خيارات البحث
النتائج 3231 - 3240 من 4,033
Root water transport of Helianthus annuus L. under iron oxide nanoparticle exposure
2016
Martínez-Fernández, Domingo | Barroso, Didac | Komárek, Michael
The application of nanomaterials in commercially available products is increasing rapidly for agriculture, phytoremediation and biotechnology. Since plants suppose the first sink for the accumulation of nanoparticles from the environment, emerging studies have focused on the general consequences for plants and their effects on the biomass production. However, effects on the root surface, as well as blockage of nutrients and water uptake by the roots, may also occur. This experiment was designed to prove if the plant water relations can be affected by the adsorption of nanoparticles on the root surface, causing a consequent stress for the plants. With this goal, plants of Helianthus annuus were previously grown in a hydroponic culture, and at age of 55 days, their roots were exposed to three different concentrations of nanomaghemite (NM) in the hydroponic solution for 5 days: control without NM; 50 and 100 mg l⁻¹ NM. The main effect was related to the reduction of the root hydraulic conductivity (L ₒ) and the nutrients uptake. The concentrations of the macronutrients Ca, K, Mg and S in the shoot were reduced relative to the control plants, which resulted in lower contents of chlorophyll pigments. Although stress was not detected in the plants, after the analysis of stress markers like the accumulation of proline or ascorbate in the tissues, reduction of the root functionality by nanoparticles has been identified here, manifested as the effect of NM on L ₒ . The treatment with 50 mg l⁻¹ NM significantly reduced the L ₒ , by up to 57 % of its control value, and it was reduced by up to 26 % at 100 mg l⁻¹ NM. These results will be an important factor to take into account with regard to the applicability of NM for long-term use in crops, particularly during privative water conditions.
اظهر المزيد [+] اقل [-]Cadmium accumulation characteristics of F1 hybrids by reciprocal hybridizing of Solanum nigrum in two climate–ecology regions
2016
Lin, Lijin | He, Jing | Wang, Xun | Wang, Jin | Lv, Xiulan | Liao, Ming’an | Wang, Zhihui | Tang, Yi | Liang, Dong | Xia, Hui | Lai, Yunsong
Different ecotypes of crop hybridization can produce heterosis effects and have wide applications in plant breeding. In this study, seedlings of cadmium (Cd) hyperaccumulator Solanum nigrum were collected from two different climate–ecology regions of the western Sichuan Basin, China, to carry out reciprocal hybridizing and to study the Cd accumulation characteristics of F1 hybrids of S. nigrum. In the two pot experiments (high and low soil Cd concentration), the biomass and Cd extraction of reciprocal hybridizing F1 hybrids were higher than those of the parents, but the Cd content in different organs was lower than those of the parents. These results indicate that the biomass and Cd extraction of F1 hybrids show over-parent heterosis, and the Cd content shows hybrid weakness. In the field experiment, the variety of the biomass, Cd content, and Cd extraction of reciprocal hybridizing F1 hybrids were the same as the pot experiments, and the Cd extraction by shoots of reciprocal hybridizing F1 hybrids increased by 17.20 and 23.08 %, relative to the two higher parents. Therefore, the reciprocal hybridizing S. nigrum of different climate–ecology regions could be efficiently used to improve the phytoremediation ability of S. nigrum to Cd-contaminated soil.
اظهر المزيد [+] اقل [-]Effects of the addition of iron and aluminum salt on phosphorus adsorption in wetland sediment
2016
Huang, Shuhui | Huang, Hong | Zhu, Huayue
Adsorption and removal of phosphorus (P) in wetland sediment from aqueous solutions were investigated by using four kinds of iron (Fe) and aluminum (Al) salt (FeCl₃, AlCl₃, poly FeCl₃, and poly AlCl₃). Under optimal temperature of 25 °C, P concentration of 50 mg/L, and mole concentration ratio of 4:1 (Fe³⁺/PO₄ ³⁻ or Al³⁺/PO₄ ³⁻), the P sorption capacities of wetland sediments by FeCl₃, poly FeCl₃, AlCl₃, and poly AlCl₃treatments were 296.03, 371.41, 276.3, and 357.85 μg/g, respectively, and were enhanced by 83.36, 158.74, 63.63, and 145.18 μg/g, respectively. The P sorption capacities based on different additives were in the order of poly FeCl₃ > poly AlCl₃ > FeCl₃ > AlCl₃. The EPC0 values, K values, and maximum adsorption capacities indicated that poly FeCl₃ was good reagent to restore P pollution in aqueous solution by wetland sediment in the consideration of both P treatment efficiency and potential environmental impact. These findings, obviously, are useful basis to develop new effective methods for P removal in waters.
اظهر المزيد [+] اقل [-]Effect of petroleum hydrocarbons in copper phytoremediation by a salt marsh plant (Juncus maritimus) and the role of autochthonous bioaugmentation
2016
Montenegro, I. P. F. M. | Mucha, A. P. | Reis, I. | Rodrigues, P. | Almeida, C. M. R.
This work aimed to investigate, under controlled but environmental relevant conditions, the effects of the presence of both inorganic and organic contaminants (copper and petroleum hydrocarbons) on phytoremediation potential of the salt marsh plant Juncus maritimus. Moreover, bioaugmentation, with an autochthonous microbial consortium (AMC) resistant to Cu, was tested, aiming an increase in the remediation potential of this plant in the presence of a co-contamination. Salt marsh plants with sediment attached to their roots were collected, placed in vessels, and kept in greenhouses, under tidal simulation. Sediments were contaminated with Cu and petroleum, and the AMC was added to half of the vessels. After 5 months, plants accumulated significant amounts of Cu but only in belowground structures. The amount of Cu was even higher in the presence of petroleum. AMC addition increased Cu accumulation in belowground tissues, despite decreasing Cu bioavailability, promoting J. maritimus phytostabilization potential. Therefore, J. maritimus has potential to phytoremediate co-contaminated sediments, and autochthonous bioaugmentation can be a valuable strategy for the recovery and management of moderately impacted estuaries. This approach can contribute for a sustainable use of the environmental resources. Graphical abstract ᅟ
اظهر المزيد [+] اقل [-]Photodegradation of the novel fungicide fluopyram in aqueous solution: kinetics, transformation products, and toxicity evolvement
2016
Dong, Bizhang | Hu, Jiye
The aqueous photodegradation of fluopyram was investigated under UV light (λ ≥ 200 nm) and simulated sunlight irradiation (λ ≥ 290 nm). The effect of solution pH, fulvic acids (FA), nitrate (NO₃ ⁻), Fe (III) ions, and titanium dioxide (TiO₂) on direct photolysis of fluopyram was explored. The results showed that fluopyram photodegradation was faster in neutral solution than that in acidic and alkaline solutions. The presence of FA, NO₃ ⁻, Fe (III), and TiO₂ slightly affected the photodegradation of fluopyram under UV irradiation, whereas the photodegradation rates of fluopyram with 5 mg L⁻¹ Fe (III) and 500 mg L⁻¹ TiO₂ were about 7-fold and 13-fold faster than that without Fe (III) and TiO₂ under simulated sunlight irradiation, respectively. Three typical products for direct photolysis of fluopyram have been isolated and characterized by liquid chromatography tandem mass spectrometry. These products resulted from the intramolecular elimination of HCl, hydroxyl-substitution, and hydrogen extraction. Based on the identified transformation products and evolution profile, a plausible degradation pathway for the direct photolysis of fluopyram in aqueous solution was proposed. In addition, acute toxicity assays using the Vibrio fischeri bacteria test indicated that the transformation products were more toxic than the parent compound.
اظهر المزيد [+] اقل [-]Sensitivity of the deep-sea amphipod Eurythenes gryllus to chemically dispersed oil
2016
Olsen, Gro Harlaug | Coquillé, Nathalie | Le Floch, Stephane | Geraudie, Perrine | Dussauze, Matthieu | Lemaire, Philippe | Camus, Lionel
In the context of an oil spill accident and the following oil spill response, much attention is given to the use of dispersants. Dispersants are used to disperse an oil slick from the sea surface into the water column generating a cloud of dispersed oil droplets. The main consequence is an increasing of the sea water–oil interface which induces an increase of the oil biodegradation. Hence, the use of dispersants can be effective in preventing oiling of sensitive coastal environments. Also, in case of an oil blowout from the seabed, subsea injection of dispersants may offer some benefits compared to containment and recovery of the oil or in situ burning operation at the sea surface. However, biological effects of dispersed oil are poorly understood for deep-sea species. Most effects studies on dispersed oil and also other oil-related compounds have been focusing on more shallow water species. This is the first approach to assess the sensitivity of a macro-benthic deep-sea organism to dispersed oil. This paper describes a toxicity test which was performed on the macro-benthic deep-sea amphipod (Eurythenes gryllus) to determine the concentration causing lethality to 50 % of test individuals (LC₅₀) after an exposure to dispersed Brut Arabian Light (BAL) oil. The LC₅₀ (24 h) was 101 and 24 mg L⁻¹ after 72 h and 12 mg L⁻¹ at 96 h. Based on EPA scale of toxicity categories to aquatic organisms, an LC₅₀ (96 h) of 12 mg L⁻¹ indicates that the dispersed oil was slightly to moderately toxic to E. gryllus. As an attempt to compare our results to others, a literature study was performed. Due to limited amount of data available for dispersed oil and amphipods, information on other crustacean species and other oil-related compounds was also collected. Only one study on dispersed oil and amphipods was found, the LC₅₀ value in this study was similar to the LC₅₀ value of E. gryllus in our study. Since toxicity data are important input to risk assessment and net environmental benefit analyses, and since such data are generally lacking on deep-sea species, the data set produced in this study is of interest to the industry, stakeholders, environmental management, and ecotoxicologists. However, studies including more deep-sea species covering different functional groups are needed to evaluate the sensitivity of the deep-sea compartments to dispersed oil relative to other environmental compartments.
اظهر المزيد [+] اقل [-]The effect of dispersed Petrobaltic oil droplet size on photosynthetically active radiation in marine environment
2016
Haule, Kamila | Freda, Włodzimierz
Oil pollution in seawater, primarily visible on sea surface, becomes dispersed as an effect of wave mixing as well as chemical dispersant treatment, and forms spherical oil droplets. In this study, we examined the influence of oil droplet size of highly dispersed Petrobaltic crude on the underwater visible light flux and the inherent optical properties (IOPs) of seawater, including absorption, scattering, backscattering and attenuation coefficients. On the basis of measured data and Mie theory, we calculated the IOPs of dispersed Petrobaltic crude oil in constant concentration, but different log-normal size distributions. We also performed a radiative transfer analysis, in order to evaluate the influence on the downwelling irradiance E d , remote sensing reflectance R ᵣₛ and diffuse reflectance R, using in situ data from the Baltic Sea. We found that during dispersion, there occurs a boundary size distribution characterized by a peak diameter d ₀ = 0.3 μm causing a maximum E d increase of 40 % within 0.5-m depth, and the maximum E d decrease of 100 % at depths below 5 m. Moreover, we showed that the impact of size distribution on the “blue to green” ratios of R ᵣₛ and R varies from 24 % increase to 27 % decrease at the same crude oil concentration.
اظهر المزيد [+] اقل [-]Hydrochemistry and coal mining activity induced karst water quality degradation in the Niangziguan karst water system, China
2016
Zhang, Xiaobo | Li, Xue | Gao, Xubo
Hydrogeochemical analysis, statistical analysis, and geochemical modeling were employed to evaluate the impacts of coal mining activities on karst water chemistry in Niangziguan spring catchment, one of the largest karst springs in Northern China. Significant water quality deterioration was observed along the flow path, evidenced from the increasing sulfate, nitrate, and TDS content in karst water. Karst water samples are Ca-Mg-HCO₃ type in the recharge areas, Ca-Mg-HCO₃-SO₄ type in the coal mining areas, and Ca-Mg-SO₄-HCO₃/HCO₃-SO₄ type in the rural areas and discharge areas. A four-factor principal component analysis (PCA) model is conducted which explains over 82.9 % of the total variation. Factor 1, which explained the largest portion (45.33 %) of the total variance, reveals that coal mining activities and natural water-rock interaction as the primary factors controlling karst water quality. Anthropogenic effects were recognized as the secondary factor with high positive loadings for NO₃⁻ and Cl⁻ in the model. The other two factors are co-precipitation removal of trace elements and silicate mineral dissolution, which explained 20.96 % of the total variance. A two-end mixing modeling was proposed to estimate the percentage of coal wastewater giving on karst water chemistry, based on the groundwater sulfate chemistry constrains rather than sulfur isotopes. Uncertainty of sulfur isotope sources led to an overestimation of coal mining water contribution. According to the results of the modeling, the contribution of coal mining waste on karst water chemistry was quantified to be from 27.05 to 1.11 % which is ca. three times lower than the values suggested using a sulfur isotope method.
اظهر المزيد [+] اقل [-]Relationships of physiologically equivalent temperature and hospital admissions due to I30–I51 other forms of heart disease in Germany in 2009–2011
2016
Shiue, Ivy | Perkins, David R. | Bearman, Nick
We aimed to understand relationships of the weather as biometeorological and hospital admissions due to other forms of heart disease by subtypes, which have been paid less attention, in a national setting in recent years. This is an ecological study. Ten percent of daily hospital admissions of the included hospitals (n = 1618) across Germany that were available between 1 January 2009 and 31 December 2011 (n = 5,235,600) were extracted from Statistisches Bundesamt, Germany. We identified I30–I51 other forms of heart disease by the International Classification of Diseases version 10 as the study outcomes. Daily weather data from 64 weather stations that have covered 13 German states, including air temperature, humidity, wind speed, cloud cover, radiation flux and vapour pressure, were obtained and generated into physiologically equivalent temperature (PET). Admissions due to other diseases of pericardium, nonrheumatic mitral valve disorders, nonrheumatic aortic valve disorders, cardiomyopathy, atrioventricular and left bundle-branch block, other conduction disorders, atrial fibrillation and flutter, and other cardiac arrhythmias peaked when PET was between 0 and 10 °C. Complications and ill-defined descriptions of heart disease admissions peaked at PET 0 °C. Cardiac arrest and heart failure admissions peaked when PET was between 0 and −10 °C while the rest did not vary significantly. A common drop of admissions was found when PET was above 10 °C. More medical resources could have been needed for heart health on days when PETs were <10 °C than on other days. Adaptation to such weather change for medical professionals and the general public would seem to be imperative.
اظهر المزيد [+] اقل [-]Stress tolerance and biocontrol performance of the yeast antagonist, Candida diversa, change with morphology transition
2016
Li, Guangkun | Chi, Mengshan | Chen, Huizhen | Sui, Yuan | Li, Yan | Liu, Yongsheng | Zhang, Xiaojing | Sun, Zhiqiang | Liu, Guoqing | Wang, Qi | Liu, Jia
As an eco-friendly management method, biological control of postharvest diseases, utilizing antagonistic yeasts, is a research topic receiving considerable attention. Detailed knowledge on the biology of yeast antagonists is crucial when considering their potential application and development as biocontrol products. Changes in the growth form, such as single-cell to pseudohyphae, have been associated with the mode of action in postharvest biocontrol yeasts. In this study, the antagonistic yeast, Candida diversa, reversibly shifted from a single-cell morphology on yeast peptone dextrose (YPD) medium with 2 % agar to a pseudohyphal morphology on YPD with 0.3 % agar. The tolerance of the pseudohyphal form to heat and oxidative stresses, as well as the biocontrol efficacy against Botrytis cinerea on apple and kiwifruit stored at 25 and 4 °C, was significantly higher as compared to the single-cell form. This study provides new information on the ability of C. diversa to change its morphology and the impact of the morphology shift on stress tolerance and biocontrol performance.
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