Уточнить поиск
Результаты 2761-2770 из 4,929
Lead uptake by the symbiotic Daucus carota L.–Glomus intraradices system and its effect on the morphology of extra- and intraradical fungal microstructures
2019
Alvarado-López, Carlos Juan | Dasgupta-Schubert, Nabanita | Ambriz, Jorge Enrique | Arteaga-Velazquez, Juan Carlos | Villegas, Javier A.
This work examines the strategies adopted by an arbuscular mycorrhizal symbiotic system to ameliorate environmental Pb stress by examining the concentrations of P, Fe, and Pb in the fungal microstructures and the host’s root. In vitro cultures of Ri-T DNA-transformed carrot (Daucus carota L.) roots were inoculated with Glomus intraradices and treated with Pb(NO₃)₂ solution and the extraradical spores and mycelia (S/M) and the root with the vesicles, mycelia, and root cells were subsequently analyzed by polarized energy dispersive x-ray fluorescence (PEDXRF) spectrometry. Upon Pb treatment, within the root, the percentages of mycorrhizal colonization, the vesicles, and mycelia increased as well as the areas of the vesicles and the (extraradical) spores, although the number of spores and arbuscules decreased. The S/M and the mycorrhizal root showed enhanced concentrations of Pb, Fe, and P. These were particularly marked for Fe in the Pb-treated cultures. This indicates a synergistic relationship between the arbuscular mycorrhizal fungus and the host that confers a higher Pb tolerance to the latter by the induction of higher Fe absorption in the host. The intraradical vesicle, mycelia, and arbuscule numbers are interpreted as a “tactic to divert” the intraradical Pb traffic away from the root cells to the higher affinity cell walls of the arbuscular mycorrhizal fungi (AMF) microstructures in the apoplast. The results of this work show that the symbiosis between the AMF G. intraradices and the host plant D. carota distinctly improves the latter’s Pb tolerance, and imply that the appropriate metal tolerant host-AMF combinations could be employed in process designs for the phytoremediation of Pb.
Показать больше [+] Меньше [-]Phosphate fertilizer premixing with farmyard manure enhances phosphorus availability in calcareous soil for higher wheat productivity
2019
Ikram, Wasiq | Akhtar, Muhammad | Morel, Christian | Rizwan, Muhammad | Ali, Shafaqat
Fixation reactions reduce the concentration of soluble phosphorus (P) and affect crop growth in alkaline calcareous soils. In lab and greenhouse studies, phosphoric acid (PA) or diammonium phosphate (DAP) were evaluated at various P rates (0, 18, 36 and 54 mg kg⁻¹ soil), either as non-mix (designated as NM-PA and NM-DAP, respectively) or after premixing with farmyard manure (FYM) at 400 mg kg⁻¹ soil (designated as PM-PA and PM-DAP, respectively). The amended soil was incubated at 25 °C and 70% water holding capacity for 7 weeks; thereafter, ³²P dynamics were measured using the Freundlich kinetic model. A greenhouse study was also conducted using the same thirteen treatments (as used in incubation experiment) and wheat cultivar (Galaxy 2013) was grown following standard agronomic practices. The results showed that application of PM-PA at the highest rate, which caused maximum change in Pr (ΔPr = 59%) in laboratory condition, also produced maximum P uptake by grain (190.3 mg pot⁻¹) and grain yield (44.1 g pot⁻¹) of wheat in greenhouse experiment. Similarly, regression analysis showed that an increase in Pr values caused a corresponding increase in crop parameters. The results suggested that pre-mixing P fertilizer with FYM could be a viable technique to increase P supply and enhance productivity of wheat in alkaline calcareous soils.
Показать больше [+] Меньше [-]A comparative study of using barberry stem powder and ash as adsorbents for adsorption of humic acid
2019
In the present research, investigation of the practical utility of barberry stem powder (BSP) and barberry stem ash (BSA) for humic acid (HA) removal from an aqueous medium by adsorption was carried out. The adsorption process was tested by varying of pH (3–11), reaction time (5–20 min), initial HA concentration (5–40 mg/L), adsorbent dosage (1–4 g/L), and temperature (15–35 °C). The isothermal results revealed that the adsorption process is favorable for both used adsorbents and it is highly described using the Freundlich and Langmuir models (R² > 0.960). Also, the maximum uptakes of BSP and BSA for HA were 20.220 and 16.950 mg/g at the abovementioned optimized conditions (pH = 7, reaction time = 10 min, temperature = 15 °C, initial HA concentration = 40 mg/L, and adsorbent amount = 1.0 g/L), respectively. The results achieved from the fitting of the experimental data with Dubinin-Radushkevich isotherm model showed that the HA molecules are adsorbed onto the BSP and BSA by physiosorption process. From the thermodynamic study, it appeared that the biosorption process of the HA onto two studied adsorbents was of exothermic nature. The kinetics of the adsorption process of HA has been found to be pseudo-second-order model (R² = 0.930–0.999). Thus, the results obtained from this paper elucidated that the BSP exhibited higher adsorption capacity in comparison to BSA, for HA removal up to permissible concentrations.
Показать больше [+] Меньше [-]Use of fatty acids as tracer of organic matter input associated with level of land urbanization
2019
Suspended sediments (SSs) were examined regarding the content of fatty acids (FAs) to associate them with sources of soil entry into the river. The source of organic matter was traced through fatty acid distribution, as well as erosion. Also, TOC, TN, and TOC/NT were used to support the results of FAs. For this, a tropical river was chosen to understand the main source of input considering the level of land occupation along the river. The Barigui river, in southern Brazil, was segmented in four distinct areas regarding the soil occupation (P1, P2, P3, and P4). Nine sampling campaigns were conducted from Nov/2014 to Nov/2015 using a time-integrated sampler. Site P1 has the lowest level of urbanization and showed the lowest concentration of FAs (16.35 μg⁻¹). In contrast, site P4, the most urbanized, showed the highest content of fatty acids, including those associated with erosion, 378.53 μg g⁻¹, specifically those with long chains. The mean concentrations of the saturated fatty acids (FAs) was 283.40 μg g⁻¹, monounsaturated fatty acids (MUFAs) was 79.46 μg g⁻¹, and polyunsaturated fatty acids (PUFAs) was 15.66 μg g⁻¹. Twenty-seven fatty acids were examined, nevertheless C15:0, C16:0, C18:0, and C18:1ω9 prevailed in all samples. Generally, those acids indicate sewage inputs. Statics analyses were used to find the relation between the source of organic matter (autochthonous, allochthones, and anthropogenic) and FAs. Finally, the input of organic matter is associated with land occupation, which can be distinguished by FA distribution.
Показать больше [+] Меньше [-]The effect of inorganic salt in wastewater on the viscosity of coal water slurry
2019
Wang, Chunyu | Zhao, Hui | Dai, Zhenghua | Li, Weifeng | Liu, Haifeng
The preparation of coal water slurry (CWS) using wastewater, which contains inorganic and organic components, is one method of wastewater utilization. In this study, the effect of inorganic salts on the viscosity of CWS was examined. The results show that monovalent salts (NaCl, KCl) decreased the viscosity of CWS. The viscosity of CWS was not affected by bivalent salts (CaCl₂, MgCl₂). However, CWS combined with trivalent salt (AlCl₃) sharply increased the viscosity. The zeta potential of CWS with inorganic salts increased which can enhance the electric repulsion and beneficial to reduce the viscosity. The content of free water in CWS with trivalent salt decreased, and the freedom of the free water in CWS with trivalent salt decreased which were all bad to the viscosity and the adsorption of the dispersant on the particles. Compared with the surface polarity of the particles without inorganic salts, the surface polarity of the particles with divalent salts was similar to those without inorganic salts. Under the comprehensive influence, divalent salt has little effect on the viscosity of CWS.
Показать больше [+] Меньше [-]Does “replacing business tax with value-added tax” promote the energy efficiency of the logistics industry in China?
2019
Liu, Zuankuo | Jiang, Yufan | Bolayog, Dennis
This paper investigates the relationship between “replacing business tax with value-added tax” (RBTVT) and the total factor energy efficiency (TFEE) of the logistics industry using regression discontinuity (RD) method, and the research shows that the TFEE of the logistics industry in China has presented a benign growth trend. RBTVT has significantly promoted the development of TFEE in the logistics industry, and its influence has mainly stemmed from the improvement of green technology progress. Moreover, the promotion mechanism of policy in the eastern region reacts more sharp than that in the central and western regions does. So this paper claims that the government should built a tax incentive mechanism of green production and energy conservation. It is necessary to use RBTVT to promote the high-quality development of the logistics industry and create an environment which coexist low-carbon environmental protection and economic benefits.
Показать больше [+] Меньше [-]Toxicity of three emerging contaminants to non-target marine organisms
2019
da Silva, Allyson Q. | de Souza Abessa, Denis Moledo
Coastal areas are continually impacted by anthropic activities because they shelter large urban conglomerates. Urban effluents directly or indirectly end up reaching the marine environment, releasing a large number of pollutants which include the so-called contaminants of emerging concern (CECs), since the conventional treatment plants are not effective in removing these compounds from the effluents. These substances include hormones, pharmaceuticals and personal care products, nanoparticles, biocides, among others. The aim of this study was to evaluate the toxicity of the 17α-ethinylestradiol (EE2), acetylsalicylic acid (ASA), and bisphenol-A (BPA) to two marine crustaceans and one echinoderm, evaluating the following parameters: survival (Artemia sp. and Mysidopsis juniae), embryo-larval development (Echinometra lucunter). The LC₅₀ values calculated in the acute toxicity tests showed that the compounds were more toxic to M. juniae than to the Artemia sp. Among the three contaminants, EE2 was the most toxic (LC₅₀₋₄₈ₕ = 18.4 ± 2.7 mg L⁻¹ to Artemia sp.; LC₅₀₋₉₆ₕ = 0.36 ± 0.07 mg L⁻¹ to M. juniae). The three tested compounds affected significantly the embryonic development of the sea urchin in all tested concentrations, including ecologically relevant concentrations, indicating the potential risk that these contaminants may present to the marine biota.
Показать больше [+] Меньше [-]Developing an electric vehicle urban driving cycle to study differences in energy consumption
2019
This paper develops a methodology for constructing a representative electric vehicle (EV) urban driving cycle as a basis for studying the differences in estimated energy consumption, taking Xi’an as an example. The test route is designed in accordance with the overall topological structure of the urban roads in the study region and the results of a traffic flow survey. Wavelet decomposition and reconstruction are utilized to preprocess the original data. Principal component analysis (PCA) is used to reduce the number of the kinetic parameters. The fuzzy C-means (FCM) clustering algorithm is used to cluster the driving segments. A representative EV urban driving cycle is constructed in accordance with the time proportions of three classes of driving segments and the correlation coefficients of the characteristic parameters. Finally, the differences in energy consumption estimates obtained using the constructed Xi’an EV urban driving cycle (XA-EV-UDC) and the international driving cycles are studied. The comparison shows that when international driving cycles are used to estimate the energy consumption and driving range of EVs, large relative errors will result, with energy consumption errors of 9.65 to 21.17% and driving range errors of 20.10 to 38.14%. Therefore, to accurately estimate energy consumption and driving range of EVs under real-world driving conditions, representative EV driving cycles for each typical city and region should be constructed.
Показать больше [+] Меньше [-]Hospital wastewaters treatment: Fenton reaction vs. BDDE vs. ferrate(VI)
2019
Mackuľak, Tomáš | Grabic, Roman | Špalková, Viera | Belišová, Noemi | Škulcová, Andrea | Slavík, Ondřej | Horký, Pavel | Gál, Miroslav | Filip, Jan | Híveš, Ján | Vojs, Marian | Staňová, Andrea Vojs | Medveďová, Alžbeta | Marton, Marián | Birošová, Lucia
Various types of micropollutants, e.g., pharmaceuticals and their metabolites and resistant strains of pathogenic microorganisms, are usually found in hospital wastewaters. The aim of this paper was to study the presence of 74 frequently used pharmaceuticals, legal and illegal drugs, and antibiotic-resistant bacteria in 5 hospital wastewaters in Slovakia and Czechia and to compare the efficiency of several advanced oxidations processes (AOPs) for sanitation and treatment of such highly polluted wastewaters. The occurrence of micropollutants and antibiotic-resistant bacteria was investigated by in-line SPE-LC-MS/MS technique and cultivation on antibiotic and antibiotic-free selective diagnostic media, respectively. The highest maximum concentrations were found for cotinine (6700 ng/L), bisoprolol (5200 ng/L), metoprolol (2600 ng/L), tramadol (2400 ng/L), sulfamethoxazole (1500 ng/L), and ranitidine (1400 ng/L). In the second part of the study, different advanced oxidation processes, modified Fenton reaction, ferrate(VI), and oxidation by boron-doped diamond electrode were tested in order to eliminate the abovementioned pollutants. Obtained results indicate that the modified Fenton reaction and application of boron-doped diamond electrode were able to eliminate almost the whole spectrum of selected micropollutants with efficiency higher than 90%. All studied methods achieved complete removal of the antibiotic-resistant bacteria present in hospital wastewaters.
Показать больше [+] Меньше [-]Characterization of chemical components and cytotoxicity effects of indoor and outdoor fine particulate matter (PM2.5) in Xi’an, China
2019
Niu, Xinyi | Ho, Kin Fai | Hu, Tafeng | Sun, Jian | Duan, Jing | Huang, Yu | Lui, Ka Hei | Cao, Junji
The chemical and cytotoxicity properties of fine particulate matter (PM₂.₅) at indoor and outdoor environment were characterized in Xi’an, China. The mass concentrations of PM₂.₅ in urban areas (93.29~96.13 μg m⁻³ for indoor and 124.37~154.52 μg m⁻³ for outdoor) were higher than suburban (68.40 μg m⁻³ for indoor and 96.18 μg m⁻³ for outdoor). The PM₂.₅ concentrations from outdoor environment due to fossil fuel combustion were higher than indoor environment. An indoor environment without central heating demonstrated higher organic carbon-to-elemental carbon (OC / EC) ratios and n-alkanes values that potentially attributed to residential coal combustion activities. The cell viability of human epithelial lung cells showed dose-dependent decrease, while nitric oxide (NO) and oxidative potential showed dose-dependent increase under exposure to PM₂.₅. The variations of bioreactivities could be possibly related to different chemical components from different sources. Moderate (0.4 < R < 0.6) to strong (R > 0.6) correlations were observed between bioreactivities and elemental carbon (EC)/secondary aerosols (NO₃⁻, SO₄²⁻, and NH₄⁺)/heavy metals (Ni, Cu, and Pb). The findings suggest PM₂.₅ is associated with particle induced oxidative potential, which are further responsible for respiratory diseases under chronic exposure.
Показать больше [+] Меньше [-]