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Analysis of a photobioreactor scaling up for tertiary wastewater treatment: denitrification, phosphorus removal, and microalgae production Полный текст
2018
Villaseñor Camacho, José | Fernández Marchante, Carmen María | Rodríguez Romero, Luis
The present work studies the removal of nutrients (nitrate and phosphate) from a synthetic wastewater simulating a secondary treatment effluent using the microalgae Chlorella vulgaris in autotrophic photobioreactors, together with an analysis of the critical points affecting the scaling-up process from laboratory to pilot scale. Laboratory experiments were done in open agitated 1-L photobioreactors under batch operation mode, while pilot-scale experiments were done using a 150-L closed tubular photobioreactor under continuous operation mode. In both scales, nitrate was the limiting substrate and the effect of its concentration on microalgae performance was studied. From laboratory experiments, an average microalgae productivity of 85 mgVSS L⁻¹ day⁻¹ and approximate maximum N-NO₃⁻ and P-PO₄³⁻ removal rates of 8 mg N gVSS⁻¹ day⁻¹, and 2.6 mg P gVSS⁻¹ day⁻¹ were found. Regarding pilot scale, the average microalgae productivity slightly decreased (76 mgVSS L⁻¹ day⁻¹) while the approximate maximum N-NO₃⁻ and P-PO₄³⁻ removal rates slightly were increased (11.7 mg N gVSS⁻¹ day⁻¹ and 3.04 mg P gVSS⁻¹ day⁻¹) with respect to the laboratory-scale results. The pilot-scale operation worked under lower levels of turbulence and higher dissolved oxygen concentration and light intensity than laboratory experiments; those parameters were difficult to control and they can be identified as the critical points in the differences found on both nutrient removal and microalgae production.
Показать больше [+] Меньше [-]Is there any association between phthalate exposure and precocious puberty in girls? Полный текст
2018
Hashemipour, Mahin | Kelishadi, Roya | Amin, MohammadMehdi | Ebrahim, Karim
Considerable increase in the prevalence of precocious puberty (PP) during the last decade has raised a lot of concerns. Some environmental endocrine disruptor chemicals (EDCs), such as phthalate esters, have intrinsic estrogen activity or increase endogenous sex hormone levels leading to PP. This study was conducted to investigate the association between exposure to phthalate esters and PP in a sample of girls. Plasma levels of seven phthalate ester metabolites were measured in 87 girls with PP and 63 age- and sex-matched controls by dispersive liquid–liquid microextraction and GC/MS analysis. History of exposure to main sources of phthalates was obtained by a checklist. Diethyl hexyl phthalate (DEHP) metabolite levels were significantly higher in those with PP than that in controls (p < 0.05), but this difference was not significant for other phthalate metabolites. 30.1% girls with PP and 12.2% of controls had played for more than 2 h/day with plastic toys in their childhood. 65.1% girls with PP and 32.8% of controls have regularly used some cosmetic products. Consumption of bottled water and beverages by those with PP was about twofold higher than that in the control group. A positive correlation was found between bottled ware consumption and plasma concentrations of four phthalate metabolites. The frequency of seafood consumption was not significantly different between the groups studied. Our findings confirm positive association between phthalate exposure and incidence of PP in girls. Control and reduction of children exposure to phthalate esters should be considered as a health priority.
Показать больше [+] Меньше [-]Interaction of pesticides with natural and synthetic solids. Evaluation in dynamic and equilibrium conditions Полный текст
2018
Otalvaro, JuliánOrtiz | Brigante, Maximiliano
Interactions between pesticides (paraquat, glyphosate, 2,4-D, atrazine, and metsulfuron methyl) and soil organic and inorganic components have been studied in batch experiments by performing adsorption, dissolution, and chemical and photochemical degradation under different conditions. The obtained results confirm that the affinity of a pesticide to the solid surface depends on the nature of both and shows that each reactant strongly affects the mobility of the other one, e.g., anionic pesticides promote the dissolution of the solid humic acid but if this last is retained into the inorganic matrix enhances the adsorption of a cationic pesticide. Adsorption also seems to protect the bonded specie to be chemical degraded, such as shown in two pesticide/clay systems at constant pH. The use of mesoporous silicas could result in a good alternative for pesticide remediation. In fact, the solid shows high adsorption capacity towards paraquat and its modification with TiO₂ nanoparticles increases not only the pesticide adsorption but also seems to catalyze its degradation under UV light to less-toxic metabolites. UV-VIS spectroscopy was relevant and novel in such sense. Electrostatic interactions, hydrogen and coordinative bonds formations, surface complexations and hydrophobic associations play a key role in the fate of mentioned pesticides on soil and ground/surface water environments.
Показать больше [+] Меньше [-]Antifungal exploitation of fungicides against Fusarium oxysporum f. sp. capsici causing Fusarium wilt of chilli pepper in Pakistan Полный текст
2018
Bashir, MuhammadRizwan | Atiq, Muhammad | Sājid, Muḥammad | Mohsan, Muhammad | Abbas, Waseem | Alam, MuhammadWaqar | Bashair, Muhammad
The research was conducted to evaluate in-vitro efficacy of numerous fungicides against Fusarium oxysporum f. sp. capsici. In present research, six treatments (T) viz. Carbendazim, Benomyl, Topsin-M, Difenoconazole, Nativo, and Alliete along with control, various concentrations (C), days (D), and their interactions, i.e., (T × C), (T × D), (C × D), and (T × C × D) were exploited in a laboratory through food poison technique. Alliete expressed maximum colony growth (1.93 cm) as compared to all other fungicides with respect to control. Interaction between treatments and concentration (T × C) exhibited maximum colony growth of all treatments (Carbendazim, Benomyl, Topsin-M, Difenoconazole, Nativo, and Alliete), i.e., 0.87, 1.23, 1.73, 2.20, 2.53, and 2.93 cm at 300 ppm as compared to 500 and 700 ppm concentrations, respectively. Similar trend was also observed concerning interaction between (fungicides × days) and (tested concentrations × days). Results of the present study revealed that among tested fungicides, Carbendazim at 700 ppm expressed significant reduction in fungal growth.
Показать больше [+] Меньше [-]Analysis method for PCBs in reclaimed oil using a fast-GC triple stage quadrupole mass spectrometer with the 13-component quantitation method Полный текст
2018
Takakuwa, Hiroshi | Miura, Takashi | Matsumura, Toru | Hashi, Norie | Kubota, Michiyo | Kutsukake, Hiroshi | Muramatsu, Kazuhiro | Kasamatsu, Takashi | Okuda, Masahiro
It is necessary for companies supplying reclaimed oil to analyze polychlorinated biphenyls (PCBs), because there is a possibility of the presence of contaminants due to trace-level PCBs in the reclaimed oil. However, common analysis methods of PCBs are time-consuming and complicated. Fast-GC triple stage quadrupole mass spectrometer with the 13-component quantitation method is an official method for analyzing PCBs in insulating oil in Japan. This method is extremely fast and simplified. The purpose of this study involves an investigation of the aforementioned fast and simple method for potential use in the analysis of reclaimed oil. Furthermore, it was attempted to combine the method with sample preparation involving only hexane dilution. The effect of sample dilutions corresponding to 100, 300, and 500 times was evaluated for reducing the matrix effect. The matrix effect was suppressed at a dilution ratio equal to or exceeding 300 times. Calibration curves of four points, namely 0.01, 0.05, 0.1, and 0.5 ng/mL, (ignored origin) by using an internal standard method were prepared for the 13 components. The square of regression coefficient (R²) values of all calibration curves exceeded 0.997. This method was adopted for the analysis of reclaimed oil containing 0.5 μg/mL PCBs, which corresponds to the judgment criteria, and accurate quantitation (accuracy value, 94.0–102%) and good repeatability (%RSD, 3.6%) were obtained. Furthermore, the required sensitivity was maintained even when 800 samples were analyzed without a cleaning ion source and an exchanging analysis column.
Показать больше [+] Меньше [-]Enhanced adsorption of uranium by modified red muds: adsorption behavior study Полный текст
2018
Wu, Wanying | Chen, Diyun | Li, Jinwen | Su, Minhua | Chen, Nan
Uranium is a hazardous and radioactive element. Effective removal of uranium from wastewater stream requires advanced functional materials and reliable technologies. Red mud is a type of low-cost adsorbent which is widely used in the adsorption process. In the present work, we successfully modified the raw red mud to gain a series of highly efficient sorbents for uranium removal. They are nitric acid dealkalized red mud (DRM), aluminum nitrate modified red mud (ARM), and ferric nitrate modified red mud (FRM). The adsorption efficiencies of uranium(VI) by DRM, ARM, and FRM were 74.50, 95.56, and 98.75% in their optimal immobilization regions, respectively. The chemisorption of uranium dominates the adsorption process of FRM, while as to physical adsorption dominates the adsorption process of ARM and DRM. Both DRM and ARM reached their maximum adsorption capacities at 10 min while that for FRM occurred at 30 min. FRM performed much stronger anti-interference ability to the influence of carbonate and calcium. The outstanding adsorption ability of these modified red muds is mainly due to the enhancement of ion exchange, co-precipitation, and electrostatic attraction by red mud’s active components and functional groups.
Показать больше [+] Меньше [-]Panel estimation for renewable and non-renewable energy consumption, economic growth, CO2 emissions, the composite trade intensity, and financial openness of the commonwealth of independent states Полный текст
2018
Rasoulinezhad, Ehsan | Saboori, Behnaz
This article investigates the long-run and causal linkages between economic growth, CO₂ emissions, renewable and non-renewable (fossil fuels) energy consumption, the Composite Trade Intensity (CTI) as a proxy for trade openness, and the Chinn-Ito index as a proxy for financial openness for a panel of the Commonwealth of Independent States (CIS) region including Armenia, Azerbaijan, Belarus, Georgia, Kazakhstan, Kyrgyzstan, Moldova, Russia, Tajikistan, Turkmenistan, Ukraine, and Uzbekistan over the period of 1992–2015. It is the first time that CTI and the Chinn-Ito indexes are used in an economic-pollution model. Employing three panel unit root tests, panel cointegration estimation methods (DOLS and FMOLS), and two panel causality tests, the main empirical results provided evidence for the bidirectional long-run relationship between all the variables in all 12 sampled countries except for economic growth-renewable energy use linkage. The findings of causality tests indicated that there is a unidirectional short-run panel causality running from economic growth, financial openness, and trade openness to CO₂ emissions and from fossil fuel energy consumption to renewable energy use.
Показать больше [+] Меньше [-]Microsatellite polymorphism of Trifolium pratense population at the conditions of radioactive and chemical contamination of soil (Komi republic, Russia) Полный текст
2018
Rybak, Anna V. | Belykh, Elena S. | Maystrenko, Tatiana A. | Velegzhaninov, Ilya O.
There is no clear understanding of microevolutionary changes in natural populations of plants and animals due to anthropogenic contamination of the environment with toxicants and mutagens. But such data are necessary to forecast long-term effects of human activity. In this research, we studied genetic polymorphism in T. pratense sampled from seven sites varying in radioactive and chemical soil contamination in the vicinity of Vodny settlement (Komi, Russia). Analysis of five SSR loci was shown to be similar in a whole (N), mean (Nₐ) and effective (Nₑ) numbers of alleles, heterozygosity indexes (Hₒ and Hₑ), and the Shannon index (I). Difference in the private allele numbers was registered: the most contaminated site has 5 and others from 0 up 2 private alleles. No difference was found in the genetic structure of T. pratense population growing at the conditions of radioactive and chemical contamination. The Bayesian analysis provided evidence of a single cluster (K = 1) due to a similar genetic structure of samples, while AMOVA results demonstrated a high variability within individuals (75%) and a low variability (1%) among groups of T. pratense from sites that differ in the contamination level. Thus, the long-term radioactive and heavy metal contamination of soil did not result in significant microevolutionary changes in T. pratense population.
Показать больше [+] Меньше [-]Groundwater vulnerability assessment in karstic aquifers using COP method Полный текст
2018
Bagherzadeh, Somayeh | Kalantari, Nasrollah | Nobandegani, Amir Fadaei | Derakhshan, Zahra | Conti, G. Oliveri (Gea Oliveri) | Ferrante, Margherita | Malekahmadi, Roya
Access to safe and reliable drinking water is amongst the important indicators of development in each society, and water scarcity is one of the challenges and limitations affecting development at national and regional levels and social life and economic activity areas. Generally, there are two types of drinking water sources: the first type is surface waters, including lakes, rivers, and streams and the second type is groundwaters existing in aquifers. Amongst aquifers, karst aquifers play an important role in supplying water sources of the world. Therefore, protecting these aquifers from pollution sources is of paramount importance. COP method is amongst the methods to investigate the intrinsic vulnerability of this type of aquifers, so that areas susceptible to contamination can be determined before being contaminated and these sources can be protected. In the present study, COP method was employed in order to spot the regions that are prone to contamination in the region. This method uses the properties of overlying geological layers above the water table (O factor), the concentration of flow (C factor), and precipitation (P factor) over the aquifer, as the parameters to assess the intrinsic vulnerability of groundwater resources. In this regard, geographical information system (GIS) and remote sensing (RS) were utilized to prepare the mentioned factors and the intrinsic vulnerability map was obtained. The results of COP method indicated that the northwest and the west of the region are highly and very vulnerable. This study indicated that regions with low vulnerability were observed in eastern areas, which accounted for 15.6% of the area. Moderate vulnerability was 40% and related to the northeast and southeast of the area. High vulnerability was 38.2% and related to western and southwestern regions. Very high vulnerability was 6.2% and related to the northwest of the area. By means of the analysis of sensitivity of the model, it was determined that the focus factor of the flow has the greatest impact on the creation of vulnerability in the region. Also, these results were validated through electrical conductivity and discharge time series of the regional springs that are located in the vulnerable zones.
Показать больше [+] Меньше [-]Eco-toxicology effect on Moina mongolica Daday exposed to Cd2+, Pb2+, and Hg2+ by the food chain Полный текст
2018
Wang, Meiru | Zhao, Wen | Jia, Xuying | Wei, Jie | Wang, Shan
As one of the most important contaminants, heavy metals can seriously influence human health via the food chain. In this study, the eco-toxicological effects of Cd²⁺, Pb²⁺, and Hg²⁺ on Moina mongolica Daday were investigated by feeding them Chlorella sp. that contained heavy metals. The relative body lengths of the M. mongolica changed rapidly, peaking at 2 days for Hg²⁺, 6 days for Cd²⁺, and 8 days for Pb²⁺. Moreover, grazing and clearance rates of the experimental group were apparently lower than those of the control group after immersion in heavy metals. Additionally, Cd²⁺ and Pd²⁺ in the food significantly influenced the mean lifespan of M. mongolica of the P and F₁ generations. Egg production per brood was also significantly impacted by Cd²⁺ and Pb²⁺ in the food in generation P. Interestingly, Pb²⁺ was the only metal that significantly influenced the reproduction times of F₂, while the reproductive times were significantly influenced by Cd²⁺ for generation P. Moreover, Cd²⁺, Pb²⁺, and Hg²⁺ in the food significantly influenced the fecundity of generation P. Evaluation of the population growth parameters of M. mongolica revealed that the intrinsic rate of increase, net reproduction rate, and finite rate of increase were significantly influenced by Cd²⁺, Pb²⁺, and Hg²⁺ in the food in generation P. Additionally, Hg²⁺ slightly impacted generation time for generation P. Finally, the acute toxicity toward M. mongolica was Hg²⁺ > Cd²⁺ > Pb²⁺. Overall, heavy metals in the food were likely to influence the growth, survival, and population growth of M. mongolica through the food chain.
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