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Relationship between wind and seagrass meadows in a non-tidal eutrophic lagoon studied by a Wave Exposure Model (WEMo) Texto completo
2013
Rubegni, Fabrizio | Franchi, Enrica | Lenzi, Mauro
The hydrodynamic action of wind and the distribution of biomass of seagrass meadows in a non-tidal eutrophic lagoon (Orbetello Lagoon, Tuscany, Italy) were analysed for correlations by simulation with a Wave Exposure Model (WEMo) on 5-year data series. WEMo and statistical analysis established a weak direct correlation between the areas that the model identified as being subject to resuspension and transport of sediment and those actually colonised by seagrass. A significant difference was found between surface and bottom hydrodynamics. The areas that the model identified as exposed to higher energy surface hydrodynamics proved to be inversely correlated with seagrass biomass. Multivariate statistical analysis ordered the model variables according to their relative importance. The model indicated the need for further study, demonstrating its utility for environmental management of eutrophic lagoons.
Mostrar más [+] Menos [-]Analysis of the bacterial community in the two typical intertidal sediments of Bohai Bay, China by pyrosequencing Texto completo
2013
Wang, Liping | Liu, Lusan | Zheng, Binghui | Zhu, Yanzhong | Wang, Xing
For full understanding of the bacterial community in the intertidal zones of Bohai Bay, China, we used pyrosequencing-based approach to analyze the 16S rRNA gene of bacteria in the sediments from the two typically intertidal zones – Qikou (Qi) and Gaoshaling (Ga). Results showed that, at a 0.03 distance, the sequences from the Qi sediment were assigned to 3252 operational taxonomic units (OTUs) which belong to 34 phyla, 69 classes and 119 genera, while the 3740 OTUs from the Ga sediment were affiliated with 33 phyla, 66 classes and 146 genera. Comparing the bacterial communities inhabiting in the two intertidal sediments, we observed significant difference in the dominant composition and distribution at phylum, class and genus levels. Canonical correspondence analysis (CCA) showed that the median grain size and DO were the most important factors regulating the bacterial abundance and diversity, while the other environmental factors have effects with different degree.
Mostrar más [+] Menos [-]Contrasting key roles of Ruppia cirrhosa in a southern Mediterranean lagoon: Reservoir for both biodiversity and harmful species and indicator of lagoon health status Texto completo
2013
Dhib, Amel | Ben Brahim, Mounir | Turki, Souad | Aleya, Lotfi
The distribution of Ruppia cirrhosa meadow density and its epiphytic organisms in relation with environmental factors were studied in summer 2011 at five stations in the Ghar El Melh lagoon (GML; southern Mediterranean Sea). Eleven epiphytic groups were recognised among which diatoms and dinoflagellates were the dominant groups and greatest contributors to temporal dissimilarity. An overwhelming concentrations of harmful microalgae was recorded, mainly represented by the toxic dinoflagellate Prorocentrum lima with maximal concentrations attaining 6×105cells 100g−1 of Ruppia fresh weight. The epifauna community accounted for only 1.4% of total epiphyte abundance and was comprised predominantly of nematodes (47.51%), ciliates (32.59%), fish eggs (7.2%) and larvae (4.95%). PERMANOVA analyses revealed a significant spatio-temporal variation of all epiphytic groups (p<0.01). In this study, R. cirrhosa and its epiphytes were studied as potential early warning indicators of the health status of GML waters.
Mostrar más [+] Menos [-]Levels and spatial distribution of perfluorinated compounds (PFCs) in superficial sediments from the marine reserves of the Tuscan Archipelago National Park (Italy) Texto completo
2013
Perra, Guido | Focardi, Silvano Ettore | Guerranti, Cristiana
Surface sediments from marine reserves of the Tuscan Archipelago National Park (Italy), including remote islands not directly affected by anthropogenic influences, were analyzed for two dominant perfluorinated compounds (PFCs), namely perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA), using LC–ESI-MS/MS. The concentrations of PFOS were low, with medians ranging from 0.25 to 1.50ng/g dry wt, whereas PFOA was always below the detection limit of 0.1ng/g dry wt. The present paper can be considered a baseline study useful in future environmental monitoring programs.
Mostrar más [+] Menos [-]Temperature–salinity modeling for Ruwais coastal area in United Arab Emirates Texto completo
2013
Elshorbagy, Walid | Azam, Mir Hammadul | Elhakeem, Abubaker
A three dimensional rectangular grid model is applied to resolve the temperature–salinity dynamics of Ruwais, a segment of the UAE coast which is well known as dense water formation zone. The model employs a heat flux module and a turbulence closure scheme that facilitate realistic calculation of temperature–salinity dynamics. A field survey campaign is carried out to support the modeling study, involving measurements of tide, currents, temperature, and salinity. Investigation is done for two meteorologically extreme conditions, i.e. summer and winter. The model study showed that the western flux develops an anticlockwise circulation in the study area. The water industrial discharges elevated the temperature and salinity of the water near the southeastern shoreline. This water mass propagated towards north under the influence of gravity.
Mostrar más [+] Menos [-]Biomagnification of persistent chlorinated and brominated contaminants in food web components of the Yellow Sea Texto completo
2013
Byun, Gyo-Hyuk | Moon, Hyo-Bang | Ch'oe, Chŏng-hwa | Hwang, Jeomshik | Kang, Chang-Keun
Concentrations of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), and polybrominated diphenyl ethers (PBDEs) were measured in 32 species inhabiting the Yellow Sea to assess their bioaccumulation potentials. The concentrations in these samples were lower than those reported for other countries or locations. Relatively high levels of BDE 209 in biota suggest an ongoing source of deca-BDE technical mixing within the Yellow Sea. The accumulation profiles of PCBs were uniform between species, but the concentrations of OCPs and PBDEs varied widely. Pelagic and benthic food-chain components were separated by their δ13C values. Significant positive correlations between δ15N and PCB 153, PCB 138, p,p′-DDE, oxy-chlordane, and trans-nonachlordane were found only for pelagic consumers, indicating that the pelagic food chain is an important bioaccumulation pathway for selected PCB and OCP compounds. The other compounds did not show any biomagnification through benthic and pelagic food chains, suggesting the lower bioaccumulation potentials of these contaminants.
Mostrar más [+] Menos [-]Health impact assessment of marine emissions in Pearl River Delta region Texto completo
2013
Lai, H.K. | Tsang, H. | Chau, J. | Lee, C.H. | McGhee, S.M. | Hedley, A.J. | Wong, C.M.
Global marine vessels emissions are adversely affecting human health particularly in southeast Asia. But health burdens from both ocean- and river-going vessels in Pearl River Delta (PRD) regions are not quantified. We estimated the potential health impacts using pooled relative risks of mortality and hospital admissions in China, and the model derived concentrations of sulfur dioxide (SO2), particulate matter (PM10), nitrogen dioxide (NO2) and ozone (O3) due to vessels emissions. SO2 concentrations due to marine emissions in Hong Kong were 13.6μgm−3 compared with 0.7μgm−3 in PRD regions that were far from the marine vessels. In PRD regions, the estimated annual numbers (per million people) of excess deaths from all natural causes and hospital admissions from cardiorespiratory causes attributable to SO2, NO2, O3 and PM10 combined from marine emissions were 45 and 265 respectively. Marine emission control measures could contribute a large reduction in mortality and hospital admissions in PRD regions especially in Hong Kong.
Mostrar más [+] Menos [-]Mercury deposition during the previous century in an upwelling region; Cabo Frio, Brazil Texto completo
2013
Figueiredo, Thiago S. | Albuquerque, Ana Luiza S. | Sanders, Christian J. | Cordeiro, Lívia G.M.S. | Silva-Filho, Emmanoel V.
To investigate the upwelling influence on Hg biogeochemical cycles and the sedimentological changes during the previous ∼150years, four sediment box-cores were sampled along an inshore offshore transect on the Southeastern Brazilian continental shelf. Mercury values were found to be relatively low, with means ranging between 8.08 and 30.4ngg−1. Mercury fluxes along the sediment cores are directly related to the well documented historical regional activity and global atmospheric deposition. The narrow relationship between mercury and organic carbon suggest that upwelling phenomenon and primary production may play an important role on Hg input and distribution along continental shelf depositional settings.
Mostrar más [+] Menos [-]Revisiting hydrocarbons source appraisal in sediments exposed to multiple inputs Texto completo
2013
Massone, Carlos G. | Wagener, Angela de L.R. | Abreu, Henrique Monteiro de | Veiga, Alvaro
The aim of this work was to test the efficiency of statistical methods as compared to the traditional diagnostic ratios to improve hydrocarbon source identification in sediments subjected to multiple inputs. Hydrocarbon determination in Guanabara Bay sediments pointed out high degradation and ubiquitous petrogenic pollution through the presence of high unresolved complex mixture. Polycyclic aromatic hydrocarbon (PAHs) ratios suggested pervasive contamination derived from combustion in all sediments and failed discriminating samples despite the specificity of sources in different sampling sites. Principal component analysis (PCA) effectively distinguished the petrogenic imprint superimposed to the ubiquitous combustion contamination, since this technique reduces the influence of PAHs distribution which is common to all samples. PCA associated to multivariate linear regression (MLR) allowed a quantitative assessment of sources confirming predominance of the pervasive contaminant component superimposed to a generalized petrogenic imprint. The pervasive component derives from combustion contributions as well as from differential PAHs degradation.
Mostrar más [+] Menos [-]Chlorinated compounds and polybrominated diphenyl ethers (PBDEs) in mussels (Mytilus galloprovincialis) collected from Apulia Region coasts Texto completo
2013
Giandomenico, Santina | Spada, Lucia | Annicchiarico, Cristina | Assennato, Giorgio | Cardellicchio, Nicola | Ungaro, Nicola | Leo, Antonella Di
This project was carried out to assess the levels and spatial distribution of organochlorine compounds in the coastal marine environment, using mussels as bioindicators to evaluate the coastal water quality. Levels of polychlorobiphenils (PCB), chlorinated pesticides (DDT isomers, HCH isomers, Aldrin, Dieldrin, alfa-Endosulfan, Hexachlorobenzene, Pentachlorobenzene) and polybrominated diphenyl ethers (PBDEs) were determined in tissues from mussels (Mytilus galloprovincialis) collected along the Apulia Region coasts (Mediterranean Sea). Results indicate that contamination by organochlorine compounds is higher in mussels sampled in the Ionian Sea than in those from the Adriatic Sea, with PCB levels up to seven times higher in mussels from Ionian than from the Adriatic Sea. Although PCB levels were above the maximum values indicated by both European Community (EC) and National regulation in several sample sites, the PCB concentrations were particularly high in some stations, suggesting that these locations require a much specific attention. Conversely, results on the mussel contamination by PBDEs highlight their ubiquitous environmental distribution, and underline the need to establish the maximum level for these compounds in foodstuff, according to European Regulations.
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