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Результаты 641-650 из 1,953
Fate of antibiotics during wastewater treatment and antibiotic distribution in the effluent-receiving waters of the Yellow Sea, northern China
2013
Zhang, Hanmin | Liu, Pengxiao | Feng, Yujie | Yang, Fenglin
Antibiotics including three β-lactams, two fluoroquinolones and two macrolides, which were the top seven most prescribed antibiotics in Dalian, China, were selected to investigate their occurrence in six municipal wastewater treatment plants (WWTPs) and their distribution in the effluent-receiving waters of the Yellow Sea. Four WWTPs employing different treatment technologies were selected to explore the mechanism of antibiotics elimination during wastewater treatment. Results showed that fluoroquinolones and macrolides were dominant species in both WWTPs effluents and the surveyed coastal waters. Biodegradation was the main pathway for β-lactams removal, however, primary treatment performed better than biological treatment for fluoroquinolones removal. Concentrations of macrolides increased dramatically after the biological treatment, which was probably due to the release of macrolides enclosed in feces particles. In the surveyed coastal waters, reduction of antibiotic concentration with distance was observed. Potential environmental risk caused by the occurrence of these antibiotics should be evaluated in future work.
Показать больше [+] Меньше [-]Droplet breakup in subsea oil releases – Part 2: Predictions of droplet size distributions with and without injection of chemical dispersants
2013
Johansen, Øistein | Brandvik, Per Johan | Farooq, Umer
A new method for prediction of droplet size distributions from subsea oil and gas releases is presented in this paper. The method is based on experimental data obtained from oil droplet breakup experiments conducted in a new test facility at SINTEF. The facility is described in a companion paper, while this paper deals with the theoretical basis for the model and the empirical correlations used to derive the model parameters from the available data from the test facility. A major issue dealt with in this paper is the basis for extrapolation of the data to full scale (blowout) conditions. Possible contribution from factors such as buoyancy flux and gas void fraction are discussed and evaluated based on results from the DeepSpill field experiment.
Показать больше [+] Меньше [-]Urban breakwaters as reef fish habitat in the Persian Gulf
2013
Burt, John A. | Feary, David A. | Cavalcante, Georgenes | Bauman, Andrew G. | Usseglio, Paolo
Breakwaters and related structures dominate near-shore environments in many Persian Gulf countries, but little is known of their ecology. To examine the influence of wave exposure on fish communities we surveyed exposed and sheltered breakwaters seasonally over 2years and compared these with natural reef assemblages. Species richness and adult, juvenile, and total abundance were generally comparable among the three habitat types each season. However, differences in multivariate community structure indicated that each habitat contained a distinct assemblage, with strongest difference between sheltered breakwaters and the exposed natural reef. All communities were characterized by marked seasonality; abundance and richness were generally higher in the warmer seasons (summer, fall) than during cooler periods (winter, spring), and there were related seasonal changes in community structure, particularly on the natural reef. Results indicate that breakwaters are important fish habitats, but that breakwater communities vary with wave exposure and are distinct from natural reefs.
Показать больше [+] Меньше [-]Application of macrobenthos functional groups to estimate the ecosystem health in a semi-enclosed bay
2013
Peng, Shitao | Zhou, Ran | Qin, Xuebo | Shi, Honghua | Ding, Dewen
In this study, the functional group concept was first applied to evaluate the ecosystem health of Bohai Bay. Macrobenthos functional groups were defined according to feeding types and divided into five groups: a carnivorous group (CA), omnivorous group (OM), planktivorous group (PL), herbivorous group (HE), and detritivorous group (DE). Groups CA, DE, OM, and PL were identified, but the HE group was absent from Bohai Bay. Group DE was dominant during the study periods. The ecosystem health was assessed using a functional group evenness index. The functional group evenness values of most sampling stations were less than 0.40, indicating that the ecosystem health was deteriorated in Bohai Bay. Such deterioration could be attributed to land reclamation, industrial and sewage effluents, oil pollution, and hypersaline water discharge. This study demonstrates that the functional group concept can be applied to ecosystem health assessment in a semi-enclosed bay.
Показать больше [+] Меньше [-]Personal exposure of commuters in public transport to PM2.5 and fine particle counts
2013
Onat, Burcu | Stakeeva, Baktygul
To investigate fine particulate air pollution generated by public transport and its microenvironment, PM2.5 measurements and particle number counts for six particle size ranges (0.3–0.5 µm, >0.5–1.0 µm, >1.0–3.0 µm, >3.0– 5.0 µm, >5.0–10 µm and >10 µm) were obtained for four public transport modes: bus, metro–bus, car and walking. The measurements were repeated for each transport mode twice a day for 7–10 measurement days. The highest average PM2.5 concentration was measured inside a bus (106 µg/m3) during rush hours. The highest single peak measurement was a concentration of 316 µg/m3 for walking during non–rush hours. The PM2.5 level in a car with the air conditioning fan off was approximately 2.5 times lower than the level with the air conditioning fan on. Moderate correlations were found between PM2.5 concentrations and wind speed. Weak correlations were found between PM2.5 concentrations, relative humidity and temperature. The results showed that the diameters of most of the particles were smaller than 0.5 µm, regardless of the transport mode. The average fine particle number (size range 0.3–0.5) for all transport modes ranged from 54 647 to 209 746 particles/103 cm3 during rush hours and from 49 423 to 184 866 particles/103 cm3 during non–rush hours.
Показать больше [+] Меньше [-]The use of the brown macroalgae, Sargassum flavicans, as a potential bioindicator of industrial nutrient enrichment
2013
Alquezar, Ralph | Glendenning, Lionel | Costanzo, Simon
Nutrient bioindicators are increasingly being recognised as a diagnostic tool for nutrient enrichment of estuarine and marine ecosystems. Few studies, however, have focused on field translocation of bioindicator organisms to detect nutrient discharge from industrial waste. The brown macroalgae, Sargassum flavicans, was investigated as a potential bioindicator of nutrient-enriched industrial effluent originating from a nickel refinery in tropical north-eastern Australia. S. flavicans was translocated to a number of nutrient enriched creek and oceanic sites over two seasons and assessed for changes in stable isotope ratios of 15N and 13C within the plant tissue in comparison to reference sites. Nutrient uptake in macroalgae, translocated to the nutrient enriched sites adjacent to the refinery, increased 3–4-fold in δ15N, compared to reference sites. Using δ15N of translocated S. flavicans proved to be a successful method for monitoring time-integrated uptake of nitrogen, given the current lack of passive sampler technology for nutrient monitoring.
Показать больше [+] Меньше [-]Marine debris removal: One year of effort by the Georgia Sea Turtle-Center-Marine Debris Initiative
2013
Martin, Jeannie Miller
Once in the marine environment, debris poses a significant threat to marine life that can be prevented through the help of citizen science. Marine debris is any manufactured item that enters the ocean regardless of source, commonly plastics, metal, wood, glass, foam, cloth, or rubber. Citizen science is an effective way to engage volunteers in conservation initiatives and provide education and skill development. The Georgia Sea Turtle Center Marine Debris Initiative (GSTC-MDI) is a grant funded program developed to engage citizens in the removal of marine debris from the beaches of Jekyll Island, GA, USA and the surrounding areas. During the first year of effort, more than 200 volunteers donated over 460h of service to the removal of marine debris. Of the debris removed, approximately 89% were plastics, with a significant portion being cigarette materials. Given the successful first year, the GSTC-MDI was funded again for a second year.
Показать больше [+] Меньше [-]Seasonal variation of metal contamination in the barnacles Pollicipes pollicipes in northwest coast of Portugal show clear correlation with levels in the surrounding water
2013
Reis, Pedro A. | Salgado, María Antonia | Vasconcelos, Vitor
The concentrations of metals were determined in northwest (NW) coast of Portugal seawaters and soft tissues of goose barnacles Pollicipes pollicipes. P. pollicipes can be used for monitoring metal contamination in these coastal seawaters, because there were significant correlations (p<0.05) for all metals between soft tissues and seawaters during the four seasons. Metal concentrations in seawaters and P. pollicipes had significant (p<0.05) spatial and seasonal variations and mean log BAFs for Fe and Cd were higher than for Cr, Cu, Mn and Zn. Regarding the metal concentrations obtained in the coastal seawaters, all NW coast of Portugal should be classified as “Class IV – Bad”, except two locations (location 7 at Summer and location 10 at Winter), which should be classified as “Class III – Moderate”. However, considering the metal concentrations bioaccumulated in P. pollicipes, all locations should be classified as “Class III – Remarkably Polluted” during all seasons of 2011.
Показать больше [+] Меньше [-]Effectiveness of emetics to study plastic ingestion by Leach’s Storm-petrels (Oceanodroma leucorhoa)
2013
Bond, Alexander L. | Lavers, Jennifer L.
Most plastic ingestion studies rely on dissection of dead birds, which are found opportunistically, and may be biased. We used Leach’s Storm-petrels (Oceanodroma leucorhoa) in Newfoundland to study the effect of dose volume, and the efficacy of emesis using syrup of ipecac as an emetic. Ipecac is a safe method of non-lethally sampling stomach contents, and recovered all ingested plastic. Almost half the storm-petrels sampled had ingested plastic, ranging from 0 to 17 pieces, and weighing 0.2–16.9mg. Using the Ecological Quality Objective for Northern Fulmars, adjusted for storm-petrels smaller size, 43% exceeded the threshold of 0.0077g of plastic. Many adult seabirds offload plastic to their offspring, so storm-petrel chicks likely experience a higher plastic burden than their parents. The ability to study plastic ingestion non-lethally allows researchers to move from opportunistic and haphazard sampling to hypothesis-driven studies on a wider range of taxa and age classes.
Показать больше [+] Меньше [-]The effects of mercury on the dynamics of the peracarida community in a temperate coastal lagoon (Ria de Aveiro, Portugal)
2013
Cardoso, P.G. | D’Ambrosio, M. | Marques, S.C. | Azeiteiro, U.M. | Coelho, J.P. | Pereira, E.
This study focuses on the impact of mercury on the dynamics and bioaccumulation patterns of suprabenthic peracarida community along a mercury gradient. Suprabenthic peracarida was negatively affected in terms of biomass, diversity and productivity. Mysids including Mesopodopsis slabberi dominated the community, presenting a regular distribution along the Hg gradient, so are considered tolerant species to mercury. Then, isopods, the second most abundant group, dominated in the most contaminated areas being considered also a tolerant group. Contrarily, amphipods were negatively correlated with higher Hg concentrations, dominating in the intermediate areas, thus are considered more sensitive species. In addition, isopods and amphipods were the taxa with higher mercury body burden, followed by mysids. This paper highlights the importance of suprabenthic peracarida as a vehicle of mercury transference through the estuarine trophic web since it is a main link between benthic and pelagic levels and an essential food resource for numerous fish species.
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