehensive geochemical dataset collected across three sampling campaigns along with integration of previously published data. Data include major and trace ions, molecular gas compositions, compound-specific stable isotopes of hydrocarbons (δ13C-CH4, δ13C-C2H6, δ2H-CH4), dissolved inorganic carbon (δ13C-DIC), nitrogen (δ15N-N2), water (δ18O, δ2H, 3H), and noble gases (He, Ne, Ar), boron (δ11B) and strontium (87Sr/86Sr) isotopic compositions of water samples from 20 drinking-water wells from the Trinity Aquifer. The compendium of data confirms mixing between a deep, naturally occurring salt- (Cl >250mg/L) and hydrocarbon-rich groundwater with a low-salinity, shallower, and younger groundwater. Hydrocarbon gases display strong evidence for sulfate reduction-paired oxidation, in some cases followed by secondary methanogenesis. A subset of drinking-water wells contains elevated levels of hydrocarbons and depleted atmospherically-derived gas tracers, which is consistent with the introduction of fugitive thermogenic gas. We suggest that gas originating from the intermediate-depth Strawn Group ("Strawn") is flowing along the annulus of a Barnett Shale gas well, and is subsequently entering the shallow aquifer system. This interpretation is supported by the expansion in the number of affected drinking-water wells during our study period and the persistence of hydrocarbon levels over time. Our data suggest post-genetic secondary water quality changes occur following fugitive gas contamination, including sulfate reduction paired with hydrocarbon oxidation and secondary methanogenesis. Importantly, no evidence for upward migration of brine or natural gas associated with the Barnett Shale was identified.

Characterization of airborne particles and cytotoxicity to a human lung cancer cell line in Guangzhou, China

Air pollution by airborne particles is a serious health problem worldwide. The present study was aimed at investigating the concentrations and composition of total suspended particles (TSPs) and PM2.5 at various industrial/commercial sites of Guangzhou, a megacity of Southern China. Major and trace elements, ions and carbonaceous fraction were determined and main components were calculated. In addition, in order to assess the potential toxic on the respiratory system of these PM, cytotoxicity of size-fractionated particles (PM10-5.6, PM5.6-3.3, PM3.3-1.1, PM1.1-0.43) for a human lung cancer cell line (A549) was also investigated. Correlations between PM constituents and toxicity were assessed. Median levels of TSPs and PM2.5 in industrial/commercial sites were 206 and 57.7 μg/m3, respectively. Nickel, Cu, Mo, Mn, Pb, and Ti were the most abundant metals in TSPs and PM2.5. Industrial activities and coal combustion were the most important sources of carbonaceous particles in the zone. MTT assays showed that PM10-5.6 and PM1.1-0.43 had the highest and the lowest cytotoxicity to A549 cell lines, respectively. Inhalable particles around the manufacturing of metal facilities and formal waste treatment plants showed a high cytotoxicity to A549 cell lines. In general terms, no significant correlations were found between main components of PM and toxicity. However, W showed a significant correlation with cell viability.

Qualitative risk aggregation problems for the safety of multiple aquifers exposed to nitrate, fluoride and arsenic contaminants by a ‘Total Information Management’ framework

The aquifer at Varzeqan plain, with multiple confined/unconfined and hard-rock boundaries, is exposed to risks from several contaminants (nitrate-N, fluoride and arsenic) originated by anthropogenic and/or geogenic activities, which are possibly accelerating by anthropogenic activities. The study is a research initiative driven by impacts of poor or non-existent planning/ regulation practices to produce insights despite the sparsity of the available data and the unknown baseline. A methodology is given, which seeks ‘total information management’ by pooling together the following five dimensions: (i) a perceptual model to collect existing knowledge-base; (ii) a conceptual model to analyse a sample of ion-concentrations by a set of existing techniques (e.g. statistical, graphical and multivariate analysis); (iii) risk cells to contextualise each contaminant; (iv) “soft modelling” to firm up information by learning from convergences and/or divergences within the conceptual model; and (v) study the processes within each risk cell through the OSPRC framework (Origins, Sources, Pathways, Receptors and Consequence). The research caters for inherent variabilities in the study area by 15 risk cells delineated within the boundaries of confined, unconfined and hard-rock aquifers as follows: 4 risk cells account for minor ions of nitrate-N pollution of anthropogenic origins; 6 for minor ions of fluoride and 5 for trace ions of geogenic arsenic anomalies. It further identifies the possibility of anthropogenic activities encouraging geogenic anomalies. The findings are presented as a descriptive model but this will be transformed into quantitative models in due course when more data become available.

An investigation to human health risks from multiple contaminants and multiple origins by introducing 'Total Information Management'.

A capability for aggregating risks to aquifers is explored in this paper for cases with sparse data exposed to anthropogenic and geogenic contaminants driven by poor/non-existent planning/regulation practices. The capability seeks 'Total Information Management' (TIM) under sparse data by studying hydrogeochemical processes, which is in contrast to Human Health Risk Assessment (HHRA) by the USEPA for using sample data and a procedure with prescribed parameters without deriving their values from site data. The methodology for TIM pools together the following five dimensions: (i) a perceptual model to collect existing knowledge-base; (ii) a conceptual model to analyse a sample of ion-concentrations to determine groundwater type, origin, and dominant processes (e.g. statistical, graphical, multivariate analysis and geological survey); (iii) risk cells to contextualise contaminants, where the paper considers nitrate, arsenic, iron and lead occurring more than three times their permissible values; (iv) 'soft modelling' to firm up information by learning from convergences and/or divergences within the conceptual model; and (v) study the processes within each risk cell through the OSPRC framework (Origins, Sources, Pathways, Receptors and Consequence). The study area comprises a series of patchy aquifers but HHRA ignores such contextual data and provides some evidence on both carcinogenic and non-carcinogenic risks to human health. The TIM capability provides a greater insight for the processes to unacceptable risks from minor ions of anthropogenic nitrate pollutions and from trace ions of arsenic, iron and lead contaminants.

Geophysical and hydrochemical studies for sustainable development of groundwater resources in northwestern part of Telangana State, India

Studies have been carried out to assess groundwater potential using geophysical analysis and water quality indices in parts of Nyalkal and Zaheerabad Mandal, Medak District, Telangana State. As a part of the study, 50 groundwater samples were collected and 103 Vertical Electrical Soundings (VES) had been carried out. The water quality was assessed with respect to various major ion chemistry and trace elements. It is found that major ions and trace elements are within the permissible limits, except Al, Pb, and Zn metals, which slightly exceeded beyond permissible limits. However, the results of VES reveal that in some parts of the study area, the resistivity range for topsoil (26.61–930 Ωm), lateritic zone (453–738 Ωm), clayey/sandy clay layer (4.71–94.2 Ωm), weathered/fractured bedrock (60.5–928 Ωm) and weathered/vesicular/massive basalt (8.05–676 Ωm) are found with the formation of thick overburden and fractured basement. It is also found that the groundwater prospects are moderate to high depending on the extent of the weathering zone.

ЗОЛОТО-СУЛЬФИДНО-КВАРЦЕВОЕ РУДОПРОЯВЛЕНИЕ АРЫСКАН (ЗАПАДНАЯ ТУВА): УСЛОВИЯ ОБРАЗОВАНИЯ И ГЕОХИМИЧЕСКИЕ ОСОБЕННОСТИ ФЛЮИДОВ

Актуальность исследования обусловлена необходимостью определения генезиса и условий образования золоторудных объектов Тувы для повышения эффективности геолого-поисковых работ по наращиванию минерально-сырьевой базы золота региона. Цель: определение условий образования и геохимических особенностей рудообразующих флюидов рудопроявления золота Арыскан в Западной Туве. Методы. Флюидные включения проанализированы с помощью микротермокамеры Linkam TMS-600 с микроскопом Olympus BX 51 с целью определения температур, солевого состава, концентрации солей и давления флюида при минералообразовании; газовый состав индивидуальных флюидных включений определен на рамановском спектрометре Ramanor U-1000 с детектором Horiba DU420E-OE-323, лазер Millennia Pro (Spectra-Physics); валовый газовый состав флюида определен на газовом хроматографе Agilent 6890, содержания анионов в водной вытяжке оценены на ионном хроматографе ЦВЕТ-3000, содержания катионов и микроэлементов – методом ICP MS (Elan-6100); соотношения изотопов серы определены на газовом масс-спектрометре Finnigan MAT Delta. Результаты. В результате проведенных исследований установлено, что березиты рудопроявления сформировались при участии углекислотных водно-солевых флюидов с соленостью 4,9–41,5 мас. % экв. NaСl при температурах не менее 250–340°C. Золотосодержащие минеральные ассоциации образовались при P ~1,8 кбар (~5,4 км) из водных растворов состава NaCl-KCl-H2O, NaCl-Na2НCO4-H2O и NaCl-H2O, содержащих CO2, с концентрациями 2,9–32,9 мас. % NaСl-экв., на фоне снижения температур в интервале 290–145 °C (золото-сульфидно-кварцевые жилы – 290–145 °С, золото-теллуридно-сульфидно-кварцевые жилы – 270–160 °С), при вариациях f O2, f S2, f Se2 и f Te2. Изотопный δ34SH2S (от –0,5 до +1,1 ‰), солевой и микроэлементный состав минералообразующего флюида свидетельствуют о его магматическом происхождении.

Biomimetic trace metals improve bone regenerative properties of calcium phosphate bioceramics.

The bone regenerative capacity of synthetic calcium phosphates (CaPs) can be enhanced through the enrichment with selected metal trace ions. However, defining the optimal elemental composition required for bone formation is challenging due to many possible concentrations and combinations of these elements. We hypothesized that the ideal elemental composition exists in the inorganic phase of the bone extracellular matrix (ECM). To study our hypothesis, we first obtained natural hydroxyapatite through the calcination of bovine bone, which was then investigated its reactivity with acidic phosphates to produce CaP cements. Bioceramic scaffolds fabricated using these cements were assessed for their composition, properties, and in vivo regenerative performance and compared with controls. We found that natural hydroxyapatite could react with phosphoric acid to produce CaP cements with biomimetic trace metals. These cements present significantly superior in vivo bone regenerative performance compared with cements prepared using synthetic apatite. In summary, this study opens new avenues for further advancements in the field of CaP bone biomaterials by introducing a simple approach to develop biomimetic CaPs. This work also sheds light on the role of the inorganic phase of bone and its composition in defining the regenerative properties of natural bone xenografts.

Concentrative isolation of uranium traces in aqueous solutions via resurfaced-magnetic carbon nanotube suspension

The concentrative isolation of metal traces from aqueous solutions is of vital importance for environmental and industrial processes. Developing reliable systems of nanoscale that can be fine-tuned to effectively isolate these metals remains an intriguing aim which can potentially beget economic benefits and mitigate major environmental concerns. Here we demonstrate a conceptual metal extraction system where magnetic multi-wall carbon nanotubes (M-MWCNTs) are surface-equipped with a molecular network of polyethylenimine (PEI) to serve as a reusable nano-ionic exchanger, referred to as “M-MWCNTs-PEI”. The designed nano-ionic exchanger forms readily stable suspensions with the metal-bearing aqueous solutions eliminating the need for vigorous agitation. Besides, it can be magnetically manipulated and separated in/from the solution. To exemplify its potential for the isolation of metal traces, the M-MWCNTs-PEI was tested with the uranium trace ions in aqueous media. The M-MWCNTs-PEI featured distinct sorption capacity of ~488 mg/g at pH 6, with moderate, but stable, binding affinity toward uranium ions. As such, excellent isolation performance is demonstrated while bound uranium ions are effectively concentrated and recovered from the interfacial PEI molecular network. This was efficiently achieved by exposing the loaded M-MWCNTs-PEI to solutions of small volumes and specific chemistry. Such combined qualities of large capacity and reusability have not been observed with the previously reported ion exchange systems. Altogether, our observations here demonstrate how functional systems of nanoscale can be adapted for industrial applications while this concept can be extended to address other important resources such as rare-earth and lanthanide elements.

Zircon U-Pb Geochronology Recorded Late Cretaceous Fluid Activation in the Central Aldan Gold Ore District, Aldan Shield, Russia: First Data

The gold mineralization in the Central Aldan ore district is genetically related to potassic calc-alkaline and alkaline magmatism dated at 115–150 Ma. The objective of this study is to establish the age of hydrothermal processes that accompanied the formation of Au-Te mineralization at the Samolazovsky Deposit. Based on the isotope-geochemical study of zircons from quartz-feldspar metasomatic rocks of the deposit, the granitoids and charnokites of the Nimnyr Complex (1 900–1 960 Ma) at the contact with the Yukhta monzonite-syenite massif (∼127 Ma) were studied. Zircon U-Pb dating was performed on a SHRIMP-II ion microprobe, and rare-earth and trace elements analyses of zircon were carried out in the same craters by secondary-ion mass spectrometry on a Cameca IMS-4f ion microprobe. It is revealed that the studied zircons have heterogeneous structures: dark core and lighter rim, which differ greatly in isotope-geochemical parameters. Zircon rims are cut by a network of fractures, extending into the central part of zircon grains. The rims yield a subconcordant age of 1 937±24 Ma, with an average total REE content of 550 ppm, which corresponds to the formation age of the Nimnyr Complex. All zircon cores yield a discordant age of 83±11 Ma and are characterized by a higher total REE content (∼1 812 ppm), as well as higher contents of U and non-formula elements (Ca, Sr, and Y) with respect to rims, due to the effect of fluid on zircons. Despite the limited number of zircon grains, the additional geochronological study of zircons from syenites of the ore-bearing Ryabinovy Massif has revealed the presence of two distinct age clusters: ∼125–138 and 76–83 Ma. The older ages of zircons from syenites are typical for the Central Aldan ore district. Until now, there is still no explanation for an age range (76–83 Ma) of single zircon grains from ore-bearing syenites of the Ryabinovy Massif. The obtained data suggest that the processes of activation (the effect of fluid) within the Central Aldan ore district continued until Late Mesozoic. With regards to the equivocal geotectonic position of the Mesozoic potassic magmatism in the study area and its high metallogenic potential, there exists an absolute necessity to determine the geochronological age of the rock formations. Therefore this study presents the Late Cretaceous geochronological data for the first time which can constrain the time-frame for the formation of gold-bearing magmatic and metasomatic rocks of the Aldan ore district.

Origin and circulation of saline springs in the Kuqa Basin of the Tarim Basin, Northwest China

It is widely accepted that hydrogeochemistry of saline springs is extremely important to understand the water circulation and evolution of saline basins and to evaluate the potential of potassiumrich evaporites. The Kuqa Basin, located in the northern part of the Tarim Basin in Northwest China, is a saline basin regarded as the most potential potash-seeking area. However, the origin and water circulation processes of saline springs have yet to be fully characterized in this saline basin. In this study, a total of 30 saline spring samples and 11 river water samples were collected from the Qiulitage Structural Belt (QSB) of the Kuqa Basin. They were analyzed for major (K+, Ca2+, Na+, Mg2+, SO42−, Cl− and HCO3−) and trace (Sr2+ and Br−) ion concentrations, stable H-O-Sr isotopes and tritium concentrations in combination with previously published hydrogeochemical and isotopic (H-O) data in the same area. It is found that the water chemical type of saline springs in the study area belonged to the Na-Cl type, and that of river water belonged to the Ca-Mg-HCO3-SO4 type. The total dissolved solid (TDS) of saline springs in the QSB ranged from 117.77 to 314.92 g/L, reaching the brine level. On the basis of the general chemical compositions and the characteristics of the stable H-O-Sr isotopes of saline springs, we infer that those saline springs mainly originated from precipitation following river water recharging. In addition, we found that saline springs were not formed by evapo-concentration because it is unlikely that the high chloride concentration of saline springs resulted in evapo-concentration and high salinity. Therefore, we conclude that saline spring water may have experienced intense evapo-concentration before dissolving the salty minerals or after returning to the surface. The results show that the origin of salinity was mainly dominated by dissolving salty minerals due to the river water and/or precipitation that passed through the halite-rich stratum. Moreover, there are two possible origins of saline springs in the QSB: one is the infiltration of the meteoric water (river water), which then circulates deep into the earth, wherein it dissolves salty minerals, travels along the fault and returns to the surface; another is the mixture of formation water, or the mixture of seawater or marine evaporate sources and its subsequent discharge to the surface under fault conditions. Our findings provide new insight into the possible saltwater circulation and evolution of saline basins in the Tarim Basin.

Detection of trace metal ions in high-purity boric acid by online two-dimensional valve switching coupled with ion chromatography-inductively coupled plasma mass spectrometry

In this paper, a two-dimensional valve switching technique was established to detect 10 trace metal ions in high-purity boric acid by ion chromatography-inductively coupled plasma mass spectrometry (IC-ICPMS). The system consisted of a quantitative loop, a matrix capture column, an iminodiacetic acid cationic chelating column, an ion chromatography column, two sample valves and an inductively coupled plasma mass spectrometer. The iminodiacetic acid cationic chelating column coupled the metal ions in the sample with its carboxyl functional groups to separate them from the matrix boric acid solution, and then eluted the chelated metal ions into the ion chromatographic column and inductively coupled plasma mass spectrometer. The proposed method feasibly achieved an online, rapid and efficient detection of 10 trace ions in high-purity boric acid with the optimized experimental conditions (1.0 mol/L HNO3), such as loading solution, loading flow rate, type of eluent, concentration of the eluent, sample matrix, etc. The experimental data showed that this method had good linearity in the range of 0.01–2.0 μg/L for 10 metal ions, such as Cr, Fe, Ni, Co, V, Mn, Cu, Zn, Cd and Pb in high-purity boric acid samples, with a correlation coefficient greater than 0.998. The limit of detection (LOD, S/N = 3) and the limit of quantitation (LOQ, S/N = 10) were 0.001–0.023 μg/L and 0.003–0.077 μg/L, respectively. The relative standard deviation (RSD) of each element was less than 3.0% (n = 6) and the spiked recoveries ranged between 83% and 110%. This method could be proposed to be suitable for determination of trace metal ions in real samples.

Pollution characteristics, sources, and health risk assessments of urban road dust in Kuala Lumpur City

Urban road dust contains anthropogenic components at toxic concentrations which can be hazardous to human health. A total of 36 road dust samples from five different urban areas, a commercial (CM), a high traffic (HT), a park (GR), a rail station (LRT), and a residential area (RD), were collected in Kuala Lumpur City followed by investigation into compositions, sources, and human health risks. The concentrations of trace metals in road dust and the bioaccessible fraction were determined using inductively couple plasma-mass spectrometry (ICP-MS) while ion concentrations were determined using ion chromatography (IC). The trace metal concentrations were dominated by Fe and Al with contributions of 53% and 21% to the total trace metal and ion concentrations in road dust. Another dominant metal was Zn while the dominant ion was Ca2+ with average concentrations of 314 ± 190μgg-1 and 3470 ± 1693μgg-1, respectively. The most bioaccessible fraction was Zn followed by the sequence Sr > Cd > Cr > Cu > Ni > Co > Mn > As > V > Pb > Fe > Al > U. The results revealed that the highest trace metal and ion concentrations in road dust and in the bioaccessible fraction were found at the LRT area. Based on the source apportionment analysis, the major source of road dust was vehicle emissions/traffic activity (47%), and for the bioaccessible fraction, the major source was soil dust (50%). For the health risk assessments, hazard quotient (HQ) and cancer risk (CR) values for each element were < 1 and in the tolerable range (1.0E-06 to 1.0E-04), except for As for the ingestion pathway. This result suggests a low risk from non-carcinogenic and probable risk from carcinogenic elements, with higher health risks for children compared to adults.

Simplified Prediction of Ion Removal in Capacitive Deionization of Multi-Ion Solutions

Capacitive deionization (CDI) is an upcoming desalination technology being increasingly considered to be a simple and cost-effective solution for brackish water, where electrosorption leads to the removal of charged species from water. Real-world water samples typically contain a multitude of ions that must be considered apart from sodium–chloride salt. In this work, we have developed a method to quantify the competitive adsorption of different ionic species during CDI processes. The method is straightforward, requiring a single calibrating experiment to extract a ‘periodic table’ of competitiveness scores for all ions present in the experiment. Using a dynamic Langmuir model that was developed by our group, it is shown that these scores could subsequently be used to predict the adsorption of any ion species in a multi-ion solution. Excellent agreement with data from the literature could be achieved with this model, and the method is especially well-suited for trace ions as these can be predicted directly. The derived method is simple and accurate for quantifying and predicting adsorption in multi-ion solutions and could be valuable for predicting the effect when applying CDI to real-world water samples.

Effect of surface ligands on gold nanocatalysts for CO2 reduction.

Nanoparticle catalysts display optimal mass activity due to their high surface to volume ratio and tunable size and structure. However, control of nanoparticle size requires the presence of surface ligands, which significantly influence catalytic performance. In this work, we investigate the effect of dodecanethiol on the activity, selectivity, and stability of Au nanoparticles for electrochemical carbon dioxide reduction (CO2R). Results show that dodecanethiol on Au nanoparticles significantly enhances selectivity and stability with minimal loss in activity by acting as a CO2-permeable membrane, which blocks the deposition of metal ions that are otherwise responsible for rapid deactivation. Although dodecanethiol occupies 90% or more of the electrochemical active surface area, it has a negligible effect on the partial current density to CO, indicating that it specifically does not block the active sites responsible for CO2R. Further, by preventing trace ion deposition, dodecanethiol stabilizes CO production on Au nanoparticles under conditions where CO2R selectivity on polycrystalline Au rapidly decays to zero. Comparison with other surface ligands and nanoparticles shows that this effect is specific to both the chemical identity and the surface structure of the dodecanethiol monolayer. To demonstrate the potential of this catalyst, CO2R was performed in electrolyte prepared from ambient river water, and dodecanethiol-capped Au nanoparticles produce more than 100 times higher CO yield compared to clean polycrystalline Au at identical potential and similar current.

Monascorubin production by Penicillium minioluteum ED24 in a solid-state fermentation using sesame seed cake as substrate

Monascorubin is one of the red Monascus pigments produced by molds. It is a kind of alcohol-soluble pigment and has been widely used in food and medicine. Natural red pigments have been gaining numerous interests in the food industry as the synthetic red pigments such as azorubine were banned. In this study, the potential use of sesame seed cake as a low-cost substrate to produce monascorubin in a solid-state fermentation by Penicillium minioluteum ED24 was examined. Response surface methodology (RSM) was employed to study the effect of moisture content, dipotassium hydrophosphate (K2HPO4) concentration, concentration of trace ion solution, incubation temperature and inoculum size on the monascorubin production and P. minioluteum ED24 growth. The experiments were designed using central composite design (CCD). The results depicted that 20 g of sesame seed cake produced highest monascorubin at 46.17 µg/ml. While the optimum conditions for monascorubin production obtained from surface analysis are moisture content 65.45%, K2HPO4 concentration 10.43% v/w, concentration of trace ion solution 11.17% v/w, incubation temperature 29.13 °C and inoculum size 9.92% v/w. Meanwhile, the addition of 1% w/w of soluble starch and 1% w/w of mycological peptone enhanced the monascorubin production and fungal growth by 56.56% and 11.53% respectively. Finally, the potential use of sesame seed cake as a low-cost fermentation medium had been presented. This study also provides important insights on the production of monascus pigment by using non-Monascus fungi and lays a foundation for future utilizations of P. minioluteum ED24 for pigment production at industrial scale.