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Результаты 1621-1630 из 3,991
Long-term weathering and continued oxidation of oil residues from the Deepwater Horizon spill
2016
White, Helen K. | Wang, Chloe H. | Williams, Patrick L. | Findley, David M. | Thurston, Alana M. | Simister, Rachel L. | Aeppli, Christoph | Nelson, Robert K. | Reddy, Christopher M.
To investigate the long-term weathering of oil from the Deepwater Horizon (DWH) incident, oil-soaked sand patties were collected from Gulf of Mexico beaches from Florida to Alabama over a three-year period from 2012 to 2014. Analysis of oil residues by gas chromatography with flame ionization detection (GC-FID), thin-layer chromatography with flame ionization detection (TLC-FID), and Fourier transform infrared spectroscopy (FT-IR) indicated uniformity in their chemical composition. Some variability within and between samples was observed, arising from differences in exposure to light and water, which increase the amount of weathering. Oxygenated hydrocarbons (OxHC) produced by weathering processes dominate the majority of oil residues. These OxHC have continued recalcitrance in the environment, and increase in relative abundance over time. Analyses of the bulk characteristics of oil residues via TLC-FID and FT-IR should be continued as these techniques provide important insight into the weathering state of oil residues.
Показать больше [+] Меньше [-]Organic matter quantity and quality, metals availability and foraminiferal assemblages as environmental proxy applied to the Bizerte Lagoon (Tunisia)
2016
Martins, Maria Virgínia Alves | Helali, Mohamed Amine | Zaaboub, Noureddine | Boukef-BenOmrane, Imen | Frontalini, Fabrizio | Reis, Darlly | Portela, Helena | Clemente, Iara Martins Matos Moreira | Nogueira, Leandro | Pereira, Egberto | Miranda, Paulo | El Bour, Monia | Aleya, Lotfi
This study analyzes the benthic trophic state of Bizerte Lagoon (Tunisia) based on the total organic matter and the bioavailability of biopolymeric carbon including proteins (PTN), carbohydrates (CHO), lipids (LIP), chlorophyll a, as well as bacteria counts. The overall simultaneously extracted metals (SEM), and acid volatile sulfides (AVS) as well as the SEM/AVS ratio indicative of the toxicity of the sediments also were analyzed aiming to study their impact in the dimension, composition and structure of both dead and living benthic foraminiferal assemblages.In the studied sites TOC content is relatively high and the PTN/CHO values indicate that they can be considered as meso-eutrophic environments. The CHO/TOC and C/N values suggest that the OM which accumulated on the sediments surface has mainly natural origin despite the introduction of municipal and industrial effluents in the lagoon and the large bacterial pool.The living assemblages of benthic foraminifera of Bizerte Lagoon are quite different to other Mediterranean transitional systems studied until now. They are composed of typical lagoonal species but also include several marine and opportunistic species including significant numbers of bolivinids, buliminids, Nonionella/Nonionoides spp. and Cassidulina/Globocassidulina spp. These assemblages seem to benefitfrom the physicochemical parameters and the sediment stability. They may however face environmental stress in the lagoon related to the AVS production as a result of the organic matter degradation and toxicity in some areas due to the available concentrations of metals. Nonetheless statistical results evidence that the structure and dimension of assemblages are being controlled mostly by OM quantity and quality related mainly to the availability of PTN, CHO and chlorophyll a. Results of this work support the importance of considering OM quantity and quality in studies of environmental impact in coastal systems.
Показать больше [+] Меньше [-]Incidence of plastic debris in Sooty Tern nests: A preliminary study on Trindade Island, a remote area of Brazil
2016
de Souza Petersen, Elisa | Krüger, Lucas | Dezevieski, Alexandre | Petry, MariaVirginia | Montone, Rosalinda Carmela
Plastic is abundant in the oceans, reaching pelagic zones away from continents. Here we present the first recordings of plastic used as nest material in Sooty Tern nests, on a remote oceanic island. We describe our findings in terms of quantity, size and color of plastic debris. A total of 78 plastics were noted in 54 nests. Four color categories were found: Blue, White, Green and Red. Blue fragments were the most frequent color, present three times as much as white debris. This pattern was present despite blue fragments being smaller and lighter. The plastic debris of lowest frequency were the larger and heavier pieces (red). To our knowledge this is the first record of plastic in Sooty Tern nests. Trindade Island is on an oceanic zone expected to accumulate garbage due to the dynamic ocean currents. Such findings call for a closer inspection of pollution in the Atlantic Ocean.
Показать больше [+] Меньше [-]Validating the use of biopsy sampling in contamination assessment studies of small cetaceans
2016
Méndez-Fernandez, Paula | Galluzzi Polesi, Paola | Taniguchi, Satie | de O. Santos, Marcos C. | Montone, Rosalinda C.
Remote biopsy sampling is the most common technique for acquiring samples from free-ranging marine mammals. However, such techniques may result in variable sampling being sometimes superficial skin and blubber biopsies. For decades, blubber has been used to monitor the exposure of marine mammals to persistent organic pollutants (POPs), but little is known regarding the variability of POPs as a function of blubber depth in small cetaceans and the available literature offers variable results. Thus, the aim of the present study was to validate biopsy sampling for monitoring contaminant concentrations in small, free-ranging cetaceans. Samples from the dorsal blubber of 10 incidentally captured Atlantic spotted dolphins (Stenella frontalis) were separated into two different layers (outer and inner) to investigate the influence of sampling depth on POP concentrations. POP concentrations were compared to those of the full blubber layer. The results revealed no significant differences in lipid content between males and females or among the inner, outer and full blubber layers (p>0.05). Moreover, the wet and lipid weight concentrations of all POP classes analysed [i.e. polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethanes (DDTs), polybrominated diphenyl ethers (PBDEs), hexachlorobenzene (HCB), hexachlorocyclohexanes (HCHs), chlordanes (CHLs) and mirex] did not differ significantly with blubber depth (p>0.05). POP classes followed the same decreasing order of wet weight concentrations in blubber layers and full blubber: PCBs>DDTs>PBDEs>mirex>HCB>HCHs>CHLs. Moreover, there was a low degree of differentiation in the accumulation of POP congeners. The present findings indicated that the distribution of contaminants was homogenous with blubber depth, which validates the use of biopsy sampling for the assessment of contaminants in small cetaceans.
Показать больше [+] Меньше [-]Proteomic analysis of bleached and unbleached Acropora palmata, a threatened coral species of the Caribbean
2016
Ricaurte, Martha | Schizas, Nikolaos V. | Ciborowski, Paweł | Boukli, Nawal M.
There has been an increase in the scale and frequency of coral bleaching around the world due mainly to changes in sea temperature. This may occur at large scales, often resulting in significant decline in coral coverage. In order to understand the molecular and cellular basis of the ever-increasing incidence of coral bleaching, we have undertaken a comparative proteomic approach with the endangered Caribbean coral Acropora palmata. Using a proteomic tandem mass spectrometry approach, we identified 285 and 321 expressed protein signatures in bleached and unbleached A. palmata colonies, respectively, in southwestern Puerto Rico. Overall the expression level of 38 key proteins was significantly different between bleached and unbleached corals. A wide range of proteins was detected and categorized, including transcription factors involved mainly in heat stress/UV responses, immunity, apoptosis, biomineralization, the cytoskeleton, and endo–exophagocytosis. The results suggest that for bleached A. palmata, there was an induced differential protein expression response compared with those colonies that did not bleach under the same environmental conditions.
Показать больше [+] Меньше [-]Isolation, identification, and crude oil degradation characteristics of a high-temperature, hydrocarbon-degrading strain
2016
Liu, Boqun | Ju, Meiting | Liu, Jinpeng | Wu, Wentao | Li, Xiaojing
In this work, a hydrocarbon-degrading bacterium Y-1 isolated from petroleum contaminated soil in the Dagang Oilfield was investigated for its potential effect in biodegradation of crude oil. According to the analysis of 16S rRNA sequences, strain Y-1 was identified as Bacillus licheniformis. The growth parameters such as pH, temperature, and salinity were optimised and 60.2% degradation of crude oil removal was observed in 5days. The strain Y-1 showed strong tolerance to high salinity, alkalinity, and temperature. Emplastic produced by strain Y-1 at high temperatures could be applied as biosurfactant. Gas chromatography analysis demonstrated that the strain Y-1 efficiently degraded different alkanes from crude oil, and the emplastic produced by strain Y-1 promoted the degradation rates of long-chain alkanes when the temperature increased to 55°C. Therefore, strain Y-1 would play an important role in the area of crude oil contaminant bioremediation even in some extreme conditions.
Показать больше [+] Меньше [-]Assessment of the impact of emissions reductions on air quality over North China Plain
2016
Han, Xiao | Zhang, Meigen | Zhu, Lingyun | Skorokhod, Andrei
The production rate of secondary pollutants was highly non-linear with the emission intensity of their precursors. In this study, the air quality modeling system RAMS-CMAQ with zero-out sensitivity test was applied to conduct source sensitivity approaches of PM2.5 for four source categories (industry, power plants, transport, and residential) over the North China Plain (NCP) in January and July of 2013. The results show that the residential and industry emission sector were the greatest contributors to domain-wide PM2.5 in January and July, respectively. The largest variation could exceed 200 μg m−3 attributed to the residential sector in January when a heavy pollution period appeared, and could reach 40–60 μg m−3 attributed to the industry sector in July in the heavy pollution area, respectively. The nonlinear relationship between the secondary pollutant formation and its precursors was reflected by this source sensitivity approaches, as the summation of the secondary pollutant variations attributed to the four sources was obviously different from the simulated baseline concentration and the mass burden of nitrate would increase upon removal of the power plants or transport emission sector in the heavy pollution regions in January. Further analysis indicated that the improvement of atmospheric oxidation capacity due to emission sector removal coupled with the sufficient precursor nitrogen oxide under severe pollution background should be the main reason of the negative variation of nitrate appeared in the sensitivity test. This feature indicates that the atmospheric oxidation capacity is an important impact factor in determining the production rate of nitrate formation, and could further influence the variation feature of PM2.5 mass burden during the pollution episode. Thus, it is suggested that the comprehensive pollution control strategies should be implemented based on the specific pollution condition. Additionally, the nonlinearity of secondary pollutants formation should be reasonably considered for developing effective emission control strategies.
Показать больше [+] Меньше [-]Seasonal size distribution and possible health implications of atmospheric aerosols collected from a rural site of eastern central India
2016
Nirmalkar, Jayant | Deshmukh, Dhananjay K. | Deb, Manas K. | Chandrawanshi, Swati | Tiwari, Swapnil
This paper contributes for the first time the seasonal mass size distribution of atmospheric aerosols and their possible health implications in a rural area of eastern central India. Size-segregated atmospheric aerosols were collected from July 2012 to June 2013 at rural site near Mahanadi riverside basin of Rajim (20° 59′N and 81°55′E), Chhattisgarh, India using nine-stage cascade impactor. Bimodal size distribution was found with stable peaks at 0.4–0.7 μm (fine mode) and 4.4–5.8 μm (coarse mode) during monsoon, winter, spring and summer seasons at study site. The mass median aerodynamic diameter of total impactor particle sizes was shifted from lower particle size in winter to higher particle size in summer. High concentrations of size-segregated aerosols were found during winter season with 45%, 55% and 36% of PM2.5–10, PM2.5 and PM1, respectively of the total PM10 aerosol. One unique observation was that the mass concentration of particulate matter increases abruptly in May and June during summer season, which was due to in situ burning of rice crop residues. The concentrations of upper respiratory tract and lungs particles were found to be highest during winter whereas respiratory airways particles showed maxima during summer season. The highest numbers of unfavorable days (i.e. value of air quality index > 101) were also observed during winter followed by summer season. The significant positive correlations found among particle in fine size bins (<0.43–2.5 μm) during winter and summer season was mainly due to the biomass burning activities during the study period at a rural site in eastern central India.
Показать больше [+] Меньше [-]Plastic debris in great skua (Stercorarius skua) pellets corresponds to seabird prey species
2016
Hammer, S. | Nager, R.G. | Johnson, P.C.D. | Furness, R.W. | Provencher, J.F.
Plastic is a common item in marine environments. Studies assessing seabird ingestion of plastics have focused on species that ingest plastics mistaken for prey items. Few studies have examined a scavenger and predatory species that are likely to ingest plastics indirectly through their prey items, such as the great skua (Stercorarius skua). We examined 1034 regurgitated pellets from a great skua colony in the Faroe Islands for plastics and found approximately 6% contained plastics. Pellets containing remains of Northern fulmars (Fulmarus glacialis) had the highest prevalence of plastic. Our findings support previous work showing that Northern fulmars have higher loads of plastics than other sympatric species. This study demonstrates that marine plastic debris is transferred from surface feeding seabird species to predatory great skuas. Examination of plastic ingestion in species that do not ingest plastics directly can provide insights into how plastic particles transfer vertically within the food web.
Показать больше [+] Меньше [-]Abiotic factors influencing biomass accumulation of green tide causing Ulva spp. on Pyropia culture rafts in the Yellow Sea, China
2016
Keesing, John K. | Liu, Dongyan | Shi, Yajun | Wang, Yujue
Annually recurrent green-tides in the Yellow Sea have been shown to result from direct disposal into the sea of fouling Ulva from Pyropia aquaculture. The role abiotic factors play in Ulva biomass accumulation on rafts was studied to find ways to mitigate this problem. Dissolved inorganic nitrogen (DIN) was very high at all sites, but the highest Ulva biomass was associated with the lowest DIN and anthropogenic N. Under luxuriant background nutrient conditions, variability in temperature and periods of emersion, rather than pH, light and salinity determined Ulva biomass. Two dominant species of Ulva displayed differing tolerances to temperature and desiccation which helped explain why Ulva prolifera dominates floating green-tides. Rather than trying to mitigate green-tides only by reducing nutrient pollution, an earlier harvest of Pyropia in southern Jiangsu Province especially before temperatures increase greatly above 10°C during April, could reduce the biomass of U. prolifera disposed from rafts.
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