خيارات البحث
النتائج 1361 - 1370 من 4,367
Blood cadmium and metallothionein concentrations in females of two sympatric pinnipeds species النص الكامل
2017
Polizzi, P. | Romero, M.B. | Chiodi Boudet, L.N. | Ponce de León, A. | Medici, S. | Costas, A. | Rodríguez, D. | Gerpe, M.
Otaria flavescens (SASL) and Arctocephalus australis (SAFS) are endemic of South America. The aims were to assess Cd concentrations in red blood cells (RBC) and plasma from free living females of both species; and to establish metallothioneins (MT) levels in blood fractions and the possible relationship between MTs and Cd. Blood of fifteen SASL and eight SAFS females from Isla de Lobos were analyzed (years 2010–2011). All animals showed Cd levels above the detection limit. Cd concentrations on SAFS were higher than those of SASL, however, no significant differences were observed on metal concentrations between cell fractions by species. Metal levels were associated with a natural presence and ecological-trophic habits of the prey items. On SASL the MT concentrations between fractions were similar; whereas, SAFS plasma concentrations were higher than RBC. The results reported constitute the first information on Cd and MT blood levels in these species.
اظهر المزيد [+] اقل [-]Continuous monitoring of noise levels in the Gulf of Catania (Ionian Sea). Study of correlation with ship traffic النص الكامل
2017
Viola, S. | Grammauta, R. | Sciacca, V. | Bellia, G. | Beranzoli, L. | Buscaino, G. | Caruso, Fabbio | Chierici, F. | Cuttone, G. | D’Amico, A. | De Luca, V. | Embriaco, D. | Favali, P. | Giovanetti, G. | Marinaro, G. | Mazzola, S. | Filiciotto, F. | Pavan, G. | Pellegrino, C. | Pulvirenti, S. | Simeone, F. | Speziale, F. | Riccobene, G.
Acoustic noise levels were measured in the Gulf of Catania (Ionian Sea) from July 2012 to May 2013 by a low frequency (<1000Hz) hydrophone, installed on board the NEMO-SN1 multidisciplinary observatory. NEMO-SN1 is a cabled node of EMSO-ERIC, which was deployed at a water depth of 2100m, 25km off Catania. The study area is characterized by the proximity of mid-size harbors and shipping lanes. Measured noise levels were correlated with the passage of ships tracked with a dedicated AIS antenna. Noise power was measured in the frequency range between 10Hz and 1000Hz. Experimental data were compared with the results of a fast numerical model based on AIS data to evaluate the contribution of shipping noise in six consecutive 1/3 octave frequency bands, including the 1/3 octave frequency bands centered at 63Hz and 125Hz, indicated by the Marine Strategy Framework Directive (2008/56/EC).
اظهر المزيد [+] اقل [-]Use of multiple functional traits of protozoa for bioassessment of marine pollution النص الكامل
2017
Zhong, Xiaoxiao | Xu, Guangjian | Xu, Henglong
Ecological parameters based on multiply functional traits have many advantages for monitoring programs by reducing “signal to noise” ratios of observed species data. To identify potential indicators for bioassessment of marine pollution in function space, the functional patterns of protozoan communities and relationships with environmental changes were studied in coastal waters of the Yellow Sea during a 1-year period. The results showed that: (1) the spatial variability in functional trait distributions of the protozoa was significantly associated with changes in environmental variables, especially chemical oxygen demand (COD) and nutrients on spatial scale; (2) the functional traits, especially food resources and feeding type, were significantly correlated with COD and nutrients; and (3) the functional diversity indices were generally related to nutrients or COD. Based on the results, we suggest that the functional traits and diversity indices of protozoan communities may be used as more effective indicators for bioassessment of marine pollution.
اظهر المزيد [+] اقل [-]Dispersal and assimilation of an aquaculture waste subsidy in a low productivity coastal environment النص الكامل
2017
White, C.A. | Nichols, P.D. | Ross, D.J. | Dempster, T.
To understand dispersal and assimilation of aquaculture waste subsidies in a naturally low-productivity environment, we applied a novel, rapid transmethylation technique to analyse sediment and biota fatty acid composition. This technique was initially validated at Atlantic salmon farms in Macquarie Harbour, Australia, where sediments were collected at farm and control locations. Subsequently, sediment, benthic polychaete and zooplankton were sampled at sites 0, 50, 250, 500 and 1000m distant from multiple cages. Results demonstrated an acute deposition zone up to 50m from cages and a diffuse zone extending 500m from cages. Changes in sediment concentration of linoleic acid, oleic acid and total fatty acids were effective tracers of farm deposition. Bacterial biomarkers indicated that aquaculture waste stimulates bacterial productivity in sediments, with elevated biomarker concentrations also detected in benthic polychaetes. Overall, fatty acid analysis was a sensitive technique to characterize the benthic footprint of aquaculture influence.
اظهر المزيد [+] اقل [-]Investigating Bermuda's pollution history through stable isotope analyses of modern and museum-held gorgonian corals النص الكامل
2017
Baker, David M. | Murdoch, Thaddeus J.T. | Conti-Jerpe, Inga | Fogel, Marilyn
For centuries, Bermuda has been challenged with wastewater management for the protection of human and environmental health. By quantifying the δ15N of the common sea fan Gorgonia ventalina sampled from 30 sites throughout Bermuda we show that sewage-derived nitrogen is detectable on nearshore coral reefs and declines across the lagoon to the outer rim. We also sampled gorgonians from two museum collections representing a 50y time-series (1958–2008). These samples revealed an increase in δ15N of >4.0‰ until the mid-1970s, after which δ15N values slowly declined by ~2.0‰. A δ15N chronology from a gorgonian skeleton exhibited a similar decline over the last 30–40years of approximately 0.6‰. We conclude that policies have been effective in reducing sewage impacts to Bermudian reefs. However, significant sources of sewage pollution persist and are likely have a strong impact on harbor and nearshore coral communities and human health.
اظهر المزيد [+] اقل [-]Petroleum hydrocarbon persistence following the Deepwater Horizon oil spill as a function of shoreline energy النص الكامل
2017
Evans, Meredith | Liu, Jiqing | Bacosa, Hernando | Rosenheim, Brad E. | Liu, Zhanfei
An important aspect of oil spill science is understanding how the compounds within spilled oil, especially toxic components, change with weathering. In this study we follow the evolution of petroleum hydrocarbons, including n-alkanes, polycyclic aromatic hydrocarbons (PAHs) and alkylated PAHs, on a Louisiana beach and salt marsh for three years following the Deepwater Horizon spill. Relative to source oil, we report overall depletion of low molecular weight n-alkanes and PAHs in all locations with time. The magnitude of depletion, however, depends on the sampling location, whereby sites with highest wave energy have highest compound depletion. Oiled sediment from an enclosed bay shows high enrichment of high molecular weight PAHs relative to 17α(H),21β(H)-hopane, suggesting the contribution from sources other than the Deepwater Horizon spill, such as fossil fuel burning. This insight into hydrocarbon persistence as a function of hydrography and hydrocarbon source can inform policy and response for future spills.
اظهر المزيد [+] اقل [-]Identification of genotoxic compounds in crude oil using fractionation according to distillation, polarity and Kow النص الكامل
2017
Park, Shin Yeong | Lee, Hyo Jin | Khim, Jong Seong | Kim, Gi Beum
We examined the degree of DNA damage caused by fractions of crude oil in accordance with the boiling points, polarity and log Kow. Relatively high DNA damage was observed in the aromatic fraction (290–330°C) and resin and polar fraction (350–400°C). The resin and polar fraction showed relatively high genotoxicity compared with the aliphatic and aromatic fraction at the 1–4 log Kow range. At the 6–7 log Kow range, the aromatic fraction showed relatively high DNA damage compared with the aliphatic and resin and polar fraction. In particular, every detailed fraction in accordance with the log Kow values (aliphatic and aromatic (310–320°C) and resins and polar fractions (370–380°C)) showed one or less than one DNA damage. However, the fractions before separation in accordance with log Kow values (aliphatic and aromatic (310–320°C) and resin and polar (370–380°C) fractions) showed high DNA damage. Thus, we confirm the synergistic action between the detailed compounds.
اظهر المزيد [+] اقل [-]Shell shape as a biomarker of marine pollution historic increase النص الكامل
2017
Márquez, F. | Primost, M.A. | Bigatti, G.
Buccinanops globulosus is a TBT sensitive marine gastropod, classified as a good indicator of imposex incidence and used as a model to study adverse contamination effects. Population and maritime industries has incremented pollution in Nuevo gulf harbor since 1970s, promoting morphological changes in B. globulosus shell shape. We study the shell shape of the species comparing present day's specimens from the harbor zone with those collected in the same zone before the increasing of maritime activity and pre-Hispanic archaeological Middens. We demonstrated that harbor pollution produces globular shell shape in B. globulosus, an effect that probably allows gastropods to isolate themselves from the external adverse environment. On the contrary, shells from pre-Hispanic periods, unpolluted sites and those collected before the expansion of maritime activities, presented an elongated shell shape. Our study confirms that shell shape variation in marine gastropods can be used as a biomarker of harbor pollution.
اظهر المزيد [+] اقل [-]Contamination assessment of mercury, lead, cadmium and arsenic in surface sediments of Chabahar Bay النص الكامل
2017
Molamohyeddin, Neda | Ghafourian, Hossein | Sadatipour, Seyed Mohamadtaghi
This study aimed to investigate heavy metals content of mercury (Hg), lead (Pb), cadmium (Cd) and arsenic (As) in surface sediments of Chabahar Bay. Sediment samples were taken from 13 stations and then analyzed. The concentration of Hg, Pb, Cd and As ranged between 0.06 and 0.14ppm, 8 and 23ppm, 0.05 and 0.9ppm and 5 and 22ppm, respectively. Arsenic content was more than ERL at some stations. Statistical analyses indicated critical importance of organic matter and mud in metal dispersion. Also, positive correlation of Al with Pb, Hg and Cd probably implies their terrestrial origination. Average enrichment factor of Hg, Pb, Cd and As were 2.67±0.95, 0.77±0.28, 6.56±9.9, and 7.53±3.44, respectively. Most stations were classified as moderately polluted and non-polluted sites.
اظهر المزيد [+] اقل [-]A dual indicator approach for monitoring benthic impacts from organic enrichment with test application near Atlantic salmon farms النص الكامل
2017
Cranford, Peter J. | Brager, Lindsay | Wong, David
The organic enrichment of surficial sediments has a known effect on benthic faunal communities due largely to oxygen depletion and sulfide toxicity. Total dissolved sulfide (free S−2=H2S+HS−+S2−) concentrations in sediments are widely measured as a practical indicator of community effects. However, the standard ion selective electrode (ISE) method for free S−2 analysis can provide biased results owing to the inclusion of non-toxic mineral sulfides and the oxidation and volatilization of free S−2. A rapid field protocol was developed that alleviates these problems while also providing data on dissolved oxygen concentrations. Sediments collected near salmon aquaculture pens over cohesive and permeable substrates were analysed using the standard and new protocols. The results confirm previous conclusions of artifacts with the standard ISE method, while the dual indicator approach more accurately describes the stages, spatial extent and magnitude of sediment geochemical alterations affecting benthic communities.
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