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Resultados 1871-1880 de 2,503
Optimization of struvite fertilizer formation from baker’s yeast wastewater: growth and nutrition of maize and tomato plants
2014
Uysal, Ayla | Demir, Sinan | Sayilgan, Emine | Eraslan, Figen | Kucukyumuk, Zeliha
Struvite precipitate obtained from yeast industry anaerobic effluent with high ammonium nitrogen (NH₄–N) was investigated for fertilizer effect on plant growth and nutrition according to applications of N, nitrogen/phosphorus/potassium (NPK), and control. Optimum struvite formation conditions were determined via Box–Behnken design. Optimum condition was obtained at pH 9.0 and Mg/N/P molar ratio of 1.5:1:1. Under these conditions, heavy metal concentrations in the obtained struvite precipitate (except Cu) were below the detection limits. In addition to high N, P, and Mg content, energy-dispersive X-ray (EDX) analysis showed that the struvite also included the nutritional elements Ca, K, Na, and Fe. X-ray diffraction (XRD) analysis revealed the complex structures of NaAl(SO₄)₂(H₂O)₁₂, NaMn²⁺Fe₂(PO₄)₃, and (Na₂,Ca)O₂(Fe,Mn)O.P₂O₅in the precipitate. High Na⁺and Ca²⁺concentrations in the anaerobic effluent reacted with phosphate during struvite precipitation. Different applications and struvite dosages significantly affected fresh and dry weights and nutrient element uptakes by plants (P < 0.05). N, P, and Mg uptakes of plants were significantly higher at struvite ×2, ×3, and ×4 dosages compared with NPK application. For adequate nutrition and supply of optimum dry weight, struvite ×2 dosage (5.71 g struvite/kg soil) was found appropriate for both maize and tomato plants.
Mostrar más [+] Menos [-]Ant cuticular response to phthalate pollution
2014
Lenoir, Alain | Touchard, Axel | Devers, Séverine | Christidès, Jean-Philippe | Boulay, Raphaël | Cuvillier-Hot, Virginie
Phthalates are common atmospheric contaminants used in the plastic industry. Ants have been shown to constitute good bioindicators of phthalate pollution. Hence, phthalates remain trapped on ant cuticles which are mostly coated with long-chain hydrocarbons. In this study, we artificially contaminated Lasius niger ants with four phthalates: dibutyl phthalate (DBP), diisobutyl phthalate (DiBP), di(2-ethylhexyl) phthalate (DEHP), and benzyl butyl phthalate (BBP). The first three have previously been found on ants in nature in Touraine (France), while the fourth has not. The four phthalates disappeared rapidly (less than 5 days) from the cuticles of live ants. In contrast, on the cuticles of dead ants, DEHP quantities remained unchanged over time. These results indicate that phthalates are actively absorbed by the cuticles of live ants. Cuticular absorption of phthalates is nonspecific because eicosane, a nonnatural hydrocarbon on L. niger cuticle, was similarly absorbed. Ants are important ecological engineers and may serve as bioindicators of ecosystem health. We also suggest that ants and more generally terrestrial arthropods may contribute to the removal of phthalates from the local environment.
Mostrar más [+] Menos [-]A short-term study to evaluate the uptake and accumulation of arsenic in Asian willow (Salix sp.) from arsenic-contaminated water
2014
Chen, Guangcai | Zou, Xiaoli | Zhou, Yuan | Zhang, Jianfeng | Owens, Gary
Five Asian willow species (Salix jiangsuensis J172, Salix matsudana, Salix integra Yizhibi, Salix integra Weishanhu, and Salix mongolica) were evaluated for their potential for phytofiltration of arsenic (As) from synthetically contaminated waters. Arsenic accumulation, tolerance, uptake influx, and phytofiltration ability of the five willow species were examined under hydroponic conditions in a glasshouse. Short-term exposure (2 weeks) to solutions containing 80 μmol L⁻¹arsenate (As(V)), resulted in significant accumulation of As in all willow species. Arsenic concentration in plant roots ranged from 322 mg kg⁻¹dry weight (DW) for S. matsudana to 604 mg kg⁻¹(DW) for S. integra Yizhibi. S. integra Yizhibi decreased As(V) concentration in water from 3.87 to 1.89 μmol L⁻¹(290 to 142 μg L⁻¹) over 168 h, which is 50 % of the total As(V) in the solution. The results suggested that even though Asian willow was not a traditional aquatic species, it still had significant potential for phytofiltration of As from contaminated waters. Of the five willow species studied, S. integra Yizhibi had the greatest capacity to remove As from As-contaminated waters. Thus, Asian willow has significant potential for the phytofiltration of As and may also be suitable for practical phytoremediation of As in highly water-logged areas.
Mostrar más [+] Menos [-]Spatiotemporal distribution of water environmental capacity—a case study on the western areas of Taihu Lake in Jiangsu Province, China
2014
Xie, Rongrong | Pang, Yong | Bao, Kun
Currently, the poor water quality in Taihu Lake is a major problem in China, so pollution control in the upstream areas has become a government priority. In Jiangsu Province, pollution emissions around the western areas of Taihu Lake, including Changzhou Municipality and Yixing City, need to be highly restricted, and calculating the water environmental capacity is important if pollution is to be reduced. In this study, 19 control units in these areas were established, and a 0-D mathematical model was used to calculate the water environmental capacity. For three important control units with important cross sections, a 1-D model was established to redress the results. Finally, the total maximum monthly loads of each control unit were obtained using temporal allocation principles. The results suggested that (1) the total pollution control of chemical oxygen demand was 58,894.2 tonnes per annum (t a⁻¹), with ammonia nitrogen, total nitrogen, and total phosphorus amounting to 3,808, 6,054.6, and 386.6 t a⁻¹, respectively; (2) water environmental capacity per unit water area in the ambient control units was smaller than that in the middle control units; and (3) the largest water environmental capacity was in June, and the smallest capacity was in December. The study provides important information for local governments, which will enable them to implement pollution control strategies that will improve the water quality in Taihu Lake.
Mostrar más [+] Menos [-]Behaviours of psychotropic substances in indoor and outdoor environments of Rome, Italy
2014
Cecinato, Angelo | Balducci, Catia | Romagnoli, Paola | Perilli, Mattia
The intensive campaign conducted in March 2013 in Rome, Italy, at one coffee bar, one primary school and two homes revealed that in indoor environments, drugs can reach concentration levels exceeding orders of magnitude those recorded outdoors, even when the same substances are not consumed there. At homes, the gross average of cocaine reached 0.13 ng/m³indoors and 0.09 ng/m³outdoors (ratio ~ 1.6); Δ⁹-tetrahydrocannabinol was 6.6 ng/m³indoors and 1.1 ng/m³outdoors (ratio ~ 7); cannabidiol reached 0.30 and 0.07 ng/m³, respectively (ratio ~ 6); and cannabinol 2.3 ng/m³indoors and 0.7 ng/m³outdoors (ratio ~ 3). At the coffee bar, the average drug burdens were even higher, namely 0.33, 4.7, 14.3 and 2.5 ng/m³, respectively, for cocaine, cannabidiol, tetrahydrocannabinol and cannabinol. The school presented a special behaviour: the indoor/outdoor concentration ratios of cocaine, cannabidiol, tetrahydrocannabinol and cannabinol accounting for ~1.5, ~0, ~4 and ~0.5, in the order. Cocaine was more abundant on weekdays at all sites except one home indoors, whilst total cannabinoids prevailed on weekends at the other home and the school. Using the regional network stations as reference, all indoor locations except one were more contaminated by cocaine by a factor ≥1.5, whilst cannabinoids were, aside from the school, up to 100 times higher.
Mostrar más [+] Menos [-]A new method for modelling roofing materials emissions on the city scale: Application for zinc in the City of Créteil (France)
2014
Sellami-Kaaniche, Emna | Gouvello, Bernard de | Gromaire, Marie-Christine | Chebbo, G. (Ghassan)
Today, urban runoff is considered as an important source of environmental pollution. Roofing materials, in particular, the metallic ones, are considered as a major source of urban runoff metal contaminations. In the context of the European Water Directive (2000/60 CE), an accurate evaluation of contaminant flows from roofs is thus required on the city scale, and therefore the development of assessment tools is needed. However, on this scale, there is an important diversity of roofing materials. In addition, given the size of a city, a complete census of the materials of the different roofing elements represents a difficult task. Information relating roofing materials and their surfaces on an urban district do not currently exist in urban databases. The objective of this paper is to develop a new method of evaluating annual contaminant flow emissions from the different roofing material elements (e.g., gutter, rooftop) on the city scale. This method is based on using and adapting existing urban databases combined with a statistical approach. Different rules for identifying the materials of the different roofing elements on the city scale have been defined. The methodology is explained through its application to the evaluation of zinc emissions on the scale of the city of Créteil.
Mostrar más [+] Menos [-]Spatial and temporal distribution of polycyclic aromatic hydrocarbons (PAHs) in surface water from Liaohe River Basin, northeast China
2014
Lv, Jiapei | Xu, Jian | Guo, Changsheng | Zhang, Yuan | Bai, Yangwei | Meng, Wei
Liaohe River Basin is an important region in northeast China, which consists of several main rivers including Liao River, Taizi river, Daliao River, and Hun River. As a highly industrialized region, the basin receives dense waste discharges, causing severe environmental problems. In this study, the spatial and temporal distribution of aqueous polycyclic aromatic hydrocarbons (PAHs) in Liaohe River Basin from 50 sampling sites in both dry (May) and level (October) periods in 2012 was investigated. Sixteen USEPA priority PAHs were quantified by gas chromatography/mass selective detector. The total PAH concentration ranged from 111.8 to 2,931.6 ng/L in the dry period and from 94.8 to 2766.0 ng/L in the level period, respectively. As for the spatial distribution, the mean concentration of PAHs followed the order of Taizi River > Daliao River > Hun River > Liao River, showing higher concentrations close to large cities with dense industries. The composition and possible sources of PAHs in the water samples were also determined. The fractions of low molecular weight PAHs ranged from 58.2 to 93.3 %, indicating the influence of low or moderate temperature combustion process. Diagnostic ratios, principal component analysis, and hierarchical cluster analysis were used to study the possible source categories in the study area, and consistent results were obtained from different techniques, that PAHs in water samples mainly originated from complex sources, i.e., both pyrogenic and petrogenic sources. The benzo[a]pyrene equivalents (EBaP) characterizing the ecological risk of PAHs to the aquatic environment suggested that PAHs in Liaohe River Basin had already caused environmental health risks.
Mostrar más [+] Menos [-]Effect of Zn toxicity on root morphology, ultrastructure, and the ability to accumulate Zn in Moso bamboo (Phyllostachys pubescens)
2014
Liu, Dan | Chen, Junren | Mahmood, Qaisar | Li, Song | Wu, Jiasen | Ye, Zhengqian | Peng, Danli | Yan, Wenbo | Lu, Kouping
The effects of zinc (Zn) on seed germination and growth of Moso bamboo (Phyllostachys pubescens) were investigated. Under zinc stress, the seed germination rate did not show significant difference from that of the control. Hydroponics experiments indicated that Moso bamboo had a strong ability to accumulate Zn in the shoot and it reached its maximum value in the shoot at 100 μM Zn. The root Zn concentration ranged from 2,329.29 to 8,642.51 mg kg⁻¹, with the root Zn concentration at 10 μM Zn being 58.23 times that of the control. The root morphology parameters slightly increased at the lower Zn treatments, while growth restriction was evident at higher Zn treatments. Root ultrastructural studies revealed that the cell structure, root tips, and organelles were significantly changed under Zn stress as compared to those of the control. Some abnormalities were evident in the cell walls, vacuoles, mitochondria, plasmalemma, tonoplast, and xylem parenchyma of root cells. While Moso bamboo seems a suitable candidate for phytoremediation, its metal remediation ability should be further explored in future investigations.
Mostrar más [+] Menos [-]Green synthesis of silver nanoparticles by microorganism using organic pollutant: its antimicrobial and catalytic application
2014
Otari, S. V. | Patil, R. M. | Nadaf, N. H. | Ghosh, S. J. | Pawar, S. H.
A novel approach for the green synthesis of silver nanoparticles (AgNPs) from aqueous solution of AgNO₃using culture supernatant of phenol degraded broth is reported in this work. The synthesis was observed within 10 h, and AgNPs showed characteristic surface plasmon resonance around 410 nm. Spherical nanoparticles of size less than 30 nm were observed in transmission electron microscopy. X-ray diffraction pattern corresponding to 111, 200, 220, and 311 revealed the crystalline nature of the as-formed nanoparticles. It was found that the colloidal solution of AgNP suspensions exhibited excellent stability over a wide range of ionic strength, pH, and temperature. The effect of pH and ionic strength indicated that stabilization is due to electrostatic repulsion arising from the negative charge of the conjugate proteins. The AgNPs showed highly potent antimicrobial activity against Gram-positive, Gram-negative, and fungal microorganisms. The as-prepared AgNPs showed excellent catalytic activity in reduction of 4-nitrophenol to 4-aminophenol by NaBH₄. By manufacturing magnetic alginate beads, the reusability of the AgNPs for the catalytic reaction has been demonstrated.
Mostrar más [+] Menos [-]Development and application of a regional-scale atmospheric mercury model based on WRF/Chem: a Mediterranean area investigation
2014
Gencarelli, Christian Natale | De Simone, Francesco | Hedgecock, Ian Michael | Sprovieri, Francesca | Pirrone, Nicola
The emission, transport, deposition and eventual fate of mercury (Hg) in the Mediterranean area has been studied using a modified version of the Weather Research and Forecasting model coupled with Chemistry (WRF/Chem). This model version has been developed specifically with the aim to simulate the atmospheric processes determining atmospheric Hg emissions, concentrations and deposition online at high spatial resolution. For this purpose, the gas phase chemistry of Hg and a parametrised representation of atmospheric Hg aqueous chemistry have been added to the regional acid deposition model version 2 chemical mechanism in WRF/Chem. Anthropogenic mercury emissions from the Arctic Monitoring and Assessment Programme included in the emissions preprocessor, mercury evasion from the sea surface and Hg released from biomass burning have also been included. Dry and wet deposition processes for Hg have been implemented. The model has been tested for the whole of 2009 using measurements of total gaseous mercury from the European Monitoring and Evaluation Programme monitoring network. Speciated measurement data of atmospheric elemental Hg, gaseous oxidised Hg and Hg associated with particulate matter, from a Mediterranean oceanographic campaign (June 2009), has permitted the model’s ability to simulate the atmospheric redox chemistry of Hg to be assessed. The model results highlight the importance of both the boundary conditions employed and the accuracy of the mercury speciation in the emission database. The model has permitted the reevaluation of the deposition to, and the emission from, the Mediterranean Sea. In light of the well-known high concentrations of methylmercury in a number of Mediterranean fish species, this information is important in establishing the mass balance of Hg for the Mediterranean Sea. The model results support the idea that the Mediterranean Sea is a net source of Hg to the atmosphere and suggest that the net flux is ≈30 Mg year⁻¹of elemental Hg.
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