خيارات البحث
النتائج 4611 - 4620 من 4,937
Integrated comparisons of thorium(IV) adsorption onto alkali-treated duckweed biomass and duckweed-derived hydrothermal and pyrolytic biochar النص الكامل
2019
Chen, Ting | Zhang, Nan | Xu, Zhao | Hu, Xin | Ding, Zhuhong
In order to remove aqueous radionuclides and find an appropriate method for the disposal of wild duckweed in eutrophic water body, alkali-treated duckweed biomass and duckweed-based hydrothermal biochar (hydrochar) and pyrolytic biochars of 300 and 600 °C were prepared. Their physicochemical properties were characterized carefully. The adsorption isothermal data fitted well with the Langmuir model and the maximum Langmuir adsorption capacities were 104.1, 96.3, 86.7, and 63.5 mg/g for hydrochar, modified biomass, and 300 and 600 °C biochars, respectively. The adsorption kinetic data fitted well with the pseudo-second-order kinetic equation. The sorption data of fixed-bed column also confirmed the high efficient removal of Th(IV) and fitted well with the Thomas model. The duckweed-based hydrothermal biochar is a low-cost adsorbent for Th(IV) removal, and it is also a resource utilization technology of the duckweed collected from eutrophic water body.
اظهر المزيد [+] اقل [-]Endocrine disruption as an adverse effect of non-endocrine targeting pharmaceuticals النص الكامل
2019
Sabir, Shakila | Akhtar, Muhammad Furqan | Saleem, Ammara
Endocrine disruptors have gained widespread attention owing to their severe adverse health impacts. These produce enormous burden of disease and are associated with high economic cost especially in developed countries. Environmental pollutants causing endocrine disruption include pesticides, industrial wastes, packaging materials, food constituents, plastics, and cosmetic products. Likewise, pharmaceutical drugs have the endocrine disrupting potential through a wide array of mechanisms. Antipsychotic, antiepileptic, antihypertensive, antiviral, antidiabetic, and anticancer drugs are among the foremost non-hormonal endocrine disruptors. Several drugs affect thyroid hormone synthesis via interaction with iodine uptake to the release of T3 and T4 by thyrocytes. Prolonged use of some drugs increase susceptibility to diabetes mellitus either by direct destruction of β cells or enhanced insulin resistance. Other drugs may cause serious developmental defects in male or female reproductive system. Appropriate understanding of the mechanisms of endocrine disruption associated with non-hormonal drugs will guide future drug development and help us prevent and cure endocrine-related toxicity of pharmaceuticals. Therefore, this review focuses on endocrine disruption by pharmaceutical drugs as their side effect.
اظهر المزيد [+] اقل [-]Correction to: Analysis of swale factors implicated in pollutant removal efficiency using a swale database النص الكامل
2019
Fardel, Alexandre | Peyneau, Pierre-Emmanuel | Béchet, Béatrice | Lakel, Abdelkader | Rodriguez, Fabrice
The original publication of this paper contains an error. Correct presentation of Equation 1 is presented in this paper.
اظهر المزيد [+] اقل [-]Research on the nitrogen transformation in rhizosphere of winter wheat (Triticum aestivum) under molybdenum addition النص الكامل
2019
Wen, Xin | Hu, Chengxiao | Sun, Xuecheng | Zhao, Xiaohu | Tan, Qiling
Molybdenum (Mo), an essential microelement for plants, animals, and microorganisms, is reported can reduce soil nitrogen (N) residues and regulate plant root growth, but little is known about its effect on soil N transformation in plant-root region. A specially designed rhizobox was used in the present study to investigate the N processes in rhizosphere and non-rhizosphere soils of winter wheat applied with different rates of Mo fertilizer. (1) In the rhizosphere soil, pH values increased with increasing rates of Mo application, nitrate (NO₃⁻-N) accumulated at the rates of 0.15 and 0.3 mg Mo kg⁻¹, potential denitrification activity (PDA) was significantly reduced by application of 0.15–1 mg Mo kg⁻¹, and the copy numbers of narG and nosZ genes were increased by application of 0.15–1 mg Mo kg⁻¹. (2) In the non-rhizosphere soil, NO₃⁻-N content decreased by application of 0.15–0.3 mg Mo kg⁻¹, and narG gene abundance increased obviously by application of 0.3–1 mg Mo kg⁻¹. (3) Soil pH, NO₃⁻-N, apparent nitrification rate (ANR), and nosZ gene abundance were significantly higher in rhizosphere than in non-rhizosphere soil. On the contrary, NH₄⁺-N and total N, PDA, the abundance of AOB, and nirK and nirS genes were significantly higher in non-rhizosphere soil. The results indicated that the N transformations in rhizosphere and non-rhizosphere soils were differently affected by soil application of Mo fertilizer, and rhizosphere played a more important role in soil N cycle processes. The regulatory effects of Mo on these processes were to increase plant biomass and N uptake, promote the NO₃⁻-N accumulation in rhizosphere soil, and weaken the denitrification in both rhizosphere and non-rhizosphere soils.
اظهر المزيد [+] اقل [-]Exposure to bisphenol A and diabetes risk in Mexican women النص الكامل
2019
Murphy, Luke | Mérida-Ortega, Ángel | Cebrián, Mariano E. | Hernández-Garciadiego, Lucia | Gómez-Ruiz, Humberto | Gamboa-Loira, Brenda | López-Carrillo, Lizbeth
Bisphenol A (BPA) is an endocrine-disrupting chemical widely used in the production of polycarbonate plastics and epoxy resins, which has been previously linked to diabetes among non-Hispanic populations. As part of a case control study for breast cancer, only controls with BPA information were included in this report. The final sample size comprises 70 self-reported diabetics and 334 non-diabetics. Urinary free bisphenol A (BPA-F) (μg/L) was determined by solid-phase extraction and HPLC/FLD analysis. Logistic regression models were used to evaluate the association between BPA-F and self-reported diabetes. After adjusting by age, urinary BPA-F (4.06–224.53 μg/g creatinine) was associated with diabetes exposure (OR = 1.85; 95% CI 1.04, 3.28) compared with women in the reference category (0.67–4.05 μg/g creatinine). BPA may be an environmental cofactor of diabetes. More studies are needed to confirm this result, especially in Hispanic populations.
اظهر المزيد [+] اقل [-]Enhanced photocatalytic activity of AgNPs-in-CNTs with hydrogen peroxide under visible light irradiation النص الكامل
2019
Jiao, Jianli | Wan, Jinquan | Ma, Yongwen | Wang, Yan
Silver nanoparticles in carbon nanotubes (AgNPs-in-CNTs) were prepared through a simple thermal decomposition method. Synthesized AgNPs-in-CNTs were characterized by X-ray diffraction (XRD), UV-vis diffuse reflectance spectroscopy, high-resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectroscopy (XPS). In the presence of hydrogen peroxide (H₂O₂), AgNPs-in-CNTs exhibited perfect photocatalytic activity in rhodamine B (RhB) degradation under visible light irradiation. Hydrogen peroxide (H₂O₂) concentration and initial pH values were comprehensively scrutinized. When the concentration of H₂O₂ was 20 mM, about 99.8% RhB (20 mg L⁻¹) could be degraded within 50 min while the initial pH (3–10) values had a negligible effect on the degradation. From the investigations of Raman spectroscopy, transient photocurrent responses, photoluminescence, and radical quenching experiments, the findings suggest that under light irradiation, AgNPs-in-CNTs can absorb photons and generate photogenerated electrons through localized surface plasmon resonance (LSPR) effect, the photogenerated electrons react with H₂O₂ to produce ·OH radicals for decomposing RhB.
اظهر المزيد [+] اقل [-]Sonophotocatalytic degradation of bisphenol A and its intermediates with graphitic carbon nitride النص الكامل
2019
Sunasee, Sharmini | Leong, Kah Hon | Wong, Kien Tiek | Lee, Gooyong | Pichiah, Saravanan | Nah, InWook | Jeon, Byong-Hun | Yoon, Yeomin | Jang, Min
Since bisphenol A (BPA) exhibits endocrine disrupting action and high toxicity in aqueous system, there are high demands to remove it completely. In this study, the BPA removal by sonophotocatalysis coupled with nano-structured graphitic carbon nitride (g-C₃N₄, GCN) was conducted with various batch tests using energy-based advanced oxidation process (AOP) based on ultrasound (US) and visible light (Vis-L). Results of batch tests indicated that GCN-based sonophotocatalysis (Vis-L/US) had higher rate constants than other AOPs and especially two times higher degradation rate than TiO₂-based Vis-L/US. This result infers that GCN is effective in the catalytic activity in Vis-L/US since its surface can be activated by Vis-L to transport electrons from valence band (VB) for utilizing holes (h⁺VB) in the removal of BPA. In addition, US irradiation exfoliated the GCN effectively. The formation of BPA intermediates was investigated in detail by using high-performance liquid chromatography-mass spectrometry (HPLC/MS). The possible degradation pathway of BPA was proposed.
اظهر المزيد [+] اقل [-]Effects of groundwater metal contaminant spatial distribution on overlaying kriged maps النص الكامل
2019
Fallah, Bahareh | Richter, Amy | Ng, Kelvin Tsun Wai | Salama, Amgad
Groundwater is a major source of drinking water for many Canadians, and contamination by heavy metals poses a significant risk to people and the environment. In this study, three water quality indices are studied in the vicinity of an unlined landfill in a semiarid climate. The study investigates indices using geostatistical analysis and ordinary kriging. This study employs a novel coupling technique in order to compare the index-based maps to a groundwater quality map from overlapping heavy metal kriged maps. A total of 11 heavy metals were evaluated in preliminary analysis, but only four (Mn, As, Fe, and U) had higher concentrations than allowable limits in some or all of the monitoring wells at the site. Results from mean-based classification of indices suggest the aquifer in proximity to the landfill has been impacted by metal contaminants. Kriged maps show that the spatial variations of Mn and U are similar, while results of Fe and As are also similar. However, the two sets of maps have distinctly different patterns. Maps for indices show an elevated plateau extending from the unlined landfill to the southeast corner, implying that the landfill may have negatively impacted groundwater quality. A groundwater quality map is developed by overlaying the heavy metal maps. The resulting map shows that the north and west parts of the study have lower groundwater pollution with respect to metal contaminants. The groundwater quality map may be more applicable for practitioners who need comprehensive water quality measurement.
اظهر المزيد [+] اقل [-]Major, trace, and rare-earth elements in the zooplankton of the Laptev Sea in relation to community composition النص الكامل
2019
Lobus, Nikolay V. | Arashkevich, Elena G. | Flerova, Ekaterina A.
We investigated the concentrations of major, trace, and rare-earth elements in zooplankton in relation to species community composition from the eastern part of the Lena Delta to the continental slope of the Laptev Sea in September 2015. The elemental composition of zooplankton inhabiting different areas demonstrated similarities. Cross-shelf changes were found for only 4 (Li, Zn, As, and U) of the 56 elements analyzed. Zinc was the only element concentration of which successively reduced across coastal–open ocean gradient. Considering own and literary data, we can assume that the cross-shelf decrease of zinc accumulation in zooplankton is a universal pattern, manifested in different climatic and biogeochemical environmental conditions and with different species compositions of the zooplankton community. Cross-shelf changes were also established for Li, As, and U. However, the concentrations of these elements increased along the gradient. We assume that increased As concentration in zooplankton across the shelf–continental slope gradient of the Laptev Sea is associated with a change in the feeding behavior of the species of the zooplankton community. However, a sharp increase in the concentrations of Li and U in zooplankton was associated with the appearance of Calanus copepods in the community. The average total concentration of rare-earth elements and yttrium in zooplankton of the Laptev Sea was 752.8 ng g⁻¹ of dry weight. We found record high levels of rare-earth elements for zooplankton of the inner shelf, near the eastern part of the Lena Delta. From the inner shelf to the continental slope of the Laptev Sea, La, Ce, and Nd were the dominant rare-earth elements. The elemental composition of zooplankton in the Arctic Seas is characterized by a much lower content of major and trace elements in comparison with the zooplankton and total plankton of the ocean.
اظهر المزيد [+] اقل [-]Persistence of tetraniliprole and reduction in its residues by various culinary practices in tomato in India النص الكامل
2019
Kaushik, Ekta | Dubey, Jatiender Kumar | Patyal, Surender Kumar | Katna, Sapna | Chauhan, Avinash | Devi, Nisha
A field experiment was conducted to study the persistence and dissipation pattern of a new molecule tetraniliprole on tomato fruits and soil. Tetraniliprole was sprayed at the rate of 60 g a.i. ha⁻¹ and 120 g a.i. ha⁻¹on the tomato crop. Tomato fruit samples were analyzed as per the method described by Bosta and Nageswara (Asian J Res Chem 8:383-388, 2015). The residues of tetraniliprole and its metabolite chinazolinon were estimated on HPLC equipped with RP C₁₈ column and photo diode array detector. Initial deposits of tetraniliprole were 0.865 and 1.747 mg kg⁻¹ on fruits and 0.092 and 0.177 mg kg⁻¹ in the soil, respectively, from the two treatments at the rate 60 g a.i. ha⁻¹ and 120 g a.i. ha⁻¹. The residues on fruits dissipated to half in 2.7 and 3.49 days, respectively. Based on the persistence studies, a waiting period of 15 days is suggested on tomato fruit from consumer’s safety point of view. The pesticide residues, left to a variable extent in the tomato after harvesting, are beyond the control of consumers and have deleterious effects on human health; hence, their residues reduction by various culinary processes were highlighted. Treated tomato fruit samples collected at 1, 3, and 5 days after application were also subjected to common household practices. Washing of tomato fruits by tap, lukewarm, and saline water reduce tetraniliprole residues up to 37.63, 44.67, and 61.49%, respectively. Microwave cooking of tomato provided >12% better relief from tetraniliprole residues in comparison with open pan cooking of 72.21%. Chinazolinon residues, a metabolite of tetraniliprole, were not detected in any analyzed processed tomato fruit sample.
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