خيارات البحث
النتائج 651 - 660 من 2,512
Monitoring red tide with satellite imagery and numerical models: A case study in the Arabian Gulf النص الكامل
2014
Zhao, Jun | Ghedira, Hosni
A red tide event that occurred in August 2008 in the Arabian Gulf was monitored and assessed using satellite observations and numerical models. Satellite observations revealed the bloom extent and evolution from August 2008 to August 2009. Flow patterns of the bloom patch were confirmed by results from a HYCOM model. HYCOM data and satellite-derived sea surface temperature data further suggested that the bloom could have been initiated offshore and advected onshore by bottom Ekman layer. Analysis indicated that nutrient sources supporting the bloom included upwelling, Trichodesmium, and dust deposition while other potential sources of nutrient supply should also be considered. In order to monitor and detect red tide effectively and provide insights into its initiation and maintenance mechanisms, the integration of multiple platforms is required. The case study presented here demonstrated the benefit of combing satellite observations and numerical models for studying red tide outbreaks and dynamics.
اظهر المزيد [+] اقل [-]Atmospheric hexachlorobenzene determined during the third China arctic research expedition: Sources and environmental fate النص الكامل
2014
Wu, Xiaoguo | Lam, James C.W. | Xia, Chonghuan | Kang, Hui | Xie, Zhouqing | Lam, Paul K.S.
In July to September 2008, air samples were collected aboard a research expedition icebreaker, Xuelong (Snow Dragon), under the support of the 2008 Chinese Arctic Research Expedition Program. All the air samples were analyzed for determination of the concentrations of Hexachlorobenzene (HCB). The levels of HCB ranged from 24 to 180pg m−3, with an average concentration of 88pg m−3. Generally, HCB were more uniform than other organchlorine pollutants in the North Pacific Ocean and the Arctic Ocean. Geographically, the average concentrations of HCB from high to low were in the following order: the Central Arctic Ocean (110±57pg m−3), the Chukchi and Beaufort Seas (93±29pg m−3), the East Asia (75±49pg m−3) and the North Pacific Ocean (69±38pg m−3). In the East Asia Sea and the North Pacific Ocean, both primary and secondary emissions of HCB from the nearby continents and/or oceans might contribute to the atmospheric HCB. In the Arctic, intense sea–ice melting in the summer of 2008 might result in the remobilization of HCB and enhance its atmospheric levels in this region.
اظهر المزيد [+] اقل [-]Population dynamics and antimicrobial susceptibility of Aeromonas spp. along a salinity gradient in an urban estuary in Northeastern Brazil النص الكامل
2014
Silva, Camila Magalhães | Evangelista-Barreto, Norma Suely | Vieira, Regine Helena Silva dos Fernandes | Mendonça, Kamila Vieira | Sousa, Oscarina Viana de
The main objective of this study was to quantify population and identify culturable species of Aeromonas in sediment and surface water collected along a salinity gradient in an urban estuary in Northeastern Brazil. Thirty sediment samples and 30 water samples were collected from 3 sampling locations (A, B and C) between October 2007 and April 2008. The Aeromonas count was 10–7050CFU/mL (A), 25–38,500CFU/mL (B) and<10CFU/mL (C) for water samples, and ∼100–37,500CFU/g (A), 1200–43,500CFU/g (B) and<10CFU/g (C) for sediment samples. Five species (Aeromonas caviae, A. sobria, A. trota, A. salmonicida and A. allosaccharophila) were identified among 41 isolates. All strains were sensitive to chloramphenicol and ceftriaxone, whereas 33 (80, 4%) strains were resistant to at least 2 of the 9 antibiotics tested. Resistance to erythromycin was mostly plasmidial. In conclusion, due to pollution, the Cocó River is contaminated by pathogenic strains of Aeromonas spp. with a high incidence of antibacterial resistance, posing a serious risk to human health.
اظهر المزيد [+] اقل [-]Assessment of pollution level using Mytilus galloprovincialis as a bioindicator species: The case of the Gulf of Trieste النص الكامل
2014
Kristan, Urška | Kanduč, Tjaša | Osterc, Andrej | Šlejkovec, Zdenka | Ramšak, Andreja | Stibilj, Vekoslava
A multidisciplinary approach was used to estimate the pollution level of the marine environment in the North Eastern Adriatic by measurement of the isotopic composition of carbon and nitrogen (δ13C, δ15N), metal/metalloids analyses (Fe, Cu, Zn, As, Se, Cd and Pb, including As speciation) in the Mytilus galloprovincialis, as well by using metallothioneins (MT) concentrations, micronuclei (MN) in gill cells and biological parameters (condition index and gonadosomatic index). Concentrations of MT were in the range from 44 to 175μgg−1 wet matter tissue and were higher at the end of the winter season. The frequency of MN did not indicate an elevated level. Sewage sludge pollution was not confirmed. Elevated As concentrations in mussel are related to salinity and low nutrients concentrations and not to pollution. Elevated concentrations of Cu, Zn and Pb were found in the Bay of Koper in comparison with the Bays of Strunjan and Piran.
اظهر المزيد [+] اقل [-]Biodegradation of aliphatic hydrocarbons in the presence of hydroxy cucurbit[6]uril النص الكامل
2014
Pasumarthi, Rajesh | Kumar, Vikash | Chandrasekharan, Sivaraman | Ganguly, Anasuya | Banerjee, Mainak | Mutnuri, Srikanth
Aliphatic hydrocarbons are one of the major environmental pollutants with reduced bioavailability. The present study focuses on the effect of hydroxy cucurbit[6]uril on the bioavailability of hydrocarbons. A bacterial consortium was used for biodegradation studies under saline and non-saline conditions. Based on denaturing gradient gel electrophoresis results it was found that the consortium under saline conditions had two different strains. The experiment was conducted in microcosms with tetradecane, hexadecane, octadecane and mixture of the mentioned hydrocarbons as the sole carbon source. The residual hydrocarbon was quantified using gas chromatography every 24h. It was found that biodegradation of tetradecane and hexadecane, as individual carbon source increased in the presence of hydroxy CB[6], probably due to the increase in their bioavailability. In case of octadecane this did not happen. Bioavailability of all three aliphatic hydrocarbons was increased when provided as a mixture to the consortium under saline conditions.
اظهر المزيد [+] اقل [-]A novel best practices approach: The MARLISCO case النص الكامل
2014
Loizidou, Xenia I. | Loizides, Michael I. | Orthodoxou, Demetra L.
Research that was undertaken to identify and evaluate best practices that can effectively minimise the amount of marine litter in European Seas is presented. Best practices were approached in a novel way that aimed to maximise the impact and added value of the FP7-funded project MARLISCO. The practices served as a tool to enhance the active participation and build capacity in key actors through the implementation of the innovative, dedicatedly-developed decision support tool, DeCyDe-4-Marlisco.This paper also presents the key ‘preference’ attributes of successful marine litter management practices and provides a snapshot of the key characteristics of the recorded best practices as a means of helping the reader, and particularly decision makers, recognise what would make their marine litter management efforts more successful.
اظهر المزيد [+] اقل [-]Indole derivatives inhibited the formation of bacterial biofilm and modulated Ca2+ efflux in diatom النص الكامل
2014
Yang, Cuiyun | Yu, Yanan | Sun, Wenjun | Xia, Chuanhai
Marine biofouling is a serious environmental problem worldwide. As an effort to find environmental friendly antifoulants, indole derivatives were determined for their activities to inhibit the growth of bacteria and diatom. The minimum inhibitory concentrations (MICs) of indole derivatives against bacteria were very low, especially for 6-chloroindole. It was proved that 6-chloroindole obviously inhibited the growth of bacteria, interfered with the formation of bacterial biofilm, destroyed bacterial cell morphology and also inhibited the growth of diatom Cylindrotheca sp. as well. By using noninvasive micro-test technique (NMT), 6-chloroindole triggered algal cellular Ca2+ efflux. The highest value was 72.03pmolcm−2s−1, 10.6 times of the control group. The present studies indicated that indole derivatives might have the potential to be new antifouling agents because of their excellent antibacterial and anti-algal activities. At the same time, Ca2+ efflux might be one of the mechanisms that indole derivatives inhibited the growth of diatom.
اظهر المزيد [+] اقل [-]Biodegradation of nitrobenzene in a lysogeny broth medium by a novel halophilic bacterium Bacillus licheniformis النص الكامل
2014
Li, Tian | Deng, Xinping | Wang, Jinjun | Chen, Yucheng | He, Lin | Sun, Yuchuan | Song, Caixia | Zhou, Zhifeng
The Bacillus licheniformis strain YX2, a novel nitrobenzene-degrading halophilic bacterium, was isolated from active sludge obtained from a pesticide factory. Strain YX2 can withstand highly acidic and alkaline conditions and high temperatures. Degradation of nitrobenzene (200mgL−1) by YX2 exceeded 70% after 72h in lysogeny broth medium (pH 4–9). Under optimal degradation conditions (33°C, pH 7 in LB medium) YX2 degraded 50, 100, 200, and 600mgL−1 nitrobenzene within 36, 36, 72, and 156h, respectively. Even in the presence of benzene, phenol or aniline, strain YX2 efficiently degraded nitrobenzene. Furthermore, strain YX2 completely degraded 600mgL−1 nitrobenzene in 7% NaCl (w/w). Thus, our data show that strain YX2 may have promise for removing nitrobenzene from complex wastewaters with high salinity and variable pH.
اظهر المزيد [+] اقل [-]Mussels as a tool for mitigation of nutrients in the marine environment النص الكامل
2014
Petersen, Jens Kjerulf | Hasler, Berit | Timmermann, Karen | Nielsen, Pernille | Tørring, Ditte Bruunshøj | Larsen, Martin Mørk | Holmer, Marianne
Long-line mussel farming has been proposed as a mitigation tool for removal of excess nutrients in eutrophic coastal waters. A full-scale mussel farm optimized for cost efficient nutrient removal was established in the eutrophic Skive Fjord, Denmark where biological and economic parameters related to nutrient removal was monitored throughout a full production cycle (1yr). The results showed that it was possible to obtain a high area specific biomass of 60tWWha−1eqvivalent to a nitrogen and phosphorus removal of 0.6–0.9 and 0.03–0.04tha−1yr, respectively. The analysis of the costs related to establishment, maintenance and harvest revealed that mussel production optimized for mitigation can be carried out at a lower cost compared to mussel production for (human) consumption. The costs for nutrient removal was 14.8€kg−1N making mitigation mussel production a cost-efficient measure compared to the most expensive land-based measures.
اظهر المزيد [+] اقل [-]Chemical characteristics of rainwater at a southeastern site of Brazil النص الكامل
2014
Facchini Cerqueira, Marcos Rodrigues | Pinto, Marcelo Fonseca | Derossi, Ingrid Nunes | Esteves, Wesley Tinoco | Rachid Santos, Mellina Damasceno | Costa Matos, Maria Auxiliadora | Lowinsohn, Denise | Matos, Renato Camargo
A total of 50 rainwater samples were analyzed in order to investigate trace elements in wet precipitation of Juiz de Fora City, during February, 2010 and February, 2011. Samples were analyzed for major cations (H3O+, Na+, NH4+, K+, Mg2+ and Ca2+) and anions (NO3−, SO42−, Cl− and HCO3−), hydrogen peroxide (H2O2), some trace metals (Cu2+, Zn2+, Cd2+ and Pb2+), as well as some other physicochemical aspects like pH, conductivity and redox potential. Rainwater pH mean was of 5.77 (±0.52). Cations and anions mean values ranged from 7.12μEq L−1 (K+) to 39.6μEq L−1 (Ca2+). Principal Component Analysis (PCA) with Varimax normalized rotation was performed, grouping the major analyzed cations and anions into different factors. Mg2+, K+, Ca2+ and HCO3− were assigned to soil contribution, Na+ and Cl− to sea–salt contribution and NO3−, SO42− and NH4+ to anthropogenic sources. Hydrogen peroxide average concentration was of 19.2±17.5μmol L−1 with higher values in summer and lower in spring and autumn, reverse case was observed for H3O+ levels. Zn2+ (7.31±2.74)μg L−1 and Cu2+ (4.07±0.74)μg L−1 were within the range of other studied areas, while Cd2+ and Pb2+ were below the detection limit.
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