خيارات البحث
النتائج 1961 - 1970 من 4,033
Rhizosphere Phytoremediation with Cyperus rotundus for Diesel-Contaminated Wetlands
2016
Hou, Yunyun | Liu, Xiaoyan | Zhang, Xinying | Hu, Xiaoxin | Cao, Liya
Diesel spills may considerably damage the sensitive coastal wetlands along Huangpu River, Shanghai, China. In this experiment, Cyperus rotundus, a dominant coastal marsh plant, was cultured in diesel-contaminated soils at concentrations of 0, 1000, 5000, 10,000, 15,000 and 20,000 mg kg⁻¹ to investigate its phytoremediation potential. In this study, plant biomass, removal characteristic of diesel, redox potential, and activities of urease, dehydrogenase, and polyphenoloxidase in soils were determined after 50-day pot experiments. The results demonstrated that soils planted with Cyperus rotundus had significantly less diesel than did unplanted soils. The residual concentrations of alkanes in soils at 10,000 mg kg⁻¹ after 50 days showed that 52.9–92.0 % of Fraction a (C₁₄–C₁₉) and 47.8–64.4 % of Fraction b (C₂₀–C₂₇) were removed in unplanted soils, while more than 90 % of both Fractions a and b were removed in planted soils. The peak value of urease and dehydrogenase activities was at 15,000 mg kg⁻¹ of diesel-contaminated concentration; however, the peak value of polyphenoloxidase activity appeared at 10,000 mg kg⁻¹. It was deduced that the diesel concentration between 10,000 and 15,000 mg kg⁻¹ might be a limit which Cyperus rotundus could tolerate diesel pollution.
اظهر المزيد [+] اقل [-]Nitrogen Removal in an Ecological Ditch Based on an Orthogonal Test
2016
Li, Songmin | Wang, Xiaoling | Tu, Jiamin | Qiao, Bin | Li, Jiansheng
Agricultural drainage plays a vital role in the discharge of non-point source pollutants into surface-receiving waters. Sustainable drainage management to mitigate nitrogen losses from cultivated land is needed. Many factors influence nitrogen removal in agricultural drainage ditches. However, existing research has not fully considered parameter sensitivity analysis of nitrogen removal. Therefore, in this study, an ecological ditch model containing a permeable dam was built, in which the influent nitrogen concentration, suspended solid concentration, influent flow, and water level were examined as influencing factors. An orthogonal test was conducted to explore the significance of these four factors and their impacts on nitrogen removal as well as the nitrogen transport characteristics along the ditch. The results revealed that the ditches had an interception effect on nitrogen pollutants, and according to importance, the four factors are influent nitrogen concentration, water level, water flow, and suspended solid concentration in descending order. The plants and permeable dam in the ditch also played an important role in nitrogen removal.
اظهر المزيد [+] اقل [-]The Tree-Ring Method of Estimation of the Effect of Industrial Pollution on Pine (Pinus sylvestris L.) Tree Stands in the Northern Part of the Sandomierz Basin (SE Poland)
2016
Barniak, Joanna | Krąpiec, Marek
In the last 40 years of the twentieth century, as a result of the growth in the exploitation and industrial processing of sulphur, the northern part of the Sandomierz Basin was one of the most polluted areas of Poland. Forests growing in this region, predominantly the Scots pine, offered an opportunity to analyse the degradation of the environment during that period using the dendrochronological method. The study was based on 814 samples, taken from 53 research surfaces belonging to nine linear transects. The investigations demonstrated that the highest reduction in growth occurred during the years 1970–1990. After that period, a considerable improvement in the condition of the pine trees was observed in most of the research plots. The spatial schedule of the trees with reductions reveals a clear relationship with the distance from the emitter i.e. the reductions were significantly lower in more distant sites. A distinct weakening of the trees is also indicated by missing rings, recorded in the years: 1964, 1974, 1978, 1979, 1980, 1985, 1990, and 2002. A definite impact on the condition of the tree stands was also due to the cone of depression around the Jeziórko mine, the post-flotation landfills, as well as pollution on a regional scale.
اظهر المزيد [+] اقل [-]Molasses melanoidin promotes copper uptake for radish sprouts: the potential for an accelerator of phytoextraction
2016
Hatano, Kenʼichi | Kanazawa, Kazuki | Tomura, Hiroki | Yamatsu, Takeshi | Tsunoda, Kin-ichi | Kubota, Kenji
Phytoextraction has been proposed as an alternative remediation technology for heavy metal contamination, and it is well known that chelators may alter the toxicity of heavy metals and the bioavailability in plants. Our previous work demonstrated that an adsorbent-column chromatography can effectively separate melanoidin-like product (MLP) from sugarcane molasses. The aim of this study was to examine the chelating property of MLP and to evaluate the facilitatory influence on the phytoextraction efficiency of Japanese radish. The result showed that MLP binds to all the metal ions examined and the binding capacity of MLP toward Cu²⁺ seems to be the highest among them. The metal detoxification by MLP followed the order of Pb²⁺ > Zn²⁺ > Ni²⁺ > Cu²⁺ > Fe²⁺ > Cd²⁺ > Co²⁺. Furthermore, in the phytoextraction experiment using copper sulfate, the application of MLP accelerated the detoxification of copper and the bioavailability in radish sprouts. Thus, these results suggest that MLP possesses the potential for an accelerator of phytoextraction in the copper-contaminated media.
اظهر المزيد [+] اقل [-]Arsenic and chromium topsoil levels and cancer mortality in Spain
2016
Núñez, Olivier | Fernández-Navarro, Pablo | Martín-Méndez, Iván | Bel-Lan, Alejandro | Locutura, Juan F. | López-Abente, Gonzalo
Spatio-temporal cancer mortality studies in Spain have revealed patterns for some tumours which display a distribution that is similar across the sexes and persists over time. Such characteristics would be common to tumours that shared risk factors, including the chemical soil composition. The objective of the present study is to assess the association between levels of chromium and arsenic in soil and the cancer mortality. This is an ecological cancer mortality study at municipal level, covering 861,440 cancer deaths in 7917 Spanish mainland towns from 1999 to 2008. Chromium and arsenic topsoil levels (partial extraction) were determined by ICP-MS at 13,317 sampling points. To estimate the effect of these concentrations on mortality, we fitted Besag, York and Mollié models, which included, as explanatory variables, each town’s chromium and arsenic soil levels, estimated by kriging. In addition, we also fitted geostatistical-spatial models including sample locations and town centroids (non-aligned data), using the integrated nested Laplace approximation (INLA) and stochastic partial differential equations (SPDE). All results were adjusted for socio-demographic variables and proximity to industrial emissions. The results showed a statistical association in men and women alike, between arsenic soil levels and mortality due to cancers of the stomach, pancreas, lung and brain and non-Hodgkin’s lymphomas (NHL). Among men, an association was observed with cancers of the prostate, buccal cavity and pharynx, oesophagus, colorectal and kidney. Chromium topsoil levels were associated with mortality among women alone, in cancers of the upper gastrointestinal tract, breast and NHL. Our results suggest that chronic exposure arising from low levels of arsenic and chromium in topsoil could be a potential risk factor for developing cancer.
اظهر المزيد [+] اقل [-]Bio-inspired sustainable and green synthesis of plasmonic Ag/AgCl nanoparticles for enhanced degradation of organic compound from aqueous phase
2016
Devi, Th Babita | Ahmaruzzaman, M.
In the current study, we report the utilization of the biogenic potential of Benincasa hispida (ash gourd) peel extract for the synthesis of Ag embedded AgCl nanoparticles nanoparticles (Ag/AgCl NPs) without the use of any external organic solvents. The appearance of dark brown color from the pale yellow color confirmed the formation of Ag/AgCl nanoparticles which was further validated by absorbance peak using UV–visible spectroscopy. The phytochemicals (flavones) present in the B. hispida peel extract acts as a reducing/stabilizing agents. The morphology and size of the synthesized NPs were characterized by transmission electron microscope (TEM), selected area electron microscope (SAED) and high resolution transmission electron microscope (HR-TEM). FT-IR spectra of the B. hispida peel extract and after the development of nanoparticles are determined to identify the functional groups responsible for the conversion of metal ions to metal nanoparticles. The synthesized nanoparticles showed an excellent photocatalytic property in the degradation of toxic dye like malachite green oxalate under sunlight irradiation. For the first time, malachite green oxalate dye was degraded by Ag/AgCl nanoparticles under sunlight irradiation.
اظهر المزيد [+] اقل [-]Biofiltration of Chloroform in a Trickle Bed Air Biofilter Under Acidic Conditions
2016
Palanisamy, Keerthisaranya | Mezgebe, Bineyam | Sorial, George A. | Sahle-Demessie, Endalkachew
In this paper, the application of biofiltration is investigated for controlled removal of gas phase chloroform through cometabolic degradation with ethanol. A trickle bed air biofilter (TBAB) operated under acidic pH 4 is subjected to aerobic biodegradation of chloroform and ethanol. The TBAB is composed of pelleted diatomaceous earth filter media inoculated with filamentous fungi species, which served as the principle biodegrading microorganism. The removal efficiencies of 5 ppmᵥ of chloroform mixed with different ratios of ethanol as cometabolite (25, 50, 100, 150, and 200 ppmᵥ) ranged between 69.9 and 80.9%. The removal efficiency, reaction rate kinetics, and the elimination capacity increased proportionately with an increase in the cometabolite concentration. The carbon recovery from the TBAB amounted to 69.6% of the total carbon input. It is postulated that the remaining carbon contributed to excess biomass yield within the system. Biomass control strategies such as starvation and stagnation were employed at different phases of the experiment. The chloroform removal kinetics provided a maximum reaction rate constant of 0.0018 s⁻¹. The highest ratio of chemical oxygen demand (COD)ᵣₑₘₒᵥₐₗ/nitrogenᵤₜᵢₗᵢzₐₜᵢₒₙ was observed at 14.5. This study provides significant evidence that the biodegradation of a highly chlorinated methane can be favored by cometabolism in a fungi-based TBAB.
اظهر المزيد [+] اقل [-]Physico-chemical and Ecotoxicological Characterization of Slaughterhouse Wastewater Resulting from Green Line Slaughter
2016
Pereira, Erlon Lopes | de Paiva, Teresa Cristina Brazil | da Silva, Flávio Teixeira
The growing production of beef has resulted in the increased volume of liquid residues generated during slaughtering and processing, known as slaughterhouse wastewater. In an attempt to reduce the organic content of this wastewater, blood has been separated from the water, generating slaughterhouse wastewater from green line slaughter and processing (SHWW in natura). The objective of this study was to determine the physical, chemical, and toxicological characteristics of SHWW in natura collected from a bovine slaughterhouse and locker. The results obtained from this characterization showed a high concentration of solids, total volatile acids, alkalinity, macro and micro nutrients, and organic matter (BOD₅ ²⁰°C, COD, and DOC). The effluent presented acute toxicity to the test-organisms P. putida, E. coli, and D. similis, and chronic toxicity to the test-organisms C. silvestri, C. dúbia, E. coli, P putida, and P. subcaptata. Based on the ecotoxicological tests, it was concluded that the compounds of the SHWW in natura were more toxic to microcrustaceans and algae than to bacteria.
اظهر المزيد [+] اقل [-]Toxic Influence of Key Organic Soil Pollutants on the Total Flavonoid Content in Wheat Leaves
2016
Copaciu, Florina | Opriş, Ocsana | Niinemets, Ulo | Copolovici, Lucian
Textile dyes and antibiotics are two main classes of environmental pollutants which could be found in soil and water. Those persistent pollutants can have a negative influence on plant growth and development and affect the level of secondary metabolites. In the present work, we studied the effect of textile dyes and antibiotics on total leaf flavonoid contents in wheat (Triticum aestivum L.). Contaminant solutions were applied daily using concentrations of 0.5 mg L⁻¹ (lower) and 1.5 mg L⁻¹ (higher dose) for either 1 or 2 weeks. We observed that exposure to the higher concentration of textile dyes resulted in a reduction in flavonoid content while antibiotics enhanced flavonoid contents at lower doses of exposure and reduced at higher doses of exposure. These results suggest that diffuse chronic pollution by artificial organic contaminants can importantly alter antioxidative capacity of plants.
اظهر المزيد [+] اقل [-]The Use of Sodium to Calibrate the Transport Modeling of Water Pollution in Sandy Formations Around an Uninsulated Sewage Disposal Site
2016
Szabó, György | Bessenyei, Éva | Hajnal, Andor | Csige, István | Szabó, Gergely | Tóth, Csaba | Posta, József | Mester, Tamás
In the present paper we suggest a novel calibration method of the model for hydrodynamic and contaminant transport using the example of a sewage disposal site set up uninsulated in a sandy environment. With the hydrodynamic model we applied time-dependent model calculations in order to fit the individual hydrodynamic parameters. For the calibration of the transport model, sodium was chosen, which has a negligible retardation factor. We demonstrated that this approach is suitable for creating a model that provides calculated results comparable to the actually measured, experimental ones. The created model proved to be appropriate for use in the estimation of the maximal spatial extension of the contamination, which—in the case of the investigated sewage disposal site—was found to be 0.1 km² in the near-surface (1–3 m deep) layers, whereas it was three times higher at a depth of 40–60 m.
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