Totally found 4269 items.

  • [期刊] Low-cost sugarcane bagasse and peanut shell magnetic-composites applied in the removal of carbofuran and iprodione pesticides
    In the present study, two agro-industrial wastes, sugarcane bagasse, and peanut shell were employed as support of magnetite nanoparticles for the synthesis of magnetic bio-composites: magnetic sugarcane bagasse (MBO) and magnetic peanut shell (MPSo). The presence of magnetite was verified by Raman spectroscopy. Magnetic nanoparticles shape and size distribution were studied by TEM, while composites morphologies were observed by SEM. Structural characteristics of the pesticides and their possible chemical adsorption on composites were analyzed by FTIR. The removal was carried out by a batch adsorption process, and UV-VIS technique was used for pesticide concentration estimation. Elovich model described better all systems pointing out to a chemical adsorption process occurring. Experimental data isotherms of carbofuran and iprodione can be best explained by more than one mathematical model, but Sip was the ordinary equation in all systems. Maximum adsorption capacities of 175 and 89.3 mg/g for carbofuran, and 119 and 2.76 mg/g for iprodione, were obtained for MBo and MPSo, respectively. References:
  • [期刊] Organochlorine pesticides in feathers of three raptor species in southern Brazil
    In this study, we determined the presence of organochlorine pesticides (OCPs) in back feathers from three raptor species, Phalcoboenus chimango, Milvago chimachima and Caracara plancus. Samples were obtained from live animals and ten OCPs were detected: alpha-HCH, beta-HCH and gamma-HCH (lindane), heptachlor, heptachlor epoxide, aldrin, endosulfan I, endosulfan II, endosulfan sulfate and p,p '-DDE. The concentrations found were higher than those reported in other raptor species, and C. plancus showed greater values than P. chimango and M. chimachima for all the substances. These differences may be justified by the species feeding habits and the characteristics of the sampling area, since C. plancus were sampled in an area with a higher concentration of agricultural crops and urbanized environments. In relation to the possible negative effects, four individuals of C. plancus presented DDE values related to sublethal effects for other species. This is the first study reporting OCPs in back feathers of these species in Brazil, and further studies evaluating OCP exposure and related effects are important for a better understanding of the consequences of different OCP concentrations on the health of these species. References: 1. WHO. Environmental Health Criteria 83; DDT and its derivatives -Environmental Aspects (1989); 2. Di Giacomo, A G. Aves de la reserva El Bagual. Historia natural y paisaje de la reserva El Bagual, Provincia de Formosa. Temas de Naturaleza y Conservacion, Monografia de Aves Argentinas (2005) 201;
  • [期刊] Organochlorine pesticides in the surrounding soils of POPs destruction facility: source fingerprinting, human health, and ecological risks assessment
    The elimination of persistent organic pollutants (POPs) obsolete pesticides stockpiles, particularly the organochlorine pesticides (OCPs), is one of the critical environmental issues faced by many developing countries. This pioneering study aimed to investigate the occurrence, source fingerprinting, human health, and ecological risks of OCPs in the surroundings of the lone POPs pesticide destruction facility in Pakistan. The sigma OCPs residual levels in soil ranged from 35.98 to 566.77 ng/g dry weight (dw), with a mean concentration of 174.42 + 111.62 ng/g (dw). The OCPs contamination levels in the soil followed the pattern as sigma HCHs >sigma endrins >sigma endosulfans >dieldrin >sigma heptachlors >sigma DDTs >sigma chlordanes >methoxychlor. The sigma HCHs residual concentrations were comparatively higher than the previous national and global soil studies. The recent accumulation of HCHs, DDTs, and heptachlor was observed in the study area as identified by beta-HCH/ n-ary sumation HCHs, (DDE + DDD)/sigma DDTs, heptachlor/sigma heptachlor, and heptachlor exo-epoxide/heptachlor ratios. The OCPs' lifetime carcinogenic risk through ingestion, dermal, and inhalation exposure routes ranged from 1.65E-08 to 2.91E-07, whereas the noncarcinogenic hazard quotient (HQ) ranged from 9.12E-05 to 1.61E-03. The risk vulnerability among age groups was in the order: adult >toddler >child >teen >infant. The calculated risk levels were within an acceptable limit of one in a million (1 x 10(-6)) for carcinogenic risk and HQ <1 for noncarcinogenic risk. The current OCPs residual levels, especially dieldrin and endrin, exhibited low to medium ecological risks when compared to various worldwide limits. The upsurge of the OCPs' environmental contamination levels over the years and consideration of the food chain transfer might amplify the human health and ecological risks intensities. References:
  • [期刊] Developing the first halophytic turfgrasses for the urban landscape from native Arabian desert grass
    Climate change is occurring and is influencing biological systems through augmented temperatures, more inconstant precipitation, and rising CO(2)in the atmosphere. For sustainable landscaping, it was essential to assess the diversity of native/wild grasses and their suitability for turf and to combat the salinity problem in the region. For this purpose, a native halophytic grass,Aeluropus lagopoides, was investigated by conducting mowing tests on its ecotypes during the year 2014-2016 under desert climatic conditions. The research was carried out in two phases, i.e. Phase-I was for collection and establishment of ecotypes from various parts of UAE, while in Phase-II, mowing tests were conducted. During mowing tests, 50 ecotypes ofA. lagopoideswere given various mowing treatments (i.e. they were cut back at 1-, 2-, 3-, 4- and 5-cm heights) in field conditions. Significant differences were found among various ecotypes for different agronomic parameters such as ground cover, canopy stiffness, leaf number, clippings fresh and dry weights and internode length. Overall, the grass exhibited better performance at mowing heights of 3 and 4 cm, which are the standard mowing heights for turfgrasses. Ecotypes FA5, RA3, RUDA2, RUDA7 and RUADA1 ofA. lagopoidesshowed the best performance against mowing shock and became the candidates for the turfgrass varieties from the native Arabian flora.
  • [期刊] Relationships between shear strength parameters and microstructure of alkaline-contaminated red clay
    The leachate (pH = 14) from alumina production changes the mechanical properties of red clay, and the shear strength parameters of the system vary due to the multiple-dimensional interactions of the microscopic parameters. In this paper, the alumina production liquid and the concentrations of the NaOH solution were designed to contaminate the red clay during 80 days. The cohesion and friction angle of the alkaline-contaminated red clay were obtained from direct shear tests. Through qualitative and quantitative analyses using scanning electron microscopy (SEM), the microstructure was observed. Based on the rock engineering systems (RES) theory, interactions among microscopic parameters were analysed, and the relationships between shear strength parameters and microscopic parameters of alkaline-contaminated red clay were established. Results show that both of the cohesion and friction angle of alkaline-contaminated red clay are increased in general; the adsorption in alumina production liquid and dispersing effect of 0.7% NaOH concentration are noticeable, and the interactions of the microscopic parameters are intense; the ratio of the intra-aggregate pore number, the probability distribution index and the number of particles can significantly influence cohesion; the particle morphology fractal dimension, aspect and probability entropy have a severe effect on friction angle. This work is expected to serve as a reference for future research on the relationship between macroscopic properties and microcosmic structure of soil.
  • [期刊] Symmetric and asymmetric effect of energy consumption and CO(2)intensity on environmental quality: using nonlinear and asymmetric approach
    This paper investigates the asymmetric impact of energy consumption and carbon dioxide (CO2) intensity on the environmental quality in Russia. The ecological footprint (a proxy for environmental quality) was used as a dependent variable, while independent variables include energy consumption, CO(2)intensity, and gross fixed capital formation as a proxy of capital for time series data spanning from 1992 to 2016. To examine the asymmetric cointegration between the selected variables, the nonlinear autoregressive distributed lag (NARDL) method was used. The structural break unit root and BDS tests were used to check data stationarity and nonlinearity, respectively. Besides, the asymmetric causality test in Gauss software was employed to check the causal relationship among the variables. Among the considered variables, the asymmetric cointegration was found. A significant unidirectional symmetric causality was found running from energy consumption to ecological footprint (Wald test = 3.956*) and from ecological footprint to capital (Wald test = 10.115**), while asymmetrically, ecological footprint granger cause energy consumption (Wald test = 6.054**) and capital (Wald test = 6.739**) respectively. On the contrary, a neutral effect was found between environmental quality and CO(2)intensity. From these findings, environmental policies are also discussed. Specifically, policymakers should support modern, controlled emission technologies, including nuclear and renewable energy sources and green portfolio investment.
  • [期刊] Application of loop-mediated isothermal amplification combined with lateral flow dipstick to rapid and sensitive detection of Alexandrium catenella
    Alexandrium catenella is one of the globally distributed toxic marine microalgae to cause paralytic shellfish poisoning that poses a great threat to marine fisheries, economy, and public health. Development of efficient and sensitive methods for accurate identification of A. catenella to minimize its damage is therefore necessary. In this study, a novel method referred to as loop-mediated isothermal amplification (LAMP) combined with lateral flow dipstick (LFD) (LAMP-LFD) was established for rapid and sensitive detection of A. catenella. The internal transcribed spacer (ITS) gene of A. catenella was cloned for sequencing and used as target for LAMP-LFD. Three sets of LAMP primers (AcLF1, AcLF2, and AcLF3) targeting the ITS were successfully designed, among which AcLF2 displaying the best performance was used in the subsequent tests. A specific LFD probe targeting the amplification region ofAcLF2 was further designed. The LAMP-LFD detection system was established and the amplification conditions were optimized. Cross-reactivity tests with common marine microalgae showed that the LAMP-LFD was exclusively specific for A. catenella. The detection limits of LAMP-LFD for A. catenella genomic DNA and the plasmid containing the ITS were 4.63 x 10(-4) ng mu L-1 and 1.26 x 10(4) copies mu L-1, displaying a sensitivity that is 10 times higher than that of SYBR Green I assay and 100 times higher than that of conventional PCR, respectively. Finally, the practicability of LAMP-LFD was confirmed by test with spiked samples. LAMP-LFD revealed a detection limit of approximately 0.1 cell mL(-1), which was 100 times more sensitive than conventional PCR. The optimized LAMP-LFD protocol can be completed within 75 min. Therefore, the established LAMP-LFD is a specific, sensitive, and rapid method that is possibly applicable to the field monitoring of A. catenella.
  • [期刊] Effects of freeze-thaw cycles on distribution and speciation of heavy metals in pig manure
    To understand the potential environmental influence of animal manure under freeze-thaw cycles, pig manure was used to conduct a simulation experiment to explore the effects of freeze-thaw cycles on heavy metal distribution and form transformation. Thirty cycles of freezing and thawing were performed alternately by freezing at - 18 +/- 2 degrees C for 24 h and thawing at 20 +/- 2 degrees C for 24 h. By a serial wet sieving procedure, manure samples were separated into different sizes of 1000, 250, 75, 38, and < 38 mu m. Solid samples were collected from the dry matter at each stage of sieve; then the washing waters were collected as liquid samples accordingly. The concentrations of heavy metals in solid/liquid samples and their five forms were analyzed. It showed that the concentrations of heavy metals in the solid and liquid samples gradually increased because of organic matter degradation during freezing and thawing cycles. The distribution of heavy metals on particles of different sizes was also affected by the degradation and breakup of pig manure; the metals showed a tendency to aggregate in small particles (< 38 mu m). Among them, the percentage of Cu and Zn on < 38 mu m particles increased by 162.3% and 554.1%, respectively. After several freeze-thaw cycles, the concentrations of EXCH-X (metals of exchangeable form) increased significantly, those of CARB-X (carbonate-bound form) and Fe/Mn-X (Fe/Mn oxide-bound form) decreased accordingly. These form transformations may be largely influenced by the enhancement of dissolved organic matter (DOM) and the reduction of pH value. Therefore, frequent freeze-thaw cycles may promote the mobility and bioavailability of heavy metals in pig manure. The results are significant for understanding the pollution risk of pig manure in the freeze-thaw regions.
  • [期刊] Adsorptive removal of lanthanum based on hydrothermally synthesized iron oxide-titanium oxide nanoparticles
    Iron oxide-titanium oxide (Fe2O3-TiO2) nanoparticles were developed as an effective adsorbent in order to extract and remove lanthanum ions selectively from aqueous media. Fe2O3-TiO2 nanoparticles were prepared by simple hydrothermal method and structurally characterized using FESEM, EDS, XRD, FTIR, and BET techniques. The analytical potential of Fe2O3-TiO2 nanoparticles was interpreted by applying the kinetic and isotherm models. The maximum static uptake capacity was 89.63 mgg(- 1) at pH 7. Adsorption isotherm data evinced that a monolayer adsorption occurred on a homogeneous adsorbent surface which is compatible with Langmuir isotherm model. Data acquired from kinetic models study proved that La (III) adsorption onto Fe2O3-TiO2 nanoparticles followed a pseudo-second-order kinetic equation. Thermodynamic study exhibited that a spontaneous process is favorable for adsorption mechanism of La (III) on Fe2O3-TiO2 nanoparticles. Moreover, the existence of different coexisting ions did not influence the extraction of La (III). Finally, the recommended methodology was applied on several environmental samples.
  • [期刊] Novel eco-friendly electrospun nanomagnetic zinc oxide hybridized PVA/alginate/chitosan nanofibers for enhanced phenol decontamination
    In the current study, poly(vinyl alcohol)/alginate/chitosan (PVA/Alg/CS) composite nanofiber was immobilized with six different ratios of nanomagnetic zinc oxide (M-ZnO) (0 wt%, 0.2 wt%, 0.4 wt%, 0.6 wt%, 0.8 wt%, and 1 wt%) via the electrospinning technique. The various fabricated composite (M-6) nanofibers were characterized using Fourier transform infrared (FTIR), X-ray diffractometer (XRD), vibrating sample magnetometer (VSM), scanning electron microscope (SEM), atomic force microscope (AFM), thermogravimetric analysis (TGA), mechanical testing machine, and optical contact angle measurement. The fabricated composite nanofibers were applied for the adsorption of phenol from aqueous solutions. The 1.0 wt% M-ZnO/PVA/Alg/CS composite nanofibers were selected as the best phenol adsorbent with removal percentage of 84.22%. The influence of different processing parameter such as contact time, composite nanofiber dosage, pH, initial pollutant concentration, and temperature were examined. Increasing nanofiber dosage and the solution temperature was found to enhance the phenol adsorption onto the prepared nanocomposites. The maximum percentage of phenol removal was achieved at 84.22% after 90 min. Meanwhile, the maximum monolayer adsorption capacity (at pH = 5.0) was estimated to be 10.03 mg g(-1)at 25 degrees C. Kinetic, isotherm, and thermodynamic studies were designated to proof the endothermic, spontaneous, and thermodynamically nature of the phenol adsorption process. These outcomes indicate the effectiveness of the fabricated M-ZnO/PVA/Alg/CS nanofibers as adsorbent materials for phenol from aqueous solutions.