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Resultados 1051-1060 de 3,207
Water–oil separation performance of technical textiles used for marine pollution disasters Texto completo
2015
Seddighi, Mahdi | Hejazi, Sayyed Mahdi
Oil is principally one of the most important energy sources in the world. However, as long as oil is explored and transported for being used, there will be the risk of the spillage into the marine environment. The use of technical textiles, i.e. fibrous beds, is a conventional separation technique for oil/water emulsion since it is efficient and easy to design. In this paper, the recovery of oil by technical textiles was mathematically modeled based on the structural parameters of textile and the capillary mechanism. Eleven types of commercial technical textiles with different properties were prepared for the experimental program. The experimental design included fiber type (polypropylene and polyester), fabric type (woven and/or nonwoven), fabric thickness and fabric areal density. Consequently, the absorption capacities of different technical textile samples were derived by the use of theoretical and experimental methods. The results show that there is a well fitness between theoretical outputs and experimental data.
Mostrar más [+] Menos [-]Changes in the water quality conditions of Kuwait's marine waters: Long term impacts of nutrient enrichment Texto completo
2015
Devlin, M.J. | Massoud, M.S. | Hamid, S.A. | Al-Zaidan, A. | Al-Sarawi, H. | Al-Enezi, M. | Al-Ghofran, L. | Smith, A.J. | Barry, J. | Stentiford, G.D. | Morris, S. | da Silva, E.T. | Lyons, B.P.
This work analyses a 30year water quality data set collated from chemical analyses of Kuwait's marine waters. Spatial patterns across six sites in Kuwait Bay and seven sites located in the Arabian Gulf are explored and discussed in terms of the changing influences associated with point and diffuse sources. Statistical modelling demonstrated significant increases for dissolved nutrients over the time period. Kuwait marine waters have been subject to inputs from urban development, untreated sewage discharges and decreasing river flow from the Shatt al-Arab River. Chlorophyll biomass showed a small but significant reduction; the high sewage content of the coastal waters from sewage discharges likely favouring the presence of smaller phytoplankton taxa. This detailed assessment of temporal data of the impacts of sewage inputs into Kuwait's coastal waters establishes an important baseline permitting future assessments to be made as sewage is upgraded, and the river continues to be extracted upstream.
Mostrar más [+] Menos [-]Heavy metal pollution assessment in relation to sediment properties in the coastal sediments of the southern Caspian Sea Texto completo
2015
Bastami, Kazem Darvish | Neyestani, Mahmoud Reza | Shemirani, Farzaneh | Soltani, Farzaneh | Haghparast, Sarah | Akbari, Atefeh
This study aimed to evaluate major elements and heavy metal concentrations of Arsenic (As), Copper (Cu), Chromium (Cr), Cobalt (Co), Vanadium (V), Nickel (Ni), lead (Pb) and Zinc (Zn) in surface sediments of the southern Caspian Sea. Metal contents in the sediment were observed in the order of: V>Cr>Zn>Ni>Co>Cu>Pb>As. Correlations between elements showed that sediment TOM, grain size and chemical composition are the main factors that influence the distribution of heavy metals. According to the pollution load index (PLI), sediments from some sampling sites were polluted. Concentrations of Ni, As, Cr and Cu were higher than sediment quality guidelines at some sampling sites, implying potential adverse impacts of these metals.
Mostrar más [+] Menos [-]Source determination of benzotriazoles in sediment cores from two urban estuaries on the Atlantic Coast of the United States Texto completo
2015
Cantwell, Mark G. | Sullivan, Julia C. | Katz, David R. | Burgess, Robert M. | Bradford Hubeny, J. | King, John
Benzotriazoles (BZTs) are used in a broad range of commercial and industrial products, particularly as metal corrosion inhibitors and as ultraviolet (UV) light stabilizer additives in plastics and polymers. In this study, dated sediment cores from two east coast estuaries were analyzed for commonly used BZTs. In Narragansett Bay, UV stabilizing BZTs (UV-BZTs) were present at high levels from 1961 on, reflecting their patent date, local production and long-term preservation in sediment. In Salem Sound, UV-BZTs were present at concentrations consistent with other coastal marine locations not influenced by BZT production. Anticorrosive BZTs (AC-BZTs) were found in both cores, with the highest levels reported to date present in Narragansett Bay, indicating sorption to, and preservation in, sediments. This study revealed that both classes of BZTs have remained structurally intact over time in coastal sediment cores, demonstrating their resistance to degradation and persistence in environmental compartments.
Mostrar más [+] Menos [-]Sterols as biomarkers in the surface microlayer of the estuarine areas Texto completo
2015
Alsalahi, Murad Ali | Latif, Mohd Talib | Ali, Masni Mohd | Dominick, Doreena | Khan, Md Firoz | Mustaffa, Nur Ili Hamizah | Nadzir, Mohd Shahrul Mohd | Nasher, Essam | Zakaria, Mohamad Pauzi
This study aims to determine the concentration of sterols used as biomarkers in the surface microlayer (SML) in estuarine areas of the Selangor River, Malaysia. Samples were collected during different seasons through the use of a rotation drum. The analysis of sterols was performed using gas chromatography equipped with a flame ionisation detector (GC–FID). The results showed that the concentrations of total sterols in the SML ranged from 107.06 to 505.55ngL−1. The total sterol concentration was found to be higher in the wet season. Cholesterol was found to be the most abundant sterols component in the SML. The diagnostic ratios of sterols show the influence of natural sources and waste on the contribution of sterols in the SML. Further analysis, using principal component analysis (PCA), showed distinct inputs of sterols derived from human activity (40.58%), terrigenous and plant inputs (22.59%) as well as phytoplankton and marine inputs (17.35%).
Mostrar más [+] Menos [-]Litter and seabirds found across a longitudinal gradient in the South Pacific Ocean Texto completo
2015
Miranda-Urbina, Diego | Thiel, Martin | Luna-Jorquera, Guillermo
Abundances and composition of marine litter and seabirds were estimated in the central South Pacific (SP) Ocean between the Chilean continental coast and the Easter Island Ecoregion. Litter was dominated by plastics throughout the study area, but the proportion of plastics was higher at sea and on the oceanic islands than in coastal waters and on continental beaches. Litter densities were higher close to the center of the SP subtropical gyre compared to the continental coast. The seabird assemblage was diverse (28 species), and several endemic species were recorded. Seabird abundances were higher in the coastal waters and around Juan Fernández Islands off the continental coast than in the Oceanic and Polynesian sectors. Endangered species breeding on Salas & Gómez Island were observed in the Polynesian sector, which suggests a high potential for negative interactions between seabirds and floating litter, both occurring in high densities in this sector.
Mostrar más [+] Menos [-]Historical trend in heavy metal pollution in core sediments from the Masan Bay, Korea Texto completo
2015
Cho, Jinhyung | Hyun, Sangmin | Han, J.-H. | Kim, Suhyun | Shin, Dong-Hyeok
The spatiotemporal distribution and their mass accumulation rate (MAR) of heavy metals were investigated to evaluate the time-dependent historical trends of heavy metal concentration. The three short cores used for this study were collected from the catchment area (MS-PC5, 60cm length), the central part (MS-PC4, 40cm length) and the offshore (MS-PC2, 60cm length) of the Masan Bay, Korea. The concentration of heavy metals (Co, Ni, Cu, Zn, Cr and Pb) in catchment area is as much as 1.5–2 times higher than central part of the Bay, and about 2 times higher than offshore area approximately. In particular, MAR of metals (Cu, Zn and Pb) show clear spatiotemporal variation, so that MAR’s of heavy metal may provide more accurate information in evaluating the degree of pollution. Temporally, the heavy metal concentration had been increased since the late 1970s, but it seems to decrease again since the 2004yr in catchment area. This may came from concentrated efforts for the government to reduce industrial waste release.
Mostrar más [+] Menos [-]Effect of air velocity on nanoparticles dispersion in the wake of a vehicle model: Wind tunnel experiments Texto completo
2015
Mehel, Amine | Murzyn, Frederic
Exposure to nanoparticles coming from road–traffic concerns a large part of urban population in both outdoor and indoor environments leading to the enhancement of short and long–term health problems. The dynamics of such small particles is very sensitive to the turbulent diffusion and Brownian motion. Hence their concentrations are dependent on the flow structure properties (length and time scales). In this paper, a wind tunnel study is conducted to assess the effect of the flow on the dispersion of nanoparticles coming out from tailpipe in the near–wake of a reduced–scale truck model. Particle number concentration (PNC) measurements are achieved at 66 positions downstream of the model. Our results point out that the interaction of the ultrafine particles (UFP) with the vortices appearing in the near-wake of a truck enhances their dispersion in both transversal and vertical directions. Increasing the inflow air velocity strengthens this spreading. Overall, we demonstrate that such wind tunnel measurements are fundamental to improve our knowledge on the existing interaction between road–traffic, turbulence and particle concentration to accurately evaluate human exposure rates to ultrafine particles and their potential consequences.
Mostrar más [+] Menos [-]Eutrophication assessment and bioremediation strategy using seaweeds co-cultured with aquatic animals in an enclosed bay in China Texto completo
2015
Wu, Hailong | Huo, Yuanzi | Hu, Ming | Wei, Zhangliang | He, Peimin
Intensive mariculture results in a rise in nutrient concentrations, then leads to serious eutrophication in coastal waters. Based on the sampling data obtained between August 2012 and July 2013, the eutrophication status in Yantian Bay was assessed, and the proportion of marine animals co-cultured with seaweeds was evaluated. The nutritional quality index (NQI) ranged from 4.37 to 13.20, indicating serious eutrophication conditions. The annual average ratio of nitrogen/phosphorus (N/P) was 25.19, indicating a nitrogen surplus in this system. DIN was selected as the best parameter to balance seaweed absorption and marine animal DIN production. Gracilaria lemaneiformis and Laminaria japonica were selected as co-cultured seaweeds. The optimal proportion of G. lemaneiformis production was assessed as 20074.14 tonnes. The optimal proportion of L. japonica production was evaluated as 15890.68 tonnes. High-temperature adapted seaweeds should be introduced for removing nutrients releasing by farmed aquatic animals in the summer in Yantian Bay.
Mostrar más [+] Menos [-]Emerging contaminants (pharmaceuticals, personal care products, a food additive and pesticides) in waters of Sydney estuary, Australia Texto completo
2015
Birch, G.F. | Drage, D.S. | Thompson, K. | Eaglesham, G. | Mueller, J.F.
The current investigation of marine water from 30 sites adjacent to stormwater outlets across the entire Sydney estuary is the first such research in Australia. The number of analytes detected were: 8/59 pharmaceutical compounds (codeine, paracetamol, tramadol, venlafaxine, propranolol, fluoxetine, iopromide and carbamazepine), 7/38 of the pesticides (2,4-dichlorophenoxyacetic acid (2,4-D), 3,4-dichloroaniline, carbaryl, diuron, 2-methyl-4-chlorophenoxyacetic acid (MCPA), mecoprop and simazine) and 0/3 of the personal care products (PCPs) analysed. An artificial sweetener (acesulfame) was detected, however none of the nine antibiotics analysed were identified. Sewage water is not discharged to this estuary, except infrequently as overflow during high-precipitation events. The presence of acesulfame (a recognised marker of domestic wastewater) and pharmaceuticals in water from all parts of the estuary after a dry period, suggests sewage water is leaking into the stormwater system in this catchment. The pesticides are applied to the environment and were discharged via stormwater to the estuary.
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