خيارات البحث
النتائج 481 - 490 من 1,908
Modeling air concentrations and risk of carcinogens and co–carcinogens in Gibraltar and source apportionment of nearby industrial facilities
2013
Fauser, Patrik | Sanderson, Hans | Lofstrom, Per
Airborne exposures of carcinogenic and co–carcinogenic pollutants, emitted from industries and various diffuse sources in a 10km radius of Gibraltar, were calculated at the west side of the Rock of Gibraltar facing the Bay. 2005 and 2008 industrial annual emission rates reported to E–PRTR and 2005 municipal diffuse annual emission rates were entered in OML–Multi, a multi–source version of an atmospheric Gaussian plume local scale dispersion model. The model results reveal that carcinogens PAH, represented by benzo[a]pyrene (BaP), arsenic and nickel, and potentially chromium are the priority pollutants with respect to human cancer risk and that the contribution from industrial sources on the Spanish coastal area exceeds that from the diffuse sources from adjacent Spanish municipalities. There is a decrease in annual mean air concentrations from industrial emissions between the years 2005 and 2008. The assessment of contribution to the Gibraltar air concentrations of the priority pollutants from industrial sources shows that refinery CEPSA, chemical industry Petresa and petroleum industry Lubricantes del Sur are significant for nickel. Chemical industry Interquisa is significant for PAHs with a notable decrease in PAH emissions from 2006 to 2007, whereas the contribution from CEPSA is more constant. For arsenic only CEPSA shows a continuous trend and contributes to the 2008 air concentration together with sewerage Edar de la Linea de la Concepcion. CEPSA and metal industry Acerinox contribute the most to the chromium air concentrations. NO2/NOx is the most critical co–carcinogen and electricity plant Central Termica Los Barrios, CEPSA, electricity plant Generacion Electrica Peninsular and electricity plant Cogeneracion de Interquisa are the most significant contributors to the air concentrations in Gibraltar. Pollutant contributions from CEPSA flaring, ship traffic in the Bay and Strait, local road traffic and local diesel generators are currently un–quantified.
اظهر المزيد [+] اقل [-]Spatial variations in polycyclic aromatic hydrocarbons concentrations at surface sediments from the Cyprus (Eastern Mediterranean): Relation to ecological risk assessment
2013
Darılmaz, Enis | Kontaş, Aynur | Uluturhan, Esin | Akçalı, İdil | Altay, Oya
The objective of the present study was to evaluate the distribution, sources, origins, and environmental risk assessment of polycyclic aromatic hydrocarbons (16 US EPA priority pollutants) pollution in 23 surface sediments from Cyprus coast. The mean total polycyclic aromatic hydrocarbons (PAHs) concentrations in the sediments from Gemi Konagi, Girne and Gazi Magusa areas were found 47, 52 and 50ng/g, respectively. Molecular ratios and principle component analysis indicated that PAH pollution originated mainly from fossil sources, with higher pyrolytic contributions. The 2–3 ring PAHs were dominant in Cyprus sediments. Concentrations of PAHs observed in this study were compared with available soil quality guidelines and the concentrations were lower than the guideline values. The guideline values suggested that the Cyprus sediments were likely to be not contaminated by toxic PAH compounds.
اظهر المزيد [+] اقل [-]Chemometric evaluation of the heavy metals distribution in waters from the Dilovası region in Kocaeli, Turkey
2013
Bingöl, Deniz | Ay, Ümit | Karayünlü Bozbaş, Seda | Uzgören, Nevin
The main objective of this study was to test water samples collected from 10 locations in the Dilovası area (a town in the Kocaeli region of Turkey) for heavy metal contamination and to classify the heavy metal (Cr, Mn, Co, Ni, Cu, Zn, As, Cd, Pb and Hg) contents in water samples using chemometric methods. The heavy metals in the water samples were identified using inductively coupled plasma-mass spectrometry (ICP-MS). To ascertain the relationship among the water samples and their possible sources, the correlation analysis, principal component analysis (PCA), and cluster analysis (CA) were used as classification techniques. About 10 water samples were classified into five groups using PCA. A very similar grouping was obtained using CA.
اظهر المزيد [+] اقل [-]Ingestion of marine debris plastic by the wedge-tailed shearwater Ardenna pacifica in the Great Barrier Reef, Australia
2013
Verlis, K.M. | Campbell, M.L. | Wilson, S.P.
We present the first evidence of ingestion of plastic by seabirds from the southern Great Barrier Reef (GBR), Australia. The occurrence of marine debris ingestion in the wedge-tailed shearwater, Ardenna pacifica, on Heron Island was the focus of this preliminary research. Our findings indicate that 21% of surveyed chicks are fed plastic fragments by their parents, having ingested 3.2 fragments on average. The most common colours of ingested plastic fragments were off/white (37.5%) and green (31.3%). Ingested fragments had a mean size of 10.17±4.55mm and a mean weight of 0.056±0.051g. Our results indicate that further research is critical to understanding the extent of ingestion, colour preferences, and what impacts ingestion may have on these and other seabird populations in the GBR.
اظهر المزيد [+] اقل [-]Assessment of contribution to PM10 concentrations from long range transport of pollutants using WRF/Chem over a subtropical urban airshed
2013
Gupta, Medhavi | Mohan, Manju
A regional chemical transport model was implemented to simulate the Respirable Suspended Particulate Matter (PM10) concentration in order to study the impact of long–range transport of air pollutants over megacity Delhi with due consideration to different geographical domains extending up to entire Asia and corresponding emissions. PM10 concentration levels over megacity Delhi remain persistently high, often exceeding the ambient air quality standards. A chemical transport model namely Weather Research and Forecasting (WRF) model Version 3.2 coupled with chemistry module (WRF/Chem) was utilized with nested domains for this purpose, subsequent to model evaluation for the period during June, 2010 that includes extremely high PM10 concentrations. A highly satisfactory model performance was interpreted based on the several statistical parameters as per the current state of the science and their recommended values. Based on model simulations representing different geographical domains encompassing Asia, India, North India and Delhi and their corresponding emissions, it was clearly reflected that contributions due to emissions of the megacity Delhi alone is 11%–41% and thus remaining (59%–89%) proportion is expected to be contributed from the sources outside of the Delhi region which is significant. It is demonstrated that the WRF/Chem model performs well for a sub–tropical urban airshed though there is scope of improvement for the consistent under– prediction with more refined emission inventories. Nevertheless, this model could be implemented to assess the long– range transport of pollutants so as to adequately address the influence of the remote sources outside the urban airshed. This can serve as an important tool towards planning and implementing the regulatory policies for air pollution control for more effective outcomes.
اظهر المزيد [+] اقل [-]Prevalence and composition of marine debris in Brown Booby (Sula leucogaster) nests at Ashmore Reef
2013
Lavers, Jennifer L. | Hodgson, Jarrod C. | Clarke, Rohan H.
Anthropogenic debris is ubiquitous in the marine environment and has been reported to negatively impact hundreds of species globally. Seabirds are particularly at risk from entanglement in debris due to their habit of collecting food and, in many cases, nesting material off the ocean’s surface. We compared the prevalence and composition of debris in nests and along the beach at two Brown Booby (Sula leucogaster) colonies on Ashmore Reef, Timor Sea, a remote area known to contain high densities of debris transported by ocean currents. The proportion of nests with debris varied across islands (range 3–31%), likely in response to the availability of natural nesting materials. Boobies exhibited a preference for debris colour (white and black), but not type. The ephemeral nature of Brown Booby nests on Ashmore Reef may limit their utility as indicators of marine pollution, however monitoring is recommended in light of increasing demand for plastic products.
اظهر المزيد [+] اقل [-]Major and minor element geochemistry of deep-sea sediments in the Azores Platform and southern seamount region
2013
Palma, Carla | Oliveira, Anabela | Valença, Manuela | Cascalho, João | Pereira, Eduarda | Lillebø, Ana I. | Duarte, Armando C. | Pinto de Abreu, Manuel
The Azores Platform and the Irving and Great Meteor seamounts south of the archipelago (38°N–29°N) have rarely been studied geochemically, a fact which is surprising given that they represent the south-eastern limit of region V outlined in the Convention for the Protection of the Marine Environment of the North-East Atlantic (OSPAR Convention). The main aim of the present work was therefore to characterise the spatial variability of major and minor elements in deep-sea sediment cores from these two regions. XRD and geochemical analyses revealed that whereas the Azores Platform sediments are composed of a mixture of biogenic and detrital volcanic material, those at the seamounts are characterised by carbonated biogenic remains. The latter sediments were found to contain very low amounts of volcanic or hydrothermal detrital material, being almost entirely comprised of CaCO3 (more than 80%).
اظهر المزيد [+] اقل [-]Is Jamaica a good model for understanding Caribbean coral reef dynamics?
2013
Côté, Isabelle M. | Precht, William F. | Aronson, Richard B. | Gardner, Toby
Caribbean reefs have experienced unprecedented changes in the past 40years. A major hypothesis to explain shifts in reef community composition relates to declining herbivory. This hypothesis was developed largely based on observations of Jamaican reefs from the 1980s onward, but it is widely held to be relevant regionally. We use a region-wide dataset on benthic composition to examine how well the pattern of ecological change on Jamaican reefs is mirrored by other Caribbean reefs. The extent to which macroalgal cover exceeds coral cover on Jamaican reefs is an order of magnitude more extreme than seen elsewhere. We suggest that Jamaican reefs are not representative of the degradation trajectory of Caribbean reefs and management based on the Jamaican experience may not be relevant elsewhere. However, the recovery of Jamaican reefs following the return of urchins gives us hope that Caribbean reefs are more resilient to catastrophic disturbances than previously thought.
اظهر المزيد [+] اقل [-]Polychlorinated biphenyls in sediments of the Yellow Sea: Distribution, source identification and flux estimation
2013
Duan, Xiaoyong | Li, Yanxia | Li, Xianguo | Zhang, Dahai | Li, Mengfang
Although there is no direct major riverine input, a large quantity of waste produced in mainland China and Korea is transported continuously to the Yellow Sea (YS) through atmospheric deposition, currents and tides; therefore, the environment is distinctly influenced by man-made pollution. This study focuses on the associated pollutant transport mechanisms and fluxes by sampling polychlorinated biphenyls (PCBs). PCBs (Σ24PCB) in YS sediments ranged between 99pg/g and 3.13ng/g of dry sediment (with a mean value of 715pg/g). PCBs produced unintentionally by industrial and other processes appeared to be the major source of PCBs in the sediments, accounting for 60.5%. Industrially synthesized PCBs with 3Cl and 5Cl accounted for 15.5% and 24.0%, respectively. PCBs were mainly from atmospheric deposition (84.5%), followed by continental runoff (15.5%). The average atmospheric deposition flux of technical PCBs was 789ng/(m2a) and flux of surface runoff was 2.27ng/L.
اظهر المزيد [+] اقل [-]Biodegradation of low-density polyethylene by marine bacteria from pelagic waters, Arabian Sea, India
2013
Harshvardhan, Kumar | Jha, Bhavanath
Sixty marine bacteria isolated from pelagic waters were screened for their ability to degrade low-density polyethylene; among them, three were positive and able to grow in a medium containing polythene as the sole carbon source. The positive isolates were identified as Kocuria palustris M16, Bacillus pumilus M27 and Bacillus subtilis H1584 based on the 16S rRNA gene sequence homology. The weight loss of polyethylene was 1%, 1.5% and 1.75% after 30days of incubation with the M16, M27 and H1584 isolates, respectively. The maximum (32%) cell surface hydrophobicity was observed in M16, followed by the H1584 and M27 isolates. The viability of the isolates growing on the polyethylene surface was confirmed using a triphenyltetrazolium chloride reduction test. The viability was also correlated with a concomitant increase in the protein density of the biomass. Polyethylene biodegradation was further confirmed by an increase in the Keto Carbonyl Bond Index, the Ester Carbonyl Bond Index and the Vinyl Bond Index, which were calculated from FT-IR spectra.
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