خيارات البحث
النتائج 801 - 810 من 1,953
Water concentrations of PAH, PCB and OCP by using semipermeable membrane devices and sediments
2013
Karacık, B. | Okay, O.S. | Henkelmann, B. | Pfister, G. | Schramm, K.-W.
Water concentrations of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) were estimated from semipermeable membrane devices (SPMDs) and from sediment pollutant concentrations. SPMDs were deployed in the Istanbul Strait and Marmara Sea and retrieved after 7 and 21days. Performance reference compounds (PRCs) were used to determine the site-specific sampling rates of the compounds. Water concentrations (Cw) of the analyzed compounds estimated by using two different calculation methods for SPMDs were found similar. Cw of total PAHs estimated from SPMDs (Cw-spmd) were found between 13 and 79ngL−1 and between 7.0 and 68ngL−1 for 7 and 21days of deployments respectively. Water concentrations of PCBs using sediment data was found as between 0.001 and 11.0ngL−1. The highest value of Cw-spmd for two deployments were 2.8ngL−1 for OCPs. Cw estimated from sediment concentrations were generally higher than those estimated from SPMDs.
اظهر المزيد [+] اقل [-]Perfluorinated compounds: Levels, trophic web enrichments and human dietary intakes in transitional water ecosystems
2013
Renzi, Monia | Guerranti, Cristiana | Giovani, Andrea | Perra, Guido | Focardi, Silvano E.
The results of a study on levels of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), analyzed in terms of HPLC-ESI-MS in water, sediment, macrophyte, bivalve, crustacean and fish samples, are reported here. The aim of the research is to define, for the first time, PFOA/S levels in a heavily human-stressed transitional water ecosystem (Orbetello lagoon, Italy) and evaluate trophic web enrichments and human dietary intakes. The results obtained show that: (i) levels significantly higher than those reported in the literature were found in mussels, clams and crabs; (ii) the river is a significant pollution source; (iii) although absolute levels are relatively low, macroalgae proliferation contributes to redistribute pollutants from river-affected areas throughout the entire lagoon basin; (iv) to the best of our current knowledge, water-filtering species considered in this study are the most exposed to PFOA/S pollution; (v) human daily dietary intakes of PFOA/S through Slow Food-endorsed product consumption are below maximum tolerable levels suggested by the EFSA.
اظهر المزيد [+] اقل [-]Use of skin and blubber tissues of small cetaceans to assess the trace element content of internal organs
2013
Aubail, A. | Méndez-Fernandez, P. | Bustamante, P. | Churlaud, C. | Ferreira, M. | Vingada, J.V. | Caurant, F.
In order to evaluate the use of biopsy samples as non-destructive tool for assessing trace element concentrations in small cetaceans, the concentrations of 14 trace elements were determined in skin, blubber, liver and kidneys of four species of small cetaceans (i.e. common dolphin Delphinus delphis, harbour porpoise Phocoena phocoena, bottlenose dolphin Tursiops truncatus and striped dolphin Stenella coeruleolba), stranded and/or by-caught along the NE Atlantic Ocean coast between 2001 and 2008. Only Cu, Fe, Hg, Mn, Ni and Zn were above the detection limit of the instruments and showed recoveries satisfactory enough to be interpreted. Among these trace elements, Hg was the only one showing a significant correlation between concentrations in and those in liver and kidneys. In consequence skin and blubber can only be used as non-invasive monitoring tissues to investigate Hg bioaccumulation in internal tissues for cetacean populations.
اظهر المزيد [+] اقل [-]Extraction of bioavailable contaminants from marine sediments: An approach to reducing toxicity using adsorbent parcels
2013
Goodsir, Freya | Fisher, Tom T. | Barry, Jon | Bolam, Thi | Nelson, Leah D. | Rumney, Heather S. | Brant, Jan L.
This paper demonstrates an approach to reducing acute toxicity in marine sediments using adsorbent parcels. Acute toxicity tests were carried using the marine amphipod Corophium volutator. Marine sediments were spiked with two know contaminants tributyltin and naphthalene and then treated with adsorbent parcels containing either amberlite XAD4 or activated carbon. Results showed that both types of adsorbent parcels were effective in reducing acute toxicity, not only within spiked sediments containing naphthalene and/or tributyltin, but also in an environmental field samples form an expected contaminated site. Adsorbent parcels such as these could provide a practical approach to remediate areas of contaminated sediment within marine environments. Furthermore adsorbents can be used as an identification tool for problematic contaminants using a toxicity identification evaluation approach.
اظهر المزيد [+] اقل [-]Baseline occurrence of organochlorine pesticides and other xenobiotics in the marine environment: Caribbean and Pacific collections
2013
Menzies, Robert | Soares Quinete, Natalia | Gardinali, Piero | Seba, Douglas
This ongoing survey reports the levels of persistent organic pollutants (POPs) in sea surface slicks collected on a global circumnavigation. Hydrophobic xenobiotic compounds such as POPs are known to accumulate on the sea surface in slicks at concentrations many fold greater than the underlying water column, raising concerns about the ecological impacts due to the high biological activity associated with this zone. Six different categories of POPs were reported: chlorobenzenes, hexachlorocyclohexanes, chlordane related compounds, organochlorine pesticides and other cyclodiene pesticides, DDTs and metabolites, and polychlorinated biphenyls. Concentrations ranged from <1ngL−1 to 18.45μgL−1. Ranking analysis indicates an independence of detected concentrations for each class of compounds and their geographical locations. Although concentrations observed were normally low and below commonly accepted toxic levels to animals and humans, they fall within the effective range of concentrations of many hormones and neurotransmitters, thus could potentially act as endocrine disrupters.
اظهر المزيد [+] اقل [-]Identification of sources of tar balls deposited along the Goa coast, India, using fingerprinting techniques
2013
Deposition of tar balls along the coast of Goa, India is a common phenomenon during the southwest monsoon. Representative tar ball samples collected from various beaches of Goa and one Bombay High (BH) crude oil sample were subjected to fingerprint analysis based on diagnostic ratios of n-alkane, biomarkers of pentacyclic tri-terpanes and compound specific stable carbon isotope (δ13C) analysis to confirm the source. The results were compared with the published data of Middle East Crude Oil (MECO) and South East Asian Crude Oil (SEACO). The results revealed that the tar balls were from tanker-wash derived spills. The study also confirmed that the source is not the BH, but SEACO. The present study suggests that the biomarkers of alkanes and hopanes coupled with stable carbon isotope analysis act as a powerful tool for tracing the source of tar balls, particularly when the source specific biomarkers fail to distinguish the source.
اظهر المزيد [+] اقل [-]Increased liver apoptosis and tumor necrosis factor expression in Atlantic bluefin tuna (Thunnus thynnus) reared in the northern Adriatic Sea
2013
(Emilio), | (Carla),
The Atlantic bluefin tuna Thunnus thynnus (ABFT) is intensely fished in the Mediterranean Sea to supply a prosperous capture-based mariculture industry. Liver apoptotic structures and tumor necrosis factor (TNF) gene expression were determined in: wild ABFT caught in the eastern Atlantic; juvenile ABFT reared in the central Adriatic Sea; juvenile ABFT reared in the northern Adriatic Sea; adult ABFT reared in the western Mediterranean. The highest density of liver apoptotic structures was found in the juveniles from the northern Adriatic. Two partial TNF cDNAs (TNF1 and TNF2) were cloned and sequenced. TNF1 gene expression was higher in juveniles than in adults. The highest expression of TNF2 was found in the juveniles from the northern Adriatic. These findings might be related to the juvenile exposure to environmental pollutants.
اظهر المزيد [+] اقل [-]Anatomy of a decision: Potential regulatory outcomes from changes to chemistry protocols in the Canadian Disposal at Sea Program
2013
Apitz, Sabine E. | Agius, Suzanne
Environment Canada currently assesses dredged material proposed for disposal at sea using a two-tiered assessment framework. Tier 1 determines sediment geophysical properties and concentrations of four regulated chemical constituents (Cd, Hg, PAH and PCB), and “other chemicals of interest” based on lower action levels; this is followed by biological assessment. EC is pursuing a “data mining” approach to evaluate potential refinements by compiling sediment chemistry and toxicity datasets, and subjecting them to a series of decision protocols. This paper reports on database development and initial use, and recommends potential changes to Tier 1 chemical protocols and further work to address other aspects of the framework. Major findings include the poor performance of Hg and Cd as sentinels for other metals, the significance of the list of analytes (vs. the specific SQGs used) in decisions, and the potential for chemical upper action levels to save the expense of unnecessary toxicity testing.
اظهر المزيد [+] اقل [-]Study on the sorption behaviour of estrone on marine sediments
2013
Zhang, Jing | Yang, Gui-Peng | Li, Quan | Cao, Xiaoyan | Liu, Guangxing
The sorption behaviour of estrone (E1) on marine sediments treated by different methods was systematically investigated. About 22h was required for sorption equilibrium of E1. Sorption isotherms of E1 were well fitted with Freundlich model. The sorption behaviour of E1 on HCl-treatment and H2O-treatment sediments related significantly with the sediment organic carbon contents. Additionally, clay minerals and surface areas of sediments played dominant roles in the sorption of E1 on H2O2-treatment sediments. Some external factors which could affect sorption behaviour of E1 were also investigated. Our results showed that the sorption capacity of E1 on the sediments increased with the increasing concentrations of cationic surfactant cetyltrimethylammonium bromide (CTAB), nonionic surfactant polyoxyethylene (80) sorbitan esters (Tween 80) and salinity of seawater. In contrast, the sorption capacity of E1 decreased with the increasing concentration of anionic surfactant sodium dodecylbenzene sulfonate (SDBS), pH value and temperature of seawater.
اظهر المزيد [+] اقل [-]Coastal urbanization leads to remarkable seaweed species loss and community shifts along the SW Atlantic
2013
Scherner, Fernando | Horta, Paulo Antunes | de Oliveira, Eurico Cabral | Simonassi, José Carlos | Hall-Spencer, Jason M. | Chow, Fungyi | Nunes, José Marcos C. | Pereira, Sonia Maria Barreto
Coastal urbanization is rapidly expanding worldwide while its impacts on seaweed communities remain poorly understood. We assessed the impact of urbanization along an extensive latitudinal gradient encompassing three phycogeographical regions in the SW Atlantic. Human population density, number of dwellings, and terrestrial vegetation cover were determined for each survey area and correlated with diversity indices calculated from seaweed percent cover data. Urban areas had significantly lower calcareous algal cover (−38%), and there was significantly less carbonate in the sediment off urban areas than off reference areas. Seaweed richness averaged 26% less in urban areas than in areas with higher vegetation cover. We observed a remarkable decline in Phaeophyceae and a substantial increase of Chlorophyta in urban areas across a wide latitudinal gradient. Our data show that coastal urbanization is causing substantial loss of seaweed biodiversity in the SW Atlantic, and is considerably changing seaweed assemblages.
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