خيارات البحث
النتائج 4241 - 4250 من 4,309
Efficient photo–catalytic degradation of malachite green using nickel tungstate material as photo–catalyst النص الكامل
2017
Helaïli, N. | Boudjamaa, A. | Kebir, M. | Bachari, K.
The present study focused on the evaluation of photo-catalytic and photo–electrochemical properties of the photo–catalyst based on nickel tungstate material prepared by a nitrate method through the degradation of malachite green (MG) dye's. The effect of catalyst loading and dye concentration was examined. Physico–chemical, optical, electrical, electrochemical, and photo–electrochemical properties of the prepared material were analyzed by X-ray diffraction (XRD), fourier transform–infrared spectroscopy (FTIR), BET analysis, optical reflectance diffuse (DR), scanning electron microscopy (SEM/EDX), electrical conductivity, cyclic voltammetry (CV), current intensity, mott–shottky, and nyquist. XRD revealed the formation of monoclinic structure with a small particle size. BET surface area of the sample was around 10 m²/g. The results show that the degradation of MG was more than 80%, achieved after 3 h of irradiation at pH 4.6 and with a catalyst loading of 75 mg. Also, it was found that the dye photo–degradation obeyed the pseudo-first order kinetic via Langmuir Hinshelwood model.
اظهر المزيد [+] اقل [-]Application of phosphate solubilizing bacteria in immobilization of Pb and Cd in soil النص الكامل
2017
Yuan, Zhimin | Yi, Honghong | Wang, Tianqi | Zhang, Yiyue | Zhu, Xiaozhe | Yao, Jun
In the present study, heavy metal (HM)-tolerant phosphate solubilizing bacteria (PSB) were isolated and their performance during the remediation of Pb and Cd in contaminated soil was studied. A total of 16 bacterial strains and one consortium were isolated, and the consortium had the highest phosphate solubilizing ability and HM tolerance. Great variations between the Fourier transform infrared (FTIR) spectra of consortium cells before and after adsorption of Pb²⁺ and Cd²⁺ revealed that amide I/amide II bonds and carboxyl on the cell surface were involved in binding of metal ions. High-throughput sequencing technique revealed that the consortium was composed of Enterobacter spp., Bacillus spp., and Lactococcus spp. The consortium was added into contaminated soil, and its potential ability in dissolution of phosphate from Ca₃(PO₄)₂ and subsequent immobilization of HMs was tested. Results showed that when Ca₃(PO₄)₂ was applied at 10.60 mg/g soil, PSB addition significantly increased soil available phosphate content from 12.28 to 17.30 mg/kg, thereby enhancing the immobilization rate of Pb and Cd from 69.95 to 80.76% and from 28.38 to 30.81%, respectively. Microcalorimetric analysis revealed that PSB addition significantly improved soil microbial activity, which was possibly related with the decreased HMs availability and the nutrient effect of the solubilized phosphate. The present study can provide a cost-effective and environmental-friendly strategy to remediate multiple HM-contaminated soils.
اظهر المزيد [+] اقل [-]Assessing the stability in dry mycelial fertilizer of Penicillium chrysogenum as soil amendment via fluorescence excitation-emission matrix spectra: organic matter’s transformation and maturity النص الكامل
2017
Wang, Bing | Cai, Chen | Li, Guomin | Liu, Huiling
Utilization as dry mycelial fertilizer (DMF) produced from penicillin fermentation fungi mycelium (PFFM) with an acid-heating pretreatment is a potential way. To study the transformation and stability of water-extractable organic matter in DMF-amended soil via fluorescence regional integration (FRI) of fluorescence excitation-emission matrix (EEM), a soil experiment in pot was carried out. The results showed that residual penicillin (about 32 mg/kg) was almost degraded in the first 5 days, indicating that the drug pollution was in control. The pH value, DOC, DON, and DOC/DON presented a classical profile, but germination index (GI) leveled off about 0.13 till day 13 in DMF-12% treatment due to the severe phytotoxicity. The addition of DMF significantly increased the soil microbial populations in contrast to the CON treatment. The EEM showed that the protein-like and microbial byproduct-like matters vanished on the 25th and 33rd days, whereas the fulvic-like substances appeared on the 7th day. The humic-like substances existed in original samples but their content greatly enhanced finally. The FRI results showed that P V, ₙ/P III, ₙ reached the highest value of 1.84 on the 25th day, suggesting that DMF maintained stable in amended soil. Because of its consistency with the results of GI and DOC/DON, the EEM-FRI has a potential to evaluate the stability of DMF in soil.
اظهر المزيد [+] اقل [-]Removal of cationic pollutants from water by xanthated corn cob: optimization, kinetics, thermodynamics, and prediction of purification process النص الكامل
2017
Kostić, Miloš | Đorđević, Miloš | Mitrović, Jelena | Velinov, Nena | Bojić, Danijela | Antonijević, Milan | Bojić, Aleksandar
The removal of Cr(III) ions and methylene blue (MB) from aqueous solutions by xanthated corn cob (xCC) in batch conditions was investigated. The sorption capacity of xCC strongly depended of the pH, and increase when the pH rises. The kinetics was well fitted by pseudo-second-order and Chrastil’s model. Sorption of Cr(III) ions and MB on xCC was rapid during the first 20 min of contact time and, thereafter, the biosorption rate decrease gradually until reaching equilibrium. The maximum sorption capacity of 17.13 and 83.89 mg g⁻¹ for Cr(III) ions and MB, respectively, was obtained at 40 °C, pH 5, and sorbent dose 4 g dm⁻³ for removal of Cr(III) ions and 1 g dm⁻³ for removal of MB. The prediction of purification process was successfully carried out, and the verification of theoretically calculated amounts of sorbent was confirmed by using packed-bed column laboratory system with recirculation of the aqueous phase. The wastewater from chrome plating industry was successfully purified, i.e., after 40 min concentration of Cr(III) ions was decreased lower than 0.1 mg dm⁻³. Also, removal of MB from the river water was successfully carried out and after 40 min, removal efficiency was about 94%.
اظهر المزيد [+] اقل [-]The effects of ocean acidification and a carbon dioxide capture and storage leak on the early life stages of the marine mussel Perna perna (Linneaus, 1758) and metal bioavailability النص الكامل
2017
Szalaj, D. | De Orte, M. R. | Goulding, T. A. | Medeiros, I. D. | DelValls, T. A. | César, A.
The study assesses the effects of carbon dioxide capture and storage (CCS) leaks and ocean acidification (OA) on the metal bioavailability and reproduction of the mytilid Perna perna. In laboratory-scale experiments, CCS leakage scenarios (pH 7.0, 6.5, 6.0) and one OA (pH 7.6) scenario were tested using metal-contaminated sediment elutriates and seawater from Santos Bay. The OA treatment did not have an effect on fertilisation, while significant effects were observed in larval-development bioassays where only 16 to 27 % of larva developed normally. In treatments that simulated CO₂ leaks, when compared with control, fertilisation success gradually decreased and no larva developed to the D-shaped stage. A fall in pH increased the bioavailability of metals to marine mussels. Larva shell size was significantly affected by both elutriates when compared with seawater; moreover, a significant difference occurred at pH 6.5 between elutriates in the fertilisation bioassay.
اظهر المزيد [+] اقل [-]The effect of anthropogenic pressure shown by microbiological and chemical water quality indicators on the main rivers of Podhale, southern Poland النص الكامل
2017
Lenart-Boroń, Anna | Wolanin, Anna | Jelonkiewicz, Ewelina | Żelazny, Mirosław
This study was aimed to determine the spatial variation in anthropogenic pressure exerted on surface water in the Podhale region (southern Poland), which is one of the most popular tourist destinations in Poland. The assessment was based on the dynamics and relationships between microbiological and chemical indicators of water quality throughout the major rivers of this region—Dunajec, Czarny Dunajec, Biały Dunajec, and Białka. Another aim was to assess the effect of land use on the quality of water in the studied rivers. The study was conducted over 1 year at 21 sampling sites distributed from the uppermost sections of rivers in the Tatra National Park through main tourist resorts until mouths of the considered rivers to the Czorsztyńskie Lake. Microbiological analysis comprised the prevalence of total and fecal types of coliforms and Escherichia coli, mesophilic, and psychrophilic bacteria. Chemical assays determined the concentrations of Na⁺, K⁺, NH₄ ⁺, Cl⁻, NO₃ ⁻, and PO₄ ³⁻. Temperature, electrical conductivity, and pH were measured onsite. It was demonstrated that there is a significant relationship between the predominant types of land use within individual catchments, which results in evident differences in the pollution of waters between the catchments. The results showed that increased share of built-up areas and arable land results in significant deterioration of water quality. Thus, waters of Czarny Dunajec were the cleanest, while Biały Dunajec was the most heavily contaminated. Also, spatial diversity in water quality was shown—the cleanest waters were sampled in the Tatra National Park and the pollution increased with the course of rivers. Point sources of pollution such as effluents from treatment plants or discharge of untreated sewage from households proved to be more important than non-point sources, such as surface runoff. Moreover, the important role of the Czorsztyńskie Lake in the purification of water was demonstrated.
اظهر المزيد [+] اقل [-]Wood-derived-biochar combined with compost or iron grit for in situ stabilization of Cd, Pb, and Zn in a contaminated soil النص الكامل
2017
Oustriere, Nadège | Marchand, Lilian | Rosette, Gabriel | Friesl-Hanl, Wolfgang | Mench, Michel
In situ stabilization of Cd, Pb, and Zn in an Austrian agricultural soil contaminated by atmospheric depositions from a smelter plant was assessed with a pine bark chip-derived biochar, alone and in combination with either compost or iron grit. Biochar amendment was also trialed in an uncontaminated soil to detect any detrimental effect. The pot experiment consisted in ten soil treatments (% w/w): untreated contaminated soil (Unt); Unt soil amended with biochar alone (1%: B1; 2.5%: B2.5) and in combination: B1 and B2.5 + 5% compost (B1C and B2.5C), B1 and B2.5 + 1% iron grit (B1Z and B2.5Z); uncontaminated soil (Ctrl); Ctrl soil amended with 1 or 2.5% biochar (CtrlB1, CtrlB2.5). After a 3-month reaction period, the soil pore water (SPW) was sampled in potted soils and dwarf beans were grown for a 2-week period. The SPW Cd, Pb, and Zn concentrations decreased in all amended-contaminated soils. The biochar effects increased with its addition rate and its combination with either compost or iron grit. Shoot Cd and Zn removals by beans were reduced and shoot Cd, Pb, and Zn concentrations decreased to common values in all amended soils except the B1 soil. Decreases in the SPW Cd/Pb/Zn concentrations did not improve the root and shoot yields of plants as compared to the Ctrl soil.
اظهر المزيد [+] اقل [-]A comparative study of inorganic elements in the blood of male and female Caspian pond turtles (Mauremys caspica) from the southern basin of the Caspian Sea النص الكامل
2017
Adel, Milad | Cortés-Gómez, Adriana A. | Dadar, Maryam | Riyahi, Hossein | Girondot, Marc
Due to their bioaccumulation and biomagnification pathways, inorganic elements can accumulate in high-level aquatic organisms in the food web. Then, this species can be used to monitor the quality of the environment. Blood concentration of nine inorganic elements, including possible toxic metals (An, Cu, Mn, Se, As, Ni, Cd, Pb, and Hg), in 20 males and 20 females from eight different locations with high industry and agriculture activities in Iran were evaluated in this work. Additionally, size, sex, condition index, and locations were also included and analyzed. Among the essential elements, Zn and Se presented very high concentrations (56.14 ± 2.66 and 8.44 ± 0.77 μg/g ww, respectively) in all locations. Regarding possible toxic elements, Pb and Cd presented concerning concentrations as well (0.52 and 0.58 μg/g ww); this is especially true for Pb, an element found in very high concentrations in tissues of turtles from the same area in a previous study. The sex and the size of the individuals also had significant differences in concentration of Pb, Cd, As, and Hg.
اظهر المزيد [+] اقل [-]Spatial distribution of triazine residues in a shallow alluvial aquifer linked to groundwater residence time النص الكامل
2017
Sassine, Lara | Le Gal La Salle, Corinne | Khaska, Mahmoud | Verdoux, Patrick | Meffre, Patrick | Benfodda, Zohra | Roig, Benoit
At present, some triazine herbicides occurrence in European groundwater, 13 years after their use ban in the European Union, remains of great concern and raises the question of their persistence in groundwater systems due to several factors such as storage and remobilization from soil and unsaturated zone, limited or absence of degradation, sorption in saturated zones, or to continuing illegal applications. In order to address this problem and to determine triazine distribution in the saturated zone, their occurrence is investigated in the light of the aquifer hydrodynamic on the basis of a geochemical approach using groundwater dating tracers (³H/³He). In this study, atrazine, simazine, terbuthylazine, deethylatrazine, deisopropylatrazine, and deethylterbuthylazine are measured in 66 samples collected between 2011 and 2013 from 21 sampling points, on the Vistrenque shallow alluvial aquifer (southern France), covered by a major agricultural land use. The frequencies of quantification range from 100 to 56 % for simazine and atrazine, respectively (LQ = 1 ng L⁻¹). Total triazine concentrations vary between 15 and 350 ng L⁻¹ and show three different patterns with depth below the water table: (1) low concentrations independent of depth but related to water origin, (2) an increase in concentrations with depth in the aquifer related to groundwater residence time and triazine use prior to their ban, and (3) relatively high concentrations at low depths in the saturated zone more likely related to a slow desorption of these compounds from the soil and unsaturated zone. The triazine attenuation rate varies between 0.3 for waters influenced by surface water infiltration and 4.8 for water showing longer residence times in the aquifer, suggesting an increase in these rates with water residence time in the saturated zone. Increasing triazine concentrations with depth is consistent with a significant decrease in the use of these pesticides for the last 10 years on this area and highlights the efficiency of their ban.
اظهر المزيد [+] اقل [-]Integrated modeling of agricultural scenarios (IMAS) to support pesticide action plans: the case of the Coulonge drinking water catchment area (SW France) النص الكامل
2017
Vernier, Françoise | Leccia-Phelpin, Odile | Lescot, Jean-Marie | Minette, Sébastien | Miralles, André | Barberis, Delphine | Scordia, Charlotte | Kuentz-Simonet, Vanessa | Tonneau, Jean-Philippe
Non-point source pollution is a cause of major concern within the European Union. This is reflected in increasing public and political focus on a more sustainable use of pesticides, as well as a reduction in diffuse pollution. Climate change will likely to lead to an even more intensive use of pesticides in the future, affecting agriculture in many ways. At the same time, the Water Framework Directive (WFD) and associated EU policies called for a “good” ecological and chemical status to be achieved for water bodies by the end of 2015, currently delayed to 2021–2027 due to a lack of efficiency in policies and timescale of resilience for hydrosystems, especially groundwater systems. Water managers need appropriate and user-friendly tools to design agro-environmental policies. These tools should help them to evaluate the potential impacts of mitigation measures on water resources, more clearly define protected areas, and more efficiently distribute financial incentives to farmers who agree to implement alternative practices. At present, a number of reports point out that water managers do not use appropriate information from monitoring or models to make decisions and set environmental action plans. In this paper, we propose an integrated and collaborative approach to analyzing changes in land use, farming systems, and practices and to assess their effects on agricultural pressure and pesticide transfers to waters. The integrated modeling of agricultural scenario (IMAS) framework draws on a range of data and expert knowledge available within areas where a pesticide action plan can be defined to restore the water quality, French “Grenelle law” catchment areas, French Water Development and Management Plan areas, etc. A so-called “reference scenario” represents the actual soil occupation and pesticide-spraying practices used in both conventional and organic farming. A number of alternative scenarios are then defined in cooperation with stakeholders, including socio-economic conditions for developing alternative agricultural systems or targeting mitigation measures. Our integrated assessment of these scenarios combines the calculation of spatialized environmental indicators with integrated bio-economic modeling. The latter is achieved by a combined use of Soil and Water Assessment Tool (SWAT) modeling with our own purpose-built land use generator module (Generator of Land Use version 2 (GenLU2)) and an economic model developed using General Algebraic Modeling System (GAMS) for cost-effectiveness assessment. This integrated approach is applied to two embedded catchment areas (total area of 360,000 ha) within the Charente river basin (SW France). Our results show that it is possible to differentiate scenarios based on their effectiveness, represented by either evolution of pressure (agro-environmental indicators) or transport into waters (pesticide concentrations). By analyzing the implementation costs borne by farmers, it is possible to identify the most cost-effective scenarios at sub-basin and other aggregated levels (WFD hydrological entities, sensitive areas). Relevant results and indicators are fed into a specifically designed database. Data warehousing is used to provide analyses and outputs at all thematic, temporal, or spatial aggregated levels, defined by the stakeholders (type of crops, herbicides, WFD areas, years), using Spatial On-Line Analytical Processing (SOLAP) tools. The aim of this approach is to allow public policy makers to make more informed and reasoned decisions when managing sensitive areas and/or implementing mitigation measures.
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