Уточнить поиск
Результаты 1091-1100 из 3,243
The use of diagnostic ratios, biomarkers and 3-way Kohonen neural networks to monitor the temporal evolution of oil spills
2015
Fernández-Varela, R. | Gómez-Carracedo, M.P. | Ballabio, D. | Andrade, J.M.
Oil spill identification relies usually on a wealth of chromatographic data which requires advanced data treatment (chemometrics). A simple approach based on Kohonen neural networks to handle three-dimensional arrays is presented. A suite of 28 diagnostic ratios was considered to monitor six oils along four months. It was found that some traditional diagnostic ratios were not stable enough. In particular, alkylated PAHs (e.g. 1-methyldibenzothiophene, 4-methylpyrene, 27bbSTER and the TA21 and TA26 triaromatic steroids) seemed less resistant to medium-weathering than biomarkers. One (or two) ratios were found to differentiate each product: 30O, 28ab (and 25nor30ab), C3-dbt/C3-phe, 27Ts, TA26 and 29Ts characterized Ashtart, Brent, Maya, Sahara, IFO and Prestige oils, respectively.
Показать больше [+] Меньше [-]A three-dimensional water quality model to evaluate the environmental capacity of nitrogen and phosphorus in Jiaozhou Bay, China
2015
Li, Keqiang | Zhang, Li | Li, Yan | Zhang, Longjun | Wang, Xiulin
Jiaozhou Bay has recently suffered from serious problems with pollution and eutrophication. Thus, land-based pollutant load must be reduced through a national control program. In this study, we developed a 3D water quality model to determine the environmental capacity of nitrogen and phosphorus in Jiaozhou Bay. A 3D hydrodynamic model (the estuarine, coastal, and ocean modeling system with sediments) was coupled with a water quality model, which was adapted from the dynamic model of nitrogen and phosphorus for a mesocosm near Jiaozhou Bay. The water quality model is divided into seven components: dissolved inorganic nitrogen, phosphate, phytoplankton, zooplankton, detritus, dissolved organic nitrogen, and dissolved organic phosphorus. Furthermore, it was calibrated based on data collected from Jiaozhou Bay in 2003. The proposed model effectively reproduced the spatiotemporal variability in nutrient concentration, thus suggesting that a reasonable numerical representation of the prototype system must be developed for further evaluation of environmental capacity.
Показать больше [+] Меньше [-]Trace metal enrichment and organic matter sources in the surface sediments of Arabian Sea along southwest India (Kerala coast)
2015
Sreekanth, Athira | Mrudulrag, S.K. | Cheriyan, Eldhose | Sujatha, C.H.
The geochemical distribution and enrichment of trace metals (Cd, Co, Cu, Fe, Mn, Ni, Pb and Zn) were determined in the surface sediments of Arabian Sea, along southwest India, Kerala coast. The results of geochemical indices indicated that surficial sediments of five transects are uncontaminated with respect to Mn, Zn and Cu, uncontaminated to moderately contaminated with Co and Ni, and moderately to strongly contaminated with Pb. The deposition of trace elements exhibited three different patterns i) Cd and Zn enhanced with settling biodetritus from the upwelled waters, ii) Pb, Co and Ni show higher enrichment, evidenced by the association through adsorption of iron–manganese nodules onto clay minerals and iii) Cu enrichment observed close to major urban sectors, initiated by the precipitation as Cu sulfides. Correlation, principal component analysis (PCA) and cluster analysis (CA) were used to confirm the origin information of metals and the nature of organic matter composition.
Показать больше [+] Меньше [-]Assessment of swimming associated health effects in marine bathing beach: An example from Morib beach (Malaysia)
2015
Praveena, Sarva Mangala | Pauzi, Norfasmawati Mohd | Hamdan, Munashamimi | Sham, Shaharuddin Mohd
A survey among beachgoers was conducted to determine the swimming associated health effects experienced and its relationship with beach water exposure behaviour in Morib beach. For beach water exposure behaviour, the highest frequency of visit among the respondents was once a year (41.9%). For ways of water exposure, whole body exposure including head was the highest (38.5%). For duration of water exposure, 30.8% respondents prefer to be in water for about 30min with low possibilities of accidental ingestion of beach water. A total of 30.8% of beachgoers in Morib beach were reported of having dermal symptoms. Bivariate analysis showed only water activity, water contact and accidental ingestion of beach water showed significant association with swimming associated health effects experienced by swimmers. This study output showed that epidemiological study can be used to identify swimming associated health effects in beach water exposed to faecal contamination.
Показать больше [+] Меньше [-]Does the chronic chemical contamination of a European flounder population decrease its thermal tolerance?
2015
Lavergne, Edouard | Pedron, Nicolas | Calves, Isabelle | Claireaux, Guy | Mazurais, David | Zambonino-Infante, José | Le Bayon, Nicolas | Cahu, Chantal | Laroche, Jean
Juvenile flounders (Platichthys flesus), collected in two estuaries with similar temperature regimes (the heavily polluted Seine and the moderately contaminated Vilaine), were submitted to a common garden experiment. After an acclimation period, both populations were challenged by a thermal stress (9–24°C for 15days, then maintenance at 24°C for 19days). The condition factor of the Vilaine fish increased in both conditions, while it decreased for the heated Seine flounders after 34days. The expression of genes related to the energetic metabolism was measured in the liver. The expression levels for ATP-F0 and COII were significantly reduced for heated vs. standard fish from both estuaries, while a decrease of the 12S expression was detected only in heated vs. standard fish from the Seine estuary. Thus, it is suggested that highly contaminated fish from Seine could display a lower tolerance to thermal stress, compared to moderately contaminated fish from Vilaine.
Показать больше [+] Меньше [-]Biodiversity and degradation potential of oil-degrading bacteria isolated from deep-sea sediments of South Mid-Atlantic Ridge
2015
Gao, Xiangxing | Gao, Wei | Cui, Zhisong | Han, Bin | Yang, Peihua | Sun, Chengjun | Zheng, Li
The indigenous oil-degrading bacterial consortia MARA and MARB were enriched from the deep-sea sediments of South Mid-Atlantic Ridge (MAR) with crude oil as sole carbon and energy sources. Biodiversity and community analyses showed that members of α-Proteobacteria were the key players in consortium MARA, whereas those of γ-Proteobacteria were the key players in consortium MARB, which were studied by MiSeq sequencing method. Gravimetric method estimated the oil degradation rates of MARA and MARB to be 63.4% and 85.8%, respectively, after 20d. Eleven cultivable oil degraders with different morphologies were isolated. These strains were identified as Alcanivorax, Bacillus, Dietzia, Erythrobacter, Marinobacter, Nitratireductor, and Oceanicola based on 16S rRNA gene sequences. Three strains belonging to Dietzia exhibited the highest oil degradation capability. Results indicated that the intrinsic biodegradation capacity of oil contaminants by indigenous microbial communities exists in South MAR sediments.
Показать больше [+] Меньше [-]Premature aging in bone of fish from a highly polluted marine area
2015
Scopelliti, Giovanna | Di Leonardo, Rossella | Tramati, Cecilia D. | Mazzola, Antonio | Vizzini, Salvatrice
Fish species have attracted considerable interest in studies assessing biological responses to environmental contaminants. In this study, the attention has been focussed on fishbone of selected fish species from a highly polluted marine area, Augusta Bay (Italy, Central Mediterranean) to evaluate if toxicant elements had an effect on the mineralogical structure of bones, although macroscopic deformations were not evident. In particular, an attempt was made to evaluate if bone mineral features, such as crystallinity, mineral maturity and carbonate/phosphate mineral content, determined by XR-Diffraction and FT-IR Spectroscopy, suffered negative effects due to trace element levels in fishbone, detected by ICP-OES. Results confirmed the reliability of the use of diffractometric and spectroscopic techniques to assess the degree of crystallinity and the mineral maturity in fishbone. In addition, in highly polluted areas, Hg and Cr contamination induced a process of premature aging of fishbone, altering its biochemical and mineral contents.
Показать больше [+] Меньше [-]Sources and ecological risk assessment of PAHs in surface sediments from Bohai Sea and northern part of the Yellow Sea, China
2015
Li, Jiafu | Dong, Han | Zhang, Dahai | Han, Bin | Zhu, Chenjian | Liu, Shaopeng | Liu, Xiangmin | Ma, Qianyao | Li, Xianguo
Sources and ecological risk of sixteen priority PAHs in surface sediments from Bohai Sea (BS) and northern part of the Yellow Sea (NPYS) were investigated. The total concentrations of PAHs varied in ranges 149.24–1211.81 and 148.28–907.47ng/g for BS and NPYS, respectively. Principal component analysis-multiple linear regression (PCA–MLR) suggested that coal combustion, vehicular emission and coke oven could be the primary PAH contributors, accounting for 56.6%, 29.2% and 14.2% of PAH concentrations, respectively. Analysis with sediment quality guidelines (SQGs) indicated that acenaphthylene, fluorene, phenanthrene, fluoranthene, pyrene and dibenzo(a,h)anthracene may occasionally cause adverse biological effects in some stations. Organic carbon (OC)-normalized analysis and mean effects range-median quotient (M-ERM-Q) suggested that the combined ecological risk of PAHs was generally low. The toxic equivalent concentrations of carcinogenic PAHs were 12.87–64.6ng/g-BaPeq and 5.95–68.80ng/g-BaPeq in BS and NPYS, respectively, suggesting low carcinogenic risk for both BS and NPYS.
Показать больше [+] Меньше [-]Oil spill contamination probability in the southeastern Levantine basin
2015
Bowman, Ronald R. | Biṭon, Eli | Brokovich, Eran | Kark, Salit | Levin, Noam
Recent gas discoveries in the eastern Mediterranean Sea led to multiple operations with substantial economic interest, and with them there is a risk of oil spills and their potential environmental impacts. To examine the potential spatial distribution of this threat, we created seasonal maps of the probability of oil spill pollution reaching an area in the Israeli coastal and exclusive economic zones, given knowledge of its initial sources. We performed simulations of virtual oil spills using realistic atmospheric and oceanic conditions. The resulting maps show dominance of the alongshore northerly current, which causes the high probability areas to be stretched parallel to the coast, increasing contamination probability downstream of source points. The seasonal westerly wind forcing determines how wide the high probability areas are, and may also restrict these to a small coastal region near source points. Seasonal variability in probability distribution, oil state, and pollution time is also discussed.
Показать больше [+] Меньше [-]Marine pollution effects on the southern surf crab Ovalipes trimaculatus (Crustacea: Brachyura: Polybiidae) in Patagonia Argentina
2015
Lezcano, Aníbal Hernán | Rojas Quiroga, María Laura | Liberoff, Ana Laura | Van der Molen, Silvina
We compared the carapace shape and thickness as well as the energy density of Ovalipes trimaculatus inhabiting areas comprising a gradient of marine pollution: high, moderate and undetected, in the Nuevo gulf (Patagonia Argentina). The carapace shape was evaluated by means of individual asymmetry scores (=fluctuating asymmetry) whereas the carapace thickness was assessed by measuring the carapace dry weight. The energy density was analyzed through its negative relationship with water content in muscle tissue. The individual asymmetry scores as well as the percentage of water content in muscle tissue were proportional to the marine pollution gradient, whereas the carapaces thickness did not differ among sampling sites. Our results are consistent with previous findings and demonstrate the direct effect of marine pollution on other taxa different from gastropods, cephalopods and polyplacophora and add to long-standing concerns about detrimental effects caused by marine pollution on the benthic community of the Nuevo gulf.
Показать больше [+] Меньше [-]