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Результаты 1591-1600 из 6,558
Rapid vitrification of uranium-contaminated soil: Effect and mechanism Полный текст
2020
Shu, Xiaoyan | Li, Yaping | Huang, Wenxiao | Chen, Shunzhang | Xu, Chen | Zhang, Shuai | Li, Bingsheng | Wang, Xiaoqiang | Qing, Qi | Lu, Xirui
Nuclear contaminated soil can seriously threaten human security. In this study, uranium-contaminated soil (0–50000 μg/g of uranium) was successfully vitrified in 30 min without complex pretreatment or any additional components. The microstructure of the vitrified forms, the immobilizing mechanism of uranium, the inner structural evolution with increased uranium concentration, and the performance in terms of chemical durability were studied in detail. In the vitrified form, uranium was surrounded by a three-dimensional network structure comprising silicon and aluminum oxide polyhedra. When the uranium content increased above 50000 μg/g, the network adjusted and local structures precipitated as mottle-shaped quartz. The normalized leaching rates of uranium were maintained at a low value (∼1 × 10⁻⁶ g/(m²·d) level) in distilled water at 90 °C after 42 days. These results suggested the feasibility of vitrifying nuclear contaminated soil in a simple and rapid way.
Показать больше [+] Меньше [-]Cross-sectional and longitudinal associations between global DNA (hydroxy) methylation and exposure biomarkers of the Hebei Spirit oil spill cohort in Taean, Korea Полный текст
2020
Chatterjee, Nivedita | Jeong, Jaeseong | Park, Myung-Sook | Ha, Mina | Cheong, Hae-Kwan | Choi, Jinhee
The Hebei Spirit oil spill (HSOS) occurred on the west coast of South Korea (Taean county) on December 7, 2007, and studies revealed that exposure to the oil spill was associated with various adverse health issues in the inhabiting population. However, no studies evaluated the association between crude-oil exposure and epigenetic changes. This study aimed to investigate the HSOS exposure-associated longitudinal and cross-sectional variations in global DNA methylation (5-mc) and/or hydroxymethylation (5-hmc) and expression profiles of related genes in Taean cohort participants from 2009 (AH-baseline) and 2014 (AH-follow-up) relative to the reference group (AL). We measured global DNA 5-mc and 5-hmc levels and related gene expression levels in whole blood. We identified significant associations between HSOS exposure and AH-baseline-5-mc, AH-baseline-5-hmc, and AH-follow-up-5-hmc. HSOS exposure was associated with lower %5-mc content and higher %5-hmc content in the same individuals from both the cross-sectional and longitudinal studies. In addition, we found a strong correlation between 5-mc and DNMT3B expression, and between 5-hmc and TET1 expression. Our findings suggested that epigenetic changes are important biomarkers for HSOS exposure and that 5-hmc is likely to be more sensitive for environmental epidemiological studies.
Показать больше [+] Меньше [-]The mixture effects of bisphenol derivatives on estrogen receptor and androgen receptor Полный текст
2020
Park, Choa | Song, Heewon | Choi, Junyeong | Sim, Seunghye | Kojima, Hiroyuki | Park, Joonwoo | Iida, Mitsuru | Lee, Youngjoo
Bisphenol A (BPA) is a well-known for endocrine-disrupting chemical (EDC) and is one of the highest amounts of chemicals produced worldwide. Some countries restrict the use of BPA, which is widely used in the production of a variety products. Considering the toxicity and limitations on use of BPA, efforts are needed to find safer alternatives. Increasingly, bisphenol F (BPF) and bisphenol S (BPS) are alternatives of BPA, which is increasing their exposure levels in various environments. There are many ways to assess whether a chemical is an EDC. Here, we evaluated the endocrine-disrupting risks of the bisphenols by investigating their agonist and antagonist activities with the estrogen (ER), androgen (AR), and aryl hydrocarbon (AhR) receptors. Our results showed that BPA, BPS, and BPF (BPs) have estrogen agonist and androgen antagonist activities and decrease the ERα protein level. Interestingly, a mixture of the BPs had ER and anti-AR activity at lower concentrations than BPs alone. The activation of AhR was not a concentration-dependent effect of BPs, although it was increased significantly. In conclusion, BPs have estrogen agonist and androgen antagonist activities, and the effect of exposure to a BPs mixture differs from that of BPs alone.
Показать больше [+] Меньше [-]Citric acid-assisted accumulation of Ni and other metals by Odontarrhena muralis: Implications for phytoextraction and metal foliar distribution assessed by μ-SXRF Полный текст
2020
do Nascimento, Clístenes Williams Araujo | Hesterberg, Dean | Tappero, Ryan | Nicholas, Sarah | da Silva, Fernando Bruno Vieira
Odontarrhena muralis is one of the most promissing plant species for Ni phytomining, and soil amendments can further increase its Ni phytoextraction ability. Here we investigated whether Ni phytomining/phytoremediation using this Ni hyperaccumulator can benefit from applying citric acid to a serpentine soil that is naturally enriched in Ni (>1000 mg kg⁻¹). Synchrotron micro X-ray fluorescence (μ-SXRF) was used to image Ni and other metal distributions in whole fresh leaves of O. muralis. Leaf Ni accumulation in plants grown on citric acid-amended soil increased up to 55% while Co, Cr, Fe, Mn, and Zn concentrations were 4-, 14-, 6-, 7- and 1.3-fold higher than the control treatment. O. muralis presented high bioconcentration factors (leaf to soil concentration ratio) to Ni and Zn whereas Cr was seemingly excluded from uptake. The μ-SXRF images showed a uniform distribution of Ni, preferential localization of Co in the leaf tip, and clear concentration of Mn in the base of trichomes. The citric acid treatments strongly increased the Co fluoerescence intensity in the leaf tip and altered the spatial distribution of Mn across the leaf, but there was no difference in Ni fluorescence counts between the trichome-base region and the bulk leaf. Our data from a serpentine soil suggests that citrate treatment enhances Ni uptake, but Co is excreted from leaves even in low leaf concentrations, which can make Co phytoming using O. muralis unfeasible in natural serpentine soils.
Показать больше [+] Меньше [-]Isolation and characterization of lead (Pb) resistant microbes and their combined use with silicon nanoparticles improved the growth, photosynthesis and antioxidant capacity of coriander (Coriandrum sativum L.) under Pb stress Полный текст
2020
Fatemi, Hamideh | Esmaiel Pour, Behrooz | Rizwan, Muhammad
Rapid global industrialization has increased the chances of toxic trace element accumulation in plants and other living things via the food chain. Thus, there is an urgent need to find suitable techniques with the aim to alleviate the stress of toxic trace elements in crops to feed the ever-increasing population with quality food. This research was based on the hypothesis that the growth traits of coriander (Coriandrum sativum L.) plants can be improved by the combined application of lead (Pb) resistant microbes and silicon nanoparticles (Si-NPs) under Pb stress. Two Pb-resistant strains of the microbes were isolated under different Pb concentrations, and then these strains were characterized for different traits. The strains were inoculated in the Pb-spiked (500 mg/kg) soil, and Si-NPs (1.5 mM) were foliar sprayed at different time (three times, two-week interval). The growth and stress tolerance of the plant were assessed by measuring the morphological traits, chlorophyll contents, proline, electrolyte leakage, and enzymatic and non-enzymatic antioxidant activities of the leaves. Results demonstrated that Pb stress had significant negative impacts on all the traits of the coriander. Si-NPs application or bacterial inoculation reversed the Pb-induced toxicities in plants, which was indicated by the improved growth, photosynthesis, and antioxidant enzyme activities of the plants under Pb stress. The effect of the combined use of Si-NPs and microbes was more pronounced than the treatments alone. It can be concluded that Pb-resistant microorganism and Si-NPs could effectively be used to alleviate Pb stress in coriander.
Показать больше [+] Меньше [-]Dynamics and dietary risk assessment of thiamethoxam in wheat, lettuce and tomato using field experiments and computational simulation Полный текст
2020
Pang, Nannan | Fan, Xueqi | Fantke, Peter | Zhao, Shengming | Hu, Jiye
Thiamethoxam is a widely used pesticide applied to different field crops. To inform risk assessment for this pesticide across relevant crops, we usually rely on field trials, which require time, costs and energy. For providing reliable data across crops and reduce experimental efforts, field trials should be complemented with dynamic modelling. In the present work, we hence focused on combining field trials with dynamic modelling to simulate mass evolutions of the pesticide-plant-system for thiamethoxam applied to wheat, lettuce and tomato as three major food crops. Field trials were conducted with QuEChERS (quick, easy, cheap, effective, rugged and safe) liquid chromatography-mass spectrometry, which gave consistent maximum residue concentrations for thiamethoxam in wheat, lettuce and tomato. We used these residues to evaluate the related dietary risk of humans consuming these food crops. Our results indicated that thiamethoxam did not provide any unacceptable dietary risk for humans across these three food crops, which is in line with findings from previous studies. Results for the studied crops could be extrapolated to other crops and with that, our study constitutes a cost- and time-efficient way of providing reliable input for risk assessment of pesticides across crops, which is relevant for both practitioners and regulators.
Показать больше [+] Меньше [-]Strong influence of surfactants on virgin hydrophobic microplastics adsorbing ionic organic pollutants Полный текст
2020
Xia, Yan | Zhou, Juan-Juan | Gong, Yan-Yan | Li, Zhan-Jun | Zeng, E. Y. (Eddy Y.)
Microplastic (MP) pollution has become an area of increasing concern because MPs accumulate various types of pollutants. Many previous studies have explored the interactions between MPs and hydrophobic pollutants. However, little research has been conducted on hydrophilic pollutants, which are of much higher concentration and ubiquitous in environment. Surfactants cause hydrophobic MPs to become hydrophilic, which may significantly enhance their capacities to adsorb hydrophilic pollutants. This study explored the influence of co-existing surfactants on the adsorption of ionic organic pollutants by MPs, and found that the presence of an ionic surfactant could significantly enhance the capacity of polyvinyl chloride (PVC, 0.2 mm) MPs to adsorb pollutants with opposite charges. The Langmuir methylene blue adsorption capacity of PVC could be increased from 172 to 4417 ppm in the presence of a sodium dodecyl benzene sulfonate surfactant. Nonionic surfactants impeded the adsorption of both cationic and anionic pollutants due to the steric resistance of the hydrophilic polyethelene glycol chains. The electrostatic interaction mechanism dominated the interfacial behaviors of ionic pollutants on surfactant-adsorbed MP interfaces. The effects of the surfactants were further verified using four different model pollutants and six surfactants. The adsorption capacities of real environmental MPs, including PVC, polyethylene (PE), polypropylene (PP), and polystyrene (PS), increased by three to twenty-six times. The adsorption properties of MPs may be determined by the presence of co-existing surfactants, rather than their polymer species or additives.
Показать больше [+] Меньше [-]Predicting the rate constants of semivolatile organic compounds with hydroxyl radicals and ozone in indoor air Полный текст
2020
Wei, Wenjuan | Sivanantham, Sutharsini | Malingre, Laeticia | Ramalho, Olivier | Mandin, Corinne
Semivolatile organic compounds (SVOCs) in air can react with hydroxyl radicals (OH), nitrate radicals (NO₃) and ozone (O₃). Two questions regarding SVOC reactivity with OH, NO₃ and O₃ in the gas and particle phases remain to be addressed: according to the existing measurements in the literature, which are the most reactive SVOCs in air, and how can the SVOC reactivity in the gas and particle phases be predicted? In the present study, a literature review of the second-order rate constant (k) was carried out to determine the SVOC reactivity with OH, NO₃ and O₃ in the gas and particle phases in ambient and indoor air at room temperature. Measured k values were available in the literature for 90 polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), organophosphates, dioxins, di(2-ethylhexyl)phthalate (DEHP) and pesticides including pyrifenox, carbamates and terbuthylazine. PAHs and organophosphates were found to be more reactive than dioxins and PCBs. Based on the obtained data, quantitative structure-activity relationship (QSAR) models were developed to predict the k value using quantum chemical, molecular, physical property and environmental descriptors. Eight linear and nonlinear statistical models were employed, including regression models, bagging, random forest and gradient boosting. QSAR models were developed for SVOC/OH reactions in the gas and particle phases and SVOC/O₃ reactions in the particle phase. Models for SVOC/NO₃ and SVOC/O₃ reactions in the gas phase could not be developed due to the lack of measured k values for model training. The least absolute shrinkage and selection operator (LASSO) regression and random forest models were identified as the most effective models for SVOC reactivity prediction according to a comparison of model performance metrics.
Показать больше [+] Меньше [-]Ambient air pollution exposed during preantral-antral follicle transition stage was sensitive to associate with clinical pregnancy for women receiving IVF Полный текст
2020
Li, Lipeng | Zhou, Lixiao | Feng, Tengfei | Hao, Guimin | Yang, Sujuan | Wang, Ning | Yan, Lina | Pang, Yaxian | Niu, Yujie | Zhang, Rong
Maternal exposure to air pollution is associated with poor reproductive outcomes in in vitro fertilization (IVF). However, the susceptible time windows are still not been known clearly. In the present study, we linked the air pollution data with the information of 9001 women receiving 10,467 transfer cycles from August 2014 to August 2019 in The Second Hospital of Hebei Medical University, Shijiazhuang City, China. Maternal exposure was presented as individual average daily concentrations of PM₂.₅, PM₁₀, NO₂, SO₂, CO, and O₃, which were predicted by spatiotemporal kriging model based on residential addresses. Exposure windows were divided to five periods according to the process of follicular and embryonic development in IVF. Generalized estimating equation model was used to evaluate adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for association between clinical pregnancy and interquartile range increased average daily concentrations of pollutants during each exposure period. The increased PM₂.₅ (adjusted OR = 0.95, 95% CI: 0.90, 0.99), PM₁₀ (adjusted OR = 0.93, 95% CI: 0.89, 0.98), NO₂ (adjusted OR = 0.89, 95% CI: 0.85, 0.94), SO₂ (OR = 0.94, 95% CI: 0.90, 0.98), CO (adjusted OR = 0.93, 95% CI: 0.89, 0.97) whereas decreased O₃ (OR = 1.08, 95% CI: 1.02, 1.14) during the duration from preantral follicles to antral follicles were the strongest association with decreased probability of clinical pregnancy among the five periods. Especially, women aged 20–29 years old were more susceptible in preantral-antral follicle transition stage. Women aged 36–47 years old were more vulnerable during post-oocyte retrieve period. Our results suggested air pollution exposure during preantral-antral follicle transition stage was a note-worthy challenge to conceive among females receiving IVF.
Показать больше [+] Меньше [-]Population-level variation in neonicotinoid tolerance in nymphs of the Heptageniidae Полный текст
2020
Rackliffe, D Riley | Hoverman, Jason T.
Anthropogenic activities can have significant ecological and evolutionary consequences on populations and communities. In the United States, neonicotinoid insecticides are widespread across the agricultural Midwest and frequently detected in stream systems. Their effect on Heptageniidae mayflies is a major concern because they are highly sensitive to neonicotinoids and have some of the lowest reported tolerance values of any organism. Our objective was to evaluate population-level variation in neonicotinoid sensitivity. We did so by conducting 96 h half maximal effective concentration (EC50₉₆₋ₕ) tests for the neonicotinoids clothianidin and thiamethoxam on populations of Stenacron, Stenonema, and Maccaffertium mayflies and testing for associations with agricultural landcover. Additionally, we collected water samples to assess temporal patterns of neonicotinoid presence in stream habitats. We found variation in neonicotinoid tolerance with EC50 values ranging from 4.9 μg/L to 32 μg/L and 19.8 μg/L to 86.5 μg/L for clothianidin and thiamethoxam, respectively. Agricultural landcover was associated with neonicotinoid tolerance for Stenacron and thiamethoxam but not for other comparisons. Moreover, water samples demonstrated that the amount of agricultural landcover was not a strong predictor of neonicotinoids presence in streams. Our data suggest that populations of Heptageniidae mayflies can vary substantially in neonicotinoid tolerance. Population-level variation should be considered in toxicity assessments and presents the potential for evolved tolerance.
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