Affiner votre recherche
Résultats 561-570 de 2,512
A three-step model to assess shoreline and offshore susceptibility to oil spills: The South Aegean (Crete) as an analogue for confined marine basins Texte intégral
2014
Alves, Tiago M. | Kokinou, Eleni | Zodiatis, George
This study combines bathymetric, geomorphological, geological data and oil spill predictions to model the impact of oil spills in two accident scenarios from offshore Crete, Eastern Mediterranean. The aim is to present a new three-step method of use by emergency teams and local authorities in the assessment of shoreline and offshore susceptibility to oil spills. The three-step method comprises: (1) real-time analyses of bathymetric, geomorphological, geological and oceanographic data; (2) oil dispersion simulations under known wind and sea current conditions; and (3) the compilation of final hazard maps based on information from (1) and (2) and on shoreline susceptibility data. The results in this paper show that zones of high to very-high susceptibility around the island of Crete are related to: (a) offshore bathymetric features, including the presence of offshore scarps and seamounts; (b) shoreline geology, and (c) the presence near the shore of sedimentary basins filled with unconsolidated deposits of high permeability. Oil spills, under particular weather and oceanographic conditions, may quickly spread and reach the shoreline 5–96h after the initial accident. As a corollary of this work, we present the South Aegean region around Crete as a valid case-study for confined marine basins, narrow seaways, or interior seas around island groups.
Afficher plus [+] Moins [-]A review of the association between air pollutant exposure and allergic diseases in children Texte intégral
2014
Lee, Jae Young | Lee, Seung–Bok | Bae, Gwi–Nam
We reviewed the results of previous studies that investigated the association between allergic symptoms in children and exposure to the major air pollutants, here identified as nitrogen dioxide (NO2), ozone (O3), particulate matter (PM2.5 and PM10), volatile organic compounds (VOCs), sulfur dioxide (SO2), soot, and carbon monoxide (CO), in terms of the odds ratios reported. We also reviewed a common procedure used in previous studies for building a whole study design based on application of an observational research method and various analysis models. Most previous studies reported odds ratios above unity and found a positive association between allergic symptoms and exposure to major air pollutants. When the strength of the associations between exposure to air pollutants and allergic disease in children were compared by normalization of the odds ratios, exposure to PM2.5 was found to have the strongest association, followed by NO2, while exposure to PM10 was found to have the weakest association.
Afficher plus [+] Moins [-]Factors contributing to elevated concentrations of PM2.5 during wintertime near Boise, Idaho Texte intégral
2014
Mwaniki, George Ruchathi | Rosenkrance, Chelsea | Will Wallace, H. | Tom Jobson, B. | Erickson, Mathew H. | Lamb, Brian K. | Hardy, Rick J. | Zalakeviciute, Rasa | VanReken, Timothy M.
Wintertime chemical composition of water–soluble particulate matter with aerodynamic diameter less than 2.5μm (PM2.5) was monitored in the Treasure Valley region near Boise, Idaho. Aerosol was sampled using a Particle Into Liquid Sampler (PILS) and subsequently analyzed using ion exchange chromatography and a total organic carbon analyzer. During the two–month sampling campaign, the region experienced varying meteorological regimes, with an extended atmospheric stagnation event towards the end of the study. For all of the weather regimes, water–soluble PM2.5 was dominated by organic material, but particulate nitrate showed the greatest variation over time. These variations in particulate nitrate concentration were found to be dependent on the time of day, nitrogen oxides (NOX) concentrations, and relative humidity. The increases in particulate nitrate did not correlate with an equivalent molar increase of ammonium concentration, ruling out solid ammonium nitrate formation as the dominant source. Instead, our analysis using an online aerosol thermodynamic model suggests that the condensation of gas phase nitric acid was possible within the meteorological conditions experienced during the study. In running this model, atmospheric chemical and physical parameters close to those observed during the study were used as model input. The simulation was run for three different scenarios, representing the different meteorological regimes experienced during the study. From the simulation particulate nitrate concentration was highest during cold and humid nights. Currently this region is in attainment with the National Ambient Air Quality Standards (NAAQS) for PM2.5; however, with the projected increase in population and economic growth, and the subsequent increase in NOX emissions, these episodic increases in particulate nitrate have the potential of pushing the area to non–attainment status.
Afficher plus [+] Moins [-]Validation trials of a shipboard filter skid (p3SFS) demonstrate its utility for collecting living zooplankton Texte intégral
2014
Drake, Lisa A. | Moser, Cameron S. | Robbins-Wamsley, Stephanie H. | Riley, Scott C. | Wier, Timothy P. | Grant, Jonathan F. | Herring, Penny R. | First, Matthew R.
Relatively large volumes of water—on the order of cubic meters—must be sampled and analyzed to generate statistically valid estimates of sparsely concentrated organisms, such as in treated ballast water. To this end, a third prototype of a shipboard filter skid (p3SFS) was designed and constructed. It consisted of two housings (each containing a 35μm mesh filter bag) and its own pump and computer controller. Additionally, the skid had a drip sampler, which collected a small volume (∼10L) of whole (unfiltered) water immediately upstream of the housings. Validation of the p3SFS occurred in two segments: (1) land-based trials, in which the collection of organisms ⩾50μm (nominally zooplankton) by the p3SFS was compared to a plankton net, and (2) shipboard trials, in which ballast water was sampled aboard a ship. In both types of trials, the data collected showed the filter skid to be an appropriate flow-through sampling device.
Afficher plus [+] Moins [-]Uptake and biological effects of synthetic glucocorticoids in common carp (Cyprinus carpio) Texte intégral
2014
Nakayama, Kei | Inoue, Yoshiyuki | Ikeda, Naomi | Hashizume, Naoki | Murakami, Hidekazu | Ishibashi, Takeshi | Ikeda, Hirofumi | Isobe, Tomohiko | Kitamura, Shin-Ichi | Suzuki, Go
Uptake and biological effects of synthetic glucocorticoids (GCs) were analyzed using common carp (Cyprinus carpio). Fish were exposed to clobetasol propionate (CP) or clobetasone butyrate (CB) individually or in mixture at 1μgL−1 for 21days. Bioconcentration factor (BCF) of CB was calculated as 100, and BCF of CP was less than 16. No effects were found in fish erythrocyte and leukocyte numbers and serum glucose levels after exposure to the selected GCs. On the other hand, serum concentrations of free amino acids significantly increased in GC-exposed groups. Thus, exposures to synthetic GCs at relatively low concentrations seemed to cause enhancement of protein degradation and subsequent increase of serum free amino acids without a corresponding increase in serum glucose levels, an effect which might be related to partial induction of gluconeogenesis by GC.
Afficher plus [+] Moins [-]Concentration, composition and sources of PAHs in the coastal sediments of the exclusive economic zone (EEZ) of Qatar, Arabian Gulf Texte intégral
2014
Soliman, Y.S. | Al Ansari, E.M.S. | Wade, T.L.
Concentration, composition and sources of PAHs in the coastal sediments of the exclusive economic zone (EEZ) of Qatar, Arabian Gulf Texte intégral
2014
Soliman, Y.S. | Al Ansari, E.M.S. | Wade, T.L.
Surface sediments were collected from sixteen locations in order to assess levels and sources of polycyclic aromatic hydrocarbons (PAHs) in sediments of Qatar exclusive economic zone (EEZ). Samples were analyzed for 16 parent PAHs, 18 alkyl homologs and for dibenzothiophenes. Total PAHs concentration (∑PAHs) ranged from 2.6ngg−1 to 1025ngg−1. The highest PAHs concentrations were in sediments in and adjacent to harbors. Alkylated PAHs predominated most of the sampling locations reaching up to 80% in offshore locations. Parent PAHs and parent high molecular weight PAHs dominated location adjacent to industrial activities and urban areas. The origin of PAHs sources to the sediments was elucidated using ternary plot, indices, and molecular ratios of specific compounds such as (Ant/Phe+Ant), (Flt/Flt+Pyr). PAHs inputs to most coastal sites consisted of mixture of petroleum and combustion derived sources. However, inputs to the offshore sediments were mainly of petroleum origin.
Afficher plus [+] Moins [-]Concentration, composition and sources of PAHs in the coastal sediments of the exclusive economic zone (EEZ) of Qatar, Arabian Gulf Texte intégral
2014
Soliman, Y.S. | Al Ansari, E.M.S. | Wade, T.L.
Surface sediments were collected from sixteen locations in order to assess levels and sources of polycyclic aromatic hydrocarbons (PAHs) in sediments of Qatar exclusive economic zone (EEZ). Samples were analyzed for 16 parent PAHs, 18 alkyl homologs and for dibenzothiophenes. Total PAHs concentration (?PAHs) ranged from 2.6 ng g-1 to 1025 ng g-1. The highest PAHs concentrations were in sediments in and adjacent to harbors. Alkylated PAHs predominated most of the sampling locations reaching up to 80% in offshore locations. Parent PAHs and parent high molecular weight PAHs dominated location adjacent to industrial activities and urban areas. The origin of PAHs sources to the sediments was elucidated using ternary plot, indices, and molecular ratios of specific compounds such as (Ant/Phe + Ant), (Flt/Flt + Pyr). PAHs inputs to most coastal sites consisted of mixture of petroleum and combustion derived sources. However, inputs to the offshore sediments were mainly of petroleum origin. | Qatar University supported investigation, QUSG-CAS-SPR-11/12-1 | Scopus
Afficher plus [+] Moins [-]Oil sorbents with high sorption capacity, oil/water selectivity and reusability for oil spill cleanup Texte intégral
2014
Wu, Daxiong | Fang, Linlin | Qin, Yanmin | Wu, Wenjuan | Mao, Changming | Zhu, Haitao
A sorbent for oil spill cleanup was prepared through a novel strategy by treating polyurethane sponges with silica sol and gasoline successively. The oil sorption capacity, oil/water selectivity, reusability and sorption mechanism of prepared sorbent were studied. The results showed that the prepared sorbent exhibited high sorption capacity and excellent oil/water selectivity. 1g of the prepared sorbent could adsorb more than 100g of motor oil, while it only picks up less than 0.1g of water from an oil–water interface under both static and dynamic conditions. More than 70% of the sorption capacity remained after 15 successive sorption–squeezing cycles, which suggests an extraordinary high reusability. The prepared sorbent is a better alternative of the commercial polypropylene sorbent which are being used nowadays.
Afficher plus [+] Moins [-]Distribution of resting cysts of the potentially toxic dinoflagellate Alexandrium pseudogonyaulax in recently-deposited sediment within Bizerte Lagoon (Mediterranean coast, Tunisia) Texte intégral
2014
Triki, Habiba Zmerli | Daly-Yahia, Ons Kéfi | Malouche, Dhafer | Komiha, Yosr | Deidun, Alan | Brahim, Mouldi | laabir, Mohamed
This study investigated the spatial distribution of Alexandrium pseudogonyaulax resting cysts in recently-deposited sediment of Bizerte lagoon (South-Western Mediterranean, Tunisia). This lagoon is the subject of many anthropogenic impacts, such as holding important fishing and aquaculture activities. A. pseudogonyaulax has been shown to produce Goniodomin A, which is a biologically-active compound. We showed that this dinoflagellate produces two types of resting cysts, which could be distinguished by the presence or the absence of a paratabulate wall. The average cyst density across the whole lagoon was rather high, reaching 639cystsg−1 of dry sediment (DS). Cyst densities varied widely among the sampled stations, with the highest density of 1685cystg−1DS being recorded at station 51 near a mussel farm. With respect to sediment characteristics, the highest cyst densities were found within silty sediments with high water content values. The distribution of A. pseudongoyaulax cysts in Bizerte lagoon appears to be related to hydrodynamic factors.
Afficher plus [+] Moins [-]Occurrence of contaminants of emerging concern along the California coast (2009–10) using passive sampling devices Texte intégral
2014
Alvarez, David A. | Maruya, Keith A. | Dodder, Nathan G. | Lao, Wenjian | Furlong, Edward T. | Smalling, Kelly L.
Three passive sampling devices (PSDs), polar organic chemical integrative samplers (POCIS), polyethylene devices (PEDs), and solid-phase microextraction (SPME) samplers were used to sample a diverse set of chemicals in the coastal waters of San Francisco Bay and the Southern California Bight. Seventy one chemicals (including fragrances, phosphate flame retardants, pharmaceuticals, PAHs, PCBs, PBDEs, and pesticides) were measured in at least 50% of the sites. The chemical profile from the San Francisco Bay sites was distinct from profiles from the sites in the Southern California Bight. This distinction was not due to a single compound or class, but by the relative abundances/concentrations of the chemicals. Comparing the PSDs to mussel (Mytilus spp.) tissues, a positive correlation exists for the 25 and 26 chemicals in common for the PEDs and SPME, respectively. Diphenhydramine was the only common chemical out of 40 analyzed in both POCIS and tissues detected at a common site.
Afficher plus [+] Moins [-]Refocusing Mussel Watch on contaminants of emerging concern (CECs): The California pilot study (2009–10) Texte intégral
2014
Maruya, Keith A. | Dodder, Nathan G. | Schaffner, Rebecca A. | Weisberg, Stephen B. | Gregorio, Dominic | Klosterhaus, Susan | Alvarez, David A. | Furlong, Edward T. | Kimbrough, Kimani L. | Lauenstein, Gunnar G. | Christensen, John D.
To expand the utility of the Mussel Watch Program, local, regional and state agencies in California partnered with NOAA to design a pilot study that targeted contaminants of emerging concern (CECs). Native mussels (Mytilus spp.) from 68 stations, stratified by land use and discharge scenario, were collected in 2009–10 and analyzed for 167 individual pharmaceuticals, industrial and commercial chemicals and current use pesticides. Passive sampling devices (PSDs) and caged Mytilus were co-deployed to expand the list of CECs, and to assess the ability of PSDs to mimic bioaccumulation by Mytilus. A performance-based quality assurance/quality control (QA/QC) approach was developed to ensure a high degree of data quality, consistency and comparability. Data management and analysis were streamlined and standardized using automated software tools. This pioneering study will help shape future monitoring efforts in California’s coastal ecosystems, while serving as a model for monitoring CECs within the region and across the nation.
Afficher plus [+] Moins [-]