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Результаты 621-630 из 3,243
Passive sampling reversed: Coupling passive field sampling with passive lab dosing to assess the ecotoxicity of mixtures present in the marine environment
2015
Claessens, Michiel | Monteyne, Els | Wille, Klaas | Vanhaecke, Lynn | Roose, Patrick | Janssen, Colin R.
This study presents a new approach in aquatic toxicity testing combining passive sampling and passive dosing. Polydimethylsiloxane sheets were used to sample contaminant mixtures in the marine environment. These sheets were subsequently transferred to ecotoxicological test medium in which the sampled contaminant mixtures were released through passive dosing. 4 out of 17 of these mixtures caused severe effects in a growth inhibition assay with a marine diatom. These effects could not be explained by the presence of compounds detected in the sampling area and were most likely attributable to unmeasured compounds absorbed to the passive samplers during field deployment.The findings of this study indicate that linking passive sampling in the field to passive dosing in laboratory ecotoxicity tests provides a practical and complimentary approach for assessing the toxicity of hydrophobic contaminant mixtures that mimics realistic environmental exposures. Limitations and opportunities for future improvements are presented.
Показать больше [+] Меньше [-]Biodegradation of dispersed Macondo oil in seawater at low temperature and different oil droplet sizes
2015
Brakstad, Odd G. | Nordtug, Trond | Throne-Holst, Mimmi
During the Deepwater Horizon (DWH) accident in 2010 a dispersant (Corexit 9500) was applied at the wellhead to disperse the Macondo oil and reduce the formation of surface slicks. A subsurface plume of small oil droplets was generated near the leaking well at 900–1300m depth. A novel laboratory system was established to investigate biodegradation of small droplet oil dispersions (10μm or 30μm droplet sizes) of the Macondo oil premixed with Corexit 9500, using coastal Norwegian seawater at a temperature similar to the DWH plume (4–5°C). Biotransformation of volatile and semivolatile hydrocarbons and oil compound groups was generally faster in the 10μm than in the 30μm dispersions, showing the importance of oil droplet size for biodegradation. These data therefore indicated that dispersant treatment to reduce the oil droplet size may increase the biodegradation rates of oil compounds in the deepwater oil droplets.
Показать больше [+] Меньше [-]Analysis of chloramphenicol residues in the macroalgae Ulva lactuca through ultra-high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS)
2015
Leston, Sara | Freitas, Andreia | Nunes, Margarida | Barbosa, Jorge | Pardal, Miguel Ângelo | Ramos, Fernando
Antibiotic use is a well-described practice to promote animal health whether for prevention or treatment. Nonetheless, it can also cause a number of potentially harmful effects that dictate the need to implement regulation to assure a reduction of hazards to the consumers and the environment. Chloramphenicol (CAP) is a broad-spectrum antibacterial excluded from use in animal food production but despite this, reports of illegal use still persist. More recently, awareness has risen that the surrounding natural ecosystems can potentially be contaminated by pharmaceuticals and the extent of their effects in non-target organisms is already under the scope of researchers. To face the demanding new challenges a methodology for the determination of CAP in the green macroalgae Ulva lactuca by ultra-high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS) was developed, optimized and fully validated following the guidelines of the EC Decision 2002/657.
Показать больше [+] Меньше [-]Climatic impact on community of filamentous macroalgae in the Neva estuary (eastern Baltic Sea)
2015
Gubelit, Yulia I.
In presented study the impact of climatic factors and North Atlantic Oscillation (NAO) on macroalgal community was analysed. Also the factors influencing algal community were defined with help of Principal Component and Classification analysis. It was found that climatic impact may depend on habitat features and that on different sites biomass of macroalgae correlated with different weather factors. Wind and surf may affect biomass of macroalgae adversely on some sites and at the same time on other sites they may accumulate biomass, transferring it is from adjacent areas. High direct correlation with temperature was found on sites which were protected from surf and had no stagnant events. Seasonal biomass inversely significantly correlated with average seasonal wind speed and annual NAO-index.
Показать больше [+] Меньше [-]Modelling the fate of micropollutants in the marine environment using passive sampling
2015
Claessens, Michiel | De Laender, Frederik | Monteyne, Els | Roose, Patrick | Janssen, Colin R.
Polydimethylsiloxane sheets were used to determine freely dissolved concentrations (Cdiss) of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in the Belgian coastal zone. Equilibrium models were used to predict the whole water concentrations (Cww) of these compounds as well as their concentrations in sediment, suspended particulate matter (SPM) and biota. In general, contaminant concentrations were predicted well for whole water and biota. Cww was increasingly underpredicted as Koc increased, possibly because of the presence of black carbon. Concentrations in biota were overestimated by the equilibrium approach when logKow exceeded 6.5, suggesting an increasing role of transformation processes. Concentrations of PAHs and PCBs in sediment and SPM were consistently underpredicted although a good correlation between measured and predicted values was observed. This was potentially due to the use of experimental Koc values which have been found to underestimate partitioning of hydrophobic substances to sediment in field studies.
Показать больше [+] Меньше [-]Environmental conditions influence tissue regeneration rates in scleractinian corals
2015
Sabine, Alexis M. | Smith, Tyler B. | Williams, Dana E. | Brandt, Marilyn E.
Natural and anthropogenic factors may influence corals’ ability to recover from partial mortality. To examine how environmental conditions affect lesion healing, we assessed several water quality parameters and tissue regeneration rates in corals at six reefs around St. Thomas, US Virgin Islands. We hypothesized that sites closer to developed areas would have poor water quality due to proximity to anthropogenic stresses, which would impede tissue regeneration. We found that water flow and turbidity most strongly influenced lesion recovery rates. The most impacted site, with high turbidity and low flow, recovered almost three times slower than the least impacted site, with low turbidity, high flow, and low levels of anthropogenic disturbance. Our results illustrate that in addition to lesion-specific factors known to affect tissue regeneration, environmental conditions can also control corals’ healing rates. Resource managers can use this information to protect low-flow, turbid nearshore reefs by minimizing sources of anthropogenic stress.
Показать больше [+] Меньше [-]Bio-indicator bacteria & environmental variables of the coastal zones: The example of the Güllük Bay, Aegean Sea, Turkey
2015
Kalkan, Samet | Altuğ, Gülşen
In this study bio-indicator bacteria and environmental variable parameters were investigated in the coastal areas of the Güllük Bay, Aegean Sea, Turkey. The seawater samples which were taken from surface (0–30cm) were tested regarding total and fecal coliform, streptococci and nutrients from May to February in 2012–2013. The primary hydrographic parameters were recorded using multiparameter (YSI 556) in situ at the sampling stations. The highest fecal pollution stress and indicator bacteria values were observed in the period between June and August. The finding showed that bacterial pollution sources of the study area, especially in the summer season, under the control of increasing anthropogenic activities. The finding showed that terrestrial pollution sources carry a potential risk for public and ecosystem health and the sustainable use of living sources. Precautions should be formulated and put into action immediately in order to protect the region from bacteriological risks.
Показать больше [+] Меньше [-]Distribution, enrichment and sources of thallium in the surface sediments of the southwestern coastal Laizhou Bay, Bohai Sea
2015
Zhuang, Wen | Gao, Xuelu
The concentrations of thallium (Tl) in the surface sediments of the southwestern coastal Laizhou Bay and the rivers it connects were determined. In riverine sediments, the Tl concentrations ranged from 0.34 to 0.76μgg−1 in summer; in autumn, the corresponding data were 0.35–1.08μgg−1. In marine sediments, the Tl concentrations ranged from 0.36 to 0.58μgg−1 in summer; and from 0.30 to 0.56μgg−1 in autumn. The grain size, Al and Fe oxides were major factors affecting Tl distribution. Tl in the surface sediments of the studied area was mainly from the natural input with the non-natural input as a subsidiary source. The low concentrations of Tl made it hard to cause potential negative environmental effects in this area.
Показать больше [+] Меньше [-]Baseline survey of marine sediments collected from the State of Kuwait: PAHs, PCBs, brominated flame retardants and metal contamination
2015
Lyons, B.P. | Barber, J.L. | Rumney, H.S. | Bolam, T.P.C. | Bersuder, P. | Law, R.J. | Mason, C. | Smith, A.J. | Morris, S. | Devlin, M.J. | Al-Enezi, M. | Massoud, M.S. | Al-Zaidan, A.S. | Al-Sarawi, H.A.
A geographically extensive baseline survey of sediment contamination was undertaken at twenty nine locations around Kuwait. Samples were assessed in relation to a wide range of industrial pollutants, including metals, PAHs, PCBs, PBDEs and HBCDs. The data generated indicated that levels of pollutants were generally low and below commonly applied sediment quality guidelines (SQGs). However, naturally high background concentrations of certain metals present in sediment from the region may prohibit the direct assessment against some of the routinely applied SQGs. Hot spots of contamination were identified for PAHs, PCBs and PBDEs, that were mainly associated with the Shuaiba Industrial Area, located south of the city, and known to contain a diverse mix of both light and heavy industry.
Показать больше [+] Меньше [-]Cumulative pressures and low protection: a concerning blend for Mediterranean MPAs
2015
Rodríguez-Rodríguez, D. | Sánchez-Espinosa, A. | Schröder, C. | Abdul Malak, D. | Rodríguez, J.
This study classifies Mediterranean marine protected areas (MPAs) according to the combined result of pressure level and protection. Six major marine environment pressures were considered: pressures from fish farms, fishing, marine litter, pressures from marinas, pollution from maritime transport, and climate change. MPA protection was assessed through legal protection and management effort. Most MPA area in the Mediterranean is under relatively high pressure level and afforded low protection. Inshore areas show higher pressure levels. Five marine ecoregions, nine countries and nineteen MPA designation categories have over 50% of their MPA area under major concern. The mean number of cumulative pressures occurring in priority MPAs ranges between three and four, although the mean combined intensity of those pressures is low. However, these figures are most likely underestimated, especially for the southern Mediterranean. The most concerning pressures to MPAs regarding extent and intensity were: climate change, fishing and pollution from maritime transport.
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