خيارات البحث
النتائج 691 - 700 من 1,310
Bioindicative potential of shell abnormalities occurring in the clam Macoma balthica (L.) from the Baltic Sea النص الكامل
2011
Smolarz, Katarzyna | Bradtke, Katarzyna
This study reports the occurrence of shell deformities in the Baltic clam Macoma balthica from the Northern Baltic Sea (Trösa Archipelago, Sweden). The functional significance and the bioindicative potential of observed exoskeleton’ anomalies was assessed using a suite of physiological and morphological biomarkers. Analyzed shell deformations (SD) included damages of the dorsal margin visible as shell excavations, destruction of the beak, umbo and hinge ligament and decreased shell’ transparency. Deformed clams exhibited worse physiological conditions and increased frequency of micronuclei. Skewed sex ratio towards male domination was observed in all studied populations. Spatial differences in the occurrence of deformed clams are reported, with more than 50% of deformed clams inhabiting polluted locations and 8% the reference station. These results are encouraging for the use of described SDs as initial and cost effective indicators of environmental health.
اظهر المزيد [+] اقل [-]Differential kinetics and temperature dependence of abiotic and biotic processes controlling the environmental fate of TNT in simulated marine systems النص الكامل
2011
Chappell, Mark A. | Porter, Beth E. | Price, Cynthia L. | Pettway, Brad A. | George, Robert D.
This work seeks to understand how the balance of abiotic and biotic kinetic processes in sediments control the residual concentration of TNT in marine systems after release from ocean-dumped source. Kinetics of TNT disappearance were followed using marine sediments at different temperatures and under both biotic and presumably abiotic conditions (through sodium azide addition). Sediments exhibiting the highest rate of TNT disappearance under biotic conditions also exhibited the highest sorption affinity for TNT under abiotic conditions. Significant temperature dependence in the abiotic processes was observed in the diffusion coefficient of TNT and not sediment sorption affinity. At higher temperature, kinetics of biotic processes outpaced abiotic processes, but at low temperature, kinetics of abiotic processes were much more significant. We concluded that the differential influence of temperature on the kinetics of abiotic and biotic processes could provide distinguishing predictions for the potential residual concentration of TNT contamination in marine-sediment systems.
اظهر المزيد [+] اقل [-]The new potential invader Linopherus canariensis (Polychaeta: Amphinomidae) in a Mediterranean coastal lake: Colonization dynamics and morphological remarks النص الكامل
2011
Cosentino, A. | Giacobbe, S.
The newly introduced polychaete Linopherus canariensis Langerhans, 1881 was found in the Lake of Faro (NE Sicily), during a study comparing the macrobenthos in artificial modules with a neighboring sandy bottom assemblage. Of a total of 4465 specimens, almost 6% showed morphological variation related to branchial turfs and mean body size. The sandy bottom exhibited an average density of 41.86indL⁻¹ and a wet biomass of 30.35mgL⁻¹, whereas the artificial substratum reached levels of 205.29indL⁻¹ and 318.44mgL⁻¹. The highest estimated immigration rate was 3.7indL⁻¹d⁻¹ (5.8mgL⁻¹d⁻¹). In the artificial microhabitat, 0.4% of the population showed mid-anterior fragmentation, with anterior- (2%), mid- (<1%) and posterior- (1%) regenerating lineages, which contributed significantly to the dispersion ability of this species. L. canariensis was a selective micro-deposit feeder, even under conditions of reduced sediments. Linopherus was found to be a new potential invader of stressed environments that is probably tied to the import of oysters.
اظهر المزيد [+] اقل [-]Critical appraisal on the identification of Reference Conditions for the evaluation of ecological quality status along the Emilia-Romagna coast (Italy) using M-AMBI النص الكامل
2011
Paganelli, Daniele | Forni, Giulia | Marchini, Agnese | Mazziotti, Cristina | Occhipinti, Anna
According to the European Water Framework Directive, the ecological status (ES) of a water body is determined by comparing observation data with undisturbed Reference Conditions (RCs). Defining RCs is crucial when evaluating the ES of a water body as it strongly affects the final outcome of any index application. Identifying RCs by observing real sites is not feasible in many marine environments, such as the Emilia-Romagna coast (Italy, N-Adriatic Sea). We used a statistical approach on a large dataset to derive RCs for the application of the benthic index M-AMBI in this area. We then applied M-AMBI to samples collected along a gradient of presumed environmental disturbance. The results put 14.8% of the Emilia-Romagna samples in “High” ES, 60.2% in “Good”, 23.0% in “Moderate” and 2.0% in “Poor”, showing a spatial gradient of improving quality. These results are in agreement with the extensive ecological knowledge available for this area.
اظهر المزيد [+] اقل [-]Levels and distribution of polybrominated diphenyl ethers and organochlorine compounds in sea turtles from Japan النص الكامل
2011
Malarvannan, Govindan | Takahashi, Shin | Isobe, Tomohiko | Kunisue, Tatsuya | Sudaryanto, Agus | Miyagi, Toshihiko | Nakamura, Masaru | Yasumura, Shigeki | Tanabe, Shinsuke
Three species of sea turtles (green, hawksbill and loggerhead turtles) stranded along the coasts or caught (by-catch) around Ishigaki Island and Kochi, Japan were collected between 1998 and 2006 and analyzed for six organohalogen compounds viz., PBDEs, PCBs, DDTs, CHLs, HCHs and HCB. The present study is the first and foremost to report the occurrence of organohalogen compounds in the sea turtles from Japan. Among the compounds analyzed, concentrations of PCBs, DDTs and CHLs were the highest in all the turtle samples. PBDEs were ubiquitously present in all the turtle species. Comparing with the other two species, concentrations of organohalogens in green turtle were relatively low and decreasing trend in the concentrations were noted with increasing carapace length. Concentrations of OCs in sea turtles from the coasts of Ishigaki Island and Kochi were relatively low as compared to those from other locations in the world.
اظهر المزيد [+] اقل [-]Evaluation of microbiological water quality in the Pettaquamscutt River (Rhode Island, USA) using chemical, molecular and culture-dependent methods النص الكامل
2011
Atoyan, Janet A. | Herron, Elizabeth M. | Amador, José A.
We evaluated microbiological water quality in the Pettaquamscutt River (Rhode Island, USA), an estuarine river. Fecal coliform (FC) and enterococci (FE) bacteria, presence of Bifidobacterium adolescentis DNA (indicating human fecal contamination), and optical brightener (OB) fluorescence (associated with laundry detergents) were determined for 14 stations from May to September 2010. Six stations had high counts of FE and FC, and the presence of B. adolescentis DNA and high OB fluorescence indicated human fecal contamination – four had septic systems as likely sources of contamination; the others were in sewered areas. The ability of FC and FE to indicate human fecal contamination was assessed against a positive B. adolescentis test. FC and FE had false positive rates of 25% and 17%, respectively, and false negatives of 44% for FC and 63% for FE. Inclusion of molecular and chemical indicators should improve tracking of human fecal contamination sources in the river.
اظهر المزيد [+] اقل [-]Status of macrobenthic community of Manifa–Tanajib Bay System of Saudi Arabia based on a once-off sampling event النص الكامل
2011
Joydas, T.V. | Krishnakumar, P.K. | Qurban, Mohammad A. | Ali, Said M. | Al-Suwailem, Abdulaziz | Al-Abdulkader, Khaled
Shallow water bays located in the western Arabian Gulf experience harsh environmental conditions. Some of these bays, including Manifa–Tanajib Bay System (MTBS), were also exposed to the 1991 oil pollution event. This study investigates the status of the macrobenthos in MTBS during 2006. This bay system is characterized by very shallow inner bays with elevated salinity and temperature compared to the rest of the bay area. As a result mainly of the hyper salinity, the inner bay communities are distinct from the outer bay communities. Overall, fairly high species richness with several rare species was observed. High Shannon–Wiener diversity values and ABC plots indicated the healthy status of the polychaete communities, while BOPA index indicated slightly polluted status in 20% of the stations. The oil sensitive amphipods were not completely re-colonized in 20% of the stations, even after 15years of recovery from the 1991 oil spill.
اظهر المزيد [+] اقل [-]Dioxin-like compounds in sediments from the Daliao River Estuary of Bohai Sea: Distribution and their influencing factors النص الكامل
2011
Zhao, Xiaofeng. | Zhang, Haijun | Fan, Jingfeng | Guan, Daoming | Zhao, Huade | Ni, Yuwen | Li, Yun | Chen, Jiping
The concentrations, compositional profiles, and potential ecological risk of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs) and polychlorinated naphthalenes (PCNs) in sediments of the Daliao River Estuary were investigated. Total concentrations of PCDD/Fs, PCBs, and PCNs were in the range of 11.3–133.2ng/kg dry weight (dw), 1 971–37 632ng/kg dw and 33.1–284.4ng/kg dw, respectively. The total TEQ values varied from 0.37 to 4.08ng/kg dw, with the dominant contributions by PCDD/Fs, then by PCBs and PCNs. The spatial distributions of PCDD/Fs, PCBs and PCNs in the river estuary were much related to hydrodynamic conditions. The risk of contamination to the deeper sea was increased in the flood seasons. Moreover, our data confirmed that both organic matter in sediments and molecular properties of dioxin-like compounds were the factors which strongly influenced the partition behavior of these dioxin-like compounds between sediments and water phase in the estuarine zone.
اظهر المزيد [+] اقل [-]Fish consumption and risk of contamination by mercury – Considerations on the definition of edible parts based on the case study of European sea bass النص الكامل
2011
Mieiro, C.L. | Pacheco, M. | Duarte, A.C. | Pereira, M.E.
Fish consumption and risk of contamination by mercury – Considerations on the definition of edible parts based on the case study of European sea bass النص الكامل
2011
Mieiro, C.L. | Pacheco, M. | Duarte, A.C. | Pereira, M.E.
In the present study, the risk to humans by consuming European sea bass (Dicentrarchus labrax), captured at three sites along a Hg contamination gradient, was evaluated by comparing muscle and kidney total Hg (T-Hg) levels with the European regulations for marketed fish. Moreover, T-Hg and organic Hg (O-Hg) levels in muscle were compared with the Provisional Tolerable Weekly Intake (PTWI) and the Reference Dose (RfD). Although T-Hg levels in muscle were below the European value allowable for marketed fish, kidney’s levels were higher than the set value, stressing the importance of redefining the concept of edible tissue and which tissues should be considered. Mercury weekly ingestion in the contaminated areas was higher than the PTWI, and O-Hg daily ingestion rates were higher than the RfD in all sampling sites. Thus, populations consuming sea bass from the contaminated sites may be at risk, with particular relevance for children and pregnant women.
اظهر المزيد [+] اقل [-]Fish consumption and risk of contamination by mercury - Considerations on the definition of edible parts based on the case study of European sea bass النص الكامل
2011 | 1000
Mieiro, C. L. | Pacheco, M. | Duarte, A. C. | Pereira, M. E.
In the present study, the risk to humans by consuming European sea bass (Dicentrarchus labrax), captured at three sites along a Hg contamination gradient, was evaluated by comparing muscle and kidney total Hg (T-Hg) levels with the European regulations for marketed fish. Moreover, T-Hg and organic Hg (O-Hg) levels in muscle were compared with the Provisional Tolerable Weekly Intake (PTWI) and the Reference Dose (RfD). Although T-Hg levels in muscle were below the European value allowable for marketed fish, kidney’s levels were higher than the set value, stressing the importance of redefining the concept of edible tissue and which tissues should be considered. Mercury weekly ingestion in the contaminated areas was higher than the PTWI, and O-Hg daily ingestion rates were higher than the RfD in all sampling sites. Thus, populations consuming sea bass from the contaminated sites may be at risk, with particular relevance for children and pregnant women.
اظهر المزيد [+] اقل [-]Oil spill detection with fully polarimetric UAVSAR data النص الكامل
2011
Liu, Peng | Li, Xiaofeng | Qu, John J. | Wang, Wenguang | Zhao, Chaofang | Pichel, William
In this study, two ocean oil spill detection approaches based on four scattering matrices measured by fully polarimetric synthetic aperture radar (SAR) are presented and compared. The first algorithm is based on the co-polar correlation coefficient, ρ, and the scattering matrix decomposition parameters, Cloud entropy (H), mean scattering angle (α) and anisotropy (A). While each of these parameters has oil spill signature in it, we find that combining these parameters into a new parameter, F, is a more effective way for oil slick detection. The second algorithm uses the total power of four polarimetric channels image (SPAN) to find the optimal representation of the oil spill signature. Otsu image segmentation method can then be applied to the F and SPAN images to extract the oil slick features. Using the L-band fully polarimetric Uninhabited Aerial Vehicle – synthetic aperture radar (UAVSAR) data acquired during the 2010 Deepwater Horizon oil spill disaster event in the Gulf of Mexico, we are able to successfully extract the oil slick information in the contaminated ocean area. Our result shows that both algorithms perform well in identifying oil slicks in this case.
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