خيارات البحث
النتائج 691 - 700 من 1,310
Estuarine ecological risk based on hepatic histopathological indices from laboratory and in situ tested fish النص الكامل
2011
Costa, Pedro M. | Caeiro, Sandra | Lobo, Jorge | Martins, Marta | Ferreira, Ana M. | Caetano, Miguel | Vale, Carlos | DelValls, T Ángel | Costa, Maria H.
Juvenile Senegalese soles were exposed through 28-day laboratory and field (in situ) bioassays to sediments from three sites of the Sado estuary (W Portugal): a reference and two contaminated by metallic and organic contaminants. Fish were surveyed for ten hepatic histopathological alterations divided by four distinct reaction patterns and integrated through the estimation of individual histopathological condition indices. Fish exposed to contaminated sediments sustained more damage, with especial respect to regressive changes like necrosis. However, differences were observed between laboratory- and field-exposed animals, with the latest, for instance, exhibiting more pronounced fatty degeneration and hepatocellular eosinophilic alteration. Also, some lesions in fish exposed to the reference sediment indicate that in both assays unaccounted variables produced experimental background noise, such as hyaline degeneration in laboratory-exposed fish. Still, the field assays yielded results that were found to better reflect the overall levels of contaminants and physico-chemical characteristics of the tested sediments.
اظهر المزيد [+] اقل [-]Comparison of metal accumulation between ‘Artificial Mussel’ and natural mussels (Mytilus galloprovincialis) in marine environments النص الكامل
2011
Gonzalez-Rey, M. | Lau, T.C. | Gomes, T. | Maria, V.L. | Bebianno, M.J. | Wu, R.
The passive sampler called ‘Artificial Mussel’ (AM) developed by Wu et al. (2007) can provide a time-integrated estimate of metal concentrations in the marine environment, and offers a potential device to assess and compare metal concentration in different marine environments worldwide. The aim of this study was to compare metal accumulation on AM and natural mussel Mytilus galloprovincialis at three sites with different metal loads along the Portuguese coast for four months. M. galloprovincialis were placed in cages alongside AMs at each site. Samples were collected monthly and Cd, Cr, Cu, Pb, and Zn concentrations in whole soft tissues and AMs compared. For both Cu and Cd, the results were similar between AMs and natural mussels. Higher concentrations of Zn were observed in natural mussels, whereas the inverse was shown for Pb (about 10-fold higher). Our results showed that AMs are promising tools for assessing metal concentrations in marine environments.
اظهر المزيد [+] اقل [-]Evaluation of the contamination of platinum in estuarine and coastal sediments (Tagus Estuary and Prodelta, Portugal) النص الكامل
2011
Cobelo-García, Antonio | Neira, Patricia | Mil-Homens, Mário | Caetano, Miguel
Platinum contamination in estuarine and coastal sediments has been evaluated in three cores collected from the Tagus Estuary and Prodelta shelf sediments. Elevated concentrations, up to 25-fold enrichment compared to background values, were found in the upper layers of the estuarine sediments. The degree of Pt enrichment in the estuarine sediments varied depending on the proximity to vehicular traffic sources, with a maximum concentration of 9.5ngg⁻¹. A considerable decrease of Pt concentrations with depth indicated the absence of significant contamination before the introduction of catalytic converters in automobiles. Platinum distribution in the Tagus Prodelta shelf sediment core showed no surface enrichment; instead a sub-surface maximum at the base of the mixed layer suggested the possibility of post-depositional mobility, thereby blurring the traffic-borne contamination signature in coastal sediments.
اظهر المزيد [+] اقل [-]What priority pollutants occurred in stormwater and wastewater? النص الكامل
2011
Zgheib, S. | Moilleron, R. | Chebbo, G. | Laboratoire Eau, Environnement et Systèmes Urbains (LEESU) ; AgroParisTech-Université Paris-Est Marne-la-Vallée (UPEM)-École nationale des ponts et chaussées (ENPC)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12) | C. Brebbia;A. Marinov
After the implementation of the Water Framework Directive (WFD), there is an increasing need to monitor pollutant concentrations entering surfaces waters. This concerns all kinds of effluents, as well as urban waters (i.e., wastewater and stormwater). This study provides the first database on the occurrence of 88 individual substances in urban water and highlights direct discharges of these substances to the aquatic environment. Indeed, these hazardous pollutants, listed or not in the WFD, could be released without any treatment to watercourses during a storm.
اظهر المزيد [+] اقل [-]Sponges and sediments as monitoring tools of metal contamination in the eastern coast of the Red Sea, Saudi Arabia النص الكامل
2011
Pan, Ke | Lee, On On | Qian, Pei-Yuan | Wang, Wen-Xiong
Sediments and sponges were collected from various locations along the eastern coast of the Red Sea, the Kingdom of Saudi Arabia. Total concentrations of Cd, Zn, Ag, Cu, Pb, As and Hg in the sediments were measured. Metal contamination was not significant in most of the studied sites and only one site was moderately polluted by Zn, Cu, and Pb. Sponges accumulated specific metals readily even though the metal exposure was low in the ambient environment. Contrasting interspecies differences in metal accumulation patterns were observed among the nine collected species of sponges. Significant positive correlations were found between the metal concentrations in the two species of sponges collected from the same sites. The strong ability to accumulate specific metals and the diversity of sponges that live in the Red Sea coastal areas make them a promising biomonitor of metal contamination in the areas.
اظهر المزيد [+] اقل [-]Benthic foraminifera distribution in a tourist lagoon in Rio de Janeiro, Brazil: A response to anthropogenic impacts النص الكامل
2011
Vilela, Claudia Gutterres | Batista, Daniele Silva | Baptista Neto, José Antonio | Ghiselli, Renato Olindo, Jr
Rodrigo de Freitas Lagoon, located in the Rio de Janeiro City, receives several types of polluted discharges. The knowledge of the sediment microfauna correlated with heavy metal and organic matter concentrations could supply important data about the conditions of the lagoon. The benthic foraminiferal assemblage presented larger diversity and more abundant samples in the lagoon entrance than in the inner area. The Ammonia tepida – Elphidiumexcavatum foraminiferal assemblage is characterized by dwarf, corroded and weak organisms. Agglutinated species were found only near the entrance. Low abundance values and sterility of five samples in the inner area (north/northeast) can be caused by high levels of heavy metals and organic matter. A. tepida shows negative correlation with increasing heavy metals values. PAHs and coprostanol high indexes, and the absence or low presence of microfauna in samples around the lagoon margin confirm illegal flows from gas stations and domestic sewage.
اظهر المزيد [+] اقل [-]Fisheries mismanagement النص الكامل
2011
O’Leary, Bethan C. | Smart, James C.R. | Neale, Fiona C. | Hawkins, Julie P. | Newman, Stephanie | Milman, Amy C. | Roberts, Callum M.
We analysed the extent to which European politicians have adhered to scientific recommendations on annual total allowable catches (TACs) from 1987 to 2011, covering most of the period of the Common Fisheries Policy (CFP). For the 11 stocks examined, TACs were set higher than scientific recommendations in 68% of decisions. Politically-adjusted TACs averaged 33% above scientifically recommended levels. There was no evidence that the 2002 reform of the CFP improved decision-making, as was claimed at the time. We modelled the effects of such politically-driven decision-making on stock sustainability. Our results suggest that political adjustment of scientific recommendations dramatically increases the probability of a stock collapsing within 40years. In 2012 European fisheries policy will undergo a once-a-decade reform. Ten years ago radical reforms were promised but the changes failed to improve sustainability. It is likely that the 2012 reform will be similarly ineffective unless decision-making is changed so that catch allocations are based on science rather than politics.
اظهر المزيد [+] اقل [-]Public awareness and attitudes towards naval sonar mitigation for cetacean conservation: A preliminary case study in Fairfax County, Virginia (the DC Metro area) النص الكامل
2011
Zirbel, K. | Balint, P. | Parsons, E.C.M.
The potential impacts of naval sonar on cetaceans has led to a series of court cases and statements of concern by international organizations. However, there has been no research conducted on attitudes of the general public with respect to this issue. To investigate this, a preliminary public survey was conducted in Fairfax, Virginia (the Washington, DC Metro region). The majority of the public sampled believed that naval sonar impacted marine mammals (51.3%), that the US Navy should not be exempt from environmental regulations in time of peace (75.2%), and that sonar use should be moderated if it impacts cetaceans (75.8%). Individuals who were conservative, Republican, and have served in the military were more likely to believe the Navy should be exempt from marine mammal protection regulations. In addition, expert interviews were conducted to gain opinions on the potential ramifications of the recent US Supreme Court case on naval sonar mitigation.
اظهر المزيد [+] اقل [-]Integrated use of biomarkers in the mussel Mytilus galloprovincialis for assessing off-shore gas platforms in the Adriatic Sea: Results of a two-year biomonitoring program النص الكامل
2011
Gomiero, Alessio | Da Ros, Luisa | Nasci, Cristina | Meneghetti, Francesca | Spagnolo, Alessandra | Fabi, Gianna
Despite a large number of gas platforms existing in the Adriatic Sea, which is a semi-enclosed basin characterized by a slow turnover rate and increasing industrial as well as other anthropogenic activities, the effects of these structures on the aquatic ecosystem require further investigation. Since 1998, multidisciplinary studies have been performed by CNR-ISMAR to comply with legislation and to support the development of protocols for the monitoring of offshore activities in the Adriatic Sea. The present study was developed to implement a biomonitoring plan to assess the ecotoxicological effects of the extraction activities of an off-shore gas platform. Biomarkers were evaluated in mussels collected from the platform in relation to physiological stress, DNA damage, cellular damage, oxidative stress and exposure effects. Organic contaminants and trace element bioaccumulation were also assessed in the soft body of the mussels to correlate bioaccumulation of pollutants with biomarker responses. The results indicate an absence of platform-related environmental stress.
اظهر المزيد [+] اقل [-]Habitat associations of floating debris and marine birds in the North East Pacific Ocean at coarse and meso spatial scales النص الكامل
2011
Titmus, Andrew J. | David Hyrenbach, K.
While many surface foraging seabirds ingest plastic, the spatial overlap of these far-ranging predators with debris aggregations at-sea is poorly understood. We surveyed concurrent distributions of marine birds and debris along a 4400km cruise track within a debris accumulation area in the North East Pacific Ocean using line and strip transect methods. Analysis of debris and bird distributions revealed associations with oceanographic and weather variables at two spatial scales: daily surveys and hourly transects. Hourly bird abundance (densities; 0–9 birds km⁻²) was higher in lower wind and shallower water. Hourly debris abundance (densities; 0–15,222 pieces km⁻²) was higher in lower wind, higher sea-level atmospheric pressure and deeper water. These results suggest that debris and seabird abundance and community structure are influenced by similar environmental processes, but in opposing ways, with only three far-ranging seabird species (Black-footed Albatross, Cook’s Petrel and Red-tailed Tropicbird) overlapping with high debris concentrations over meso-scales.
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