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Результаты 2201-2210 из 3,208
Effects of hydrodynamic conditions on the sorption behaviors of aniline on sediment with coexistence of nitrobenzene Полный текст
2015
Wang, Peng | Hua, Zulin | Cai, Yunjie | Shen, Xia | Li, Qiongqiong | Liu, Xiaoyuan
The sorption behaviors of pollutants affected by hydrodynamic conditions were confirmed in natural water environment. The effects of hydrodynamic conditions on the sorption behaviors of aniline on sediment with coexistence of nitrobenzene were investigated. The particle entrainment simulator (PES) was used to simulate varied bottom shear stresses. The batch equilibrium method was applied to the experiments with the stress levels and the action time controlled at 0.2–0.5 N/m² and 24 h, respectively. The findings indicated that apparent partition coefficient of aniline on sediment increased with the shear stress significantly, while decreased with nitrobenzene concentration. On the contrary, both the sorption amount of aniline on suspended particulate matter (Q ₛ) and the effect of nitrobenzene concentration on Q ₛ declined as the shear stress increased. The sorption kinetic results showed that the sorption process followed the pseudo-second-order kinetics equation, and the process included two stages: fast sorption stage and slow sorption stage, among which the average sorption rate of fast stage was 7.5–9.5 times that of slow one. The effect of shear stress on the average sorption rate of aniline was enhanced with the increase of nitrobenzene concentration. And shear stress weakened the disturbance of cosolute on main solute sorption process. In addition, experiment results of sorption kinetic show that only the initial sorption rate was affected by shear stress and cosolute concentration. In the first 5 min, shear stress had positive effects on the sorption rate. After that, the sorption rate barely changed with shear stress and cosolute concentration.
Показать больше [+] Меньше [-]Phytoextraction of metals by Erigeron canadensis L. from fly ash landfill of power plant “Kolubara” Полный текст
2015
Krgović, Rada | Trifković, Jelena | Milojković-Opsenica, Dušanka | Manojlović, Dragan | Kokanović, Marijana | Mutić, Jelena
The objectives of this study were to determine the concentrations of Pb, Cd, As, Cr, Cu, Co, Ni, Zn, Ba, Fe, Al and Ag in Erigeron canadensis L. growing on fly ash landfill of power plant “Kolubara”, Serbia. The content of each element was determined in every part of plant separately (root, stalk and inflorescence) and correlated with the content of elements in each phase of sequential extraction of fly ash. In order to ambiguously select the factors that are able to decidedly characterize the particular part of plant, principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) were performed. The bioconcentration factors and translocation factors for each metal were calculated in order to determine the feasibility of the use of plant E. canadensis L. for phytoremediation purpose. There were strong positive correlations between metals in every part of plant samples, and metals from pseudo total form of sequential extraction indicate that the bioavailability of elements in fly ash is similarly correlated with total form. Retained Al, Fe, Cr and Co in the root indicate its suitability for phytostabilization. This plant takes up Cd and Zn from the soil (bioconcentration factors (BCFs) greater than 1), transporting them through the stalk into the inflorescence (translocation factors (TFs) higher than 1). Regarding its dominance in vegetation cover and abundance, E. canadensis L. can be considered adequate for phytoextraction of Cd and Zn from coal ash landfills at Kolubara.
Показать больше [+] Меньше [-]Possibility of biological control of primocane fruiting raspberry disease caused by Fusarium sambucinum Полный текст
2015
Shternshis, Margarita V. | Belyaev, Anatoly A. | Matchenko, Nina S. | Shpatova, Tatyana V. | Lelyak, Anastasya A.
Biological control agents are a promising alternative to chemical pesticides for plant disease suppression. The main advantage of the natural biocontrol agents, such as antagonistic bacteria compared with chemicals, includes environmental pollution prevention and a decrease of chemical residues in fruits. This study is aimed to evaluate the impact of three Bacillus strains on disease of primocane fruiting raspberry canes caused by Fusarium sambucinum under controlled infection load and uncontrolled environmental factors. Bacillus subtilis, Bacillus licheniformis, and Bacillus amyloliquefaciens were used for biocontrol of plant disease in 2013 and 2014 which differed by environmental conditions. The test suspensions were 10⁵ CFU/ml for each bacterial strain. To estimate the effect of biological agents on Fusarium disease, canes were cut at the end of vegetation, and the area of outer and internal lesions was measured. In addition to antagonistic effect, the strains revealed the ability to induce plant resistance comparable with chitosan-based formulation. Under variable ways of cane treatment by bacterial strains, the more effective were B. subtilis and B. licheniformis demonstrating dual biocontrol effect. However, environmental factors were shown to impact the strain biocontrol ability; changes in air temperature and humidity led to the enhanced activity of B. amyloliquefaciens. For the first time, the possibility of replacing chemicals with environmentally benign biological agents for ecologically safe control of the raspberry primocane fruiting disease was shown.
Показать больше [+] Меньше [-]Influence of Rhizophagus irregularis inoculation and phosphorus application on growth and arsenic accumulation in maize (Zea mays L.) cultivated on an arsenic-contaminated soil Полный текст
2015
Cattani, I. | Beone, G. M. | Gonnelli, C.
Southern Tuscany (Italy) is characterized by extensive arsenic (As) anomalies, with concentrations of up to 2000 mg kg soil⁻¹. Samples from the location of Scarlino, containing about 200 mg kg⁻¹of As, were used to study the influence of the inoculation of an arbuscular mycorrhizal (AM) fungus (Rhizophagus irregularis, previously known as Glomus intraradices) and of phosphorus (P) application, separately and in combination, on As speciation in the rhizosphere of Zea mays on plant growth and As accumulation. Also, P distribution in plant parts was investigated. Each treatment produced a moderate rise of As(III) in the rhizosphere, increased As(III) and lowered As(V) concentration in shoots. P treatment, alone or in combination with AM, augmented the plant biomass. The treatments did not affect total As concentration in the shoots (with all the values <1 mg kg⁻¹dry weight), while in the roots it was lowered by P treatment alone. Such decrease was probably a consequence of the competition between P and As(V) for the same transport systems, interestingly nullified by the combination with AM treatment. P concentration was higher with AM only in both shoots and roots. Therefore, the obtained results can be extremely encouraging for maize cultivation on a marginal land, like the one studied.
Показать больше [+] Меньше [-]Empirical approach to predict leached nutrients from landfill site Полный текст
2015
Barman, Pranab Jyoti | Kartha, Suresh A. | Pradhan, Bulu
An empirical approach is made in this investigation to predict the leached concentrations of sodium (Na), calcium (Ca), and potassium (K) in the effluents from a landfill site. Water at certain predetermined inflow filling rate is applied to a specific ponding depth, at the top of an experimental column filled with landfill refuse soil at the top (upper layer) and normal local soil at the bottom (base layer). The water infiltrates into the upper layer soil, percolates through the pores in upper and base layers, and in the process leaches the nutrients from the soils that are collected at the bottom of the column. The experimentations were for different combinations of heights of upper and base layer soils, water ponding depth, and inflow filling rates. The nutrient concentrations in the outflow leachates are measured using flame photometer. The observations showed mixed responses of leaching and trapping of nutrients in the soil layers for the various combinations. The experimental observations also inferred that the nutrient leaching is more for cases involving higher ponding depths and higher inflow filling rates. Empirical relationships with respect to the geometrical parameters, to predict the leached concentrations of Na, Ca, and K, are developed from the experimental observations using nonlinear least squares regressive techniques. Exponential equations gave the best empirical fit among various nonlinear relations in the regression technique. The empirical models also predicted well for each subcategory of independent variables that are substantiated by high correlation coefficients.
Показать больше [+] Меньше [-]Evaluation of some selected herbs on arsenic-affected cattle in Nadia District, West Bengal, India Полный текст
2015
Hazarika, Jantu M. | Sarkar, Prasanta K. | Chattopadhyay, Abichal | Mandal, Tapan K. | Sarkar, Samar
Arsenic poisoning due to contaminated subsoil water is one of the most alarming environment hazards in West Bengal, India. Cattle are also affected by arsenic due to ingestion of arsenic contaminated water, paddy straw, crops and vegetables. Thirty milch cattle having arsenic content in the range of 3.5 to 4.5 mg/kg in hair were chosen for this experiment from cattle of five respective villages in Nadia District, West Bengal, India. The cattle were divided into three groups containing 10 animals each. Group I cattle were treated with turmeric powder (Curcuma longa) 20 g/day orally for 60 days. Group II cattle were treated with turmeric powder (10 g/day) and Amaranthus spinosus powder (10 g/day) orally for 60 days. Group III cattle were treated with turmeric powder (10 g/day) and Eclipta alba powder (10 g/day) orally for 60 days. Ten apparently healthy milch cows with no history of exposure to arsenic were selected and kept as control group (group IV). Arsenic content in hair, faeces, urine and milk; different biochemical and haematological parameters and DNA fragmentation percentage assay were carried out before commencement of the treatment, after 30 days and after 60 days of treatment. The test drugs were found significantly (p < 0.05) effective to eliminate arsenic from the body and lead to significant improvement in different biochemistry, pathology and DNA fragmentation assay. These drugs also give protection from possible damage caused by arsenic exposure.
Показать больше [+] Меньше [-]Comparison of the MBBR denitrification carriers for advanced nitrogen removal of wastewater treatment plant effluent Полный текст
2015
Yuan, Quan | Wang, Haiyan | Hang, Qianyu | Deng, Yangfan | Liu, Kai | Li, Chunmei | Zheng, Shengzhi
The moving bed biofilm reactors (MBBRs) were used to remove the residual NO₃ ⁻-N of wastewater treatment plant (WWTP) effluent, and the MBBR carriers for denitrification were compared. The results showed that high denitrification efficiency can be achieved with polyethylene, polypropylene, polyurethane foam, and haydite carriers under following conditions: 7.2 to 8.0 pH, 24 to 26 °C temperature, 12 h hydraulic retention time (HRT), and 25.5 mg L⁻¹ external methanol dosage, while the WWTP effluent total nitrogen (TN) was between 2.6 and 15.4 mg L⁻¹ and NO₃ ⁻-N was between 0.2 and 12.6 mg L⁻¹. The MBBR filled with polyethylene carriers had higher TN and NO₃ ⁻-N removal rate (44.9 ± 19.1 and 83.4 ± 13.0 %, respectively) than those with other carriers. The minimum effluent TN and NO₃ ⁻-N of polyethylene MBBR were 1.6 and 0.1 mg L⁻¹, respectively, and the maximum denitrification rate reached 23.0 g m⁻² day⁻¹. When chemical oxygen demand (COD)/TN ratio dropped from 6 to 4, the NO₃ ⁻- N and TN removal efficiency decreased significantly in all reactors except for that filled with polyethylene, which indicated that the polyethylene MBBR can resist influent fluctuation much better. The three-dimensional excitation–emission matrix analysis showed that all the influent and effluent of MBBRs contain soluble microbial products (SMPs)-like organics and biochemical oxygen demand (BOD), which can be removed better by MBBRs filled with haydite and polyethylene carriers. The nitrous oxide reductase (nosZ)-based terminal restriction fragment length polymorphism (T-RFLP) analysis suggested that the dominant bacteria in polyethylene MBBR are the key denitrificans.
Показать больше [+] Меньше [-]Evolution of dissolved organic matter during abiotic oxidation of coal tar—comparison with contaminated soils under natural attenuation Полный текст
2015
Hanser, Ogier | Biache, Coralie | Boulangé, Marine | Parant, Stéphane | Lorgeoux, Catherine | Billet, David | Michels, Raymond | Faure, Pierre
In former coal transformation plants (coking and gas ones), the major organic contamination of soils is coal tar, mainly composed of polycyclic aromatic compounds (PACs). Air oxidation of a fresh coal tar was chosen to simulate the abiotic natural attenuation impact on PAC-contaminated soils. Water-leaching experiments were subsequently performed on fresh and oxidized coal tars to study the influence of oxidation on dissolved organic matter (DOM) quality and quantity. The characterization of the DOM was performed using a combination of molecular and spectroscopic techniques (high-performance liquid chromatography–size-exclusion chromatography (HPLC-SEC), 3D fluorescence, and gas chromatography coupled with mass spectrometry (GC–MS)) and compared with the DOM from contaminated soils sampled on the field exposed to natural attenuation for several decades. An increase in the oxygenated polycyclic aromatic compound concentrations was observed with abiotic oxidation both in the coal tar and the associated DOM. Polycyclic aromatic hydrocarbon concentrations in the leachates exceeded pure water solubility limits, suggesting that co-solvation with other soluble organic compounds occurred. Furthermore, emission excitation matrix analysis combined with synchronous fluorescence spectra interpretation and size-exclusion chromatography suggests that oxidation induced condensation reactions which were responsible for the formation of higher-molecular weight compounds and potentially mobilized by water. Thus, the current composition of the DOM in aged soils may at least partly result from (1) a depletion in lower-molecular weight compounds of the initial contamination stock and (2) an oxidative condensation leading to the formation of a higher-molecular weight fraction. Abiotic oxidation and water leaching may therefore be a significant combination contributing to the evolution of coal tar-contaminated soils under natural attenuation.
Показать больше [+] Меньше [-]Olive mill waste biochar: a promising soil amendment for metal immobilization in contaminated soils Полный текст
2015
Hmid, Amine | Al Chami, Ziad | Sillen, Wouter | De Vocht, Alain | Vangronsveld, Jaco
The potential use of biochar from olive mill waste for in situ remediation of metal contaminated soils was evaluated. Biochar was mixed with metal contaminated soil originating from the vicinity of an old zinc smelter. Soil–biochar mixtures were equilibrated for 30 and 90 days. At these time points, Ca(NO₃)₂exchangeable metals were determined, and effects of the biochar amendment on soil toxicity were investigated using plants, bacteria, and earthworms. Bean (Phaseolus vulgaris) growth, metal content, antioxidative enzymes activities, and soluble protein contents were determined. Furthermore, effects on soil microbial communities (activity, diversity, richness) were examined using Biolog ECOplates. After 120 days of soil–biochar equilibration, effects on weight and reproduction of Eisenia foetida were evaluated. With increasing biochar application rate and equilibration period, Ca(NO₃)₂exchangeable metals decreased, and growth of bean plants improved; leaf metal contents reduced, the activities of antioxidative stress enzymes decreased, and soluble protein contents increased. Soil microbial activity, richness, and diversity were augmented. Earthworm mortality lowered, and their growth and reproduction showed increasing trends.
Показать больше [+] Меньше [-]Detecting genomic damages in the frog Dendropsophus minutus: preserved versus perturbed areas Полный текст
2015
Gonçalves, M. W. | Vieira, T. B. | Maciel, N. M. | Carvalho, W. F. | Lima, L. S. F. | Gambale, P. G. | da Cruz, A. D. | Nomura, F. | Bastos, R. P. | Silva, D. M.
The aim of the study was to use the comet assay (single-cell gel electrophoresis) and micronucleus test to assess the extent of genomic damage in the whole blood of Dendropsophus minutus from agroecosystems with great use of agrochemicals and to compare the results to those obtained from animals living in unpolluted areas. Our results indicated that specimens of D. minutus collected in perturbed areas exhibited higher amounts of DNA damage in blood cells in comparison to animals from areas free of agricultural activities. The average and standard deviation of all comet assay parameters (tail length, percentage of DNA in the tail, and olive tail moment) and micronuclei frequency were significantly higher in specimens collected in perturbed areas than in the animals from preserved areas. Our study showed that animals from perturbed areas, such as agroecosystems, tend to have higher amounts of DNA damage than animals from reference areas. Moreover, we can conclude that D. minutus tadpoles could be included as a model organism in biomonitoring studies.
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