Refinar búsqueda
Resultados 731-740 de 2,503
Role of gamma radiation in changing phytotoxic effect of elevated level of ozone in Trifolium alexandrinum L. (Clover)
2014
Chaudhary, Nivedita | Agrawal, Shashi Bhushan
The present study was conducted on clover (Trifolium alexandrinum L. cv Wardan), to investigate the effect of ambient and elevated (ambient +10 ppb O3) ozone (O3) on plants grown in open top chambers (OTCs) germinated from gamma (γ) irradiated seeds. Dry seeds were subjected to irradiation with 0, 5, 10 and 20 krad doses of γ rays from 60Co source. Dose dependent differential responses were observed on growth and biomass, photosynthetic pigments, metabolites, antioxidative defense system of plant. Growth parameters and biomass of plants were severely affected under elevated O3 with increasing radiation doses, except, 5 krad which showed a reverse trend of response. Photosynthetic pigments and total soluble proteins were also reduced with higher dose of γ radiation and elevated O3. Reactive oxygen species formation and membrane damage increased significantly to different extents. Plants grown from seeds irradiated with low dose (5 krad) of γ irradiation depicted more induction of antioxidants (enzymatic and non–enzymatic) than higher doses suggesting their high ameliorative capability against elevated O3. Principal component analysis has also confirmed that plants grown from 5 krad γ irradiated seeds performed better against O3 depicting reduction in negative effect against elevated O3. The experimental findings evidently showed that 5 krad γ radiations altered the O3 induced stress and thus minimized the loss in biomass of the test plant.
Mostrar más [+] Menos [-]Quality assessment of the blue mussel (Mytilus edulis): Comparison between commercial and wild types
2014
De Witte, B. | Devriese, L. | Bekaert, K. | Hoffman, S. | Vandermeersch, G. | Cooreman, K. | Robbens, J.
This study compared species identity, microplastics, chemical and microbial contamination between consumption mussels and wild type mussels, collected at Belgian department stores and Belgian groynes and quaysides, respectively. Species identification based on genetic analysis showed a high number of Mytilus (M.) edulis compared to M. galloprovincialis and M. edulis/galloprovincialis hybrid mussels. The number of total microplastics varied from 2.6 to 5.1fibres/10g of mussel. A higher prevalence of orange fibres at quaysides is related to fisheries activities. Chemical contamination of polycyclic aromatic hydrocarbons and polychlorobiphenyls could be related to industrial activities and water turbidity, with maximum concentrations at the quayside of port Zeebrugge. The inverse was noted for Escherichia coli contamination, which was relatively low at Zeebrugge quayside with a total count of 3.9×102CFU/100g tissue, due to limited agricultural effluents. Results of this complementary analysis stress the importance of integrated monitoring and quality assessment.
Mostrar más [+] Menos [-]Trace element concentrations in barramundi (Lates calcarifer) collected along the coast of Vietnam
2014
Tu, Nguyen Phuc Cam | Ha, Nguyen Ngoc | Haruta, Shinsuke | Takeuchi, Ichirō
We determined concentrations of 23 trace elements (TEs), and stable carbon and nitrogen isotope (δ13C and δ15N) signatures in barramundi (Lates calcarifer) specimens collected along the coast of Vietnam in the Northern (NCZ), Central (CCZ) and Southern (SCZ) zones in the period 2007–2010. A combination of δ13C and δ15N signatures provided insight into ontogenetic shifts in barramundi foraging choices. There were clear zone-dependent differences in Mn, As, Sr and Tl concentrations; levels of Tl were highest in the NCZ, As in the CCZ, and Mn and Sr in the SCZ. Lowest concentrations of Rb occurred in the NCZ, Bi was lowest in the CCZ, and Cd and Cs were lowest in the SCZ. δ15N values significantly increased with increasing Zn, Se, Sn and Cs. Concentrations of TEs in barramundi from Vietnam were below worldwide guidelines for human consumption.
Mostrar más [+] Menos [-]210Po, Cd and Pb distribution and biomagnification in the yellowfin tuna Thunnus albacares and skipjack tuna Katsuwonus pelamis from the Eastern Pacific
2014
Ruelas-Inzunza, J. | Soto-Jiménez, M.F. | Ruiz-Fernández, A.C. | Ramos-Osuna, M. | Mones-Saucedo, J. | Páez-Osuna, F.
We measured Cd and Pb in the muscle and stomach contents of Thunnus albacares and Katsuwonus pelamis to define the distribution of the elements in the tissues and their degrees of biomagnification. 210Po was measured in the livers of both species and compared to the results of similar studies. The trophic position of the tuna species was determined by N isotope measurements. The average activity of 210Po in the liver ranged from 119 to 157 (Bqkg−1 wet weight) in K. pelamis and T. albacares. The trophic position of T. albacares (4.60) was higher than that of K. pelamis (3.94). The Cd content of the muscle increased significantly with the trophic position of the tuna. δ13C in T. albacares and K. pelamis varied, with values of 3.13 and 1.88‰, respectively. The δ15N values in yellowfin tuna were higher than in skipjack tuna. The trophic position of T. albacares (4.60±0.67) was therefore more elevated than that of K. pelamis (3.94±1.06). Pb was biomagnified in T. albacares (transfer factor=1.46).
Mostrar más [+] Menos [-]Study of landscape patterns of variation and optimization based on non-point source pollution control in an estuary
2014
Jiang, Mengzhen | Chen, Haiying | Chen, Qinghui | Wu, Haiyan
Appropriate increases in the “sink” of a landscape can reduce the risk of non-point source pollution (NPSP) to the sea at relatively lower costs and at a higher efficiency. Based on high-resolution remote sensing image data taken between 2003 and 2008, we analyzed the “source” and “sink” landscape pattern variations of nitrogen and phosphorus pollutants in the Jiulongjiang estuary region. The contribution to the sea and distribution of each pollutant in the region was calculated using the LCI and mGLCI models. The results indicated that an increased amount of pollutants was contributed to the sea, and the “source” area of the nitrogen NPSP in the study area increased by 32.75km2. We also propose a landscape pattern optimization to reduce pollution in the Jiulongjiang estuary in 2008 through the conversion of cultivated land with slopes greater than 15° and paddy fields near rivers, and an increase in mangrove areas.
Mostrar más [+] Menos [-]ALien Biotic IndEX (ALEX) – A new index for assessing impacts of alien species on benthic communities
2014
Çinar, Melih Ertan | Bakir, Kerem
Biotic indices are mainly aimed at assessing levels of deterioration caused by chemical or organic pollution. However, no biotic index to date has been developed to detect impacts of alien species on benthic communities. In this paper, a new biotic index, namely ALEX, is proposed to address the objectives of the Water Framework Directive and was tested in Mersin Bay (Levantine Sea, Turkey). Species were divided into four biogeographic groups, namely native species, casual species, established species and invasive species, and the metric considers the relative importance of these groups in samples. The index classified the ecological status of some stations which are shallow, and close to harbor and river mouths as bad or poor in February and October. The ALEX values were positively and significantly correlated with total nitrogen, silicate and silt percentage in sediment, and negatively correlated with depth and the distance from the harbor.
Mostrar más [+] Menos [-]A multivariate approach to the determination of an indicator species pool for community-based bioassessment of marine water quality
2014
Xu, Guangjian | Zhong, Xiaoxiao | Wang, Yangfan | Warren, Alan | Xu, Henglong
Previous studies in Chinese coastal waters of the Yellow Sea have shown that periphytic ciliates are reliable indicators of marine water quality. However, traditional community-based bioassessments are time-consuming because they rely on the identification and enumeration of all species within the community. In order to improve bioassessment efficiency, step-best-matching analysis was used to identify which are the most reliable indicator species among periphytic marine ciliate communities. Based on indices of species richness, diversity and evenness, a subset of 48 species (out of a total of 141) was found to retain sufficient information for accurately predicting water quality, and was more strongly related to changes of environmental variables than the full species set. These results demonstrate that the step-best-matching analysis is a powerful approach for identifying an indicator species pool from a full species dataset of a community, and allows the development of time-efficient sampling protocols for community-based marine bioassessment.
Mostrar más [+] Menos [-]A comparative study of marine litter on the seafloor of coastal areas in the Eastern Mediterranean and Black Seas
2014
Ioakeimidis, C. | Zeri, C. | Kaberi, H. | Galatchi, M. | Antoniadis, K. | Streftaris, N. | Galgani, F. | Papathanassiou, E. | Papatheodorou, G.
In the present work, abundance, spatial distribution and qualitative composition, of benthic marine litter, were investigated in five study areas from the Eastern Mediterranean and Black Seas (Saronikos, Patras and Echinades Gulfs; Limassol Gulf; Constanta Bay). Surveys were performed using the monitoring protocol proposed by the Technical Group for Marine Litter. Densities ranged from 24items/km2 to 1211items/km2, with the Saronikos Gulf being the most affected area. Plastics were predominant in all study areas ranging from 45.2% to 95%. Metals and Glass/Ceramics reached maximum values of 21.9% and of 22.4%. The size distribution of litter items showed that ⩾50% fall into medium size categories (10×10cm, 20×20cm) along with an elevated percentage of small-sized (<5×5cm) plastic litter items. The comparative analysis of the data highlighted the dependence of the marine litter problem on many local factors (human sources and oceanographic conditions) and the urgent need for specific actions.
Mostrar más [+] Menos [-]Patterns of marine debris distribution on the beaches of Rottnest Island, Western Australia
2014
Smith, Stephen D.A. | Gillies, Chris L. | Shortland-Jones, Helen
Rottnest Island, Western Australia, receives >500,000visitorsy−1, who are mainly attracted by the Island’s natural values. Marine debris is a threat to both these natural values and to Island wildlife, and is consequently an important issue for managers. Engaging with volunteers, we quantified marine debris at 16 beach sites around the Island. The highest loads occurred on the SW coast and primarily comprised items originating from fishing activities. Sites on the NE coast, where >95% of the Island’s accommodation is located, supported the highest abundance of items deposited in situ (e.g. bottles and cigarette butts). We conclude that marine debris management may require a range of strategies to address the different primary sources. Raising awareness through education and intervention may be highly effective at popular beaches on the NE coast, but broader liaison with commercial and recreational fishers will be necessary to address the issue at the Island scale.
Mostrar más [+] Menos [-]Regional distribution of halogenated organophosphate flame retardants in seawater samples from three coastal cities in China
2014
Hu, Mengyang | Li, Jun | Zhang, Beibei | Cui, Qinglan | Wei, Si | Yu, Hongxia
Thirteen samples of seawater were collected from Yellow Sea and East China Sea near Qingdao, Lianyungang, and Xiamen, China. They were analyzed for halogenated organophosphorus flame retardants (OPFRs). The compounds selected for detection were Tris(2-chloroethyl) phosphate (TCEP), Tris(2-chloroisopropyl) phosphate (TCPP), Tris (1,3-dichloro-2-propyl) phosphate (TDCPP), and Tris(2,3-dibromopropyl) phosphate (TDBPP). The total concentrations ranged from 91.87 to 1392ng/L and the mean concentrations of these four chemicals were 134.44, 84.12, 109.28, and 96.70ng/L, respectively. TCEP exhibited the highest concentrations, although concentrations of TCPP and TDCPP were also fairly high in Lianyungang and Xiamen. Generally, Lianyungang was the most heavily polluted district, with very high concentrations of TCEP at LYG-2 (550.54ng/L) and LYG-4 (617.92ng/L). The main sources of halogenated OPFRs were municipal and industrial effluents of wastewater treatment plants in the nearby economic and industrial zones.
Mostrar más [+] Menos [-]