A simulation study was performed to compare three statistical tests with respect to their performances in the two-sample location problem for contaminated normal distributions. The three tests were: the t-test, the rank-transformed t-test, and the Wilcoxon rank-sum test. The results showed the t-test to be inferior to the other two tests. 相似文献
The possible arsenic tolerance mechanisms were explored in Arundo donax L. under various supplied arsenic concentrations. The treatments included control (no metal) and five doses of arsenic trioxide i.e., 0, 50, 100, 300, 600 and 1000 μg L−1 As to A. donax. The phytoextraction ability of A. donax L. plants was assessed using both the translocation and bioaccumulation factors. The transpirates were collected to analyze the arsenic concentration volatilized along-with study of anatomical characteristics of the plant parts. In general, the arsenite and arsenate accumulation linearly increased in roots, shoot and leaves with the increasing supplied arsenic levels i.e., from 2.348, 2.775 and 3.25 μg g−1 at 50 μg L−1 to 50, 53.125 and 64.25 μg g−1 arsenite, at 1000 μg L−1, from 4.075, 5.425 and 13.56 μg g−1 at 50 μg L−1 to 71, 62.02 and 436.219 μg g−1 arsenate at 1000 μg L−1, respectively. The order of arsenic accumulation in A. donax L. was: solution As(III) < Root As(III) < Shoot As(III) < Leaf As(III) < Solution As(V) < Root As(V) < Shoot As(V) < Leaf As(V). The range of arsenic volatilization by A. donax L. was 7.2–22% at higher supplied arsenic (300–1000 μg L−1). Volatilization was an important mechanism to avoid toxic effects of arsenic by A. donax L. in addition to bioaccumulation. 相似文献
Strains V113T, V92 and V120 have been isolated from sand samples taken at the Atlantic intertidal shore in Galicia, Spain, after the Prestige oil spill. A preliminary analysis of the 16S rRNA and the partial rpoD gene sequences indicated that these strains belonged to the Pseudomonas genus, but they were distinct from any known Pseudomonas species. They were extensively characterized by a polyphasic taxonomic approach and phylogenetic data that confirmed that these strains belonged to the Pseudomonas pertucinogena group. Phylogenetic analysis of 16S rRNA, gyrB and rpoD gene sequences showed that the three strains were 99% similar and were closely related to members of the P. pertucinogena group, with less than 94% similarity to strains of established species; Pseudomonas pachastrellae was the closest relative. The Average Nucleotide Index based on blast values was 89.0% between V113T and the P. pachastrellae type strain, below the accepted species level (95%). The predominant cellular fatty acid contents and whole cell protein profiles determined by MALDI-TOF mass spectrometry also differentiated the studied strains from known Pseudomonas species. We therefore conclude that strains V113T, V92 and V120 represent a novel species of Pseudomonas, for which the name Pseudomonas gallaeciensis is proposed; the type strain is V113T (= CCUG 67583T = LMG 29038T). 相似文献
In this study, 341 Bacillus sp. strains were isolated from agricultural soils of Turkey. The potent extracellular lipase producer was selected. It was identified by 16S rRNA, named as Bacillus cereus ATA179. Optimal nutritional and physical parameters for lipase production were determined. Sucrose as the carbon source, (NH4)2HPO4 as the nitrogen source, CaCl2 as the metal ion were obtained. The best results of physical parameters were stated at 45°C, pH 7.0, shaking rate 50 rpm, inoculation amount 7% and inoculum age 24 h. ATA179 strain showed a 51% increase in enzyme production in the modified medium created by optimizing nutritional and physical conditions. Optimum pH value and temperature were found as 6.0 and 55 °C, respectively. CaCl2, Tween 20, Triton X-100 had an activating effect on enzyme activity. Vmax and Km kinetic values were found as 18.28 U/mL and 0.11 mM, respectively. The molecular weight was determined as 47 kDa. Lipase was found to be stable up to 75 days at -20 ºC. The potential of the enzyme in detergent industry was also investigated. It was not affected by detergent additives, but was found to be effective in removing oils from contaminated fabrics. This new lipase may have potential to be used in detergent industry. 相似文献
The purpose of this study was to develop a fungal bioremediation method that could be used for soils heavily contaminated with persistent organic compounds, such as polyaromatic hydrocarbons (PAHs). Sawmill soil, contaminated with PAHs, was mixed with composted green waste (1:1) and incubated with or without fungal inoculum. The treatments were performed at the laboratory and field scales. In the laboratory scale treatment (starting concentration 3500 mg kg−1, sum of 16 PAH) the high molecular weight PAHs were degraded significantly more in the fungal-inoculated microcosms than in the uninoculated ones. In the microcosms inoculated with Phanerochaete velutina, 96% of 4-ring PAHs and 39% of 5- and 6-ring PAHs were removed in three months. In the uninoculated microcosms, 55% of 4-ring PAHs and only 7% of 5- and 6-ring PAHs were degraded. However, during the field scale (2 t) experiment at lower starting concentration (1400 mg kg−1, sum of 16 PAH) the % degradation was similar in both the P. velutina-inoculated and the uninoculated treatments: 94% of the 16 PAHs were degraded in three months. In the field scale experiment the copy number of gram-positive bacteria PAH-ring hydroxylating dioxygenase genes was found to increase 1000 fold, indicating that bacterial PAH degradation also played an important role. 相似文献
Conventional techniques for site characterisation are time consuming, cost intensive, and often do not support decision making
with regard to sustainable remediation. Therefore, new techniques for step by step site characterization with smart feed back
loops are necessary that are able to support a future “soil framework directive”. Advanced geophysical site characterization
techniques combined with new types of vegetation analysis will be developed. Based on these non-invasive surveys, the extension
of sources, contamination levels (THP, BTEX, PAH, CHC, explosives, heavy metals and radio nuclides) and soil heterogeneities
will be localized first. Hot spots will then be investigated by new direct push probing systems integrated with geophysical
and hydrogeological methods and combined with chemical and isotopic contaminant analysis for source localization and identification
(environmental forensics). The actually occurring bioprocesses, such as contaminant degradation or sorption and mobilization
processes, will be assessed using biosensors, in situ microcosms, and stable isotope and biomarker analysis. These new techniques
and tools will be evaluated against best practice of conventional methods. The ModelPROBE project (EU-FP7 collaborative project)
gives the opportunity to test, optimize and demonstrate the proposed approach at fully equipped and characterized European
brownfield reference sites in Germany, Italy, Norway and the Czech Republic. Integrated statistical analysis and modelling
at different stages, the step by step approach will result in an improved view of soil and subsurface contamination and will
provide a sound basis for a cost-effective risk assessment and decision in the choice of the most appropriate sustainable
remediation strategy. 相似文献
This work was aimed at evaluating the feasibility of a remediation treatment performed by means of a supercritical carbon dioxide extraction on a sandy soil recently contaminated by light polycyclic aromatic hydrocarbons.
The soil utilized in this study was artificially contaminated by naphthalene and anthracene. The artificial contamination process was intended to simulate a recent accidental spillage of hydrocarbon fuels.
Several extractions, aimed at singling out the operating parameters (pressure, temperature, supercritical fluid mass flow rate) that are able to obtain the residual required concentration (50 mg/kg dry soil) in the shortest time, were carried out on a on-purpose made system.
The best extraction conditions were 120 bar and 40°C for a naphthalene contaminated soil and 200 bar and 80–100°C for an anthracene contaminated soil.
The results obtained in the experimental tests made it possible to build an analytical model able to correlate, for the given soil, the extraction length to the operating parameters such as supercritical fluid density, temperature and mass flow rate.
In order to evaluate the economic feasibility of the process, a unit treatment cost was evaluated for the case of an extraction carried out in a 10 m3 reactor in the presence of the best extraction conditions that were previously determined. The extraction unit cost was therefore equal to 35 000–65 000 €/t for a soil with a starting contaminant concentration equal to 1000 mg/kg of dry soil. 相似文献