خيارات البحث
النتائج 1631 - 1640 من 3,991
Sewage contamination of sediments from two Portuguese Atlantic coastal systems, revealed by fecal sterols
2016
Rada, Jesica P.A. | Duarte, Armando C. | Pato, Pedro | Cachada, Anabela | Carreira, Renato S.
Fecal sterols in sediments were used to assess the degree of sewage contamination in Ria de Aveiro lagoon and Mondego River estuary for the first time. Coprostanol, the major fecal sterol, averaged 1.82±4.12μgg−1, with maxima of 16.6μgg−1. The northwestern sector of the Ria and a marina at Mondego estuary showed the highest level of sewage contamination. This scenario was confirmed by several diagnostic ratios based on fecal sterols and other phytosterols. Our data revealed that in spite of the improvements achieved in the last decades, there is still a need for control the organic inputs into the aquatic environment in the studied regions.
اظهر المزيد [+] اقل [-]The invasive lionfish, Pterois volitans, used as a sentinel species to assess the organochlorine pollution by chlordecone in Guadeloupe (Lesser Antilles)
2016
Charlotte, Dromard R. | Yolande, Bouchon-Navaro | Cordonnier, Sebastien | Claude, Bouchon
In Guadeloupe, many marine organisms are affected by an organochlorine pollution used in the past by the banana industry to fight against the banana weevil. In the present study, we evaluated the level of contamination of the invasive Indo-Pacific lionfish, Pterois volitans, all around the island. Concentrations of chlordecone varied from 3 to 144μg.kg−1 wet weight. The highest concentrations were recorded when samples were captured in the marine zones located downstream of the previous banana plantations. This contamination seemed to decrease rapidly with the distance from the coast. Mean concentration of chlordecone in Pterois volitans was higher than that of five other fish species collected in similar sites. Due to its position at the top of the trophic web, lionfish was affected by bioaccumulation of chlordecone and can be used as a sentinel species to assess and control the level of contamination of the marine environment by chlordecone.
اظهر المزيد [+] اقل [-]Metal contamination and its ecological risk assessment in the surface sediments of Anzali wetland, Caspian Sea
2016
Jamshidi, Siamak | Bastami, Kazem Darvish
In this study, the accumulation of metals, including Al, Fe, Zn, V, Ni, Cu, Cr, Cd, Co, As, and Pb, in sediments of Anzali wetland in the southwest region of the Caspian Sea was investigated. For this purpose, the sediments were collected from 17 sampling sites in Anzali wetland, Caspian Sea. The samples were then analyzed using inductively coupled plasma–optical emission spectrometry (ICP-OES). Pearson correlation coefficient showed significant and positive correlation between concentration of all metals (except As and Cd). Furthermore, the results implied that Al and Fe are probably responsible for the transportation of heavy metals into the sediments of Anzali wetland. According to mean effects range-median quotient (mean ERM quotient), the sediments from Anzali wetland had a 21% probability of toxicity.
اظهر المزيد [+] اقل [-]Assessment of the fitness of the mussel Mytilus galloprovincialis two years after the Hebei Spirit oil spill
2016
Donaghy, Ludovic | Hong, Hyun-Ki | Kim, Moonkoo | Park, Heung-Sik | Choi, Kwang-Sik
In December 2007, >150km of the West coast of Korea were heavily polluted by crude oil leaked from the oil tanker Hebei Spirit, leading to mass mortality of bivalve mollusks on the intertidal areas. Two years after, mussels Mytilus galloprovincialis were collected from two impacted sites to investigate sub-lethal effects of the oil spill. Tissue content in polycyclic aromatic hydrocarbons (PAHs), hemocyte parameters, reproductive status and energetic reserves were analyzed. PAHs in tissues of mussels as well as hemocyte parameters were not different between impacted and control sites. Energetic reserves were altered in mussels from the impacted sites. Glycogen content remained low at polluted sites, whatever the season. Two years after the Hebei Spirit oil spill, mussels then presented altered energetic metabolism. Further investigations are thus warranted to monitor the sustainability of mussel populations on the oil spilled West coast of Korea.
اظهر المزيد [+] اقل [-]Temporal persistence of intra-urban spatial contrasts in ambient NO2, O3 and Ox in Edinburgh, UK
2016
Lin, Chun | Feng, Xiaofan | Heal, Mathew R.
Ambient NO2, O3 and Ox (the sum of NO2 and O3) are associated with adverse health outcomes. Quantitative assessment of the health burden from these pollutants requires knowledge of small-scale variations in their concentrations in urban environments. In particular, we were interested in the temporal stability of intra-urban spatial contrasts in these pollutants. This was investigated by concurrent measurements of NO2 and O3 by passive samplers at 30 sites in Edinburgh, UK, repeated 12 × 1-weekly for NO2 and 6 × 2-weekly for O3 in summer and winter. Temporally persistent and large spatial variations in both NO2 and O3 concentrations were observed. Concentrations of NO2 across the sites ranged on average by a factor of 14 between suburban parks and heavily-trafficked roadsides, corresponding to a difference in NO2 on average of ∼80 μg m−3. Intra-urban O3 concentrations also varied substantially, on average by a factor of 4 (average range 45 μg m−3) and with strong anticorrelation to NO2 concentrations across the 30 sites. Consequently intra-urban variability was considerably lower for Ox than for NO2 and O3. The temporal stability in relative NO2 and O3 concentrations indicate potential for deriving intra-urban spatial fields of NO2 and O3 at different times by scaling models of long-term spatial patterns of NO2 and O3 by the measurements at a single site. If Ox is a key determinant of adverse health then the large intra-urban spatial contrasts in NO2 and O3 may be less relevant, with Ox concentrations across an urban area determined at a suitable background site.
اظهر المزيد [+] اقل [-]Characteristics of haze weather in Chongqing, China and its determinants analysis based on automatic monitoring stations
2016
Li, Mingsheng | Jia, Lin | Zhang, Fengying | Hu, Maogui | Shi, Yu | Chen, Xi
Statistical analyses were carried out on the characteristics of haze weather and their relation with air quality and meteorological factors using data recorded by the national air quality and meteorological monitoring network of Chongqing, China in 2013. The results showed that the hourly occurrence rate of haze in Chongqing was 81.3% and that 67.2% of the total number of haze hours was at the level of mild to light haze. Haze was more likely to occur in autumn and winter (67.2% of the total number of hours; occurrence rate 97.5%) and was more likely to occur between 22:00 and 10:00. Haze mainly occurred when the wind speed was <1.2 m s−1 and the relative humidity was >50%. Haze rarely occurred when the wind speed was >3.0 m s−1 and the relative humidity was <30%. There was a positive correlation between temperature and visibility. The occurrence rate was higher with positive variations in the 24-h temperature records. The main factor affecting haze was the level of PM2.5 pollution. Haze mainly occurred when ρ(PM2.5) was between 35 and 250 μg m−3, accounting for 86.4% of the total number of hours of haze. When ρ(PM2.5) was >75 μg m−3, the occurrence rate of haze was 100.0%. The mean value of ρ(PM2.5)/ρ(PM10) during the hours of haze was 72.9%, 17.7% higher than that at other times. The number of hours with air pollution accounted for 48.8% of the total number of hours, far less than the occurrence of haze. When the ambient air quality was excellent or good, haze was present in 65.4% of hours. We suggest that there are differences between the assessment of air quality and the definition of haze used in China. The relationship between haze and air quality would be better matched if we used the World Meteorological Organization's definition of haze (visibility < 5.0 km).
اظهر المزيد [+] اقل [-]A preliminary approach of the spatio-temporal distribution of cationic aerosol components in the ambient atmosphere of Kochi, India
2016
Gayathree Devi, P.K. | Sujatha, C.H.
Kochi City, situated in the vicinity of the industrial hub and marine niche, is significantly loaded with ionic compounds and get into the atmospheric aerosols which deteriorate the health status of the environment. The distribution of both acid and water extractable cations (Na+, NH4+, K+, Mg2+ and Ca2+) with respect to time and space, in the two phases (I and II) were performed at distinct sites of Kochi, Kerala, India. The study revealed that the water soluble Na+ ion is highlighted in the estuarine site (E1) with momentous load at the coastal site (C1) implying the sea salt influence at these two sites. The average NH4+ and K+ concentration (acid and water soluble fractions) recorded is mostly at the industrial site (R2) which may be endorsed due to the application of NPK fertilizers and also from the process of wood burning sources. Further, K+ is the prominent acid and water soluble cation recorded in the study. Mg2+ ion having both oceanic and anthropogenic origin contributes the present observed pollution load. Average acid soluble Ca2+ content is noted maximum at the estuarine spot E1, where as the hike with respect to water soluble fraction of this ion is noticed at the industrial site, R2. These inferences justify the influence of point sources such as industrial, crustal and construction related activities affecting in and around this metropolis.
اظهر المزيد [+] اقل [-]Corticosterone stress hormone responses in oil rehabilitated and non-rehabilitated little penguins
2016
Chilvers, B.L. | Finlayson, G. | Candy, E.J. | Sriram, A. | Morgan, K.J. | Cockrem, J.F.
Whether oiled wildlife should be rehabilitated during an oil spill is internationally debated. Research on little penguins (LP, Eudyptula minor) rehabilitated and released back into a cleaned environment after the New Zealand C/V Rena grounding oil spill in 2011 found the rehabilitation process was effective at treating and reversing the negative effects of oil-contamination on penguin post-release survival, productivity and diving behaviour. Here we investigated the acute corticosterone stress response of LPs to determine if responses of rehabilitated birds differed from those of “control” birds. Corticosterone responses of LPs two years after an oil spill did not differ between rehabilitated and non-rehabilitated penguins. These results show that the rehabilitation process for LP did not affect their long-term physiological responses to humans. This indicates that wildlife can be rehabilitated and returned to the wild with similar human tolerance levels to non-rehabilitated birds and an absence of habituation.
اظهر المزيد [+] اقل [-]Weathering of field-collected floating and stranded Macondo oils during and shortly after the Deepwater Horizon oil spill
2016
Stout, Scott A. | Payne, James R. | Emsbo-Mattingly, Stephen D. | Baker, Gregory
Chemical analysis of large populations of floating (n=62) and stranded (n=1174) Macondo oils collected from the northern Gulf of Mexico sea surface and shorelines during or within seven weeks of the end of the Deepwater Horizon oil spill demonstrates the range, rates, and processes affecting surface oil weathering. Oil collected immediately upon reaching the sea surface had already lost most mass below n-C8 from dissolution of soluble aliphatics, monoaromatics, and naphthalenes during the oil's ascent with further reductions extending up to n-C13 due to the onset of evaporation. With additional time, weathering of the floating and stranded oils advanced with total PAH (TPAH50) depletions averaging 69±23% for floating oils and 94±3% for stranded oils caused by the combined effects of evaporation, dissolution, and photo-oxidation, the latter of which also reduced triaromatic steroid biomarkers. Biodegradation was not evident among the coalesced floating oils studied, but had commenced in some stranded oils.
اظهر المزيد [+] اقل [-]Microplastics elutriation from sandy sediments: A granulometric approach
2016
Kedzierski, Mikaël | Le Tilly, Véronique | Bourseau, Patrick | Bellegou, Hervé | César, Guy | Sire, Olivier | Bruzaud, Stéphane
Although relatively easy to extract in the marine environment, microplastics are very difficult to recover when they are trapped in sediments. The elutriation column is one of the best tools currently available for extracting plastics from sediment, but with a high sand recovery yield. This study aims to address the following questions: (i) is it possible to use a sedimentological approach to limit the sand recovery? (ii) does the extraction velocity of the sand and plastic particles vary according to density and granulometry? (iii) what is the relative recovery efficiency obtained for dense polymer particles mixed with marine sand? Based on a new granulometric classification, different plastic particle-size fractions are defined. Their extraction velocities are experimentally determined on particles of sediment and different plastics (PA, PVC). The particle recovery experiments indicate that it is possible to extract >90% of dense plastic particles in cases of negligible sand recovery.
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