خيارات البحث
النتائج 1221 - 1230 من 4,044
An in-depth survey of the oil spill literature since 1968: Long term trends and changes since Deepwater Horizon النص الكامل
2016
Murphy, David | Gemmell, Brad | Vaccari, Liana | Li, Cheng | Bacosa, Hernando | Evans, Meredith | Gemmell, Colbi | Harvey, Tracy | Jalali, Maryam | Niepa, Tagbo H.R.
In order to characterize the state of oil spill research and describe how the field has changed since its inception in the 1960s and since the Deepwater Horizon spill in 2010, we examined approximately 10% of oil spill literature (1255 of over 11,000 publications) published from 1968 to 2015. We find that, despite its episodic nature, oil spill research is a rapidly expanding field with a growth rate faster than that of science as a whole. There is a massive post-Deepwater Horizon shift of research attention to the Gulf of Mexico, from 2% of studies in 2004–2008 to 61% in 2014–2015, thus ranking Deepwater Horizon as the most studied oil spill. There is, however, a longstanding gap in research in that only 1% of studies deal with the effects of oil spills on human health. These results provide a better understanding of the current trends and gaps within the field.
اظهر المزيد [+] اقل [-]Ultrasound-assisted extraction combined with reverse phase-dispersive liquid-liquid micro extraction as a new approach for preconcentration and spectrophotometric determination of total phenol in marine sediments of Chabahar Bay النص الكامل
2016
Ziyaadini, Morteza | Zahedi, Mir Mahdi | Khosravinia, Saeid
In this study, Reverse phase dispersive liquid–liquid micro extraction (RP-DLLME) technique have been successfully developed to preconcentrate trace amount of phenol from sediment samples as a prior step to its derivatization with 4-aminoantipyrine and enhanced determination by UV–Vis spectrophotometry after primary ultrasonic extraction. In this procedure, 50μL 0.7M NaOH solution was chosen as extraction solvent and other factors including pH, extraction time, concentration of 4-aminoantipyrine, type and volume of dispersive solvents were optimized. Under selected conditions, the limit of detection, the linearity range, relative standard deviation and enrichment factor of method were obtained 15μg·kg−1, 50–1800μg·kg−1, 4.8% (n=10) and 33, respectively. Finally, using the high sensitivity, low organic solvent consumption and waste generation method, total phenol content in marine sediments from several locations in Chabahar Bay (southeast Iran) was estimated at 55.8–73.2μg·kg−1.
اظهر المزيد [+] اقل [-]Indoor-to-outdoor pollutant concentration ratio modeling of CO2, NO2, and lung-deposited nanoparticles النص الكامل
2016
Lee, Jae Young | Ryu, Sung Hee | Kim, Chang Hyeok | Bae, Gwi-Nam
Knowledge of the levels of pollutants to which the occupants of a residential home are exposed is important, because of the potential adverse effect of the pollutants on the occupants' health. This study presents the first indoor-to-outdoor ratio (IOR) prediction models for CO2, NO2, and the lung-deposited nanoparticles (defined as particulate matters of 10–1000 nm in diameter). The IORs of CO2, NO2, and the lung-deposited nanoparticles (LDN) were measured in 20 residential homes in Seoul, South Korea, and meteorological information, building characteristics, and information relating to occupants' indoor activities were collected as predictor candidates. A correlation analysis and a multistep multivariate linear regression analysis were performed to develop the IOR models. Based on the analysis, the selected predictors of the IOR for a home are the number of occupants, the type of stove, and the number of cooking activities for CO2, the temperature and number of cooking activities for NO2, and the number of occupants and floor level on which the home is located for LDN. The accuracies of the models were examined in terms of R2, and were found to be 0.70, 0.54, and 0.79 for CO2, NO2, and LDN models, respectively.
اظهر المزيد [+] اقل [-]Host condition and accumulation of metals by acanthocephalan parasite Echinorhynchus gadi in cod Gadus morhua from the southern Baltic Sea النص الكامل
2016
Podolska, M. | Polak-Juszczak, L. | Nadolna-Ałtyn, K.
In this study, we analyzed the relationship between concentration of metals in the host-parasite system (cod - acanthocephalan Echinorhynchus gadi) and Fulton's condition factor (FCF) of the host. The relationship between metal (Ca, Cd, Cr, Cu, Fe, Hg, K, Mg, Mn, Na, Pb, Sr, Zn) concentrations in E. gadi and cod tissues was expressed as a bioconcentration factor (BCF), the ratio of the concentration in the parasite tissue to that in host tissues. Acanthocephalans accumulated mainly toxic metals (Cd, Pb), as well as Sr, Ca, Na. Cadmium showed the highest bioconcentration in parasites (BCF >200) compared to fish muscle. Significant negative correlation was detected between FCF and the concentration of Cd and Hg in cod liver. In contrast, FCF was positively correlated with the concentration of Hg in acanthocephalan tissues.
اظهر المزيد [+] اقل [-]Biodegradation potentiality of psychrophilic bacterial strain Oleispira antarctica RB-8T النص الكامل
2016
Gentile, G. | Bonsignore, M. | Santisi, S. | Catalfamo, M. | Giuliano, L. | Genovese, L. | Yakimov, M.M. | Denaro, R. | Genovese, M. | Cappello, S.
The present study is focused on assessing the growth and hydrocarbon-degrading capability of the psychrophilic strain Oleispira antarctica RB-8T. This study considered six hydrocarbon mixtures that were tested for 22days at two different cultivation temperatures (4 and 15°C). During the incubation period, six sub-aliquots of each culture at different times were processed for total bacterial abundance and GC–FID (gas chromatography–flame ionization detection) hydrocarbon analysis.Results from DNA extraction and DAPI (4′,6-diamidino-2-phenylindole) staining showed a linear increase during the first 18days of the experiment in almost all the substrates used; both techniques showed a good match, but the difference in values obtained was approximately one order of magnitude. GC–FID results revealed a substantial hydrocarbon degradation rate in almost all hydrocarbon sources and in particular at 15°C rather than 4°C (for commercial oil engine, oily waste, fuel jet, and crude oil). A more efficient degradation was observed in cultures grown with diesel and bilge water at 4°C.
اظهر المزيد [+] اقل [-]Chemical speciation of aerosols and air quality degradation during the festival of lights (Diwali) النص الكامل
2016
Pervez, Shamsh | Chakrabarty, Rajan K. | Dewangan, Shippi | Watson, John G. | Chow, Judith C. | Matawle, Jeevan Lal
Ambient PM2.5 (particulate matter less than 2.5 μm) samples, collected in a 8-week wintertime sampling program in two residential sites of Bhilai, India during the Indian Diwali festival in November 2012, were chemically characterized for 38 chemical species including eight speciated carbonaceous fractions (SCFs) of elemental (EC) and organic carbon (OC), twenty one metallic elements, and nine water soluble ionic species. Our objectives were to investigate: 1) relative abundances of SCFs contained in PM2.5during the Diwali festival period compared to normal days, and 2) enrichment pattern of potential inorganic markers of firework emission in ambient PM2.5during the festival days. Eight-fold increase inPM2.5mass concentrations were measured during the Diwali festival days compared to concentrations occurring in normal days. Bursting of firecrackers in the residential streets have shown significant contribution to the emission markers (K, Mg, Zn, S, EC and OC) along with crustal markers (Ca, Fe, Al) in ambient PM2.5aerosol samples. Concentrations of water soluble ionic species were found to be 10 times greater than those found in normal days. Further, the anion/cation ratios were found to reach a factor of 2; indicating the acidic character of emissions resulting from fireworks. The relative abundance of SCFs and higher ratios of OC to EC during the Diwali episode suggested the significant formation of secondary organic carbon (SOC) aerosols. We estimate that aerosols emitted from firework bursting contribute up to 32% of total ambient PM2.5 during the Diwali festival.
اظهر المزيد [+] اقل [-]Living oysters and their shells as sites of nitrification and denitrification النص الكامل
2016
Caffrey, Jane M. | Hollibaugh, James T. | Mortazavi, Behzad
Oysters provide a critical habitat, are a food resource for higher trophic levels and support important commercial fisheries throughout the world. Oyster reefs can improve water quality by removing phytoplankton. While sediment denitrification may be enhanced adjacent to oyster reefs, little is known about nitrification and denitrification associated with living oysters and their shells. We measured nitrification and denitrification in living oysters (Crassostrea virginica and Crassostrea gigas) and empty oyster shells. Nitrification was similar between live oysters and empty oyster shells, however, denitrification was enhanced significantly on living oysters compared to shells. This is the first demonstration of nitrification and denitrification associated with living oysters and their shells. Our data suggest that loss of historic oyster reefs has likely affected the resilience of estuaries to eutrophication. The additional benefit of oyster mediated denitrification should be considered in restoration of oyster reefs as a tool for managing eutrophication.
اظهر المزيد [+] اقل [-]Use of baited remote underwater video (BRUV) and motion analysis for studying the impacts of underwater noise upon free ranging fish and implications for marine energy management النص الكامل
2016
Roberts, Louise | Pérez-Dominguez, Rafael | Elliott, Michael
Free-ranging individual fish were observed using a baited remote underwater video (BRUV) system during sound playback experiments. This paper reports on test trials exploring BRUV design parameters, image analysis and practical experimental designs. Three marine species were exposed to playback noise, provided as examples of behavioural responses to impulsive sound at 163–171dB re 1μPa (peak-to-peak SPL) and continuous sound of 142.7dB re 1μPa (RMS, SPL), exhibiting directional changes and accelerations. The methods described here indicate the efficacy of BRUV to examine behaviour of free-ranging species to noise playback, rather than using confinement. Given the increasing concern about the effects of water-borne noise, for example its inclusion within the EU Marine Strategy Framework Directive, and the lack of empirical evidence in setting thresholds, this paper discusses the use of BRUV, and short term behavioural changes, in supporting population level marine noise management.
اظهر المزيد [+] اقل [-]An assessment of Qatar's coral communities in a regional context النص الكامل
2016
Burt, John A. | Smith, Edward G. | Warren, Christopher | Dupont, Jennifer
Qatar's once extensive coral communities have undergone considerable change in recent decades. We quantitatively surveyed three coral assemblages in Qatar to assess current status, and compared these against 14 sites in Bahrain and the United Arab Emirates to evaluate Qatar in a larger biogeographic context. Umm Al-Arshan had the highest species richness of 17 sites examined in the southern Arabian Gulf, as well as the highest coral cover and the only Acropora observed on sites in Qatar. Coral cover and richness were more modest at Fuwayrit and Al-Ashat, reflecting greater impacts from earlier stress events. Two distinct communities were identified across the southern Gulf, with Umm Al-Arshan clustering with high-cover, mixed merulinid/poritid assemblages that were less impacted by earlier bleaching and long-term stress, while Fuwayrit and Al-Ashat grouped with a lower-cover, stress-tolerant community characteristic of more extreme environments in the southern Gulf. We recommend implementation of a nation-wide baseline assessment of coral communities to guide development of an MPA network and long-term coral monitoring program for Qatar.
اظهر المزيد [+] اقل [-]Distribution, sources and ecological risk assessment of PAHs in surface sediments from the Luan River Estuary, China النص الكامل
2016
Zhang, Daolai | Liu, Jinqing | Jiang, Xuejun | Cao, Ke | Yin, Ping | Zhang, Xunhua
The distribution, sources and risk assessment of 16 polycyclic aromatic hydrocarbons (PAHs) of surface sediments in the Luan River Estuary, China, have been investigated in the research. The results indicated that the total concentrations of 16 PAHs in surface sediments of the Luan River Estuary ranged from 5.1 to 545.1ngg−1dw with a mean value of 120.8ngg−1dw, which is relatively low in comparison with other estuaries around the world. The PAHs in the study area were mainly originated from pyrogenic sources. Besides, PAHs may be contaminated by petrogenic PAHs as indicated by the selected ratios of PAHs, the 2-tailed Pearson correlation analysis and principal components analysis at different sites. The result of the ecological risk assessment shows little negative effect for most individual PAHs in surface sediments of the Luan River Estuary, China.
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