خيارات البحث
النتائج 871 - 880 من 2,459
Isolation and characterization of a novel hydrocarbon-degrading bacterium Achromobacter sp. HZ01 from the crude oil-contaminated seawater at the Daya Bay, southern China
2014
Deng, Mao-Cheng | Li, Jing | Liang, Fu-Rui | Yi, Meisheng | Xu, Xiao-Ming | Yuan, Jian-Ping | Peng, Juan | Wu, Chou-Fei | Wang, Jiang-Hai
Microorganisms play an important role in the biodegradation of petroleum contaminants, which have attracted great concern due to their persistent toxicity and difficult biodegradation. In this paper, a novel hydrocarbon-degrading bacterium HZ01 was isolated from the crude oil-contaminated seawater at the Daya Bay, South China Sea, and identified as Achromobacter sp. Under the conditions of pH 7.0, NaCl 3% (w/v), temperature 28°C and rotary speed 150rpm, its degradability of the total n-alkanes reached up to 96.6% after 10days of incubation for the evaporated diesel oil. Furthermore, Achromobacter sp. HZ01 could effectively utilize polycyclic aromatic hydrocarbons (PAHs) as its sole carbon source, and could remove anthracene, phenanthrene and pyrence about 29.8%, 50.6% and 38.4% respectively after 30days of incubation. Therefore, Achromobacter sp. HZ01 may employed as an excellent degrader to develop one cost-effective and eco-friendly method for the bioremediation of marine environments polluted by crude oil.
اظهر المزيد [+] اقل [-]A three-step model to assess shoreline and offshore susceptibility to oil spills: The South Aegean (Crete) as an analogue for confined marine basins
2014
Alves, Tiago M. | Kokinou, Eleni | Zodiatis, George
This study combines bathymetric, geomorphological, geological data and oil spill predictions to model the impact of oil spills in two accident scenarios from offshore Crete, Eastern Mediterranean. The aim is to present a new three-step method of use by emergency teams and local authorities in the assessment of shoreline and offshore susceptibility to oil spills. The three-step method comprises: (1) real-time analyses of bathymetric, geomorphological, geological and oceanographic data; (2) oil dispersion simulations under known wind and sea current conditions; and (3) the compilation of final hazard maps based on information from (1) and (2) and on shoreline susceptibility data. The results in this paper show that zones of high to very-high susceptibility around the island of Crete are related to: (a) offshore bathymetric features, including the presence of offshore scarps and seamounts; (b) shoreline geology, and (c) the presence near the shore of sedimentary basins filled with unconsolidated deposits of high permeability. Oil spills, under particular weather and oceanographic conditions, may quickly spread and reach the shoreline 5–96h after the initial accident. As a corollary of this work, we present the South Aegean region around Crete as a valid case-study for confined marine basins, narrow seaways, or interior seas around island groups.
اظهر المزيد [+] اقل [-]Screening of biosurfactant producers from petroleum hydrocarbon contaminated sources in cold marine environments
2014
Cai, Qinhong | Zhang, Baiyu | Chen, Bing | Zhu, Zhiwen | Lin, Weiyun | Cao, Tong
An overview of literature about isolating biosurfactant producers from marine sources indicated no such producers have been reported form North Atlantic Canada. Water and sediment samples were taken from petroleum hydrocarbon contaminated coastal and offshore areas in this region. Either n-hexadecane or diesel was used as the sole carbon source for the screening. A modified colony-based oil drop collapsing test was used to cover sessile biosurfactant producers. Fifty-five biosurfactant producers belong to genera of Alcanivorax, Exiguobacterium, Halomonas, Rhodococcus, Bacillus, Acinetobacter, Pseudomonas, and Streptomyces were isolated. The first three genera were established after 1980s with interesting characteristics and limited relevant publications. Some of the 55 isolated strains were found with properties such as greatly reducing surface tension, stabilizing emulsion and producing flocculant. Isolates P6-4P and P1-5P were selected to demonstrate the performance of biosurfactant production, and were found to reduce the surface tension of water to as low as 28dynes/cm.
اظهر المزيد [+] اقل [-]Growth, nutrient status, and photosynthetic response to diesel-contaminated soil of a cordgrass, Spartina argentinensis
2014
Redondo-Gómez, Susana | Petenello, María C. | Feldman, Susana R.
The present study was conduced to investigate the tolerance limits of Spartina argentinensis, which occurs in inland marshes of the Chaco-Pampean regions of Argentina, to diesel-contaminated soil. A glasshouse experiment was designed to investigate the effect of diesel fuel from 0% to 3% on growth and photosynthetic apparatus of S. densiflora by measuring gas exchange and photosynthetic pigments. We also performed chemical analysis of plant samples, and determined mycorrhizal index. Tiller and root biomasses declined with increasing diesel fuel concentration, as well as photosynthetic rate (A). Reductions in A could be accounted for by non-stomatal limitations. Mycorrhizal roots of S. argentinensis were reduced by the presence of diesel fuel, but did not affect its nutritional status; in fact, most element concentrations increased with diesel contamination. Despite the negative effect of diesel-contaminated soil, S. argentinensis continued growing, which could be useful management options for phytorremediation of diesel-contaminated soils.
اظهر المزيد [+] اقل [-]Influence of urban runoff, inappropriate waste disposal practices and World War II on the heavy metal status of sediments in the southern half of Saipan Lagoon, Saipan, CNMI
2014
Denton, Gary R.W. | Emborski, Carmen A. | Habana, Nathan C. | Starmer, John A.
Heavy metals were examined in sediments from the southern half of Saipan Lagoon. These waters provided tactical access for US troops during WWII and were heavily shelled at the time. Mercury profiles in sediments were, to some extent, reflective of this event. Samples from the southern end of the lagoon, where an old post-war dumpsite once existed, were found to be substantially enriched with Pb, Cu and Zn. Further north, the lagoon was primarily impacted by urban runoff. Metal enrichment in sediments from this region was generally highest at storm drain outlets and attenuated seawards. Moderate enrichment was rarely exceeded for any element other than Hg beyond the 50m mark. Sediment quality guidelines used to flag potentially adverse ecological health effects revealed no PEL exceedances. TEL exceedances for Pb and Cu were identified in sediments near the former dumpsite. The public health implications of the data are briefly addressed.
اظهر المزيد [+] اقل [-]Validation trials of a shipboard filter skid (p3SFS) demonstrate its utility for collecting living zooplankton
2014
Drake, Lisa A. | Moser, Cameron S. | Robbins-Wamsley, Stephanie H. | Riley, Scott C. | Wier, Timothy P. | Grant, Jonathan F. | Herring, Penny R. | First, Matthew R.
Relatively large volumes of water—on the order of cubic meters—must be sampled and analyzed to generate statistically valid estimates of sparsely concentrated organisms, such as in treated ballast water. To this end, a third prototype of a shipboard filter skid (p3SFS) was designed and constructed. It consisted of two housings (each containing a 35μm mesh filter bag) and its own pump and computer controller. Additionally, the skid had a drip sampler, which collected a small volume (∼10L) of whole (unfiltered) water immediately upstream of the housings. Validation of the p3SFS occurred in two segments: (1) land-based trials, in which the collection of organisms ⩾50μm (nominally zooplankton) by the p3SFS was compared to a plankton net, and (2) shipboard trials, in which ballast water was sampled aboard a ship. In both types of trials, the data collected showed the filter skid to be an appropriate flow-through sampling device.
اظهر المزيد [+] اقل [-]Uptake and biological effects of synthetic glucocorticoids in common carp (Cyprinus carpio)
2014
Nakayama, Kei | Inoue, Yoshiyuki | Ikeda, Naomi | Hashizume, Naoki | Murakami, Hidekazu | Ishibashi, Takeshi | Ikeda, Hirofumi | Isobe, Tomohiko | Kitamura, Shin-Ichi | Suzuki, Go
Uptake and biological effects of synthetic glucocorticoids (GCs) were analyzed using common carp (Cyprinus carpio). Fish were exposed to clobetasol propionate (CP) or clobetasone butyrate (CB) individually or in mixture at 1μgL−1 for 21days. Bioconcentration factor (BCF) of CB was calculated as 100, and BCF of CP was less than 16. No effects were found in fish erythrocyte and leukocyte numbers and serum glucose levels after exposure to the selected GCs. On the other hand, serum concentrations of free amino acids significantly increased in GC-exposed groups. Thus, exposures to synthetic GCs at relatively low concentrations seemed to cause enhancement of protein degradation and subsequent increase of serum free amino acids without a corresponding increase in serum glucose levels, an effect which might be related to partial induction of gluconeogenesis by GC.
اظهر المزيد [+] اقل [-]High thresholds for avoidance of sonar by free-ranging long-finned pilot whales (Globicephala melas)
2014
Antunes, R. | Kvadsheim, P.H. | Lam, F.P.A. | Tyack, P.L. | Thomas, L. | Wensveen, P.J. | Miller, P.J.O.
The potential effects of exposing marine mammals to military sonar is a current concern. Dose–response relationships are useful for predicting potential environmental impacts of specific operations. To reveal behavioral response thresholds of exposure to sonar, we conducted 18 exposure/control approaches to 6 long-finned pilot whales. Source level and proximity of sonar transmitting one of two frequency bands (1–2kHz and 6–7kHz) were increased during exposure sessions. The 2-dimensional movement tracks were analyzed using a changepoint method to identify the avoidance response thresholds which were used to estimate dose–response relationships. No support for an effect of sonar frequency or previous exposures on the probability of response was found. Estimated response thresholds at which 50% of population show avoidance (SPLmax=170dB re 1μPa, SELcum=173dB re 1μPa2s) were higher than previously found for other cetaceans. The US Navy currently uses a generic dose–response relationship to predict the responses of cetaceans to naval active sonar, which has been found to underestimate behavioural impacts on killer whales and beaked whales. The navy curve appears to match more closely our results with long-finned pilot whales, though it might underestimate the probability of avoidance for pilot-whales at long distances from sonar sources.
اظهر المزيد [+] اقل [-]Phytoplankton dynamics in the Gulf of Aqaba (Eilat, Red Sea): A simulation study of mariculture effects
2014
Laiolo, Leonardo | Barausse, Alberto | Dubinsky, Z. (Zvy) | Palmeri, Luca | Goffredo, Stefano | Kamenir, Yury | Al-Najjar, Tariq | Iluz, David
The northern Gulf of Aqaba is an oligotrophic water body hosting valuable coral reefs. In the Gulf, phytoplankton dynamics are driven by an annual cycle of stratification and mixing. Superimposed on that fairly regular pattern was the establishment of a shallow-water fish-farm initiative that increased gradually until its activity was terminated in June 2008. Nutrient, water temperature, irradiation, phytoplankton data gathered in the area during the years 2007–2009, covering the peak of the fish-farm activity and its cessation, were analyzed by means of statistical analyses and ecological models of phytoplankton dynamics. Two datasets, one from an open water station and one next to the fish farms, were used. Results show that nutrient concentrations and, consequently, phytoplankton abundance and seasonal succession were radically altered by the pollution originating from the fish-farm in the sampling station closer to it, and also that the fish-farm might even have influenced the open water station.
اظهر المزيد [+] اقل [-]Accumulation of trace metals in grey mangrove Avicennia marina fine nutritive roots: The role of rhizosphere processes
2014
Chaudhuri, Punarbasu | Nath, Bibhash | Birch, Gavin
Mangrove sediment has long been recognized as being important in restricting the mobility of contaminants in estuarine environments. To investigate the role of rhizosphere processes in the accumulation of trace metals in mangrove fine nutritive roots, the mangrove sediments and associated fine nutritive roots are collected from five major embayments of Sydney estuary (Australia) for geochemical studies. In this estuary Avicennia marina sediments are accumulating large quantities of trace metals due to presence of abundant fine sediment (<62.5μm) and organic matter as well as anthropogenic input. Accumulation of trace metals in fine nutritive roots responds to total sediment chemistry mainly due to rhizosphere sediment geochemical processes resulting in a strong linear correlation between metal concentrations in fine nutritive roots vs. total and bio-available contents in sediments. Accumulation of trace metals in fine nutritive roots is almost always exceeds rhizosphere total sediment metal concentrations.
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