خيارات البحث
النتائج 701 - 710 من 1,310
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 [-]Influence of multiple stressors on the auto-remediation processes occurring in salt marshes النص الكامل
2011
Sousa, Ana I. | Lillebø, Ana I. | Pardal, Miguel A. | Caçador, Isabel
Due to increasing global population, salt marshes have been subjected to multiple stressors such as increasing nutrient loadings and historical contamination. In order to better understand how does the salt marsh plants auto-remediation capacity (phytoaccumulation of metals) is affected by cultural eutrophication, an experiment was performed under controlled conditions. Plants were exposure to equal metal concentrations (Zn, Cu, and Ni – micronutrients, and Cd – class B metal) simulating historical contamination and three different concentrations of nitrogen (nitrate) simulating steps of cultural eutrophication. According to our study, under the tested concentrations, cultural eutrophication does not seem to affect Zn, Cu and Ni phytoremediation of H. portulacoides, but the ecosystem service of Cd phytoremediation seems to be promoted. Nevertheless, Cd high toxicity and bioaccumulation should be taken into account, as well as the vulnerability of salt marsh ecosystems, whose reduction will have drastic consequences to the ecosystem health.
اظهر المزيد [+] اقل [-]Spatial modeling of environmental vulnerability of marine finfish aquaculture using GIS-based neuro-fuzzy techniques النص الكامل
2011
Navas, Juan Moreno | Telfer, Trevor C. | Ross, Lindsay G.
Combining GIS with neuro-fuzzy modeling has the advantage that expert scientific knowledge in coastal aquaculture activities can be incorporated into a geospatial model to classify areas particularly vulnerable to pollutants. Data on the physical environment and its suitability for aquaculture in an Irish fjard, which is host to a number of different aquaculture activities, were derived from a three-dimensional hydrodynamic and GIS models. Subsequent incorporation into environmental vulnerability models, based on neuro-fuzzy techniques, highlighted localities particularly vulnerable to aquaculture development. The models produced an overall classification accuracy of 85.71%, with a Kappa coefficient of agreement of 81%, and were sensitive to different input parameters. A statistical comparison between vulnerability scores and nitrogen concentrations in sediment associated with salmon cages showed good correlation. Neuro-fuzzy techniques within GIS modeling classify vulnerability of coastal regions appropriately and have a role in policy decisions for aquaculture site selection.
اظهر المزيد [+] اقل [-]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 [-]Gillnet fisheries as a major mortality factor of Magellanic penguins in wintering areas النص الكامل
2011
Cardoso, Luis Gustavo | Bugoni, Leandro | Mancini, Patrícia Luciano | Haimovici, Manuel
The incidental capture in fisheries is probably the main conservation problem affecting seabirds. While the capture of albatrosses and petrels on longline hooks is well-known worldwide, the bycatch of diving seabirds in gillnets is an overlooked conservation problem. During a winter coastal fishing trip, the capture of Magellanic penguins (Spheniscus magellanicus) was recorded in driftnet and bottom setnet fisheries for the first time in southern Brazil. The highest captures rates were found in driftnets, from 146.5 to 545.5penguins/km² of net and a total of 56 dead penguins were recorded. In the bottom gillnet, a total of 12 birds were killed and the capture rates varied from 41.7 to 125.0penguins/km² of net. Although preliminary, the results presented in this paper were consistent between sets. If we consider the magnitude of driftnet and setnet fishing fleets, and that most dead penguins were adults, the impact upon Magellanic penguin populations is probably significant.
اظهر المزيد [+] اقل [-]Endocrine effects of methoxylated brominated diphenyl ethers in three in vitro models النص الكامل
2011
Hu, Wei | Liu, Hongling | Sun, Hong | Shen, Ouxi | Wang, Xinru | Lam, Michael H.W. | Giesy, John P. | Zhang, Xiaowei | Yu, Hongxia
Methoxylated brominated diphenyl ethers (MeO-BDEs) in aquatic environments have been found to be primarily of natural origin in the marine environment and not from biotransformation of synthetic PBDEs. Two of the eight MeO-PBDEs (2′-MeO-BDE-68 and 6-MeO-BDE-47) that were detected in anchovy from the Yangtze River Delta, were natural products from marine organisms. So 2′-MeO-BDE-68 and 6-MeO-BDE-47 were chosen to study the potential to modulate androgen, estrogen, or thyroid hormone receptor- (AR, ER, ThR) mediated responses by use of reporter gene assays. 2′-MeO-BDE-68 was antiandrogenic at 50μM, estrogenic at 10μM and antiestrogenic at 10 and 50μM (IC₅₀=4.88μM). 2′-MeO-BDE-68 enhanced luciferase expression by 5nM T3 at 50μM. 6-MeO-BDE-47 exhibited potent antiandrogenicity at 1μM and greater (IC₅₀=41.8μM) and possessed estrogenic activity at 10μM and antiestrogenic activity at 10 and 50μM (IC₅₀=6.02μM).
اظهر المزيد [+] اقل [-]Sedimentology of a wreck: The Rainbow Warrior revisited النص الكامل
2011
Smith, Abigail M. | Kregting, Louise | Fern, Sophie | Fraser, Ceridwen I.
The wreck of the Rainbow Warrior, a 40-m ship sunk on 12 December 1987 in Matauri Bay (34° 59′ S, 173° 56′ E), Cavalli Islands, northeastern New Zealand, offers an opportunity to investigate the impact of artificial substrate on temperate carbonate sedimentation. Surface sediment samples showed no significant textural or compositional difference between sediments near the wreck and those far from it. The large and diverse carbonate-producing community resident on the wreck (dominated by bryozoans, corals and sponges) has not had a measurable influence on adjacent bottom sediments (dominated by bivalves and barnacles), even after 21years. It is likely that carbonate production on the Rainbow Warrior is insufficient to leave any sedimentary record over the potential lifetime of the wreck on the seafloor, which informs our understanding of the long-term impacts of shipwrecks (and other artificial substrata) on the local benthic environment in shallow temperate ecosystems.
اظهر المزيد [+] اقل [-]Hydrocarbon composition and distribution in a coastal region under influence of oil production in northeast Brazil النص الكامل
2011
Wagener, Angela de L.R. | Carreira, Renato S. | Hamacher, Claudia | Scofield, Arthur de L. | Farias, Cassia O. | Cordeiro, Lívia G.M.S. | Luz, Letícia G. | Baêta, Aída P. | Kalas, Francine A.
Waters and sediments from the Potiguar Basin (NE Brazilian coast) were investigated for the presence and nature of polycyclic aromatic hydrocarbons (PAH) and aliphatic hydrocarbons. The region receives treated produced waters through a submarine outfall system serving the industrial district. The total dispersed/dissolved concentrations in the water column ranged from 10–50ngL⁻¹ for ∑16PAH and 5–10μgL⁻¹ for total aliphatic hydrocarbons. In the sediments, hydrocarbon concentrations were low (0.5–10ngg⁻¹for ∑16PAH and 0.01–5.0μgg⁻¹ for total aliphatic hydrocarbons) and were consistent with the low organic carbon content of the local sandy sediments. These data indicate little and/or absence of anthropogenic influence on hydrocarbon distribution in water and sediment. Therefore, the measured values may be taken as background values for the region and can be used as future reference following new developments of the petroleum industry in the Potiguar Basin.
اظهر المزيد [+] اقل [-]Characterization of organic matter in sediment cores of the Todos os Santos Bay, Bahia, Brazil, by elemental analysis and ¹³C NMR النص الكامل
2011
Costa, A.B. | Novotny, E.H. | Bloise, A.C. | de Azevedo, E.R. | Bonagamba, T.J. | Zucchi, M.R. | Santos, V.L.C.S. | Azevedo, A.E.G.
The impact of human activity on the sediments of Todos os Santos Bay in Brazil was evaluated by elemental analysis and ¹³C Nuclear Magnetic Resonance (¹³C NMR). This article reports a study of six sediment cores collected at different depths and regions of Todos os Santos Bay. The elemental profiles of cores collected on the eastern side of Frades Island suggest an abrupt change in the sedimentation regime. Autoregressive Integrated Moving Average (ARIMA) analysis corroborates this result. The range of depths of the cores corresponds to about 50years ago, coinciding with the implantation of major onshore industrial projects in the region. Principal Component Analysis of the ¹³C NMR spectra clearly differentiates sediment samples closer to the Subaé estuary, which have high contents of terrestrial organic matter, from those closer to a local oil refinery. The results presented in this article illustrate several important aspects of environmental impact of human activity on this bay.
اظهر المزيد [+] اقل [-]Heavy metal concentrations and biomarkers of oxidative stress in native mussels (Mytilus edulis chilensis) from Beagle Channel coast (Tierra del Fuego, Argentina) النص الكامل
2011
Duarte, Claudia A. | Giarratano, Erica | Amin, Oscar A. | Comoglio, Laura I.
The aim of this study was to evaluate the usefulness of oxidative stress biomarkers of pollution in native mussels Mytilus edulis chilensis from the Beagle Channel. Spatial and seasonal variations of catalase, glutathione-S-transferase and lipid peroxidation in gills and digestive gland were analyzed in relation to environmental parameters, heavy metals in sediment and in tissue. Four sites with anthropogenic impact and a control site were selected and monitored during the four seasons of 2007. We found significant differences among sites in concentrations of dissolved nutrients and heavy metals in sediments, with the highest values recorded at sites with anthropogenic pressure. Different patterns were observed between concentrations of metals in tissues and in sediments suggesting differences in bioavailability. There were also significant differences in biomarker responses among sites, despite the strong seasonal variability. Our results showed relatively moderate levels of pollution in the study area as a result of urban influences.
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