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The tarballs on Texas beaches following the 2014 Texas City “Y” Spill: Modeling, chemical, and microbiological studies النص الكامل
2016
Bacosa, Hernando P. | Thyng, Kristen M. | Plunkett, Stefanie | Erdner, Deana L. | Liu, Zhanfei
We modeled the transport of oil, source-fingerprinted 44 tarball samples from Galveston Island (GV) and Mustang Island (MT), and determined the hydrocarbon and bacterial community composition of these tarballs following the 2014 Texas City “Y” Oil Spill (TCY). Transport modeling indicated that the tarballs arrived in MT before the samples were collected. Source-fingerprinting confirmed that the tarballs collected from GV and MT, 6d and 11d after the TCY, respectively, originated from the spill. Tarballs from GV showed 21% depletion of alkanes, mainly C9–C17, and 55% depletion of PAHs mainly naphthalenes, and dominated by alkane-degrading Alcanivorax and Psychrobacter. Samples from MT were depleted of 24% alkanes and 63% PAHs, and contained mainly of PAH-degrading Pseudoalteromonas. To the best of our knowledge, this is the first study to relate oil transport, tarball source-fingerprinting, chemistry, and microbiology, which provides insights on the fate of oil in the northern Gulf of Mexico.
اظهر المزيد [+] اقل [-]Air quality over a populated Andean region: Insights from measurements of ozone, NO, and boundary layer depths النص الكامل
2016
Cazorla, Maria
In this study, a hypothesis based on observations is offered to explain levels of ambient ozone in Quito, a busy urban center located at high altitude along the equatorial Andes. Supporting data includes first-time measurements of boundary layer depths in addition to ozone, NO (nitric oxide), and oxidized nitrogen observations. Mixing layer measurements were taken in June and July 2014 and in April 2015. The air quality data set is presented for the months of July through September 2014. From a total of four midday soundings launched under sunny conditions, a deep mixing layer up to 2200 magl (meters above ground level) was found only once when surface temperature was unusually high. In the other three cases, layered structures were found with the top of the mixing layer at 687 magl on average. These measurements were obtained when surface temperatures were within the usual range. Furthermore, the morning boundary layer depth was measured twice between 07:00 and 08:00. On average, a depth of 185 magl was determined. Air quality measurements for the study period show that ozone stayed below 55 ppbv while NO levels were routinely higher than 100 ppbv in the morning rush hour, and oxidized nitrogen stayed high during daytime. Observations of a generally shallow boundary layer indicate that the environment at this Andean location has the potential to accumulate pollutants. Thus, vertical dilution alone is unable to explain the observed low levels of ambient ozone. When ozone reached the highest values in the second half of September 2014, it was found that it increases with decreasing NO levels during daylight hours between 11:00 and 16:00. Therefore, air quality observations along with findings of shallow mixing layers suggest that inhibition of ozone production potentially occurs due to a NOx-saturated chemical regime.
اظهر المزيد [+] اقل [-]Chemical characterization and source apportionment of aerosol at an urban area of Central Delhi, India النص الكامل
2016
Sharma, Sudhir Kumar | Sharma, Ashima | Saxena, Mohit | Choudhary, Nikki | Masiwal, Renu | Mandal, Tuhin Kumar | Sharma, C. (Chhemendra)
The concentrations of organic carbon (OC), elemental carbon (EC), water soluble inorganic ionic components (WSIC), and major & trace elements of PM10 were studied in Delhi, an urban site of the Indo Gangetic Plain (IGP), India during January 2013 to June 2014. The average mass concentration of PM10 recorded as 249.7 ± 103.9 μg m−3 (average ± standard deviation) with a range of 61.4–584.8 μg m−3. The strong seasonal variation was noticed in the mass concentration of PM10 and its chemical composition with maxima during winter (PM10: 293.9 ± 95.6 μg m−3; OC: 30.5 ± 13.7 μg m−3; EC: 15.2 ± 7.4 μg m−3) and minima during monsoon (PM10: 143.9 ± 36.3 μg m−3; OC: 19.9 ± 16.2 μg m−3; EC: 7.4 ± 5.4 μg m−3). The average concentration of major and trace elements (Na, Mg, Al, P, S, Cl, K, Ca, Si, Cr, Ti, As, Br, Pb, Fe, Zn and Mn) was accounted for ∼18.5% of PM10 mass. Results of Positive Matrix Factorization (PMF) model, HYSPLIT4 trajectory model, PSCF analysis and cluster analysis provide region of sources and its strength and types of sources of PM10 over Delhi. Positive PMF provides that the major source of PM10 are soil dust (22.7%) followed by secondary aerosols (20.5%), vehicle emissions (17.0%), fossil fuel burning (15.5%), biomass burning (12.2%), industrial emissions (7.3%) and sea salts (4.8%) at the observational site of Delhi. The cluster analysis of air mass trajectories calculated by HYSPLIT model indicates that the air mass approaches to the observational site mainly from 4 sides (north-western IGP, Pakistan (10%); north-western IGP, Northwest Asia (45%); eastern IGP (38%); Pakistan and Arabian Sea (6%)) during study. Potential Source Contribution Function (PSCF) analysis also supports the cluster analysis indicating that the concentration of PM10 mass contributed, is mainly from IGP region (Uttar Pradesh, Haryana and Punjab etc.), Afghanistan, Pakistan and surrounding areas.
اظهر المزيد [+] اقل [-]Investigation on the differences of accumulating Escherichia coli in three types of shellfish species, involving in the environmental factors النص الكامل
2016
Jin, Lei | Li, Tiejun | Liu, Huan | Zhu, Jinping
This study investigated accumulation of Escherichia coli and aerobic colony count in three types of shellfish species. The results indicated that the capability of accumulating E. coli and aerobic colony count for Sinonovacula constricta was stronger than that for Meretrix meretrix and Tegillarca granosa, and capability of accumulating E. coli for M. meretrix was slightly stronger than that for T. granosa. However, no significant difference was observed in the capability of accumulating aerobic colony count between M. meretrix and T. granosa. Moreover, accumulation of E. coli in S. constricta is affected by contaminated seawater and E. coli were accumulated much faster and more in S. constricta when the seawater contaminated more serious. Meanwhile, the results suggested that the populations of E. coli in S. constricta changed in accordance with the weather. This is the first study to investigate the differences of accumulating E. coli in three types of shellfish species.
اظهر المزيد [+] اقل [-]Preliminary investigation of perfluoroalkyl substances in exploited fishes of two contaminated estuaries النص الكامل
2016
Taylor, Matthew D. | Johnson, Daniel D.
Perfluoroalkyl substances (PFASs) are being increasingly detected in a range of aquatic and terrestrial ecosystems, often resulting from the use of legacy fire-fighting foams. This study conducted an initial investigation of the concentrations of PFASs in the commercially and recreationally exploited species Dusky Flathead, Mud Crab, School Prawn, Sea Mullet, Yellowfin Bream, Eastern King Prawn and Sand Whiting, across two contaminated estuaries. All samples contained perfluoro-n-octane sulfonate (PFOS) except four Yellowfin Bream samples (two from each estuary). Perfluoro-n-octanoic acid (PFOA) was detected only in School Prawn samples from Fullerton Cove, while perfluoro-n-hexane sulfonate (PFHxS) was detected in prawn muscle and in fish liver samples from both estuaries. This study presents one of the first surveys of PFAS in a range of edible saltwater fish and crustaceans in Australia, and these baseline levels of contamination will prove useful for informing future surveys of these emerging contaminants.
اظهر المزيد [+] اقل [-]Influence of enhancing electrolytes on the removal efficiency of heavy metals from Gabes marine sediments (Tunisia) النص الكامل
2016
Missaoui, Amel | Said, Imen | Lafhaj, Zoubeir | Hamdi, Essaieb
This study focused on the feasibility of the treatment of heavy metals-contaminated sediments from Gabes harbor (Tunisia) using enhanced electrokinetic process. It presented a laboratory short-time electrokinetic experiment. The enhancing agents, as citric, acetic acids and sodium dodecyl sulfate (SDS) were used regarding their low environmental hazard. The electrokinetic cell was specially designed in order to elaborate two experiments at the same time. This paper is composed of three parts. The first part introduces the characterization of Gabes sediments. The second part describes the design of laboratory electrokinetic cell and the followed methods. The third part is dedicated to the results analysis. Treatment efficiency revealed that more than 80% of lead was removed from Gabes marine sediments. The reduction of cooper concentration, in sediments after treatment, ranged from 74 to 87%. Despite, the high removal of cadmium that ranged from 58 to 79%, treated sediments presented Cd concentration above the threshold limit.
اظهر المزيد [+] اقل [-]Effects of Costa Concordia shipwreck on epiphytic assemblages and biotic features of Posidonia oceanica canopy النص الكامل
2016
Bacci, T. | Penna, M. | Rende, S.F. | Trabucco, B. | Gennaro, P. | Bertasi, F. | Marusso, V. | Grossi, L. | Cicero, A.M.
This research provides first information about Posidonia oceanica canopy in the area affected by Costa Concordia wreck. Percentage cover of algal and animal taxa on the leaves was estimated and biotic features of the meadow were measured in the period just after the shipwreck until its removal from the impacted site. Changes in epiphytic assemblages and some biotic features were detected in the Disturbed site compared with Control ones, highlighting effects due to the wreck presence and activities related to its removal. A temporary decrease of encrusting macroalgae and an increase of erected macroalgae and foraminifers, as well as a temporary increase of tip erosion of the canopy were detected in the Disturbed site. The obtained results were discussed and hypotheses about possible synergic effects occurred near the wreck were commented.
اظهر المزيد [+] اقل [-]A surface tension based method for measuring oil dispersant concentration in seawater النص الكامل
2016
Cai, Zhengqing | Gong, Yanyan | Liu, Wen | Fu, Jie | O'Reilly, S.E. | Hao, Xiaodi | Zhao, Dongye
This work developed a new method to determine concentration of Corexit EC9500A, and likely other oil dispersants, in seawater. Based on the principle that oil dispersants decrease surface tension, a linear correlation was established between the dispersant concentration and surface tension. Thus, the dispersant concentration can be determined by measuring surface tension. The method can accurately analyze Corexit EC9500A in the concentration range of 0.5–23.5mg/L. Minor changes in solution salinity (<0.3%), pH (7.9–9.0), and dissolved organic matter (<2.0mg/L as TOC) had negligible effects on the measurements. Moreover, effects of extracts from marine sediments were negligible, and thus, the method may be directly applied to seawater–sediment systems. The method accuracy was confirmed by comparing with direct TOC analysis. This simple, fast, economical method offers a convenient analytical tool for quantifying complex oil dispersants in water/seawater, which has been desired by the oil spill research community and industries.
اظهر المزيد [+] اقل [-]Turbulent transport of particle-bound PAHs: A feasibility study combining GC-APLI-MS and eddy covariance النص الكامل
2016
Stader, Christian | Deventer, Malte Julian | Klemm, Otto | Achten, Christine
A novel approach combining gas chromatography-atmospheric pressure laser ionization-time-of-flight-mass spectrometry (GC-APLI-MS) with the micrometeorological eddy covariance (EC) technique is demonstrated to quantify particle-bound polycyclic aromatic hydrocarbons (PAH) mass fluxes above a central European city. During the case study, 18 different PAH compounds could be identified in two one-hour particle samples and, in combination with size-resolved particle deposition velocities obtained from EC measurements, inferred particulate PAH mass fluxes for two respective size fractions (0.060–0.108 μm and 0.170–10 μm) were quantified. Maximum concentrations and fluxes (in the order of 0.9 ± 0.09–17 ± 8 ng m−2 hr−1) were estimated for the 5-ring PAHs benzo[e]pyrene, benzo[a]pyrene and perylene. Fingerprints of PAH concentrations suggest strong pyrogenic sources, particularly wood burning.
اظهر المزيد [+] اقل [-]The protective service of mangrove ecosystems: A review of valuation methods النص الكامل
2016
Barbier, Edward B.
Concern over the loss of mangrove ecosystems often focuses on their role in protecting coastal communities from storms that damage property and cause deaths and injury. With climate change, mangrove loss may also result in less protection against coastal storms as well as sea-level rise, saline intrusion and erosion. Past valuations of the storm protection benefit of mangroves have relied on the second-best replacement cost method, such as estimating this protective value with the cost of building human-made storm barriers. More reliable methods instead model the production of the protection service of mangroves and estimate its value in terms of reducing the expected damages or deaths avoided by coastal communities. This paper reviews recent methods of valuing the storm protection service of mangroves and their role in protecting coastal areas and communities of tropical developing countries.
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