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Resultados 981-990 de 2,459
Enhanced biodegradation of total polycyclic aromatic hydrocarbons (TPAHs) by marine halotolerant Achromobacter xylosoxidans using Triton X-100 and β-cyclodextrin – A microcosm approach
2014
Dave, Bharti P. | Ghevariya, Chirag M. | Bhatt, Jwalant K. | Dudhagara, Dushyant R. | Rajpara, Rahul K.
Ability of Achromobacter xylosoxidans, a chrysene degrading marine halotolerant bacterium to degrade polycyclic aromatic hydrocarbons (PAHs) using a cost effective laboratory microcosm approach, was investigated. Effect of variables as chrysene, glucose as a co-substrate, Triton X-100 as a non-ionic surfactant and β-cyclodextrin as a PAHs solubilizer was examined on degradation of low molecular weight (LMW) and high molecular weight (HMW) PAHs. A total of eleven PAHs detected from polluted saline soil were found to be degraded. Glucose, in combination with Triton X-100 and β-cyclodextrin resulted in 2.8 and 1.4-fold increase in degradation of LMW PAHs and 7.59 and 2.23-fold increase in degradation of HMW PAHs, respectively. Enhanced biodegradation of total PAHs (TPAHs) by amendments with Triton X-100 and β-cyclodextrin using Achromobacter xylosoxidans can prove to be promising approach for in situ bioremediation of marine sites contaminated with PAHs.
Mostrar más [+] Menos [-]Transforming management of tropical coastal seas to cope with challenges of the 21st century
2014
Sale, Peter F. | Agardy, Tundi | Ainsworth, Cameron H. | Feist, Blake E. | Bell, Johann D. | Christie, Patrick | Hoegh-Guldberg, Ove | Mumby, P. J. (Peter J.) | Feary, David A. | Saunders, Megan I. | Daw, Tim M. | Foale, Simon J. | Levin, Phillip S. | Lindeman, Kenyon C. | Lorenzen, Kai | Pomeroy, R. S. (Robert S.) | Allison, Edward H. | Bradbury, R.H. | Corrin, Jennifer | Edwards, Alasdair J. | Obura, David O. | Sadovy de Mitcheson, Yvonne J. | Samoilys, Melita A. | Sheppard, Charles R.C.
Over 1.3 billion people live on tropical coasts, primarily in developing countries. Many depend on adjacent coastal seas for food, and livelihoods. We show how trends in demography and in several local and global anthropogenic stressors are progressively degrading capacity of coastal waters to sustain these people. Far more effective approaches to environmental management are needed if the loss in provision of ecosystem goods and services is to be stemmed. We propose expanded use of marine spatial planning as a framework for more effective, pragmatic management based on ocean zones to accommodate conflicting uses. This would force the holistic, regional-scale reconciliation of food security, livelihoods, and conservation that is needed. Transforming how countries manage coastal resources will require major change in policy and politics, implemented with sufficient flexibility to accommodate societal variations. Achieving this change is a major challenge – one that affects the lives of one fifth of humanity.
Mostrar más [+] Menos [-]Nitrogen and phosphorus losses from agricultural systems in China: A meta-analysis
2014
Cao, Di | Cao, Wenzhi | Fang, Jing | Cai, Longyan
Studies worldwide have indicated that agricultural pollution is the main source of nitrogen and phosphorus (N and P) in surface waters. A systematic understanding of N and P sources and sinks in agricultural systems is important for selecting the appropriate remedial strategies to control nutrient losses and water pollution. Based on nationwide data and a long-term monitoring program in Southeast China, the nationwide spatial and temporal patterns of N and P losses and the relationships between such losses and N and P inputs and rainfall were analyzed. The results showed that the annual nutrient losses from agricultural systems in China strongly varied, and the N/P values ranged from 0.01 to 51.0, with a majority at approximately 0–20, and an arithmetic mean of 9.73; these values mostly overlap the suitable range of N/P (6–15) for red bloom algae.
Mostrar más [+] Menos [-]Early contamination of European flounder (Platichthys flesus) by PCDD/Fs and dioxin-like PCBs in European waters
2014
Nunes, Margarida | Martinho, Filipe | Vernisseau, Anaïs | Marchand, Philippe | Le Bizec, Bruno | van der Veer, Henk W. | Cabral, Henrique N. | Ramos, Fernando | Pardal, Miguel A.
Contamination levels and profiles of 7 polychlorinated-p-dioxins, 10 polychlorinated furans (PCDD/Fs) and 12 dioxin-like polychlorinated biphenyls (dl-PCBs) were investigated in juvenile European flounder (Platichthys flesus) captured in different nursery areas in the northeastern Atlantic coast across its geographical distribution range. The toxic equivalent concentrations (WHO-TEQfish) were also determined in order to evaluate which P. flesus population was more exposed to dioxin-like toxicity. Juveniles caught in the Sørfjord (Norway) showed the lowest WHO-TEQfish concentration (0.052pg WHO-TEQfishg−1wet weight) whereas the highest value was observed in fish from the Wadden Sea (The Netherlands; 0.291pg WHO-TEQfishg−1ww), mainly due to the greater contribution of 2,3,7,8-tetrachlorodibenzo-p-dioxin, the most toxic congener. Nonetheless, when comparing the results with existent tissue residue-based toxicity benchmarks, no adverse effects resulting from PCDD/Fs and dl-PCBs are expected to occur in flounder from the studied systems.
Mostrar más [+] Menos [-]Copper bioavailability and toxicity to Mytilus galloprovincialis in Shelter Island Yacht Basin, San Diego, CA
2014
Bosse, Casey | Rosen, Gunther | Colvin, Marienne | Earley, Patrick | Santore, Robert | Rivera-Duarte, Ignacio
The bioavailability and toxicity of copper (Cu) in Shelter Island Yacht Basin (SIYB), San Diego, CA, USA, was assessed with simultaneous toxicological, chemical, and modeling approaches. Toxicological measurements included laboratory toxicity testing with Mytilus galloprovincialis (Mediterranean mussel) embryos added to both site water (ambient) and site water spiked with multiple Cu concentrations. Chemical assessment of ambient samples included total and dissolved Cu concentrations, and Cu complexation capacity measurements. Modeling was based on chemical speciation and predictions of bioavailability and toxicity using a marine Biotic Ligand Model (BLM). Cumulatively, these methods assessed the natural buffering capacity of Cu in SIYB during singular wet and dry season sampling events. Overall, the three approaches suggested negligible bioavailability, and isolated observed or predicted toxicity, despite an observed gradient of increasing Cu concentration, both horizontally and vertically within the water body, exceeding current water quality criteria for saltwater.
Mostrar más [+] Menos [-]The origin of the Ulva macroalgal blooms in the Yellow Sea in 2013
2014
Zhang, Jianheng | Huo, Yuanzi | Wu, Hailong | Yu, Kefeng | Kim, Jang Kyun | Yarish, Charles | Qin, Yutao | Liu, Caicai | Xu, Ren | He, Peimin
Green algal blooms have occurred in the Yellow Sea for seven consecutive years from 2007 to 2013. In this study, satellite image analysis and field shipboard observations indicated that the Ulva blooms in 2013 originated in the Rudong coast. The spatial distribution of Ulva microscopic propagules in the Southern Yellow Sea also supported that the blooms originated in the Rudong coast. In addition, multi-source satellite data were used to evaluate the biomass of green algae on the Pyropia aquaculture rafts. The results showed that approximately 2784 tons of Ulva prolifera were attached to the rafts and possessed the same internal transcribed spacer and 5S rDNA sequence as the dominant species in the 2013 blooms. We conclude that the significant biomass of Ulva species on the Pyropia rafts during the harvesting season in radial tidal sand ridges played an important role in the rapid development of blooms in the Yellow Sea.
Mostrar más [+] Menos [-]Molecular phylogeny and PSP toxin profile of the Alexandrium tamarense species complex along the coast of China
2014
Zou, Cheng | Ye, Rui-Min | Zheng, Jian-Wei | Luo, Zhao-He | Gu, Hai-Feng | Yang, Wei-Dong | Li, Hong-Ye | Liu, Jie-Sheng
To explore the genetic diversity and paralytic shellfish poisoning (PSP) toxin profile of the Alexandrium tamarense species complex along the coast of China, 67 strains of A. tamarense from the China Sea were collected and genetic diversity were analyzed based on the rDNA sequences. In addition, PSP toxin compositions and contents were detected by HPLC. According to the 5.8S rDNA and ITS, and LSU rDNA D1–D2 sequence, A. tamarense in the China Sea comprises at least Group IV and Group I ribotypes. In these Chinese strains, the toxins with the highest concentration in the profile were C1/2, gonyautoxins 1/4 (GTX1/4) and neosaxitoxin (NEO). However, the toxin profiles were atypical and C1/2 toxins were not detected in some strains. No strict correlation was observed between the PSP toxins profile and the geographical distribution.
Mostrar más [+] Menos [-]Depletion and biodegradation of hydrocarbons in dispersions and emulsions of the Macondo 252 oil generated in an oil-on-seawater mesocosm flume basin
2014
Brakstad, Odd G. | Daling, Per S. | Faksness, Liv-G. | Almås, Inger K. | Vang, Siv-H. | Syslak, Line | Leirvik, Frode
Physically and chemically (Corexit 9500) generated Macondo 252 oil dispersions, or emulsions (no Corexit), were prepared in an oil-on-seawater mesocosm flume basin at 30–32°C, and studies of oil compound depletion performed for up to 15days. The use of Corexit 9500 resulted in smaller median droplet size than in a physically generated dispersion. Rapid evaporation of low boiling point oil compounds (C⩽15) appeared in all the experiments. Biodegradation appeared to be an important depletion process for compounds with higher boiling points in the dispersions, but was negligible in the surface emulsions. While n-alkane biodegradation was faster in chemically than in physically dispersed oil no such differences were determined for 3- and 4-ring PAH compounds. In the oil dispersions prepared by Corexit 9500, increased cell concentrations, reduction in bacterial diversity, and a temporary abundance of bacteria containing an alkB gene were associated with oil biodegradation.
Mostrar más [+] Menos [-]Three dimensional simulation of transport and fate of oil spill under wave induced circulation
2014
Liu, Tianyi | Peter Sheng, Y.
An oil spill model is developed and coupled to a current-wave model to simulate oil spill transport in aquatic environments where waves are present. The oil spill model incorporates physical–chemical processes of oil spill, and simulates oil slick transport by a circulation-driven Lagrangian Parcel model. Using the coupled oil spill model and the current-wave model CH3D-SWAN, a laboratory observed wave induced circulation and oil slick evolution are successfully simulated, while different current-wave coupling schemes generate different flow patterns and oil slick evolution. The modeling system is also shown to simulate Langmuir circulation and resulting oil slicks. Hypothetical scenarios of oil spill near Virginia coast during Hurricane Isabel and Irene are simulated using the oil spill model and the CH3D-Storm Surge Modeling System to assess the role of storm waves during oil spill. The spill area is significantly larger when storm waves are considered, implying waves significantly increase oil spill dispersion.
Mostrar más [+] Menos [-]Managing ocean information in the digital era – Events in Canada open questions about the role of marine science libraries
2014
Wells, P. G.
Information is the foundation of evidence-based policies for effective marine environmental protection and conservation. In Canada, the cutback of marine science libraries introduces key questions about the role of such institutions and the management of ocean information in the digital age. How vital are such libraries in the mission of studying and protecting the oceans? What is the fate and value of the massive grey literature holdings, including archival materials, much of which is not in digital form but which often contains vital data? How important is this literature generally in the marine environmental sciences? Are we likely to forget the history of the marine pollution field if our digital focus eclipses the need for and access to comprehensive collections and skilled information specialists? This paper explores these and other questions against the backdrop of unprecedented changes in the federal libraries, marine environmental science and legislation in Canada.
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