خيارات البحث
النتائج 641 - 650 من 3,208
Occurence and antimicrobial resistance of Staphylococcus aureus and Salmonella spp. in retail fish samples in Turkey النص الكامل
2015
Ertas Onmaz, Nurhan | Abay, Secil | Karadal, Fulden | Hizlisoy, Harun | Telli, Nihat | Al, Serhat
The aims of this study were to investigate the presence of Staphylococcus aureus and staphylococcal enterotoxins, as well as Salmonella spp. and to determine the antimicrobial susceptibilities of the isolates from fish samples. A total of 100 fish samples were analysed consisting of 30 anchovy, 35 trout and 35 sea bream. The presence of SEs was detected using ELISA and its genes confirmed by mPCR. Also, S. aureus and Salmonella spp. were detected in 9 (9%) and 5 (5%) samples, respectively. None of the S. aureus isolates had SEs and SEs genes. The resistance rates of the S. aureus isolates to erythromycin, tetracycline, and penicillin G were found to be 33% while Salmonella spp. isolates were resistant to trimethoprim-sulfamethoxazole, gentamicin and neomycine in 20%, 20% and 80%, respectively of the samples. It is of utmost important for public health that retail fish markets need to use hygienic practices in handling and processing operations.
اظهر المزيد [+] اقل [-]Marine litter education boosts children’s understanding and self-reported actions النص الكامل
2015
Hartley, Bonny L. | Thompson, Richard C. | Pahl, Sabine
Marine litter is a significant environmental problem inherently linked to individuals’ purchasing, use and disposal behaviour. This research examined 176 British schoolchildren’s (aged 8–13years) baseline marine litter understanding and self-reported actions, and tested the impact of an educational intervention. All children participated in the educational intervention and completed a pre- and post-intervention questionnaire. At baseline, children were quite concerned about marine litter and recognised some of the causes and impacts of the problem. Children also reported taking a number of actions to help solve the problem. After the intervention, children were significantly more concerned, had a better understanding of the causes and negative impacts, and reported engaging in more actions to reduce the potential causes of marine litter. Understanding the perceptions and behaviours of children is crucial as they represent current and future actors and a potentially important source of social influence among their peers, parents and community.
اظهر المزيد [+] اقل [-]AERONET data–based determination of aerosol types النص الكامل
2015
Tan, Fuyi | Lim, Hwee San | Abdullah, Khiruddin | Yoon, Tiem Leong | Holben, Brent
Aerosols are among the most interesting topics investigated by researchers because of their complicated characteristics and poor quantification. Moreover, significant uncertainties are associated with changes in the Earth's radiation budget. Previous studies have shown numerous difficulties and challenges in quantifying aerosol influences. In addition, the heterogeneity from aerosol loading and properties, including spatial, temporal, size, and composition features, presents a challenge. In this study, we investigated aerosol characteristics over two regions with different environmental conditions and aerosol sources. The study sites are Penang and Kuching in Malaysia, where a ground–based AErosol RObotic NETwork (AERONET) sun–photometer was deployed. The types of aerosol, such as biomass burning, urban/industrial, marine, and dust aerosols, for both study sites were identified by analyzing aerosol optical depth and angstrom exponent. Seasonal monsoon variation results in different aerosol optical properties, characteristics, and types of aerosols that are dominant in Penang and Kuching. Seasonal monsoon flow trend patterns from a seven–day back–trajectory frequency plotted by the Hybrid Single–Particle Lagrangian Integrated Trajectory model illustrated the distinct origins of trans–boundary aerosol sources. Finally, we improved our findings in Malaysian sites using the AERONET data from Singapore and Indonesia. Similarities in the optical properties of aerosols and the distribution types (referred to as homogeneous aerosol) were observed in the Penang–Singapore and the Kuching–Pontianak sites. The dominant aerosol distribution types were completely different for locations in the western (Penang–Singapore) and eastern (Kuching–Pontianak) parts of the South China Sea. This is a result of spatial and temporal heterogeneity. The spatial and temporal heterogeneities for the western and eastern portions of South China Sea provide information on the natural or anthropogenic processes that take place.
اظهر المزيد [+] اقل [-]Physiological and visible injury responses in different growth stages of winter wheat to ozone stress and the protection of spermidine النص الكامل
2015
Liu, Xin | Sui, Lihua | Huang, Yizong | Geng, Chunmei | Yin, Baohui
The open top chamber (OTC) method was used in a farmland to study the influence of different levels of O3 concentrations (40 ppb, 80 ppb and 120 ppb) on the enzymatic activity and metabolite contents of the antioxidation system of the winter wheat leaves during the jointing, heading and milk stage. The protective effect of exogenous spermidine (Spd) against the antioxidation of winter wheat under the O3 stress was investigated. With the increasing O3 concentrations and fumigation time, the injuries of the winter wheat leaves were observed to be more serious. For instance, when the O3 concentration reached 120 ppb, the activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and nitrate reductase (NR) in the jointing stage decreased by 50.3%, 64.9%, 75.5% and 92.9%, respectively; peroxidase (POD) and glutathione reductase (GR) increased by 45.1% and 80.5%, respectively; the contents of malondialdehyde (MDA), ascorbic acid (AsA) and reduced glutathione (GSH) increased by 314.3%, 8.4% and 31.7%, respectively; and the soluble protein (SP) content decreased by 47.5%. The O3 stress also had significant impact on the contents of proline (Pro), NO3––N and NH4+–N of the winter wheat leaves. During the heading stage, when the O3 concentration was 40 ppb and 80 ppb, the content of Pro was 163.9% and 173.2% higher than that in the control group, respectively. But under 120 ppb, it was decreased by 42.4%. Exogenous application of Spd increased the activities of SOD, POD, CAT, APX and GR, as well as the contents of GSH and SP, but decreased the contents of MDA and AsA. This indicates that Spd is an effective antioxidant to relieve the O3 stress on winter wheat leaves, thereby might be applicable to protect winter wheat from the harm of O3.
اظهر المزيد [+] اقل [-]Mercury and selenium in tissues and stomach contents of the migratory sailfish, Istiophorus platypterus, from the Eastern Pacific: Concentration, biomagnification, and dietary intake النص الكامل
2015
Bergés-Tiznado, Magdalena E. | Fernando Márquez-Farías, J. | Torres-Rojas, Yassir | Galván-Magaña, Felipe | Páez Osuna, Federico
Mercury and selenium were assessed in the sailfish, Istiophorus platypterus, from the Eastern Pacific. Sixty-seven individuals were sampled, muscle, liver, kidney, gonads and the prey found in the stomach contents were isolated during fishing 2011–2013 tournaments. Hg exhibited the following pattern (μgg−1 wet weight): liver (0.57±0.07)>muscle (0.56±0.04)>kidney (0.44±0.08)>gonad (0.14±0.01). The maximum concentration of Se was found in kidneys (14.1±1.9μgg−1), and the minimum in muscles (0.67±0.03μgg−1). High Se:Hg ratios were found for muscle (4.1±0.3), kidney (132.4±12.1), liver (54.0±4.4) and gonads (88.2±7.9); Hg:Se molar ratios were several orders of magnitude lower (muscle<0.4 and liver, kidney and gonad<0.03). Sailfish feed mainly on fishes and cephalopods with low Hg levels (<0.13μgg−1), these results indicate biomagnification of Hg and Se. The muscle of I. platypterus should be consumed (according the provisional tolerable weekly intake) by people cautiously so as not to exceed the recommended intake of 215g per week.
اظهر المزيد [+] اقل [-]Surface oil footprint and trajectory of the Ixtoc-I oil spill determined from Landsat/MSS and CZCS observations النص الكامل
2015
Sun, Shaojie | Hu, Chuanmin | Tunnell, John W.
The Ixtoc-I oil spill occurred in 1979 in shallow waters (50m) of the Bay of Campeche, Mexico. Although it is known that a large portion of the released oil from this second largest accidental marine oil spill in history reached the surface, to date there has been no attempt to document the surface footprint and trajectory of the released oil. Our study attempts to fill this knowledge gap using remote sensing data collected by Landsat/MSS and CZCS. Both showed the same general patterns of oil trajectory to the northwest and north, nearly parallel to the coastline of the western Gulf of Mexico (GoM) with possible oil landing on Mexican and Texas beaches. Field observations at selected beaches and islands along the coast of the western and southern GoM during and after the spill confirmed these satellite-based findings, which were also used to help in planning a recent field campaign to collect sediment samples in the southern GoM.
اظهر المزيد [+] اقل [-]A new approach to the prediction of PM10 concentrations in Central Anatolia Region, Turkey النص الكامل
2015
Ozel, Gamze | Cakmakyapan, Selen
Environmental pollution control is one of the most important goals in pollution risk assessment. In this sense, modern and precise tools that allow scientists to quantify and predict air pollution are of particular interest. In this study, we describe an air quality evaluation in terms of particulate matter having a diameter < 10μm (PM10), using a gamma–Poisson process. PM10 measurements from 2007 to 2013 at 24 air quality monitoring stations of Ministry of Environment and Urbanization (Turkey), was used to predict air pollution levels in Central Anatolia Region of Turkey. We assume that the number of PM10 peaks follows a Poisson process and PM10 amount of each peak fits a gamma distribution. The findings indicate that daily average of number for the threshold exceedance of PM10 concentration is 1.3 for all monitoring stations. The probability of exceedance the PM10 concentration threshold once a day is 0.35 for all monitoring stations. The results also show that the probabilities of total PM10 concentrations exceeding threshold are rapidly decreasing after 158μg/m3 which will occur in one day. The average of daily total PM10 concentration is 148μg/m3, the average of monthly total PM10 concentration is 4 437μg/m3, and the average of yearly total PM10 concentrations is 53 984μg/m3. It is found that there is a moderate correlation between the number of threshold exceedances and the total PM10 concentrations in Central Anatolia Region. Thus, it was concluded that gamma–Poisson process could be promising for air pollutant prediction for a given period of time.
اظهر المزيد [+] اقل [-]Chemical comparison and acute toxicity of water accommodated fraction (WAF) of source and field collected Macondo oils from the Deepwater Horizon spill النص الكامل
2015
Faksness, Liv-Guri | Altin, Dag | Nordtug, Trond | Daling, Per S. | Hansen, Bjørn Henrik
Two Source oils and five field collected oil residues from the Deepwater Horizon incident were chemically characterized. Water accommodated fractions (WAFs) of the Source oils and two of the field-weathered oils were prepared to evaluate the impact of natural weathering on the chemical composition and the acute toxicity of the WAFs. Toxicity test species representing different tropic levels were used (the primary producer Skeletonema costatum (algae) and the herbivorous copepod Acartia tonsa). The results suggest that the potential for acute toxicity is higher in WAFs from non-weathered oils than WAFs from the field weathered oils. The Source oils contained a large fraction of soluble and bioavailable components (such as BTEX (benzene, toluene, ethyl benzene, xylenes) and naphthalene), whereas in the surface collected oils these components were depleted by dissolution into the water column as the oil rose to the surface and by evaporative loss after reaching the sea surface.
اظهر المزيد [+] اقل [-]Macrofaunal recolonization of copper-contaminated sediments in San Diego Bay النص الكامل
2015
Neira, Carlos | Mendoza, Guillermo | Porrachia, Magali | Stransky, Chris | Levin, Lisa A.
Effects of Cu-loading on macrofaunal recolonization were examined in Shelter Island Yacht Basin (San Diego Bay, California). Sediments with high and low Cu levels were defaunated and Cu-spiked, translocated, and then placed back into the environment. These demonstrated that the alteration observed in benthic communities associated with Cu contamination occurs during initial recolonization. After a 3-month exposure to sediments with varying Cu levels, two primary colonizing communities were identified: (1) a “mouth assemblage” resembling adjacent background fauna associated with low-Cu levels that was more diverse and predominantly dominated by surface- and subsurface-deposit feeders, burrowers, and tube builders, and (2) a “head assemblage” resembling adjacent background fauna associated with high-Cu concentrations, with few dominant species and an increasing importance of carnivores and mobile epifauna. Cu loading can cause reduced biodiversity and lower structural complexity that may last several months if high concentrations persist, with a direct effect on community functioning.
اظهر المزيد [+] اقل [-]Environmental triggers for primary outbreaks of crown-of-thorns starfish on the Great Barrier Reef, Australia النص الكامل
2015
Wooldridge, Scott A. | Brodie, J. E. (Jon E.)
In this paper, we postulate a unique environmental triggering sequence for primary outbreaks of crown-of-thorns starfish (COTS, Acanthaster planci) on the central Great Barrier Reef (GBR, Australia). Notably, we extend the previous terrestrial runoff hypothesis, viz. nutrient-enriched terrestrial runoff→elevated phytoplankton ‘bloom’ concentrations→enhanced COTS larval survival, to include the additional importance of strong larvae retention around reefs or within reef groups (clusters) that share enhanced phytoplankton concentrations. For the central GBR, this scenario is shown to occur when El Niño-Southern Oscillation (ENSO) linked hydrodynamic conditions cause the ‘regional’ larval connectivity network to fragment into smaller ‘local’ reef clusters due to low ocean current velocities. As inter-annual variations in hydrodynamic circulation patterns are not amenable to direct management intervention, the ability to reduce the future frequency of COTS outbreaks on the central GBR is shown to be contingent on reducing terrestrial bioavailable nutrient loads ~20–40%.
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