خيارات البحث
النتائج 3891 - 3900 من 4,033
Ecological implication of variation in the secondary metabolites in Parmelioid lichens with respect to altitude النص الكامل
2016
Shukla, Vertika | Patel, D. K. | Bajpai, Rajesh | Semwal, Manoj | Upreti, D. K.
Lichens are known to synthesize a variety of secondary metabolites having multifunctional activity in response to external environmental condition. Two common lichen extrolites, atranorin and salazinic acid, are known to afford antioxidant as well as photoprotectant nature depending on the abiotic/biotic stress. The present investigation aims to study the influence of altitudinal gradient on the quantitative profile of atranorin and salazinic acid in three lichen species, Bulbothrix setschwanensis (Zahlbr.) Hale, Everniastrum cirrhatum (Fr.) Hale and Parmotrema reticulatum (Taylor) Choisy, Parmeliaceae using liquid chromatography-mass spectrometry (LC-MS/MS) technique. Samples were collected from high-altitude area, usually considered as non-polluted sites of Garhwal Himalaya. Characterization and quantification of the lichen substances in samples were carried out comparing with the standards of atranorin and salazinic acid. Results indicated significant variation in the chemical content with the rising altitude. All the three lichen species showed higher quantities of chemical substances with the altitudinal rise, while among the three lichen species, E. cirrhatum showed the highest quantity of total lichen compounds. The higher abundance and frequency of E. cirrhatum with increasing altitude as compared to B. setschwanensis and P. reticulatum may be attributed due to the presence of higher quantity of photoprotecting/antioxidant chemicals especially salazinic acid. Thus, the present study shows the prominent role of secondary metabolite in wider ecological distribution of Parmelioid lichens at higher altitudes.
اظهر المزيد [+] اقل [-]Evaluation of coexposure to inorganic arsenic and titanium dioxide nanoparticles in the marine shrimp Litopenaeus vannamei النص الكامل
2016
Cordeiro, Lucas | Müller, Larissa | Gelesky, Marcos A. | Wasielesky, Wilson | Fattorini, Daniele | Regoli, Francesco | Monserrat, José Marìa | Ventura-Lima, Juliane
The acute toxicity of titanium dioxide nanoparticles (nTiO₂) that occur concomitantly in the aquatic environment with other contaminants such as arsenic (As) is little known in crustaceans. The objective of the present study is to evaluate whether coexposure to nTiO₂ can influence the accumulation, metabolism, and oxidative stress parameters induced by arsenic exposure in the gills and hepatopancreas of the shrimp Litopenaeus vannamei. Organisms were exposed by dissolving chemicals in seawater (salinity = 30) at nominal concentrations of 10 μg/L nTiO₂ or Asᴵᴵᴵ, dosed alone and in combination. Results showed that there was not a significant accumulation of As in either tissue type, but the coexposure altered the pattern of the metabolism. In the hepatopancreas, no changes were observed in the biochemical response, while in the gills, an increase in the glutamate-cysteine-ligase (GCL) activity was observed upon exposure to As or nTiO₂ alone, an increase in the reduced glutathione (GSH) levels was observed upon exposure to As alone, and an increase in the total antioxidant capacity was observed upon exposure to nTiO₂ or nTiO₂ + As. However, these modulations were not sufficient enough to prevent the lipid damage induced by nTiO₂ exposure. Our results suggest that coexposure to nTiO₂ and As does not alter the toxicity of this metalloid in the gills and hepatopancreas of L. vannamei but does alter its metabolism, favoring its accumulation of organic As species considered moderately toxic.
اظهر المزيد [+] اقل [-]Additional disturbances as a beneficial tool for restoration of post-mining sites: a multi-taxa approach النص الكامل
2016
Řehounková, Klára | Čížek, Lukáš | Řehounek, Jiří | Šebelíková, Lenka | Tropek, Robert | Lencová, Kamila | Bogusch, Petr | Marhoul, Pavel | Máca, Jan
Open interior sands represent a highly threatened habitat in Europe. In recent times, their associated organisms have often found secondary refuges outside their natural habitats, mainly in sand pits. We investigated the effects of different restoration approaches, i.e. spontaneous succession without additional disturbances, spontaneous succession with additional disturbances caused by recreational activities, and forestry reclamation, on the diversity and conservation values of spiders, beetles, flies, bees and wasps, orthopterans and vascular plants in a large sand pit in the Czech Republic, Central Europe. Out of 406 species recorded in total, 112 were classified as open sand specialists and 71 as threatened. The sites restored through spontaneous succession with additional disturbances hosted the largest proportion of open sand specialists and threatened species. The forestry reclamations, in contrast, hosted few such species. The sites with spontaneous succession without disturbances represent a transition between these two approaches. While restoration through spontaneous succession favours biodiversity in contrast to forestry reclamation, additional disturbances are necessary to maintain early successional habitats essential for threatened species and open sand specialists. Therefore, recreational activities seem to be an economically efficient restoration tool that will also benefit biodiversity in sand pits.
اظهر المزيد [+] اقل [-]Adsorption behaviors of fungicide-derived copper onto various size fractions of aggregates from orchard soil النص الكامل
2016
Wang, Quan-Ying | Hu, Bo | Yu, Hong-Wen
Although the gradual accumulations of Cu in orchard soils due to the application of Cu-based fungicides have been widely reported, limited information is available about the retention characteristics of fungicide-derived Cu in soil, especially in various size soil aggregates. This study described the adsorption characteristics of Cu from commonly used fungicide, Bordeaux mixture (CuSO₄ + Ca(OH)₂), onto various aggregate fractions (2000–1000, 1000–500, 500–250, 250–106, and <106 μm) of orchard soil. The Cu(NO₃)₂ was selected as a comparison. Two different types of adsorption experiments were conducted as follows: variable pH and variable Cu concentration experiments. The adsorption processes of Bordeaux mixture and Cu(NO₃)₂ onto the studied soil samples followed well with the Freundlich isotherm, and the adsorption isotherms were the S shaped. The adsorption amounts of Cu from different Cu compounds differed, and Bordeaux mixture can result in more Cu retention in soil than Cu(NO₃)₂. The adsorption ability of different size soil aggregates varied, and it was mainly governed by soil properties. The findings of this study suggested that both the chemical compositions of Cu compounds and the soil physical structure should be taken into account when performing soil Cu retention experiments with fungicide-derived Cu.
اظهر المزيد [+] اقل [-]Isolation and characterization of two novel psychrotrophic decabromodiphenyl ether-degrading bacteria from river sediments النص الكامل
2016
Wang, Linqiong | Li, Yi | Zhang, Wenlong | Niu, Lihua | Du, Juan | Cai, Wei | Wang, Jing
Decabromodiphenyl ether (BDE-209) is a brominated flame retardant and a priority contaminant. Currently, little information is available about its significance in the environment, specifically about its susceptibility to aerobic biotransformation at low temperature. In this work, five phylogenetically diverse BDE-209-degrading bacterial strains were isolated from river sediments of northern China. These strains were distributed among four different genera—Acinetobacter, Pseudomonas, Bacillus and Staphylococcus. All five isolates were capable of growing on BDE-209, among which two isolates show better growth. By detailed morphological, physiological, and biochemical characteristics and 16S rDNA sequence analysis, the two strains were identified and named as Staphylococcus haemolyticus LY1 and Bacillus pumilus LY2. The two bacteria can grow in mineral salt medium containing BDE-209 substrate across the temperatures ranging from 2.5 to 35 °C, with an optimum temperature of 25 °C which could be considered as psychrotrophs accordingly. The degradation experiment showed that more than 70.6 and 85.5 % of 0.5 mg/L BDE-209 were degraded and the highest mineralization efficiencies of 29.8 and 39.2 % were achieved for 0.5 mg/L BDE-209 by S. haemolyticus LY1 and B. pumilus LY2, respectively. To the best of our knowledge, this is the first demonstration for the biodegradation of BDE-209 by two psychrotrophic bacteria isolated from environment.
اظهر المزيد [+] اقل [-]Sulfadimethoxine transport in soil columns in relation to sorbable and non-sorbable tracers النص الكامل
2016
Park, Jong Yol | Huwe, Bernd
In this study, miscible displacement experiment and batch sorption experiments were performed with sulfadimethoxine, dye tracer, Brilliant Blue FCF (BB) and a conservative tracer (bromide) to depict, analyse and interpret transport paths of sulfadimethoxine in undisturbed and disturbed soil columns. Batch sorption experiment revealed that sorption potential increased in the order: Brilliant Blue FCF > sulfadimethoxine > bromide. The horizontal spatial patterns of sulfadimethoxine and the tracers were analysed in each depth, and selective samples were taken in horizontal cross-section. Non-adsorbable and conservative tracer, bromide spread more widely into longitudinal and horizontal direction than sulfadimethoxine and Brilliant Blue FCF, since adsorption reduced transversal dispersion of the sulfadimethoxine and dye. In non-stained area, residual concentrations of sulfadimethoxine were relatively lower than in stained areas. Therefore, Brilliant Blue FCF distribution can be used to approximate sulfadimethoxine movement in soil. However, presence of preferential flow networks found in undisturbed soil cores can enhance mobility of sulfadimethoxine and the tracers, due to faster flow velocities and non-equilibrium adsorption. Our findings showed that other dye tracers may also be applicable to identify transport pathways of various organic contaminants, of which physico-chemical properties are similar to those of the dye tracers. Preferential flow should be considered for drinking water managements and transport modelling, since this allows faster pollutants transport from their sources, and create critical consequences for groundwater quality and solute transport modelling.
اظهر المزيد [+] اقل [-]The effect of anaerobic–aerobic and feast–famine cultivation pattern on bacterial diversity during poly-β-hydroxybutyrate production from domestic sewage sludge النص الكامل
2016
Liu, Changli | Liu, Di | Qi, Yingjie | Zhang, Ying | Liu, Xi | Zhao, Min
The main objective of this work was to investigate the influence of different oxygen supply patterns on poly-β-hydroxybutyrate (PHB) yield and bacterial community diversity. The anaerobic–aerobic (A/O) sequencing batch reactors (SBR1) and feast–famine (F/F) SBR2 were used to cultivate activated sludge to produce PHB. The mixed microbial communities were collected and analyzed after 3 months cultivation. The PHB maximum yield was 64 wt% in SBR1 and 53 wt% in SBR2. Pyrosequencing analysis 16S rRNA gene of two microbial communities indicated there were nine and four bacterial phyla in SBR1 and SBR2, respectively. Specifically, Proteobacteria (36.4 % of the total bacterial community), Actinobacteria (19.7 %), Acidobacteria (14.1 %), Firmicutes (4.4 %), Bacteroidetes (1.7 %), Cyanobacteria/Chloroplast (1.5 %), TM7 (0.8 %), Gemmatimonadetes (0.2 %), and Nitrospirae (0.1 %) were present in SBR1. Proteobacteria (94.2 %), Bacteroidetes (2.9 %), Firmicutes (1.9 %), and Actinobacteria (0.7 %) were present in SBR2. Our results indicated the SBR1 fermentation system was more stable than that of SBR2 for PHB accumulation.
اظهر المزيد [+] اقل [-]On the geotechnical characterisation of the polluted submarine sediments from Taranto النص الكامل
2016
Vitone, Claudia | Federico, Antonio | Puzrin, A. M. (Alexander M.) | Ploetze, Michael | Carrassi, Elettra | Todaro, Francesco
This paper reports the results of the first geomechanical laboratory experiments carried out on the polluted submarine clayey sediments of the Mar Piccolo in Taranto (South of Italy). The study had to face with extreme difficulties for the very soft consistency of the sediments and the contaminants. The mineralogy, composition and physical properties of the sediments were analysed, along with their compression and shearing behaviour. The investigation involved sediments up to about 20 m below the seafloor, along three vertical profiles in the most polluted area of the Mar Piccolo, facing the Italian Navy Arsenal. The experimental results were used to derive a preliminary geotechnical model of the site, necessary for the selection and design of the most sustainable in situ mitigation solutions. Moreover, the experimental data reveal that the clayey sediments of the most polluted top layer do not follow the classical geotechnical correlations for normally consolidated deposits. This seems to open interesting perspectives about the effects of pollutants on the geotechnical behaviour of the investigated sediments.
اظهر المزيد [+] اقل [-]Assessment of trace metal contamination in the sea cucumber (Holothuria tubulosa) and sediments from the Dardanelles Strait (Turkey) النص الكامل
2016
Turk Culha, Saniye | Dereli, Hakkı | Karaduman, Fatma Rabia | Culha, Mehmet
This study was performed to determine the concentrations of some trace metals (Cd, Cu, Pb, Ni, Zn, and Fe) in Holothuria tubuosa (Gmelin, 1788) belonging to Echinoderm species and in sediments that they live at three different stations (Gelibolu, Umur Bey/Lapseki, and Dardanos) on Dardanelles Strait between April 2013 and March 2014. The mean trace metal concentrations determined in H. tubulosa and sediment were as follows: Cd 0.18 mg/kg, Cu 2.43 mg/kg, Pb 2.09 mg/kg, Ni 14.58 mg/kg, Zn 16.86 mg/kg, and Fe 73.46 mg/kg and Cd 0.70 mg/kg, Cu 5.03 mg/kg, Pb 14.57 mg/kg, Ni 27.15 mg/kg, Zn 54.52 mg/kg, and Fe 3779.9 mg/kg, respectively. It was detected that the statistical difference between trace metals determined seasonally in muscle tissue of H. tubulosa was significant (p > 0.05). As a result of the study, it was detected that H. tubulosa is a bioindicator species in determining Ni trace metal in sediment. The results were compared to the limit values of National and International Food Safety, and it was detected that Cd and Ni concentrations measured in sediment were above LEL of Ni and Cd concentrations according to Sediment Quality Guidelines.
اظهر المزيد [+] اقل [-]Efficient biodegradation of phenanthrene by a novel strain Massilia sp. WF1 isolated from a PAH-contaminated soil النص الكامل
2016
Wang, Haizhen | Lou, Jun | Gu, Haiping | Luo, Xiaoyan | Yang, Li | Wu, Laosheng | Liu, Yong | Wu, Jianjun | Xu, Jianming
A novel phenanthrene (PHE)-degrading strain Massilia sp. WF1, isolated from PAH-contaminated soil, was capable of degrading PHE by using it as the sole carbon source and energy in a range of pH (5.0–8.0), temperatures (20–35 °C), and PHE concentrations (25–400 mg L⁻¹). Massilia sp. WF1 exhibited highly effective PHE-degrading ability that completely degraded 100 mg L⁻¹ of PHE over 2 days at optimal conditions (pH 6.0, 28 °C). The kinetics of PHE biodegradation by Massilia sp. WF1 was well represented by the Gompertz model. Results indicated that PHE biodegradation was inhibited by the supplied lactic acid but was promoted by the supplied carbon sources of glucose, citric acid, and succinic acid. Salicylic acid (SALA) and phthalic acid (PHTA) were not utilized by Massilia sp. WF1 and had no obvious effect on PHE biodegradation. Only two metabolites, 1-hydroxy-2-naphthoic acid (1H2N) and PHTA, were identified in PHE biodegradation process. Quantitatively, nearly 27.7 % of PHE was converted to 1H2N and 30.3 % of 1H2N was further metabolized to PHTA. However, the PHTA pathway was broken and the SALA pathway was ruled out in PHE biodegradation process by Massilia sp. WF1.
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