Significant Contamination Research Articles

Accounting for Overcounting Induced by 222Rn Contamination in 14C Measurements Performed with Liquid Scintillation Counting

Abstract This research paper introduces a methodology for estimating overcounting resulting from uranium series radionuclides, with a specific focus on 222Rn contamination. The method is demonstrated using the Quantulus 1220TM spectrometer. Exponential fitting is employed for the calculations, utilizing a custom algorithm developed in MATLAB® R2022b. The proposed method allows for the determination of the sample count rate correction, F14C and radiocarbon age without the need for additional chemical treatment or specialized electronics during liquid scintillation counting (LSC) measurements with the Quantulus 1220TM spectrometer. However, the method does have certain limitations. It requires a significant number of cycles and extended measurement time per cycle, but it can be applied to samples with significant 222Rn contamination that require rapid 14C analysis.

Effects of copper sulfate exposure on the nervous system of the Hirudo verbana leech

Copper is a significant environmental contaminant resulting from electronic waste and pesticide use. It is also a micronutrient that is essential for life because it is an enzyme cofactor. However, excess exposure to this heavy metal can lead to adverse physiologic effects. Prior studies have demonstrated neurotoxic effects of copper exposure on arthropods, mollusks, amphibians, and mammals, via mechanisms ranging from oxidative stress to changes in neurotransmitter levels. We focused on toxic effects of copper exposure on the nervous system of the Hirudo verbana leech, hypothesizing that copper exposure leads to neurobehavioral changes associated with structural changes to and proteomic changes within nerve ganglia. After exposing leeches to graded concentrations of copper sulfate, we performed neurobehavioral testing to measure their ability to ingest liver and record their movements in a 3-D printed pool. We dissected out nerve ganglia and examined them with light microscopy following hematoxylin and eosin staining. We also extracted, identified, and quantified proteins from the nerve ganglia using high performance liquid chromatography-mass spectrometry. We found that copper exposure was associated with neurobehavioral changes including food avoidance, diminished dark-seeking behavior, and decreased motility. Furthermore, we found histopathologic changes and proteomic alterations within nerve ganglia of copper-exposed leeches. These findings contribute to our understanding of potential mechanisms for nervous system damage with copper exposure. The results are concerning as they indicate that copper accumulation in the environment has tangible neurological consequences for exposed organisms.

Mitigation of Wind Turbine Clutter With Digital Phased Array Radar

Wind turbine clutter (WTC) contamination affects polarimetric meteorological observations and automatic high-impact weather detection algorithms in several ways, such as, misidentification of precipitation echoes, false mesocyclone detections, and incorrect storm cell identification. With the dramatic growth of the wind power industry, this would only aggravate in the future. Since fully digital Phased Array Radar (PAR) is a promising candidate technology for the next generation of weather radars, evolutionary signal processing algorithms that make use of their capabilities should be investigated to mitigate WTC contamination. This article investigates the use of Space-Time Adaptive Processing (STAP) to mitigate WTC contamination with ground-based polarimetric PAR. First, a flexible wind turbine time-series signal simulator is developed to characterize the contamination signatures in the space-time domain. Then, a STAP algorithm that removes the contamination is presented and demonstrated on simulated data. Two digital radar back-end architectures are considered to evaluate the performance of the proposed algorithm. One with digital sub-array outputs the other one with fully digital outputs (i.e., element-level digital). Results indicate the the WTC spectrum has a characteristic structure in the space-time domain, and that biases induced in polarimetric weather variables can be more effectively mitigated using an fully digital PAR.

Prevalence, antimicrobial resistance, and genetic characteristics of Staphylococcus aureus isolates in frozen flour and rice products in Shanghai, China

Staphylococcus aureus is widely recognized as a highly hazardous pathogen that poses significant threats to food safety and public health. This study aimed to assess the prevalence, antimicrobial resistance, and genetic characteristics of S. aureus isolates recovered from 288 frozen flour and rice product samples in Shanghai, China, between September 2019 and May 2020. A total of 81 S. aureus isolates were obtained, representing 25 sequence types (STs), with ST7 being the most prevalent (17.28%, n = 14). The majority of S. aureus isolates (85.19%, n = 69) carried at least one enterotoxin gene, with the seg gene being the most frequently detected (51.85%, n = 42). Additionally, 12 isolates (14.81%) were identified as methicillin-resistant S. aureus (MRSA) through mecA gene detection. Notably, this study reported the presence of an ST398 MRSA isolate in frozen flour and rice products for the first time. All MRSA isolates displayed multidrug resistance, with the highest resistance observed against cefoxitin (100.00%), followed by penicillin (91.67%) and erythromycin (66.67%). Genomic analysis of the 12 MRSA isolates revealed the presence of twenty distinct acquired antimicrobial resistance genes (ARGs), eight chromosomal point mutations, and twenty-four unique virulence genes. Comparative genome analysis indicated close genetic relationships between these MRSA isolates and previously reported MRSA isolates from clinical infections, highlighting the potential transmission of MRSA through the food chain and its implications for public health. Significantly, the identification of three plasmids harboring ARGs, insertion sequences (ISs), the origin of transfer site (oriT), and the relaxase gene suggested the potential for horizontal transfer of ARGs via conjugative plasmids in S. aureus. In conclusion, this study revealed significant contamination of retail frozen flour and rice products with S. aureus, and provided essential data for ensuring food safety and protecting public health.

Mechanochemical destruction of per- and polyfluoroalkyl substances in aqueous film-forming foams and contaminated soil.

Per- and polyfluoroalkyl substances (PFASs) are a class of synthetic chemicals of concern that exhibit extreme persistence within the environment and possess physicochemical properties that are resistant to targeted degradation. Comprising substantial concentrations of PFASs, aqueous film-forming foams (AFFFs) present a major exposure pathway to the environment having been applied to land at firefighting-training sites globally for decades. This has led to significant contamination of environmental media. Herein, we demonstrate that mechanochemical destruction (MCD) is an effective method for the destruction of PFASs in an AFFF concentrate and an authentic sample of PFAS-contaminated soil derived from a decommissioned firefighting training facility. Both targeted analysis and non-targeted analysis were used in this study to evaluate the degradation of PFASs in complex substrates during MCD treatment. Destruction efficiencies of target PFAS subgroups ranged from 99.88% to 100%. The only additive employed for MCD treatment was quartz sand, which was used only for the liquid AFFF sample, with no additives required for the destruction of PFASs in the contaminated soil. This confirms the viability of MCD for both the remediation of PFAS-contaminated land and the destruction of stockpiled AFFFs.

Geochemistry and petrogenesis of Late Permian basalts from the Sichuan Basin, SW China: Implications for the geodynamics of the Emeishan mantle plume

Plume-lithosphere interactions are significant in the formation of Large Igneous Provinces (LIPs). The Permian Emeishan Large Igneous Province (ELIP) is considered to be the result of a mantle plume. The Emeishan flood basalts comprise a major part of the ELIP and they define three zones: the inner, intermediate and outer zones. Both high-Ti and low-Ti basalts are present in the inner zone, whereas only high-Ti basalts are found in the intermediate zone and outer zone. However, there are only sparse outcrops in the outer zone, and so geochemical data on basalts from the outer zone are rare and the role of plume-lithosphere interaction in the petrogenesis of volcanic rocks in the outer zone remains poorly understood. In the Sichuan basin, the Basalt Formation is found between the Permian Maokou Formation limestone and the Longtan Formation marl in some drill cores as well as in outcrops in the basin. This relationship demonstrates that the basaltic layer in the basin is part of the Emeishan flood basalts. These basalts have TiO2 contents of 3.7–4.2 wt% and Ti/Y ratios of 604–720, being high-Ti sub-alkaline basalts. They display chondrite-normalized rare earth elements (REE) patterns enriched in light rare earth elements (LREE) relative to heavy rare earth elements (HREE) and have elevated large ion lithophile elements (LILE) and high field strength elements (HFSE). Lead isotope ratios are high (206Pb/204Pb(t) = 18.102–18.392, 207Pb/204Pb(t) = 15.578–15.606, 208Pb/204Pb(t) = 38.410–38.850), and εNd(t) values are −0.38 ∼ 1.17. Detailed petrology and geochemistry suggest that the high-Ti basalts from the Sichuan Basin did not experience significant contamination of crustal and lithospheric mantle material during the ascent of magma. We infer that these basalts resulted from low-degree melting of the plume mantle source and underwent fractional crystallization of clinopyroxene. The distribution and petrogenesis of the Sichuan Basin basalts in the outer zone are different from those of the basalts in the inner zone and there are clearly different plume-lithosphere interactions in different parts of the ELIP. In the inner zone, the temperature of the lithosphere mantle was markedly elevated due to underplating of the mantle plume, causing a substantial quantity of lithosphere mantle melting and the initial formation of low-Ti basalts. This was followed by melting of the mantle plume and the formation of high-Ti basalts. In the outer zone, lower temperatures further from the plume centre were insufficient to generate extensive melting of the lithospheric mantle. Consequently, only the mantle plume melted in the outer zone, resulting in the formation of high-Ti basalts with minimal lithospheric input.

Óleos essenciais de plantas condimentares e medicinais no controle de contaminantes da micropropagação de Myrciaria dubia

Abstract The main limitation of the micropropagation of camu-camu (Myrciaria dubia) is related to in vitro contamination. In order to overcome contamination, the effect of essential oils was studied as an alternative to conventional chemical treatments. This study aimed to analyze the action of essential oils from four condiment and medicinal plants (Oregano, Origanum vulgare L.; Garlic, Allium sativum L.; Citronella, Cymbopogon nardus L.;and Ginger, Zingiber officinale Rosc.) in reducing microbial contamination growth and on the survival rate of explants in the micropropagation of camu-camu. The antimicrobial activity of essential oils was analyzed on the in vitro contamination of tissue culture from camu-camu at concentrations of 0.5, 1, 2, 3 and 4 µL mL-1 in woody plant medium (WPM), emulsified with 1% Polysorbate 80 (Tween 80). The antibacterial activity of essential oils on strains isolated from camu-camu tissue culture was also analyzed using agar diffusion and broth microdilution methods. The use of essential oils allowed a reduction in the rate of in vitro contamination in tissue culture, it being observed that, from the concentration of 2 µL mL-1, there was no manifestation of fungal contaminants, with a significant reduction in the rate of bacterial contamination, with the exception of ginger essential oil that showed significant contamination in all analyzed concentrations. Inversely in relation to the reduction in microbial growth in vitro, there is an increase in explant oxidation as concentrations increase, with citronella and oregano oils showing phytotoxic potential from the lowest concentrations. Garlic essential oil showed better balance, with lower oxidation rates and greater control of microorganisms in tissue culture at concentrations of 0.5 and 1 µL mL-1. Oregano and citronella essential oils showed better antibacterial activity in the agar diffusion test.

Micro(nano)plastic pollution in terrestrial ecosystem: emphasis on impacts of polystyrene on soil biota, plants, animals, and humans

Pollution with emerging microscopic contaminants such as microplastics (MPs) and nanoplastics (NPs) including polystyrene (PS) in aquatic and terrestrial environments is increasingly recognized. PS is largely used in packaging materials and is dumped directly into the ecosystem. PS micro-nano-plastics (MNPs) can be potentially bioaccumulated in the food chain and can cause human health concerns through food consumption. Earlier MP research has focused on the aquatic environments, but recent researches show significant MP and NP contamination in the terrestrial environments especially agricultural fields. Though PS is the hotspot of MPs research, however, to our knowledge, this systematic review represents the first of its kind that specifically focused on PS contamination in agricultural soils, covering sources, effects, and ways of PS mitigation. The paper also provides updated information on the effects of PS on soil organisms, its uptake by plants, and effects on higher animals as well as human beings. Directions for future research are also proposed to increase our understanding of the environmental contamination of PS in terrestrial environments.

Studying the pre-implantation uterine microbiota in cattle using transabdominal laparoscopic low-volume lavage: Aiming for zero-contamination

Recent studies have suggested that bacteria associated with the female reproductive tract – the uterine microbiota – may be important for reproductive health and pregnancy success. Therefore, uterine microbiome research gained much interest in the last few years. However, it is challenging to study late postpartum uterine samples, since they hold a low microbial biomass. Next-generation sequencing techniques are very sensitive for microbial identification, but they cannot make a distinction between actual microbiota and contaminant bacteria or their DNA. Our aim was to test a new method to sample the bovine uterine lumen in vivo, while minimizing the risk of cross-contamination. In order to evaluate this method, we performed a descriptive assessment of the microbial composition of the obtained samples. Transabdominal, laparoscopic sampling of the uterine lumen was conducted in five Holstein-Friesian cows. Uterine fluid from the uterine horns was collected by low-volume lavage. DNA from the samples was extracted using two different DNA extraction methods, and negative controls (sampling blank controls and DNA extraction blank controls) were included. Bacteria were identified using 16S rRNA gene amplicon sequencing. In this proof-of-concept study, no evidence for authentically present uterine microbiota could be found. During laparoscopic sampling, some practical challenges were encountered, and the reliability of low-volume-lavage for the collection of a low microbial biomass could be questioned. By comparing two DNA extraction methods, a significant contamination background could be noticed originating from the DNA extraction kits.

Determination of glyphosate and AMPA in indoor settled dust by hydrophilic interaction liquid chromatography with tandem mass spectrometry and implications for human exposure

The widespread application of glyphosate leads to significant contamination of outdoor environmental compartments, notably air and soil, which can contaminate indoor air and dust. This study assessed the contamination of indoor household dust for the first time in France and potential exposure to glyphosate through the inadvertent ingestion of dust. A specific and new analytical method was developed using HILIC MS/MS (hydrophilic interaction liquid chromatography with tandem mass spectrometry) to measure polar pesticides, such as glyphosate, aminomethylphosphonic acid, and glufosinate, in indoor dust, with a low quantification limit (25 ng/g). The dust from vacuum cleaner bags of 60 rural and urban households (Brittany, France) was analyzed. All samples contained glyphosate (median 1675 ng/g for rural dwellings (n = 29), 457 ng/g for urban dwellings (n = 31)), more than 90 % contained aminomethylphosphonic acid, and none contained glufosinate. Concentrations were influenced by the rural or urban setting, the proximity of crops, and the use of weed killers on driveways or lawns. Glyphosate exposure via indoor dust ingestion was < 1 % of both acceptable daily intake and dietary intake. However, the high quantification limit of the glyphosate concentration in the food analysis method probably leads to overestimation of the dose from food.

326. Optimizing DNA Extraction from Pediatric Stool for Diagnosing Tuberculosis and Use in Next Generation Sequencing

Abstract Background Next generation sequencing (NGS) is quickly coming to the forefront of diagnostic tools to provide efficient, highly informative information from patient samples. Recently, it was established that patients with pulmonary Tuberculosis (TB) have Mycobacterium tuberculosis DNA present in their stool samples, which can augment current diagnostic gaps. Optimizing extraction of DNA from stool for analysis via sequencing technologies is a paramount initial step to ensure accuracy of downstream sequencing applications. Methods Attenuated strains of Mycobacterium bovis derived from BCG were used as a model for Mtb. Human stool samples were spiked with varying known concentrations of BCG and extracted with four different DNA extraction kits (Fast DNA Spik Kit for Soil, DNeasy Blood and Tissue Kit, MagAttract HMW DNA Kit, and PowerFecal Pro DNA Kit). Each sample was subjected to quantitative polymerase chain reaction using designed primers and probes specific for identifying Mtb infection from stool. The samples underwent further analysis to assess overall DNA yield (Qubit fluorometer), DNA fragment length (Agilent tape measure), and DNA purity (Nanodrop spectrophotometer). Results Overall, the Fast DNA Spin Kit for Soil extraction kit showed the most optimal results. DNA isolated via this method showed the lowest cycle thresholds of Mtb amplification, indicating the most preserved amount of BCG specific DNA. In addition, this method showed the highest overall DNA yield and highest proportion of long DNA fragment lengths. Fluorometric analysis showed significant contamination in the 230 nm wavelength range, which was amended with an additional AMPure bead cleanup step. Quantiative PCR of Spiked BCG Quantitative PCR Cycle Threshold Values by Different DNA Extraction Kits Conclusion The MPFast Soil Extraction kit, when compared to three other DNA extraction kits, performed the best on stool samples for isolating BCG DNA. Overall DNA yield, DNA length, and amount of specific BCG DNA were best optimized with this method and provided the best samples for sequencing analysis. This critical step is the first of many to realize the promise of stool-based NGS. DNA Quantity Quantity of Total DNA by Different DNA Extraction Kits Spectrophotometric Analysis Analysis of Absorption of Extracted DNA by Different DNA Extraction Kits Spectrophotometric Results Spectrophotometry Results of DNA Samples Extracted by Different DNA Extraction Kits Disclosures Lennard A. Meiwes, n/a, German Center for Infection Research (DZIF): Grant/Research Support.

Abundance, spatial distribution, and characteristics of microplastics in agricultural soils and their relationship with contributing factors

Agro-ecosystem contamination with microplastics (MPs) is of great concern. However, limited research has been conducted on the agricultural soil of tropical regions. This paper investigated MPs in the agro-ecosystem of Hainan Island, China, as well as their relationships with plastic mulching, farming practices, and social and environmental factors. The concentration of MPs in the study area ranged from 2800 to 82500 particles/kg with a mean concentration of 15461.52 particles/kg. MPs with sizes between 20 and 200 μm had the highest abundance of 57.57%, fragment (58.16%) was the most predominant shape, while black (77.76%) was the most abundant MP colour. Polyethylene (PE) (71.04%) and polypropylene (PP) (19.83%) were the main types of polymers. The mean abundance of MPs was significantly positively correlated (p < 0.01) with all sizes, temperature, and shapes except fibre, while weakly positively correlated with the population (p = 0.21), GDP (p = 0.33), and annual precipitation (p = 0.66). In conclusion, plastic mulching contributed to significant contamination of soil MPs in the study area, while environmental and social factors promoted soil MPs fragmentation. The current study results indicate serious contamination with MPs, which poses a concern regarding ecological and environmental safety.

Zircon Hf-O isotopic constraints on the origin and temporal evolution of the Toba volcanic system, Indonesia

Combined U-Pb-Hf-O isotopic analyses of zircons are useful probes to investigate the origin and temporal evolution of long-lived magma reservoirs feeding large eruptions. This study presents a complete dataset of zircon Hf-O isotopes of the latest five Toba eruptions in Quaternary. The new isotopic data differ slightly within and between eruptive units, with the majority of zircons having ε Hf values between −8 to −5 and δ 18 O values between 6 and 6.8. These Hf-O isotopic compositions of zircons were considered to inherit from an enriched and slightly heterogenous magma source. Specifically, zircons of the Oldest Toba Tuff (OTT) have rather restricted and constant Hf-O isotopes, which may crystallize from a reservoir protractedly supplied from the same magma source. Zircons of the Middle Toba Tuff (MTT) have a large range of δ 18 O values varying from ~6 to 8, with low ε Hf values extending to −14, indicating shallow-level crustal contamination. The largely negative correlations between ε Hf and δ 18 O for zircons from the MTT is indicative of contamination of high-δ 18 O crustal materials, whereas those of the positive correlations for zircons from the Youngest Toba Tuff (YTT) implies contamination of hydrothermally altered low-δ 18 O crustal materials. It is important that the Hf-O isotopes of all the zircons do not record any single batch of magma that was derived from partial melting of depleted mantle peridotites, but are consistent with an enriched and heterogenous mantle source hybridized by the subducted sediments, followed by contamination of low-δ 18 O or high-δ 18 O materials during their ascent to the surface or storage in the shallow magma reservoirs. The increase of zircon δ 18 O values towards eruptions in both the MTT and YTT suggests that the two eruptions may be accompanied by roof collapse that added high-δ 18 O materials to the magma. Thus, assimilation of high-δ 18 O crustal materials could be a possible trigger for the MTT and YTT eruptions. • Toba volcanic rocks were derived from an isotopically enriched and heterogenous mantle source with significant crustal contamination. • Hf-O isotopes of MTT zircon crystals exhibit characteristics of shallow-level crustal contamination. • The YTT magma reservoir was contaminated by both high- and low-δ 18 O crustal materials. • Assimilation of high-δ 18 O materials by roof collapse could be a likely eruption trigger for the MTT and YTT eruptions.

Nano-sized Ce-substituted hexagonal Co2–Y ferrite; a valuable catalyst for heterogeneous reduction of toxic nitro-organic pollutants

This paper describes the synthesis of Ce-substituted Y-type barium hexaferrites (Co 2 –Y) {Ba 2 Co 2 Fe 12-x Ce x O 22 (0 ≤ x ≥ 0.30)} through the sol-gel auto-combustion route and its suitability as a heterogeneous catalyst for the reduction of nitroaromatic-compounds, one of the significant water contaminants. The synthesized nanocrystalline hexaferrite powders were characterized using XRD, FTIR, BET, SEM, and VSM. Furthermore, the catalytic functioning of the Co 2 –Y hexaferrite powder was evaluated based on the isolated yield of aniline in the reaction product through column chromatography. It was found that 100 mg pure Co 2 –Y hexaferrite samples could provide complete conversion of nitrobenzene and 65% selectivity of aniline within the water as a solvent and two mmol of reducing agent, hydrated hydrazine (N 2 H 2 .H 2 O), at 100 °C for 12 h. The influence of Ce substitution at the iron site for the aniline selectivity was also investigated in optimized situations. In comparison with pure Co 2 –Y hexaferrite, the catalytic efficiency was considerably enriched in all substituted samples and obtained its extreme performance (73% selectivity of aniline) with Ba 2 Co 2 Fe 11.80 Ce 0.20 O 22 ferrite. The enriched performance was explained with the help of surface chemistry using the XPS & BET analysis for these samples. The as-prepared catalysts were magnetically-separable and recycled for five subsequent trials without any significant losses of catalytic performance. This catalyst may be convenient to be adopted for industrial applications due to its ease of synthesis, extraordinary stability, superior catalytic competence, and cost-effectiveness.

Effect of the Growing Season, Trichoderma, and Clinoptilolite Application on Potentially Toxic Elements Uptake by Cucumis melo L.

The extent to which different agricultural strategies may affect the uptake of potentially toxic elements (PTEs) by cropped plants is not entirely understood at a field scale. This study addresses the effect of seasonality, Trichoderma inoculation alone, or combined with different applications of commercial-grade clinoptilolite (i.e., foliar action, fertigation, and pellet) on the PTE content of early- and late-ripening cultivars of Cucumis melo L. Two similar field experiments were performed in spring and summer. For each cultivar/treatment combination, the input of PTEs [namely, chromium (Cr), copper (Cu), and lead (Pb)] into the soil-crop system through irrigation water, fertilizers, pesticides, and treatment products (i.e., Trichoderma and clinoptilolite products), as well as the PTE content of melon stem, leaves, and fruit, were measured through inductively coupled plasma-optic emission spectrometry (ICP-OES). Neither Trichoderma alone nor with clinoptilolite had a visible effect on PTE uptake by plants, whereas early season cultivation was strongly associated with reduced uptake of Cu and Pb. The high correlation of Cu and Pb content with stem and leaf calcium (Ca) content (used as a proxy for different transpiration rates under different growing seasons) indicated a possible uptake of these metals through Ca nonselective cation channels as a defense against drought stress. Reduced Cu and Pb concentrations were found in early-ripening fruit cultivated in spring. Concerning Cu and Pb risk management, in case of significant contamination in Mediterranean calcareous soils, early-ripening Cucumis melo L. cultivars are suggested instead of late-ripening ones.

Massive quiescent galaxies at z ∼ 3: A comparison of selection, stellar population, and structural properties with simulation predictions

ABSTRACT We study stellar population and structural properties of massive log (M⋆/M⊙) &amp;gt; 11 galaxies at z ≈ 2.7 in the Magneticum and IllustrisTNG hydrodynamical simulations and GAEA semi-analytic model. We find stellar mass functions broadly consistent with observations, with no scarcity of massive, quiescent galaxies at z ≈ 2.7, but with a higher quiescent galaxy fraction at high masses in IllustrisTNG. Average ages of simulated quiescent galaxies are between ≈0.8 and ${1.0\, \textrm {Gyr}}$, older by a factor ≈2 than observed in spectroscopically confirmed quiescent galaxies at similar redshift. Besides being potentially indicative of limitations of simulations in reproducing observed star formation histories, this discrepancy may also reflect limitations in the estimation of observed ages. We investigate the purity of simulated UVJ rest-frame colour-selected massive quiescent samples with photometric uncertainties typical of deep surveys (e.g. COSMOS). We find evidence for significant contamination (up to ${60\, \rm {per\, cent}}$) by dusty star-forming galaxies in the UVJ region that is typically populated by older quiescent sources. Furthermore, the completeness of UVJ-selected quiescent samples at this redshift may be reduced by $\approx {30\, \rm {per\, cent}}$ due to a high fraction of young quiescent galaxies not entering the UVJ quiescent region. Massive, quiescent galaxies in simulations have on average lower angular momenta and higher projected axis ratios and concentrations than star-forming counterparts. Average sizes of simulated quiescent galaxies are broadly consistent with observations within the uncertainties. The average size ratio of quiescent and star-forming galaxies in the probed mass range is formally consistent with observations, although this result is partly affected by poor statistics.

Contamination and Environmental Risk Assessment of Potentially Toxic Elements in Soils of Palm Farms in Northwest Riyadh, Saudi Arabia

Thirty-four surface soil samples were collected from the palm farms of the Al-Ammariah area, northwest Riyadh, Saudi Arabia to assess the contamination and environmental risk of potentially toxic elements (PTEs). Aluminum (Al), arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), mercury (Hg), manganese (Mn), nickel (Ni), lead (Pb), antimony (Sb), strontium (Sr), uranium (U), vanadium (V), and zinc (Zn) were analyzed using inductively coupled plasma–atomic emission spectroscopy (ICP–AES). Several pollution indices were employed to assess contamination and to evaluate the environmental risks of these PTEs. Average values (mg/kg) for Cr (19.97), Pb (5.08), Cu (11.36), Zn (52.16), Ni (26.94), Co (3.89), and V (18.94) were under the values recorded for soils globally, while the average values of Hg (0.50) and U (8.06) were greater than the average values of worldwide soils. Pollution indices indicated that the studied soils exhibited indications of severe enrichment and significant contamination with Hg, and moderately severe enrichment with U and As. The potential ecological (RI) findings indicated a moderate level of risk posed by PTEs in the study area. The potentially toxic elements originated from both natural and human sources, largely due to chemical weathering of the neighboring mountains, in addition to the widespread utilization of insecticides and fertilizers.

Pollution and Health Risk Assessments of Potentially Toxic Elements in the Fine-Grained Particles (10−63 µm and

Fine road dust is a major source of potentially toxic elements (PTEs) pollution in urban environments, which adversely affects the atmospheric environment and public health. Two different sizes (10−63 and <10 μm) were separated from road dust collected from Apia City, Samoa, and 10 PTEs were analyzed using inductively coupled plasma mass spectrometry (ICP-MS). Fine road dust (<10 μm) had 1.2−2.3 times higher levels of copper (Cu), zinc (Zn), arsenic (As), cadmium (Cd), antimony (Sb), lead (Pb), and mercury (Hg) than 10−63 μm particles. The enrichment factor (EF) value of Sb was the highest among PTEs, and reflected significant contamination. Cu, Zn, and Pb in road dust were also present at moderate to significant levels. Chromium (Cr), cobalt (Co), and nickel (Ni) in road dust were mainly of natural origins, while Cu, Zn, Sb, and Pb were due to traffic activity. The levels of PTEs in road dust in Samoa are lower than in highly urbanized cities, and the exposure of residents in Samoa to PTEs in road dust does not pose a noncarcinogenic health risk. Further studies of the effects of PTEs contamination in road dust on the atmosphere and living organisms are needed.

Ca. 2.1 Ga low-δ18O gabbro-diorite association in southern North China Craton: Implications for an intraplate rifting

Although widespread ca. 2.2–2.1 Ga igneous activities were identified through the North China Craton (NCC), their petrogenesis and implications for the Paleoproterozoic tectonic regime of the NCC are still under hot debate. Here we present the 2.18–2.14 Ga gabbro-diorite plutons in the Xiong'ershan Taihua Complex, southern North China Craton. They are dominantly gabbros with minor as gabbroic-dioritic rocks. The samples exhibit transitional geochemical characteristics from tholeiitic to calc-alkali series with enrichment in LREEs (e.g., La/Yb N = 1.90–13.9) and LILEs (e.g., Rb, Ba and Sr) but depletion in HFSE (e.g., Nb, Ta and Ti), corresponding to affinity of arc-related magmatism. The high Fe 2 O 3 (8.90–14.91 wt%), CaO (6.78–9.81 wt%) contents, and Ti/Y ratios (179–635), low Th concentrations (0.11–4.08 ppm), and consistent La/Nb and Th/Nb ratios, preclude significant crustal contamination during magma emplacement. The samples show negative zircon ε Hf (t) (−7.3–−1.6) and whole-rock ε Nd (t) (−4.0–+0.9) values with much older model ages ( T DM Hf = 2811–2606 Ma and T DM Nd = 3069–2711 Ma) than their formation ages, along with high La/Nb (1.69–6.21) and low La/Ba (0.01–0.05) ratios, indicating a refertilized Archean lithospheric mantle source. Considering that zircons of 2.18–2.14 Ga gabbro-diorite in the Xiong'ershan area lack metamict features and exhibit originally low but homogeneous δ 18 O values in the mantle source (3.04‰ to 5.07‰, 4.21‰ on average), we prefer they derived from preexisting 18 O-depleted mantle source, which might be a highly heterogeneous metasomatized SCLM by subducted-fluid during the Archean cratonization. The consistent Sm/Yb and La/Sm ratios indicate ∼5–30% partial melting of the garnet-spinel dominant source region. Combing the low δ 18 O signature and within-plate (high Zr, Zr/Y, Th/Hf and Ta/Hf) geochemical features, we suggest a thermal anomaly linked to a rift setting could account for the mantle melting. The intraplate ca. 2.1 Ga low-δ 18 O magmatism possibly resembles those during the Neoproterozoic glaciations associated with major dispersal periods of Rodinia. To better understand the Paleoproterozoic tectonic evolution of the NCC, we have also comprehensively compiled all the published ages and geochemical data of the 2.2–2.1 Ga mafic-felsic igneous rocks. The mafic suites can be divided into two groups based on ages and geochemical affinities. Mafic rocks of Group 1 (2.19–2.12 Ga) belong to rift-related basalts, together with spatially associated 2.19–2.13 Ga A-type granitic rocks and volcano-sedimentary associations, likely indicating an intraplate rift setting. Whereas mafic rocks of Group 2 (2.15–2.06 Ga) show geochemical affinity of island arc calc-alkaline basalts, together with coeval 2.18–2.05 Ga I-S type granitic associations, implying an arc-related setting and recording a possible tectonic transition from extension to subduction-collision. The rifting events in the NCC during 2.2–2.1 Ga may coincide with the global lithospheric break-up of the supercontinent, and the subsequent tectonic transition could correspond to development of the globally orogenesis at 2.1–1.8 Ga. • The Paleoproterozoic low-δ 18 O gabbro-diorite plutons were formed at 2.18–2.14 Ga. • The mafic association was derived from an ancient metasomatized SCLM source. • They were formed in an intraplate rifting system. • The extensive 2.2–2.1 Ga magmatism in the NCC corresponds to global breakup event.

Determination of N-nitrosodimethyl amine impurity in valsartan by HPLC and LC-MS/MS methods

In this study, two novel, rapid, sensitive, and specific chromatographic methods were developed and validated for the determination of N -nitrosodimethylamine (NDMA) impurity in the valsartan drug substance. The first method is a high-performance liquid chromatography method with a diode array detector (HPLC-DAD). The method was validated according to ICH Q2 (R1) guidelines and was used for the determination of NDMA in valsartan drug substances from different suppliers. Satisfactory validation results were obtained in terms of linearity with a range from 9.10 to 29.5 µg L −1 and R 2 = 0.994, precisions with a coefficient of variation of 1.2%, accuracy with recovery between 94.5% and 103.1%, limit of detection (LOD) and limit of quantitation (LOQ) were 0.0027 and 0.0091 mg kg −1 , respectively. Assay of NDMA in valsartan drug substances using the developed HPLC-DAD method showed that samples from Zhejiang Huahai supplier, obtained between 2012 and 2017, contained high levels of NDMA that exceed the acceptable limits with an average concentration of 59.3 mg kg −1 . On the other hand, the new Zhejiang Huahai samples, obtained after November 2018, did not show significant contamination with NDMA. For confirmation of our results, a second method was developed which is the liquid chromatography method with tandem mass spectrometry detection (LC-MS/MS). The new LC-MS/MS method was developed and validated for confirmation of the results of the NDMA assay in the new valsartan samples obtained from Zhejiang Huahai after November 2018. The new LC-MS/MS method has been more selective than the HPLC-DAD method with LOD and LOQ values of 0.0021 and 0.0070 mg kg −1 , respectively. The results of LC-MS/MS show good agreement with those obtained with the HPLC-DAD method.