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Результаты 1061-1070 из 3,243
Relationship between the lability of sediment-bound Cd and its bioaccumulation in edible oyster
2015
Chakraborty, Parthasarathi | Ramteke, Darwin | Chakraborty, Sucharita | Chennuri, Kartheek | Bardhan, Pratirupa
A linkage between Cd speciation in sediments and its bioaccumulation in edible oyster (Crassostrea sp.) from a tropical estuarine system was established. Bioaccumulation of Cd in edible oyster increased with the increasing lability and dissociation rate constants of Cd-sediment complexes in the bottom sediments. Total Cd concentration in sediment was not a good indicator of Cd-bioavailability. Increasing trace metal competition in sediments increased lability and bioavailability of Cd in the tropical estuarine sediment. Low thermodynamic stability and high bioavailability of Cd in the estuarine sediment were responsible for high bioaccumulation of Cd in edible oysters (3.2–12.2mgkg−1) even though the total concentration of Cd in the bottom sediment was low (0.17–0.49mgkg−1).
Показать больше [+] Меньше [-]Pollution risk assessment of oil spill accidents in Garorim Bay of Korea
2015
Lee, Moonjin | Jung, Jung-Yeul
This study presents a model to assess the oil spill risk in Garorim Bay in Korea, where large-scale oil spill accidents frequently occur. The oil spill risk assessment is carried out by using two factors: 1) The impact probability of the oil spill, and 2) the first impact time of the oil that has been spilt. The risk assessment is conducted for environmentally sensitive areas, such as the coastline and aquaculture farms in the Garorim Bay area. Finally, Garorim Bay is divided into six subareas, and the risks of each subarea are compared with one another to identify the subarea that is most vulnerable to an oil spill accident. These results represent an objective and comprehensive oil spill risk level for a specific region. The prediction of the oil spill spread is based on real-time sea conditions and can be improved by integrating our results, especially when sea conditions are rapidly changing.
Показать больше [+] Меньше [-]Estimating the willingness to pay to protect coral reefs from potential damage caused by climate change—The evidence from Taiwan
2015
Tseng, William Wei-Chun | Hsu, Shu-Han | Chen, Chi-Chung
Coral reefs constitute the most biologically productive and diverse ecosystem, and provide various goods and services including those related to fisheries, marine tourism, coastal protection, and medicine. However, they are sensitive to climate change and rising temperatures. Taiwan is located in the central part of the world's distribution of coral reefs and has about one third of the coral species in the world. This study estimates the welfare losses associated with the potential damage to coral reefs in Taiwan caused by climate change. The contingent valuation method adopted includes a pre-survey, a face-to-face formal survey, and photo illustrations used to obtain reliable data. Average annual personal willingness to pay is found to be around US$35.75 resulting in a total annual willingness to pay of around US$0.43 billion. These high values demonstrate that coral reefs in Taiwan deserve to be well preserved, which would require a dedicated agency and ocean reserves.
Показать больше [+] Меньше [-]Marine litter education boosts children’s understanding and self-reported actions
2015
Hartley, Bonny L. | Thompson, Richard C. | Pahl, Sabine
Marine litter is a significant environmental problem inherently linked to individuals’ purchasing, use and disposal behaviour. This research examined 176 British schoolchildren’s (aged 8–13years) baseline marine litter understanding and self-reported actions, and tested the impact of an educational intervention. All children participated in the educational intervention and completed a pre- and post-intervention questionnaire. At baseline, children were quite concerned about marine litter and recognised some of the causes and impacts of the problem. Children also reported taking a number of actions to help solve the problem. After the intervention, children were significantly more concerned, had a better understanding of the causes and negative impacts, and reported engaging in more actions to reduce the potential causes of marine litter. Understanding the perceptions and behaviours of children is crucial as they represent current and future actors and a potentially important source of social influence among their peers, parents and community.
Показать больше [+] Меньше [-]Seasonal variability and flux of particulate trace elements from the Yellow River: Impacts of the anthropogenic flood event
2015
Hu, Bangqi | Li, Jun | Bi, Naishuang | Wang, Houjie | Yang, John | Wei, Helong | Zhao, Jingtao | Li, Guogang | Yin, Xuebo | Liu, Ming | Zou, Liang | Li, Song
In this study, the suspended particulate matter (SPM) of the Yellow River (Huanghe) was collected biweekly at the outlet and analyzed for particulate trace element contents. The seasonal variations of the trace elements were primarily controlled by hydrological processes, which determined different sources of the SPM. Moreover, As, Co, Cr, and Ni primarily originated from lithogenic sources, whereas Cd, Cu, Pb and Zn were influenced by anthropogenic activities. The Yellow River has suffered moderate to considerable ecological risk during the late stage of Water and Sediment Regulation (WSR). Using the discharge-weighted contents method, the annual trace element fluxes were estimated, with ca. 30% of the annual fluxes occurring within the short WSR period (6% of one year). More specifically, 75% of the Cd flux was from an anthropogenic source, which likely posed a significant threat to the estuary and the adjacent coastal ecosystems.
Показать больше [+] Меньше [-]Macrofaunal recolonization of copper-contaminated sediments in San Diego Bay
2015
Neira, Carlos | Mendoza, Guillermo | Porrachia, Magali | Stransky, Chris | Levin, Lisa A.
Effects of Cu-loading on macrofaunal recolonization were examined in Shelter Island Yacht Basin (San Diego Bay, California). Sediments with high and low Cu levels were defaunated and Cu-spiked, translocated, and then placed back into the environment. These demonstrated that the alteration observed in benthic communities associated with Cu contamination occurs during initial recolonization. After a 3-month exposure to sediments with varying Cu levels, two primary colonizing communities were identified: (1) a “mouth assemblage” resembling adjacent background fauna associated with low-Cu levels that was more diverse and predominantly dominated by surface- and subsurface-deposit feeders, burrowers, and tube builders, and (2) a “head assemblage” resembling adjacent background fauna associated with high-Cu concentrations, with few dominant species and an increasing importance of carnivores and mobile epifauna. Cu loading can cause reduced biodiversity and lower structural complexity that may last several months if high concentrations persist, with a direct effect on community functioning.
Показать больше [+] Меньше [-]Microplastic in a macro filter feeder: Humpback whale Megaptera novaeangliae
2015
Besseling, E. | Foekema, E.M. | Van Franeker, J.A. | Leopold, M.F. | Kühn, S. | Bravo Rebolledo, E.L. | Heße, E. | Mielke, L. | IJzer, J. | Kamminga, P. | Koelmans, A.A.
Marine filter feeders are exposed to microplastic because of their selection of small particles as food source. Baleen whales feed by filtering small particles from large water volumes. Macroplastic was found in baleen whales before. This study is the first to show the presence of microplastic in intestines of a baleen whale (Megaptera novaeangliae). Contents of its gastrointestinal tract were sieved, dissolved in 10% potassium hydroxide and washed. From the remaining dried material, potential synthetic polymer particles were selected based on density and appearance, and analysed by Fourier transform infrared (FTIR) spectroscopy. Several polymer types (polyethylene, polypropylene, polyvinylchloride, polyethylene terephthalate, nylon) were found, in varying particle shapes: sheets, fragments and threads with a size of 1mm to 17cm. This diversity in polymer types and particle shapes, can be interpreted as a representation of the varying characteristics of marine plastic and the unselective way of ingestion by M. novaeangliae.
Показать больше [+] Меньше [-]Experimental and numerical investigations on reliability of air barrier on oil containment in flowing water
2015
Lu, Jinshu | Xu, Zhenfeng | Xu, Song | Xie, Sensen | Wu, Haoxiao | Yang, Zhenbo | Liu, Xueqiang
Air barriers have been recently developed and employed as a new type of oil containment boom. This paper presents systematic investigations on the reliability of air barriers on oil containments with the involvement of flowing water, which represents the commonly-seen shearing current in reality, by using both laboratory experiments and numerical simulations. Both the numerical and experimental investigations are carried out in a model scale. In the investigations, a submerged pipe with apertures is installed near the bottom of a tank to generate the air bubbles forming the air curtain; and, the shearing water flow is introduced by a narrow inlet near the mean free surface. The effects of the aperture configurations (including the size and the spacing of the aperture) and the location of the pipe on the effectiveness of the air barrier on preventing oil spreading are discussed in details with consideration of different air discharges and velocities of the flowing water. The research outcome provides a foundation for evaluating and/or improve the reliability of a air barrier on preventing spilled oil from further spreading.
Показать больше [+] Меньше [-]Adsorption–synergic biodegradation of diesel oil in synthetic seawater by acclimated strains immobilized on multifunctional materials
2015
Wang, Xin | Wang, Xuejiang | Liu, Mian | Bu, Yunjie | Zhang, Jing | Chen, Jie | Zhao, Jianfu
Using enrichment culture technique, three isolates marked as ODB-1, ODB-2 and ODB-3, were selected from oil contaminated seawater. 16S rDNA gene sequencing indicated that ODB-1 affiliated with Pseudomonas sp. while ODB-2 and ODB-3 affiliated with Brevundimonas sp. Subsequently, the bacterial cells were immobilized on the surface of expanded graphite (EG), expanded perlite (EP) and bamboo charcoal (BC). Among the three isolates, ODB-1 showed a strong binding to the bio-carriers through extracellular polysaccharides, while ODB-2 and ODB-3 made the adhesion to bio-carrier through direct physical adsorption. The immobilized bacteria exhibited good salinity tolerance compared with the planktonic bacteria. Their total diesel oil removal rates were more than 85% after 6 days’ incubation. Adsorption–biodegradation process played an important role in the oil-pollution remediation. EG-bacteria system was treated as a promising remediation method, which achieved nearly 100% removal of diesel oil. Thereinto, over 83% removal of diesel oil owed to biodegradation.
Показать больше [+] Меньше [-]Intercomparison between NIOSH, IMPROVE_A, and EUSAAR_2 protocols: Finding an optimal thermal–optical protocol for Philippines OC/EC samples
2015
Bautista, Angel T. | Pabroa, Preciosa Corazon B. | Santos, Flora L. | Quirit, Leni L. | Asis, Joannes Luke B. | Dy, Marie Alexandra K. | Martinez, Jason Patrick G.
Thermal–optical analysis is one of the most widely–recognized methods for measuring organic carbon (OC) and elemental carbon (EC) in atmospheric particulates. Up to date however, there is no standard protocol of analysis and different protocols give varying OC/EC apportionments. This study aims to find an optimal thermal–optical analysis protocol for Philippine OC/EC samples by comparing three widely–used protocols: NIOSH, IMPROVE_A and EUSAAR_2. Philippines is particularly interesting because it has one of the highest EC concentration and lowest OC/EC ratio in the region. In terms of total OC and EC quantification, NIOSH and IMPROVE_A show negative and positive EC bias, respectively – NIOSH exhibits premature EC evolution in the OC4 pure He phase, while IMPROVE_A OC4 temperature step (580 °C) is not sufficiently high, causing some OC to be carried over to He/O2 phase to be measured mainly as EC2. EUSAAR_2 minimizes both effects and may be most accurate in this aspect. However, IMPROVE_A is the only method that is capable of properly resolving individual OC and Philippines’s particularly abundant EC fractions owing to the protocol’s variable step durations. Concurrently, IMPROVE_A and EUSAAR_2 yield lowest pyrolized carbon (PC) formation for urban and rural site, respectively. Minimal PC formation is desired to minimize errors associated with its correction. Finally, transmittance laser correction is preferred over reflectance as it is capable of accounting for char formed within filter. The study thus recommends a modified IMPROVE_A, with increased OC4 temperature step (650 °C, adopted from EUSAAR_2) and transmittance laser correction, as optimal. This protocol is expected to give proper OC and EC evolution, fractionation, and measurement with minimized PC formation and proper correction, leading to more accurate results. Preliminary testing shows that recommended protocol meets those expectations. Application to larger number and wider variety of samples is needed to more properly assert these findings.
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