خيارات البحث
النتائج 831 - 840 من 1,908
Environmental harm assessment of a wastewater discharge from Hammerfest LNG: A study with biomarkers in mussels (Mytilus sp.) and Atlantic cod (Gadus morhua)
2013
Beyer, Jonny | Aarab, Nadia | Tandberg, Anne Helene | Ingvarsdottir, Anna | Bamber, Shaw | Børseth, Jan Fredrik | Camus, Lionel | Velvin, Roger
Biologically treated wastewater (WW) from the Hammerfest LNG (liquefied natural gas) plant is discharged to the sea. A study using biomarkers in mussels and Atlantic cod was performed to examine whether this discharge meets a zero harmful emission requirement. Caging of mussels close to the outfall and exposure of mussels and fish to WW in the laboratory were conducted, and a suite of contaminant responsive markers was assessed in exposed animals. In mussels the markers included chemical contaminant levels, haemocyte lysosomal instability and nucleus integrity, cellular energy allocation, digestive gland and gonad histopathology and shell-opening behaviour. In fish, biliary PAH metabolites and gill histopathology biomarkers were measured. A consistent cause-effect relationship between WW treatments and markers measured in test animals was not found. The results therefore indicate that the WW emission is unlikely to represent a significant stress factor for the local marine environment under the conditions studied.
اظهر المزيد [+] اقل [-]Influence of size and density on filtration rate modeling and nutrient uptake by green mussel (Perna viridis)
2013
Tantanasarit, Chayarat | Babel, Sandhya | Englande, A. J. | Shettapong Meksumpun,
This study investigates green mussel filtration rates based on variation of the mussel size and density, and attempts to correlate these with the amount of Chaetoceros calcitrans consumed by kinetic modeling. The filtration rates were found to be more effective in small mussels and with greater volumes of seawater/mussel which represent low mussel densities in the mussel farms. Under field condition, the first order kinetic model is useful for evaluation of mussel filtration rate. However, the composite exponential kinetic model was determined to better describe filtration rates in a close system. Higher ratios of seawater volume L/g DW mussel tissue, resulted in an increasing filtration rate until a maximum plateau was reached at 10.37L/h/g DW tissue as determined by first order kinetics. Based on the filtration rate, carbon, nitrogen, and phosphorus uptake by green mussels were found to be 2128.72, 265.41, and 66.67mg/year/indv, respectively.
اظهر المزيد [+] اقل [-]Marine debris in central California: Quantifying type and abundance of beach litter in Monterey Bay, CA
2013
Rosevelt, C. | Los Huertos, M. | Garza, C. | Nevins, H.M.
Monitoring beach litter is essential for reducing ecological threats towards humans and wildlife. In Monterey Bay, CA information on seasonal and spatial patterns is understudied. Central California’s coastal managers require reliable information on debris abundance, distribution, and type, to support policy aimed at reducing litter. We developed a survey method that allowed for trained citizen scientists to quantify the types and abundance of beach litter. Sampling occurred from July 2009–June 2010. Litter abundance ranged from 0.03 to 17.1itemsm−2. Using a mixed model approach, we found season and location have the greatest effect on litter abundance. Styrofoam, the most numerically abundant item, made up 41% of the total amount of litter. Unexpected items included fertilizer pellets. The results of this study provide a baseline on the types and abundance of litter on the central coast and have directly supported policy banning Styrofoam take out containers from local municipalities.
اظهر المزيد [+] اقل [-]Effects of fish farming on phytoplankton community under the thermal stress caused by a power plant in a eutrophic, semi-enclosed bay: Induce toxic dinoflagellate (Prorocentrum minimum) blooms in cold seasons
2013
Jiang, Zhibing | Liao, Yibo | Liu, Jingjing | Shou, Lu | Chen, Quanzhen | Yan, Xiaojun | Zhu, Genhai | Zeng, Jiangning
Six cruises were conducted in a fish farm adjacent to the Ninghai Power Plant in Xiangshan Bay, East China Sea. Fish farming significantly increased NH4+, DIP, and TOC concentrations, while it significantly decreased the DO level. These increase/decrease trends were more pronounced in warmer seasons. Although culture practices did not significantly increase phytoplankton density, it drastically enhanced dinoflagellate abundance and domination. Significant differences in species diversity and community composition between the cages and the control area were also observed. Temperature elevation caused by thermal discharge associated with eutrophication resulted in a dominant species shift from diatoms alone to dinoflagellates and diatoms. This is the first report of stress-induced toxic dinoflagellate (Prorocentrum minimum) blooms in winter and the winter–spring transition in this bay. Therefore, the effects of aquaculture activity and power plant construction in such a eutrophic, semi-enclosed bay require further attention.
اظهر المزيد [+] اقل [-]Polybrominated diphenyl ethers do not affect metamorphosis but alter the proteome of the invasive slipper limpet Crepidula onyx
2013
Mukerji, Joy | Po, Beverly H.K. | Chiu, Jill M.Y. | Wu, Rudolf S.S. | Qian, Pei-Yuan | Thiyagarajan, Vengatesen
Man-made polybrominated diphenyl ethers (PBDEs) used as flame retardants in various consumer products may be harmful to marine organisms. Larvae of some marine invertebrates, especially invasive species, can develop resistance to PBDEs through altered protein expression patterns or proteome plasticity. This is the first report of a proteomics approach to study BDE-47 induced molecular changes in the invasive limpet Crepidula onyx. Larvae of C. onyx were cultured for 5days (hatching to metamorphosis) in the presence of BDE-47 (1μgL−1). Using a 2-DE proteomics approach with triple quadrupole and high-resolution TOF-MS, we showed that BDE-47 altered the proteome structure but not the growth or metamorphosis of C. onyx larvae. We found eight significant differentially expressed proteins in response to BDE-47, deemed the protein expression signature, consisting of cytoskeletal, stress tolerance, metabolism and energy production related proteins. Our data suggest C. onyx larvae have adequate proteome plasticity to tolerate BDE-47 toxicity.
اظهر المزيد [+] اقل [-]Isolation and characterization of alkane degrading bacteria from petroleum reservoir waste water in Iran (Kerman and Tehran provenances)
2013
Hassanshahian, Mehdi | Ahmadinejad, Mohammad | Tebyanian, Hamid | Kariminik, Ashraf
Petroleum products spill and leakage have become two major environmental challenges in Iran. Sampling was performed in the petroleum reservoir waste water of Tehran and Kerman Provinces of Iran. Alkane degrading bacteria were isolated by enrichment in a Bushnel–Hass medium, with hexadecane as sole source of carbon and energy. The isolated strains were identified by amplification of 16S rDNA gene and sequencing. Specific primers were used for identification of alkane hydroxylase gene. Fifteen alkane degrading bacteria were isolated and 8 strains were selected as powerful degradative bacteria. These 8 strains relate to Rhodococcus jostii, Stenotrophomonas maltophilia, Achromobacter piechaudii, Tsukamurella tyrosinosolvens, Pseudomonas fluorescens, Rhodococcus erythropolis, Stenotrophomonas maltophilia, Pseudomonas aeruginosa genera. The optimum concentration of hexadecane that allowed high growth was 2.5%. Gas chromatography results show that all strains can degrade approximately half of hexadecane in one week of incubation. All of the strains have alkane hydroxylase gene which are important for biodegradation. As a result, this study indicates that there is a high diversity of degradative bacteria in petroleum reservoir waste water in Iran.
اظهر المزيد [+] اقل [-]Extraction of bioavailable contaminants from marine sediments: An approach to reducing toxicity using adsorbent parcels
2013
Goodsir, Freya | Fisher, Tom T. | Barry, Jon | Bolam, Thi | Nelson, Leah D. | Rumney, Heather S. | Brant, Jan L.
This paper demonstrates an approach to reducing acute toxicity in marine sediments using adsorbent parcels. Acute toxicity tests were carried using the marine amphipod Corophium volutator. Marine sediments were spiked with two know contaminants tributyltin and naphthalene and then treated with adsorbent parcels containing either amberlite XAD4 or activated carbon. Results showed that both types of adsorbent parcels were effective in reducing acute toxicity, not only within spiked sediments containing naphthalene and/or tributyltin, but also in an environmental field samples form an expected contaminated site. Adsorbent parcels such as these could provide a practical approach to remediate areas of contaminated sediment within marine environments. Furthermore adsorbents can be used as an identification tool for problematic contaminants using a toxicity identification evaluation approach.
اظهر المزيد [+] اقل [-]Fingerprint and weathering characteristics of crude oils after Dalian oil spill, China
2013
Wang, Chuanyuan | Chen, Bing | Zhang, Baiyu | He, Shijie | Zhao, Mingming
In an attempt to analyze the chemical characterization of oil residues and examine the suitability of chemical fingerprinting methods in oil spill investigations, multiple parameters sensitive to both sources and degree of weathering were used to characterize oil residues from “7–16” Dalian oil spill, China. Oil residues collected 90days to 120days after the spill showed a weathering pattern where significant amounts of light to middle molecular weight normal alkanes were depleted with pristane and phytane as dominant peaks. Diagnostic ratios developed from n-alkane and selected isoprenoids (e.g. Pr/Ph, n-C17/Pr, n-C18/Ph, carbon preference index, LMW/HMW-alkanes ratio), all display obvious changes over weathering time, indicating that these ratios are not valid for oil source identification. Furthermore, the biomarker ratios of hopanes and steranes with relative standard deviations (RSDs) of 0.88–4.08% were useful for source identification even for severely weathered oil residues. In addition, RSD of δ13C values of individual n-alkanes in oil residue varied from 0.07% to 0.20%, which suggest that stable carbon isotope profile of n-alkanes can also be a useful tool for tracing the source of an oil spill.
اظهر المزيد [+] اقل [-]Interfacial film formation: Influence on oil spreading rates in lab basin tests and dispersant effectiveness testing in a wave tank
2013
King, Thomas L. | Clyburne, Jason A.C. | Lee, Kenneth | Robinson, Brian J.
Test facilities such as lab basins and wave tanks are essential when evaluating the use of chemical dispersants to treat oil spills at sea. However, these test facilities have boundaries (walls) that provide an ideal environment for surface (interfacial) film formation on seawater. Surface films may form from surfactants naturally present in crude oil as well as dispersant drift/overspray when applied to an oil spill. The objective of this study was to examine the impact of surface film formation on oil spreading rates in a small scale lab basin and on dispersant effectiveness conducted in a large scale wave tank. The process of crude oil spreading on the surface of the basin seawater was influenced in the presence of a surface film as shown using a 1st order kinetic model. In addition, interfacial film formation can greatly influence chemically dispersed crude oil in a large scale dynamic wave tank.
اظهر المزيد [+] اقل [-]Microplastic pollution in the surface waters of the Laurentian Great Lakes
2013
Eriksen, Marcus | Mason, Sherri | Wilson, Stiv | Box, Carolyn | Zellers, Ann | Edwards, William | Farley, Hannah | Amato, Stephen
Neuston samples were collected at 21 stations during an ∼700 nautical mile (∼1300km) expedition in July 2012 in the Laurentian Great Lakes of the United States using a 333μm mesh manta trawl and analyzed for plastic debris. Although the average abundance was approximately 43,000 microplastic particles/km2, station 20, downstream from two major cities, contained over 466,000particles/km2, greater than all other stations combined. SEM analysis determined nearly 20% of particles less than 1mm, which were initially identified as microplastic by visual observation, were aluminum silicate from coal ash. Many microplastic particles were multi-colored spheres, which were compared to, and are suspected to be, microbeads from consumer products containing microplastic particles of similar size, shape, texture and composition. The presence of microplastics and coal ash in these surface samples, which were most abundant where lake currents converge, are likely from nearby urban effluent and coal burning power plants.
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