خيارات البحث
النتائج 1501 - 1510 من 4,309
Spatial distribution, risk assessment and source identification of heavy metals in sediments of the Yangtze River Estuary, China النص الكامل
2017
Han, Deming | Cheng Jinping, | Hu, Xianfeng | Jiang, Zhenyi | Mo, Lei | Xu, Hao | Ma, Yuning | Chen, Xiaojia | Wang, Heling
The aim of this study was to determine the spatial distribution, potential risks and sources of seven heavy metals in sediments of the Yangtze River Estuary. Analyses of 55 sediment samples revealed that the distributions of metals within the YRE were determined by the combined effects of their sources, hydrodynamic conditions, pH and Eh. According to the geoaccumulation index (Igeo) and sediment quality guidelines, Pb, Cd and Cr were present at low levels of pollution, with Cd posing the largest ecological risk. Positive Factor Matrix (PMF) results indicated that Hg, Zn, As, Pb and Cr mainly originated from natural geological background sources, while Cu originated from anthropogenic activities and atmospheric deposition was the source of Cd. These three sources contributed to 53.0%, 32.8% and 14.2%, respectively of total heavy metal concentrations. These results suggest that reducing the emission of Cd would promote a reduction of potential risks in sediments of the YRE.
اظهر المزيد [+] اقل [-]Contamination and ecological risk assessment of trace elements in sediments of the rivers of Sundarban mangrove forest, Bangladesh النص الكامل
2017
Islam, M.A. | Al-mamun, A. | Hossain, F. | Quraishi, S.B. | Naher, K. | Khan, R. | Das, S. | Tamim, U. | Hossain, S.M. | Nahid, F.
In this study, total concentrations of 16 trace elements (Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Cd, Sb, Hg, Pb, Th and U) in sediments of the rivers of the Sundarban mangrove forest, after the catastrophic oil spill accident in the Sela river of Sundarban, were determined. The overall mean concentrations of V, Cr, Fe and Cd in surface sediments of the Sundarban are remarkably higher than available literature data of those elements. Trace element contamination assessment, using different environmental contamination indices, reveals that As, Sb, Th and U are low to moderately contaminated while Cd is moderately to severely contaminated in the sediments of this area. The multivariate statistical analyses were applied to reveal the origin and behavior of the elements during their transport in the mangrove ecosystem. High Cr, Ni, Cu and As concentrations suggest the risk of potentially adverse biological effects in the ecosystem.
اظهر المزيد [+] اقل [-]Ecosystem uptake and transfer of Sellafield-derived radiocarbon (14C) part 2: The West of Scotland النص الكامل
2017
Tierney, Kieran M. | Muir, Graham K.P. | Cook, Gordon T. | MacKinnon, Gillian | Howe, John A. | Heymans, Johanna J. | Hughes, D. J. (David J.) | Xu, Sheng
Ecosystem uptake and transfer of Sellafield-derived radiocarbon (14C) were examined within the West of Scotland marine environment. The dissolved inorganic carbon component of seawater, enriched in 14C, is transported to the West of Scotland where it is transferred through the marine food web. Benthic and pelagic biota with variable life-spans living in the North Channel and Clyde Sea show comparable 14C activities. This suggests that mixing of 14C within the Irish Sea results in a relatively constant northwards dispersal of activity. Benthic species in the Firth of Lorn have similar 14C enrichments, demonstrating that Irish Sea residual water is the dominant source to this area. Measured 14C activities in biota show some similarity to western Irish Sea activities, indicating that dispersion to the West of Scotland is significant with respect to the fate of Sellafield 14C releases. Activities measured in commercially important species do not pose any significant radiological risk.
اظهر المزيد [+] اقل [-]Use of moss biomonitors for turbulent transport coefficient estimation for industrial emissions النص الكامل
2017
Ryzhakova, Nadezhda K. | Borisenko, Alexei L. | Babicheva, Valentina O.
The important mechanism transporting substances in the surface layer of the atmosphere is turbulent diffusion. The intensity of turbulent transport is characterized by the turbulent diffusion coefficient. Calculation is a difficult task without a unique characterization. Distinguished turbulent models of atmospheric flow have been developed for particular atmospheric states and simple landscapes. These restrictions complicate the use of such models when assessing the distribution of industrial emissions in the atmosphere. The aims of the present work are to (i) develop a semi-empirical method for estimating the turbulent diffusion coefficient of the emissions of large industries, and (ii) study the turbulence intensity dependence of fundamental factors: the wind speed and landscape. The method relies on the distribution function of the concentration of contaminants measured along any direction of the altitude of a point source. Epiphytic mosses (Pylaisia polyantha, Sanionia uncinata) were used with an exposure time of 3 years. The chemical contents of the mosses were determined by neutron activation analysis and atomic emissive spectrometry. It is shown that in the territories of the coal-fired thermal power station and aluminum plant, the average values of the turbulent transport coefficient at heights above 1 m are k1¯=0.15 m2/s and k1¯=0.02 m2/s respectively. High turbulence within the location of the thermal power station is explained by obstacles of various heights and a higher wind speed. The proposed method is useful for the estimation and forecast of the spatial distribution of emissions from large industries and for determining the zones of their influence.
اظهر المزيد [+] اقل [-]Occurrence of pharmaceuticals and UV-filters in riverine run-offs and waters of the German Baltic Sea النص الكامل
2017
Fisch, Kathrin | Waniek, J. J. (Joanna J.) | Schulz-Bull, Detlef E.
The occurrence of pharmaceuticals and personal care products (PPCPs) in the marine environment is of great concern. This study was done to determine the emergence of eight pharmaceuticals and eleven ultraviolet filters (UV-Filters) in 5 rivers/streams discharging into the Baltic Sea. Furthermore, a focus was put on the influence of wastewater treatment plant as indirect source and the occurrence of the PPCPs in close beach proximity. Two pharmaceuticals (sulfamethoxazole, salicylic acid) and two UV-filters (2-phenylbenzimidazole-5-sulfonic acid, octocrylene) were detected in all analyzed water samples, with concentration ranging from 0.6ng/L to 836.3ng/L. In all rivers the PPCP concentration decreases towards the Baltic Sea. Sulfamethoxazole was detected at comparable concentration along the coast, which leads to the assumption of stable concentration in beach proximity. Along the coast UV-filters appeared in varying concentrations, leading to the conclusion that the direct input into the marine environment plays a bigger role than the indirect input.
اظهر المزيد [+] اقل [-]Methods comparison, transport and distribution of polar herbicides in the Baltic Sea النص الكامل
2017
Skeff, Wael | Orlikowska, Anna | Schulz-Bull, Detlef E.
Two LC-MS/MS methods including different sample preparation and quantitative processes showed a good agreement for analysis of the herbicides MCPA, mecoprop, isoproturon, bentazon and chloridazon, and the metabolite chloridazon-methyl-desphenyl (CMD) in estuarine waters. Due to different sensitivity of the methods only one could be used to analyze marine samples. The transport of these compounds to the Baltic Sea via ten German estuaries and their distribution between coastal water and sediments was studied. The results showed that all selected compounds can be transported to the Baltic Sea (0.9–747ng/L). Chloridazon, bentazon, isoproturon and CMD were detected (0.9–8.9ng/L) in the coastal waters and chloridazon and isorproturon in the sediments (5–136pg/g d.w.). Levels of contaminants in the sediments could be influenced by the total organic carbon content. Concentrations observed in the Baltic Sea are most likely not high enough to cause acute effects, but long term effect studies are strongly recommended.
اظهر المزيد [+] اقل [-]Mercury contamination in Southern New England coastal fisheries and dietary habits of recreational anglers and their families: Implications to human health and issuance of consumption advisories النص الكامل
2017
Taylor, David L. | Williamson, Patrick R.
Total mercury (Hg) was measured in coastal fishes from Southern New England (RI, USA), and Hg exposure was estimated for anglers and family members that consumed these resources. Fish Hg was positively related to total length (n = 2028 across 7 fish species), and interspecies differences were evident among legally harvestable fish. Many recreational anglers and their families experienced excessively high Hg exposure rates, which was attributed to the enriched Hg content of frequently consumed fishes. Specifically, 51.5% of participants in this study had Hg exposures exceeding the US EPA reference dose, including 50.0% of women of childbearing years. These results are noteworthy given that Hg neurotoxicity occurs in adults and children from direct and prenatal low-dose exposure. Moreover, this study underscores the need for geographic-specific research that accounts for small-scale spatial variations in fish Hg and dietary habits of at-risk human populations.
اظهر المزيد [+] اقل [-]Biomarker responses of Cu-induced toxicity in European seabass Dicentrarchus labrax: Assessing oxidative stress and histopathological alterations النص الكامل
2017
Díaz-de-Alba, M. | Canalejo Raya, A. | Granado-Castro, M.D. | Oliva Ramírez, M. | El Mai, B. | Córdoba García, F. | Troyano-Montoro, M. | Espada-Bellido, E. | Torronteras Santiago, R. | Galindo-Riaño, M.D.
A comprehensive approach to chemical accumulation and biological effects of short-term Cu exposure in juveniles of European seabass (Dicentrarchus labrax) has been achieved. Fish were exposed to 0.01–10mgL−1 nominal Cu concentrations for 24–96h. Metal concentrations in water and gills, liver, muscle and brain tissues were studied along with oxidative stress biomarkers (superoxide dismutase, catalase, glutathione peroxidase, lipid peroxidation). Induction of oxidative damage was observed in all the organs with differential antioxidant responses; gills appearing as the most sensitive from low environmentally water Cu concentrations as 0.01mgL−1. Histopathological alterations were also observed in liver and gills, even without a significant Cu accumulation.The results show that the combination of oxidative stress parameters, particularly lipid peroxidation and glutathione peroxidase activities, and histopathological alterations provide a good model fish and reliable early biomarkers for monitoring Cu pollution in seawater and might call for the protection agencies to revise the Cu environmental standards.
اظهر المزيد [+] اقل [-]Increasing contribution of coccolithophorids to the phytoplankton in the northeastern Black Sea النص الكامل
2017
Yasakova, Olga N. | Okolodkov, Yuri B. | Chasovnikov, Valeriy K.
During 2005–2011, 418 phytoplankton samples were collected in Novorossiysk and Tuapse ports and near the resort cities of Anapa and Gelendzhik in the northeastern Black Sea. The maximal values of both abundance and biomass of phytoplankton related to high nutrient concentration, probably due to anthropogenic load, were observed at Novorossiysk (5.82×105cells/l, 1.492g/m3); in other bays values were about three times lower. The annual cycle included two to four phytoplankton abundance peaks. Emiliania huxleyi was the most abundant coccolithophorid (1.15×105cells/l offshore and 2.20×104cells/l in bays and ports). In spring-summer it contributed up to 90% of the phytoplankton abundance offshore. The maximal abundance of E. huxleyi was observed offshore of Gelendzhik (up to 1.32×106cells/l); the minimum was in the coastal zone in the port of Novorossiysk (on average 7.7×103cells/l). Generally, the species appears to avoid eutrophic waters.
اظهر المزيد [+] اقل [-]Ambient noise dynamics in a heavy shipping area النص الكامل
2017
Kinda, G Bazile | Le Courtois, Florent | Stephan, Yann
The management of underwater noise within the European Union's waters is a significant component (Descriptor 11) of the Marine Strategy Framework Directive (MSFD). The indicator related to continuous noise, is the noise levels in two one-third octave bands centered at 63Hz and 125Hz. This paper presents an analysis of underwater noise in the Celtic Sea, a heavy shipping area which also hosts the seasonal Ushant thermal front. In addition to the MSFD recommended frequency bands, the analysis was extended to lower and upper frequency bands. Temporal and spatial variations as well as the influence of the properties of the water column on the noise levels were assessed. The noise levels in the area had a high dynamic range and generally exceeded 100dB re 1μPa. Finally, the results highlighted that oceanic mooring must be designed to minimize the pseudo-noise and consider the water column physical properties.
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