Refinar búsqueda
Resultados 721-730 de 2,513
Spatial patterns of metals, PCDDs/Fs, PCBs, PBDEs and chemical status of sediments from a coastal lagoon (Pialassa Baiona, NW Adriatic, Italy) Texto completo
2014
Guerra, Roberta | Pasteris, Andrea | Lee, Seok-hyung | Park, No-jin | Ok, Gon
The European Water Framework Directive (WFD) establishes a framework for the protection and improvement of all water bodies including transitional waters; its final objective is to achieve at least ‘good status’ by 2015. In the present work, a hierarchical sampling design was applied to analyze the influence of anthropogenic inputs on the spatial distribution of metals, polychlorinated dibenzo-p-dioxins (PCDDs) dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in sediment at four areas in Pialassa Baiona coastal lagoon. In order to assess the chemical status, levels of priority substances and other pollutants were compared with the recently developed national Environmental Quality Standards (EQS) and site specific background levels for metals. Levels of mercury and PCBs were particularly high and exceeded their national EQS values at all sampled areas, thus not contributing to the achievement of a good chemical status of this transitional water body according to the WFD classification.
Mostrar más [+] Menos [-]Simulation of the potential effects of CO2 leakage from carbon capture and storage activities on the mobilization and speciation of metals Texto completo
2014
de Orte, Manoela Romanó | Sarmiento, Aguasanta M. | DelValls, T Ángel | Riba, Inmaculada
One of the main risks associated with carbon capture and storage (CCS) activities is the leakage of the stored CO2, which can result in several effects on the ecosystem. Laboratory-scale experiments were performed to provide data on the possible effects of CO2 leakage from CCS on the mobility of metals previously trapped in sediments. Metal-contaminated sediments were collected and submitted to acidification by means of CO2 injection using different pH treatments. The test lasted 10days, and samples were collected at the beginning and at the end of the experiment for metal analysis. The results revealed increases in the mobility of metals such as Co, Cu, Fe, Pb and Zn due to pH decreases. Geochemical modeling demonstrated that acidification influenced the speciation of the metals, increasing the concentrations of their free forms. These data suggest the possible sediment contamination consequences of accidental CO2 leakage during CCS activities.
Mostrar más [+] Menos [-]Diffusion of microcystins (cyanobacteria hepatotoxins) from the reservoir of Isahaya Bay, Japan, into the marine and surrounding ecosystems as a result of large-scale drainage Texto completo
2014
Takahashi, Tohru | Umehara, Akira | Tsutsumi, Hiroaki
In the artificial reservoir of the Isahaya reclaimed land, Nagasaki, Japan, algal blooms have become an annual event, dominated primarily by the microcystin (MC) producing cyanobacteria Microcystis aeruginosa. Although the majority of MCs are either degraded by bacteria or washed out to sea, some remain in the sediment of the reservoir and bay throughout the year. As a result, they also accumulate in aquatic organisms (mullet, oyster, etc.) that inhabit the reservoir and surrounding areas, as well as midge flies that spend their larval period in the bottom of the reservoir. Accordingly, MCs also accumulate in the predators of these organisms, allowing the toxin to spread from the hydrosphere to terrestrial ecosystems. The most effective method for resolving this potentially dangerous condition is to introduce seawater into the reservoir by opening the drainage gates at high tide.
Mostrar más [+] Menos [-]Bioremediation potential of microorganisms derived from petroleum reservoirs Texto completo
2014
Dellagnezze, Bruna Martins | de Sousa, Gabriel Vasconcelos | Martins, Laercio Lopes | Domingos, Daniela Ferreira | Limache, Elmer E.G. | de Vasconcellos, Suzan Pantaroto | da Cruz, Georgiana Feitosa | de Oliveira, Valéria Maia
Bacterial strains and metagenomic clones, both obtained from petroleum reservoirs, were evaluated for petroleum degradation abilities either individually or in pools using seawater microcosms for 21days. Gas Chromatography–Flame Ionization Detector (GC–FID) and Gas Chromatography-Mass Spectrometry (GC–MS) analyses were carried out to evaluate crude oil degradation. The results showed that metagenomic clones 1A and 2B were able to biodegrade n-alkanes (C14 to C33) and isoprenoids (phytane and pristane), with rates ranging from 31% to 47%, respectively. The bacteria Dietzia maris CBMAI 705 and Micrococcus sp. CBMAI 636 showed higher rates reaching 99% after 21days. The metagenomic clone pool biodegraded these compounds at rates ranging from 11% to 45%. Regarding aromatic compound biodegradation, metagenomic clones 2B and 10A were able to biodegrade up to 94% of phenanthrene and methylphenanthrenes (3-MP, 2-MP, 9-MP and 1-MP) with rates ranging from 55% to 70% after 21days, while the bacteria Dietzia maris CBMAI 705 and Micrococcus sp. CBMAI 636 were able to biodegrade 63% and up to 99% of phenanthrene, respectively, and methylphenanthrenes (3-MP, 2-MP, 9-MP and 1-MP) with rates ranging from 23% to 99% after 21days. In this work, isolated strains as well as metagenomic clones were capable of degrading several petroleum compounds, revealing an innovative strategy and a great potential for further biotechnological and bioremediation applications.
Mostrar más [+] Menos [-]The distribution of heavy metals including Pb, Cd and Cr in Kendari Bay surficial sediments Texto completo
2014
Armid, Alrum | Shinjo, Ryuichi | Zaeni, Ahmad | Sani, Asrul | Ruslan, Ruslan
The surficial coastal sediments in Kendari Bay are sampled in the field to determine the concentration and pollution level of three heavy metals (Pb, Cd and Cr). Twenty-five sampling points ranging from the inner (Wanggu River) to the outer area of the bay have been chosen. The physicochemical properties, such as temperature, pH, salinity and TDS of the overlying water, as well as the sediment type and TOC of the surficial sediments, are also measured. The total concentrations of the Pb, Cd and Cr in the sediment samples are quantified using inductively-coupled plasma mass spectrometry (ICP-MS). The concentrations of the heavy metals (Pb, Cd and Cr) ranged from 0.84 to 17.02μg/g, 0.02 to 0.17μg/g and 1.92 to 40.11μg/g (dry weight), respectively, following the Cr>Pb>Cd sequence. To assess the degree of contamination, a geoaccumulation index (Igeo) is measured. Kendari Bay is not a contaminated area regarding Pb, Cd and Cr.
Mostrar más [+] Menos [-]Fishing down the largest coral reef fish species Texto completo
2014
Fenner, Douglas
Studies on remote, uninhabited, near-pristine reefs have revealed surprisingly large populations of large reef fish. Locations such as the northwestern Hawaiian Islands, northern Marianas Islands, Line Islands, U.S. remote Pacific Islands, Cocos-Keeling Atoll and Chagos archipelago have much higher reef fish biomass than islands and reefs near people. Much of the high biomass of most remote reef fish communities lies in the largest species, such as sharks, bumphead parrots, giant trevally, and humphead wrasse. Some, such as sharks and giant trevally, are apex predators, but others such as bumphead parrots and humphead wrasse, are not. At many locations, decreases in large reef fish species have been attributed to fishing. Fishing is well known to remove the largest fish first, and a quantitative measure of vulnerability to fishing indicates that large reef fish species are much more vulnerable to fishing than small fish. The removal of large reef fish by fishing parallels the extinction of terrestrial megafauna by early humans. However large reef fish have great value for various ecological roles and for reef tourism.
Mostrar más [+] Menos [-]Persistent organic pollutants in liver of Brazilian sharpnose shark (Rhizoprionodon lalandii) from southeastern coast of Brazil Texto completo
2014
Cascaes, M.J. | Oliveira, R.T. | Ubarana, M.M. | Sato, R.M. | Baldassin, P. | Colabuono, F.I. | Leonel, J. | Taniguchi, S. | Weber, R.R.
In the present study, persistent organic pollutants (POPs) were determined in 14 livers from specimens of the Brazilian sharpnose shark (Rhizoprionodon lalandii), which is an important economic resource for small-scale fisheries on the southeastern coast of Brazil. The following concentrations (lipid weight) of POPs were found: ∑PCBs: 1019±267ngg−1; ∑DDTs: 111±40ngg−1 and ∑PBDEs: 10.4±4.78. PCB 153 made the greatest contribution to ∑PCB (21.4%), followed by PCB 138 (14.6%) and PCB 180 (9.94%). Among chlorinated pesticides, only the p,p′-DDE and p,p′-DDD isomers had concentrations above the detection limit. Moreover, levels above the detection limit were found only for PBDE congeners 47 and 100 (BDEs 47>99). On average, BDE 47 accounted for 88% of the total PBDE load. The feeding habits of the Brazilian sharpnose shark close to the Brazilian coastline are likely the most important difference regarding the accumulation of POPs in comparison to oceanic species that feed in deeper waters. Thus, this species may be used to evaluate the pollution of coastal areas as well as human exposure to contaminants, as the Brazilian sharpnose shark is a frequently used for human consumption. Further studies in other areas of Brazil and involving other species are needed to clarify the mechanisms and potential impact of POPs, which can affect the biology of different organisms and cause population declines.
Mostrar más [+] Menos [-]Distribution of resting cysts of the potentially toxic dinoflagellate Alexandrium pseudogonyaulax in recently-deposited sediment within Bizerte Lagoon (Mediterranean coast, Tunisia) Texto completo
2014
Triki, Habiba Zmerli | Daly-Yahia, Ons Kéfi | Malouche, Dhafer | Komiha, Yosr | Deidun, Alan | Brahim, Mouldi | laabir, Mohamed
This study investigated the spatial distribution of Alexandrium pseudogonyaulax resting cysts in recently-deposited sediment of Bizerte lagoon (South-Western Mediterranean, Tunisia). This lagoon is the subject of many anthropogenic impacts, such as holding important fishing and aquaculture activities. A. pseudogonyaulax has been shown to produce Goniodomin A, which is a biologically-active compound. We showed that this dinoflagellate produces two types of resting cysts, which could be distinguished by the presence or the absence of a paratabulate wall. The average cyst density across the whole lagoon was rather high, reaching 639cystsg−1 of dry sediment (DS). Cyst densities varied widely among the sampled stations, with the highest density of 1685cystg−1DS being recorded at station 51 near a mussel farm. With respect to sediment characteristics, the highest cyst densities were found within silty sediments with high water content values. The distribution of A. pseudongoyaulax cysts in Bizerte lagoon appears to be related to hydrodynamic factors.
Mostrar más [+] Menos [-]Organohalogen contaminants and trace metals in North-East Atlantic porbeagle shark (Lamna nasus) Texto completo
2014
Bendall, Victoria A. | Barber, Jonathan L. | Papachlimitzou, Alexandra | Bolam, Thi | Warford, Lee | Hetherington, Stuart J. | Silva, Joana F. | McCully, Sophy R. | Losada, Sara | Maes, Thomas | Ellis, Jim | Law, Robin J.
The North-East Atlantic porbeagle (Lamna nasus) population has declined dramatically over the last few decades and is currently classified as ‘Critically Endangered’. As long-lived, apex predators, they may be vulnerable to bioaccumulation of contaminants. In this study organohalogen compounds and trace elements were analysed in 12 specimens caught as incidental bycatch in commercial gillnet fisheries in the Celtic Sea in 2011. Levels of organohalogen contaminants were low or undetectable (summed CB and BDE concentrations 0.04–0.85mgkg−1wet weight). A notably high Cd concentration (7.2mgkg−1wet weight) was observed in one mature male, whereas the range observed in the other samples was much lower (0.04–0.26mgkg−1wet weight). Hg and Pb concentrations were detected only in single animals, at 0.34 and 0.08mgkg−1wet weight, respectively. These contaminant levels were low in comparison to other published studies for shark species.
Mostrar más [+] Menos [-]Cryptosporidium and Giardia in tropical recreational marine waters contaminated with domestic sewage: Estimation of bathing-associated disease risks Texto completo
2014
Betancourt, Walter Q. | Duarte, Diana C. | Vásquez, Rosa C. | Gurian, Patrick L.
Sewage is a major contributor to pollution problems involving human pathogens in tropical coastal areas. This study investigated the occurrence of intestinal protozoan parasites (Giardia and Cryptosporidium) in tropical recreational marine waters contaminated with sewage. The potential risks of Cryptosporidium and Giardia infection from recreational water exposure were estimated from the levels of viable (oo) cysts (DIC+, DAPI+, PI−) found in near-shore swimming areas using an exponential dose response model. A Monte Carlo uncertainty analysis was performed in order to determine the probability distribution of risks. Microbial indicators of recreational water quality (enterococci, Clostridium perfringens) and genetic markers of sewage pollution (human-specific Bacteroidales marker [HF183] and Clostridium coccoides) were simultaneously evaluated in order to estimate the extent of water quality deterioration associated with human wastes. The study revealed the potential risk of parasite infections via primary contact with tropical marine waters contaminated with sewage; higher risk estimates for Giardia than for Cryptosporidium were found. Mean risks estimated by Monte Carlo were below the U.S. EPA upper bound on recreational risk of 0.036 for cryptosporidiosis and giardiasis for both children and adults. However, 95th percentile estimates for giardiasis for children exceeded the 0.036 level. Environmental surveillance of microbial pathogens is crucial in order to control and eradicate the effects that increasing anthropogenic impacts have on marine ecosystems and human health.
Mostrar más [+] Menos [-]