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Resultados 1081-1090 de 3,208
The use of flow cytometric applications to measure the effects of PAHs on growth, membrane integrity, and relative lipid content of the benthic diatom, Nitzschia brevirostris Texto completo
2015
Croxton, April N. | Wikfors, Gary H. | Schulterbrandt-Gragg, Richard D.
This laboratory study measured the direct effects of three polycyclic aromatic hydrocarbon (PAH) compounds (naphthalene, pyrene, and benzo(a)pyrene) upon cell growth, membrane integrity, and BODIPY-stained lipid fluorescence intensity of the benthic diatom Nitzschia brevirostris using flow cytometry as an analysis tool. Previous field and laboratory studies have reported reductions in algal populations following PAH exposure, but specific, functional responses of the microalgae to these pollutants could not be revealed by cell numbers alone. Using flow-cytometric measurements, we confirmed that maximal cell densities in PAH-exposed diatom cultures were significantly lower compared to controls; however, we also discovered increases in lipids and cells with compromised membranes in PAH-exposed cultures. These results highlight new tools for measuring the direct effects of organic pollutants upon the physiology of taxa comprising microphytobenthic communities important in estuarine food webs.
Mostrar más [+] Menos [-]Contaminant profiles for surface water, sediment, flora and fauna associated with the mangrove fringe along middle and lower eastern Tampa Bay Texto completo
2015
Lewis, M.A. | Russell, M.J.
Contaminant concentrations are reported for surface water, sediment, flora and fauna collected during 2010–2011 from the mangrove fringe along eastern Tampa Bay, Florida. Concentrations of trace metals, chlorinated pesticides, atrazine, total polycyclic aromatic hydrocarbons, and polychlorinated biphenyls were species-, chemical- and location-specific. Contaminants in sediments did not exceed proposed individual sediment quality guidelines. Most sediment quality assessment quotients were less than one indicating the likelihood of no inhibitory effect based on chemical measurements alone. Faunal species typically contained more contaminants than plant species; seagrass usually contained more chemicals than mangroves. Bioconcentration factors for marine angiosperms were usually less than 10 and ranged between 1 and 31. Mercury concentrations (ppm) in blue crabs and fish did not exceed the U.S. Environmental Protection Agency fish tissue criterion of 0.3 and the U.S. Food and Drug Administration action level of 1.0. In contrast, total mercury concentrations in faunal species often exceeded guideline values for wildlife consumers of aquatic biota.
Mostrar más [+] Menos [-]on–road measurement of gaseous emissions and fuel consumption for two hybrid electric vehicles in Macao Texto completo
2015
Wu, Xiaomeng | Zhang, Shaojun | Wu, Ye | Li, Zhenhua | Ke, Wenwei | Fu, Lixin | Hao, Jiming
Hybrid electric vehicles (HEVs) are promoted in China to ease increasing pressures of urban air pollution and oil security. In this paper, we measured two Toyota Prius HEVs by using a portable emission measurement system (PEMS) to evaluate their real–world performance with regard to gaseous emission factors and fuel consumption. Our results indicated that their average exhaust emission factors of CO, THC, NOX and CO2 were 0.25±0.08 gkm–1, 0.015±0.002 gkm–1, 0.009±0.005 gkm–1 and 136±21 gkm–1 (i.e., 5.81±0.90 L 100km–1 for fuel consumption) respectively, while driving the averaged on–road traffic pattern. Compared to conventional gasoline and diesel vehicles, the tested HEVs demonstrated significant advantages in simultaneously mitigating major air pollutants (e.g., NOX), greenhouse gas emissions (CO2) and fuel consumption. For example, average CO2 emission factors are reduced by approximately 35% and 15% relative to conventional gasoline and diesel cars in Macao. Unlike conventional gasoline and diesel cars, relative CO2 emission factors of HEVs were much less sensitive to speed change, while their relative NOX emission factors were reduced as average speed became lower. This indicates significant environmental and energy benefits from HEVs under congested driving conditions. Our assessment suggests that HEVs are a competitive technology option for the taxi fleet in Macao with strong advantages in saving fuel cost for taxi drivers and mitigating NOX emissions.
Mostrar más [+] Menos [-]Oil spill hazard from dispersal of oil along shipping lanes in the Southern Adriatic and Northern Ionian Seas Texto completo
2015
Liubartseva, S. | De Dominicis, M. | Oddo, P. | Coppini, G. | Pinardi, N. | Greggio, N.
An assessment of hazard stemming from operational oil ship discharges in the Southern Adriatic and Northern Ionian (SANI) Seas is presented. The methodology integrates ship traffic data, the fate and transport oil spill model MEDSLIK-II, coupled with the Mediterranean Forecasting System (MFS) ocean currents, sea surface temperature analyses and ECMWF surface winds. Monthly and climatological hazard maps were calculated for February 2009 through April 2013. Monthly hazard distributions of oil show that the zones of highest sea surface hazard are located in the southwestern Adriatic Sea and eastern Ionian Sea. Distinctive “hot spots” appear in front of the Taranto Port and the sea area between Corfu Island and the Greek coastlines. Beached oil hazard maps indicate the highest values in the Taranto Port area, on the eastern Greek coastline, as well as in the Bari Port area and near Brindisi Port area.
Mostrar más [+] Menos [-]Drivers and annual estimates of marine wildlife entanglement rates: A long-term case study with Australian fur seals Texto completo
2015
McIntosh, Rebecca R. | Kirkwood, Roger | Sutherland, Duncan R. | Dann, Peter
Methods of calculating wildlife entanglement rates are not standardised between studies and often ignore the influence of observer effort, confounding comparisons. From 1997–2013 we identified 359 entangled Australian fur seals at Seal Rocks, south-eastern Australia. Most entanglement materials originated from commercial fisheries; most frequently entangling pups and juveniles. Using Generalized Additive Mixed Models, which incorporated observer effort and survey frequency, we identified that entanglements were observed more frequently amongst pups from July to October as they approached weaning. Neither the decline in regional fishing intensity nor changing seal population size influenced the incidence of entanglements. Using the models, we estimated that 302 (95% CI=182–510) entangled seals were at Seal Rocks each year, equivalent to 1.0% (CI=0.6–1.7%) of the site population. This study highlights the influence of observer effort and the value of long-term datasets for determining the drivers of marine debris entanglements.
Mostrar más [+] Menos [-]Environmental risk assessments and spatial variations of polycyclic aromatic hydrocarbons in surface sediments in Yangtze River Estuary, China Texto completo
2015
Yu, Wenwen | Liu, Ruimin | Xu, Fei | Shen, Zhenyao
In this study, based on sampling data from 30 sites in August 2010, the environmental risks associated with 16 priority PAHs were estimated in surface sediments from the Yangtze River Estuary (YRE). The results indicated that the toxic equivalent quantities of the benzo[a]pyrene (TEQBap) from 30 sites were in the range of 1.93–75.88ngg−1, and the low-molecular-weight PAHs were the dominated species with higher potential toxicity. The results of the Incremental Lifetime Cancer Risk (ILCR) model indicated that the ILCR values of dermal contact were higher than 10−6 in the northeast region, suggesting that there were significant potential carcinogenic health risks for fishermen exposure to sedimentary PAHs via dermal contact in these areas. RQ values of PAHs indicated the various distributions of ecological risk levels in the study area. These variations might be caused by the natural and anthropogenic inputs and currents in the YRE.
Mostrar más [+] Menos [-]Spatial–temporal variations and diversity of the bacterioplankton communities in the coastal waters of Kuwait Texto completo
2015
Almutairi, Awatef
The dynamics and composition of the bacterial community in the coastal waters of Kuwait are poorly understood. In this study, the spatial–temporal variations in the bacterial composition in the surface water along the Kuwaiti coast was examined by 16S rRNA denaturing gradient gel electrophoresis (DGGE) fingerprinting and phylogeny analyses. The sampling sites were Kuwait Bay, Al-Sabbiya (north of the bay) and Al-Khairan (to the south). The bacterial composition was more variable in the summer for all sites. A cluster analysis of the DGGE fingerprint revealed two main clusters, indicating a temporal similarity between sites. Kuwait Bay and Al-Khairan were more similar to each other than to Al-Sabbiya. The bacterial community composition exhibited distinctive spatial variations, with more diversity at Al-Khairan and less diversity at Al-Sabbiya. At all sites, the dominant bacteria were Alphaproteobacteria, in particular Rhodobacteraceae, followed by Alteromonadaceae (Gammaproteobacteria) and Bacteroidetes.
Mostrar más [+] Menos [-]Organophosphorus flame retardants (PFRs) and plasticisers in harbour porpoises (Phocoena phocoena) stranded or bycaught in the UK during 2012 Texto completo
2015
Papachlimitzou, Alexandra | Barber, Jonathan L. | Losada, Sara | Bersuder, Philippe | Deaville, Rob | Brownlow, Andrew | Penrose, Rod | Jepson, Paul D. | Law, Robin J.
A suite of twenty organophosphorus flame retardant compounds have been determined in blubber and liver tissue of twenty harbour porpoises stranded or bycaught in the UK during 2012 in order to establish current levels of contamination. Fourteen of the twenty compounds were below the limits of quantification in all samples. Six could be quantified at maximum concentrations (in blubber) between 6.7 and 246μgkg−1 wet weight. These levels do not suggest a high level of concern regarding potential impacts and do not indicate that routine monitoring in UK porpoises is warranted at this time.
Mostrar más [+] Menos [-]Physiological perturbations in juvenile cuttlefish Sepia officinalis induced by subchronic exposure to dissolved zinc Texto completo
2015
Le Pabic, Charles | Caplat, Christelle | Lehodey, Jean-Paul | Dallas, Lorna | Koueta, N. (Noussithé)
Although cephalopod early life stage development often occurs in coastal areas where contamination is real and continuous, the physiological perturbations induced by contaminants have been rarely investigated. This study focused on the Zn as it is one of the trace metals the most concentrated in coastal waters, worldwide. As Zn-tolerance limits were unknown in juvenile Sepia officinalis, the aim of this study was to estimate the threshold inducing mortality during the 2-first weeks post-hatching, and to determine its sensitivity using digestive and immune enzymatic assays, as well as growth and behavior follow-up during the first 5weeks post-hatching. Our study highlighted a Zn-mortality threshold lying between 185 and 230μgl−1, and growth reductions occurring after 5-week at 108μgl−1 and above, associated with enzymatic perturbations. These results underline a relatively important sensitivity of juvenile cuttlefish to Zn, pointed out by a wide diversity of biomarkers.
Mostrar más [+] Menos [-]Inputs of anthropogenic nitrogen influence isotopic composition and trophic structure in SE Australian estuaries Texto completo
2015
Mazumder, Debashish | Saintilan, Neil | Alderson, Brendan | Hollins, Suzanne
Urban development in coastal settings has increased the input of nitrogen into estuaries globally, in many cases changing the composition of estuarine ecosystems. By focussing on three adjacent estuaries with a gradient of anthropogenic N loadings, we used stable isotopes of N and C to test for changes due to increased anthropogenic N input on the structure of some key trophic linkages in estuaries. We found a consistent enrichment in δ15N corresponding to increased anthropogenic N at the three ecosystem levels studied: fine benthic organic matter, grazing invertebrate, and planktivorous fish. The degree of enrichment in δ15N between fine benthic organic matter and the grapsid crab Parasesarma erythrodactyla was identical across the three sites. The glassfish Ambassis jacksoniensis showed lower levels of enrichment compared to basal food sources at the higher N-loaded sites, suggesting a possible effect of anthropogenic N in decreasing food-chain length in these estuaries.
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