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Resultados 1131-1140 de 4,307
Phospholipid fatty acid (PLFA) analysis for profiling microbial communities in offshore produced water Texto completo
2017
Fan, Fuqiang | Zhang, Baiyu | Morrill, Penny L.
A method based on phospholipid fatty acid (PLFA) analysis for profiling microbial communities in offshore produced water was optimized. The operation parameters affecting final PLFA profiling performance from the solid phase extraction (SPE) purification and fatty acid methyl esters (FAMEs) yielding process were investigated. Under the selected conditions, 92.9%, 96.3% and 92.8% of the spiked phospholipid standards C16:1 (cis-9) PC, C18:1 (cis-9) PC, and C19:0 PC were recovered, respectively, using 10mL methanol as elution solvent on a non-commercial SPE column. Over 90% of spiked C19:0 PC was recovered before sample transesterification. Four parameters including alkaline reagent, volume of acid for neutralization, time and temperature for FAMEs derivatization were examined. Gas Chromatography-Mass Spectrometry (GC-MS) was used to analyze FAMEs and the method linearities, recoveries of 29 FAMEs during transesterification, detection limits, relative standard deviations were presented. The results provided valuable information for biological reservoir souring control.
Mostrar más [+] Menos [-]Excess seawater nutrients, enlarged algal symbiont densities and bleaching sensitive reef locations: 2. A regional-scale predictive model for the Great Barrier Reef, Australia Texto completo
2017
Wooldridge, Scott A. | Heron, Scott F. | Brodie, J. E. (Jon E.) | Done, Terence J. | Masiri, Itsara | Hinrichs, Saskia
A spatial risk assessment model is developed for the Great Barrier Reef (GBR, Australia) that helps identify reef locations at higher or lower risk of coral bleaching in summer heat-wave conditions. The model confirms the considerable benefit of discriminating nutrient-enriched areas that contain corals with enlarged (suboptimal) symbiont densities for the purpose of identifying bleaching-sensitive reef locations. The benefit of the new system-level understanding is showcased in terms of: (i) improving early-warning forecasts of summer bleaching risk, (ii) explaining historical bleaching patterns, (iii) testing the bleaching-resistant quality of the current marine protected area (MPA) network (iv) identifying routinely monitored coral health attributes, such as the tissue energy reserves and skeletal growth characteristics (viz. density and extension rates) that correlate with bleaching resistant reef locations, and (v) targeting region-specific water quality improvement strategies that may increase reef-scale coral health and bleaching resistance.
Mostrar más [+] Menos [-]Organotins and new antifouling biocides in water and sediments from three Korean Special Management Sea Areas following ten years of tributyltin regulation: Contamination profiles and risk assessment Texto completo
2017
A simultaneous monitoring study on organotins (butyltins and phenyltins) and most frequently used alternative antifouling biocides (Irgarol 1051, Diuron, Sea-Nine 211 and M1) in water and sediments (n=44) collected from three Special Management Sea Areas operated by Korean government. The lower concentration of butyltins (BTs) than that of new antifouling biocides (NEW) was found in water but the significant greater concentration of BTs than that of NEW was still found in sediments. The tributyltin (TBT) levels in water exceeded the chronic criterion to protect seawater aquatic life at several sites. Even ten years after the ban of the use of TBT-based antifouling paint, the concentrations of TBT, Diuron and Irgarol 1051 in sediments from shipyards exceeded global sediment quality guidelines and potentially poses adverse risks on marine organisms and extremely high concentration of TBT up to 2304ng/g was found for a sediment collected at a shipyard.
Mostrar más [+] Menos [-]Nitric-oxide generation induced by metals plays a role in their accumulation by Phallusia nigra hemocytes Texto completo
2017
Ascidians are good monitors for assessing water quality, since they filter large volumes of water; however, little is known about how xenobiotics, including metals, can affect ascidian hemocytes. Metals can be either toxic or beneficial to health, inducing many different responses. The response mechanism depends on the class of metals to which organisms are exposed: essential, nonessential, and borderline. To analyze the influence of metals from different classes on the protective mechanisms of an ascidian, we investigated the production of nitric oxide (NO) after exposure to various concentrations of Mg, Mn and Pb over different time periods. We also determined the amounts of each metal in the hemocytes. Our results indicated that especially Pb could stimulate NO production. Although Pb induced the highest NO production, cell viability was not severely altered in all Pb concentrations and time periods. Ascidians might serve as biomonitor for Pb, since their vanadocytes accumulate Pb.
Mostrar más [+] Menos [-]Bio-effect-monitoring of long-term thermal wastes on the oyster, Crassostrea gigas, using heat shock proteins Texto completo
2017
We bio-monitored the stress of oyster, Crassostrea gigas, for possible long term effects of thermal waste from a power plant. The expression level of its heat shock proteins (HSPs) was measured by real time-reverse transcript PCR along with their density and growth in the field. Oyster size varied in a distance dependent pattern. Physics modeling for evaluation of spreading of the thermal effluent revealed that station A is affected by the thermal effluents abundance, and the size of C. gigas showed a negative relationship with distance to the power plant. The abundance and size of C. gigas were smallest at station A, which was closest to the thermal effluent outlet. The kinetics of changes in the hsp70 and hsp90 mRNA levels in the mantle of C. gigas were also investigated. Regardless of the higher expression level of hsp70 mRNA than hsp90, both hsp70 and hsp90 mRNA levels were significantly higher at station A. The expression levels decreased inversely with distance from the thermal effluent outlet, with expression of hsp70 mRNA at station A being approximately 7-fold higher than at station B and 15-fold higher than at station C. Similarly, expression of hsp90 mRNA at station A was approximately 14-fold higher than at station B and 22-fold higher than at station C. The present findings provide new insights on biological correlation among the growth of individuals and population size and the molecular index in C. gigas following thermal effects.
Mostrar más [+] Menos [-]Phosphorus effects on radial oxygen loss, root porosity and iron plaque in two mangrove seedlings under cadmium stress Texto completo
2017
Dai, Minyue | Liu, Jingchun | Liu, Wenwen | Lu, Haoliang | Jia, Hui | Hong, Hualong | Yan, Chongling
Phosphorus is an indispensable element for plants, but its role in alleviating the cadmium toxicity of mangrove seedlings is poorly documented. In this study, mangrove seedlings were grown in hydroponics and exposed to various Cd and P treatments. Data suggested that the inhibitory effect of Cd on the rate of radial oxygen loss and root porosity was alleviated by P. A. marina had a higher rate of ROL and POR, indicating that it had a stronger adaptability to anaerobic environment. K. obovata induced a higher Fe concentration in iron plaque under co-application of Cd and P, which may relate to higher biomass. Furthermore, P increased Cd concentration in iron plaque, implying that iron plaque can be an obstacle to prevent Cd entering into the plant, but most Cd was still distributed in its roots. These findings highlight a novel mechanism of Cd detoxification with P addition in mangrove seedlings.
Mostrar más [+] Menos [-]Spatial and seasonal trends of polychlorinated dioxins, furans and dioxin-like polychlorinated biphenyls in air using passive and active samplers and inhalation risk assessment Texto completo
2017
Francisco, Ana Paula | Nardocci, Adelaide Cássia | Tominaga, Maria Yumiko | da Silva, Camila Rodrigues | Assunção, João Vicente de
Thirty-five and eleven air samples were collected using, respectively, active samplers (filter + PUF) and passive samplers (PUF disks), over two consecutive four-month periods (spring and autumn-winter), in urban, urban/industrial, and rural (background) sites in São Paulo, Brazil. All the samples were extracted with toluene:acetone (9:1) in a Soxhlet apparatus, and the extracts were then purified. Analysis for polychlorinated dioxins and furans (PCDD/Fs) and for dioxin-like polychlorinated biphenyls (dl-PCBs) were made by High Resolution Gas Chromatography/High Resolution Mass Spectrometry (HRGC-HRMS). Human exposure risk was evaluated using inhalation risk assessment. Results showed: (1) there are statistical differences for PCDD/F concentrations in air between periods 1 and 2 (p = 0.03), whereas dl-PCB levels were not statistically different (p = 0.52); (2) PCDD/F and dl-PCB air levels were in the following order: urban/industrial > urban > rural for both active and passive samples; (3) PCDD/F and dl-PCB concentrations ranged from 7.76 to 453 fg TEQ/m³ in active air samples, and from 6.11 to 469 fg TEQ/m³ in passive air samples; (4) sampling rates for PCDD/Fs by the two approaches used showed considerable differences; (5) average daily intake by inhalation ranged from 18.1 to 55.6 fg TEQ/kg day, respectively, for adults and children, representing 1.8–5.6% of the lower range of the Tolerable Daily Intake recommended by the World Health Organization. Based on these results, the inhalation risk for PCDD/Fs and dl-PCBs, for local São Paulo residents, should be considered low.
Mostrar más [+] Menos [-]Effects of metal contamination on the gene expression profile of two benthic species: Cerastoderma edule and Ruditapes philippinarum Texto completo
2017
This study aimed to identify new biomarkers for metal exposure in two bivalve species. Suppressive Subtractive Hybridization (SSH) was employed to evaluate the transcriptomic response of Cerastoderma edule and Ruditapes philippinarum to metal pollution. Protein synthesis and catalytic activity were the most affected metabolic processes in C. edule and R. philippinarum, respectively. Also, different genes responded to the effect of contamination in each species. The different response observed in both species reinforces the importance of including more than one bioindicator species in risk assessment studies. These results provide the basis for new studies, which are necessary for further validation of the use of the identified genes as molecular biomarkers for metal exposure.
Mostrar más [+] Menos [-]Benthic ecological status of Algerian harbours Texto completo
2017
This work is an overview of all available benthic data collected in the Algerian harbours between 1983 and 2001. So, total of 571 stations were reported in the 10 major Algerian harbours along the Algerian coast (1200km). Two main categories of harbours were distinguished according to their hydrodynamic regime and volume of water exchange between inner harbour basins and the entrance of the harbours. Univariate, multivariate, benthic indices and Biological Traits of Life approaches were applied on stations sampled in the late 1990s and long-term observations in six out of these ten harbours. These approaches assessed the main characteristics and ecological statuses from these south Mediterranean harbours. One of the main characteristics of the Algerian harbours was the very high species diversity (847 species). Although all the fauna was dominated by pollution-tolerant species; some harbours such as Bethioua and Djendjen hosted normal benthic communities as found in the open sea, but also included some pollution indicator species typical of a slight polluted system. On the contrary, the newly constructed port of Skikda showed perturbed benthic communities in relation to hydrocarbon pollution. Biological Traits of Life analysis reinforced the separation of benthic species along a gradient reflecting their sensitivity or tolerance to pollution. This response was related to an increase in organic matter content, probably associated with a general organic and metal contamination, from the entrance of the harbour to the innermost basins in areas with weak circulation, high sedimentation rate and concentrations of pollutants. Except for Oran harbour, where the poor to moderate ecological status remained unchanged with time, the other harbours showed an improvement or a slight degradation. A strategy of long-term monitoring should be promoted, based on a restricted and selected number of stations characteristic of the different basins and water masses occupying the harbours.
Mostrar más [+] Menos [-]Evaluation of Soil Function Following Remediation of Petroleum Hydrocarbons—a Review of Current Remediation Techniques Texto completo
2017
O’Brien, Peter L. | DeSutter, Thomas M. | Casey, Francis X. M. | Wick, Abbey F. | Khan, Eakalak
PURPOSE OF REVIEW: Management of lands contaminated by petroleum hydrocarbons (PHC) continues to evolve, as project goals may be shifting from contaminant reduction to ecosystem restoration. Restoring soil function is vital to overall ecosystem recovery, as soils perform numerous processes that are inhibited by PHC contamination. The purpose of this review is to summarize the effects of various remediation strategies on soil properties and evaluate how those effects relate to soil functions. RECENT FINDINGS: All remediation techniques alter soil function, and the extent of alteration is based on project-specific operational parameters. Broadly, most techniques alter soil organic matter (SOM) content and soil pH, which are important variables associated with many soil processes. Additionally, recent technological advances have made the characterization of soil microbial communities and activities more accessible, so the field continues to gain knowledge on how remediation strategies affect soil microorganisms that are vital in nutrient cycling and waste management. This review identified soil properties and functions that are likely to be affected by each strategy and that should be monitored following successful remediation. The extent of changes in soil properties is dictated by specific implementation of remediation methods, so general comparisons between methods may not be appropriate. While important variables like SOM and pH are valuable indicators of soil function, the dynamic relationships between all soil properties should not be overlooked following soil remediation. Thus, future research on soil remediation should strive to assess changes in how soils function, in addition to contaminant removal efficiency.
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