Уточнить поиск
Результаты 501-510 из 1,956
Eco-hydro-acoustic modeling and its use as an EIA tool Полный текст
2013
Rossington, Kate | Benson, Tom | Lepper, Paul | Jones, Diane
The effects of anthropogenic underwater noise on marine life is of growing concern and assessment of impacts on marine life is often carried out using predictive underwater noise models to map zones of influence for marine species. However, these models do not predict how a species may react to that noise. In this paper, the results from a modified predictive underwater noise model and a hydrodynamic model are used in an individual based model (IBM) to predict the impacts on cod (Gadhus moruha) from noise generated during a pile driving event at an offshore wind farm in Liverpool Bay, UK. The model included cod which were sensitive to noise and those which were insensitive (‘deaf’). Fish movement was from the outer bay into the Dee Estuary, a known feeding ground. The IBM indicated that the cod which could hear took up to 7days longer to reach their destination than the cod which were deaf. This technique could be used during the consenting process for offshore projects to better understand the potential impact on marine species.
Показать больше [+] Меньше [-]Role of shellfish hatchery as a reservoir of antimicrobial resistant bacteria Полный текст
2013
Miranda, Claudio D. | Rojas, Rodrigo | Garrido, Marcela | Geisse, Julieta | González, Gerardo
The main aim of this study was to determine the occurrence of resistant bacteria in florfenicol-treated and untreated scallop larval cultures from a commercial hatchery and to characterize some selected florfenicol-resistant strains. Larval cultures from untreated and treated rearing tanks exhibited percentages of copiotrophic bacteria resistant to florfenicol ranging from 0.03% to 10.67% and 0.49–18.34%, respectively, whereas florfenicol resistance among oligotrophic bacteria varied from 1.44% to 35.50% and 3.62–95.71%, from untreated and treated larvae, respectively. Florfenicol resistant microbiota from reared scallop larvae mainly belonged to the Pseudomonas and Pseudoalteromonas genus and were mainly resistant to florfenicol, chloramphenicol, streptomycin and co-trimoxazole. This is the first study reporting antimicrobial resistant bacteria associated to a shellfish hatchery and the results suggest that a continuous surveillance of antimicrobial resistance even in absence of antibacterial therapy is urgently required to evaluate potential undesirable consequences on the surrounding environments.
Показать больше [+] Меньше [-]Research on the nitrogen cycle in rhizosphere of Kandelia obovata under ammonium and nitrate addition Полный текст
2013
Weng, Bosen | Xie, Xiangyu | Yang, Jinjin | Liu, Jingchun | Lu, Haoliang | Yan, Chongling
The present study investigated nitrogen process in rhizosphere of Kandelia obovata under nitrogen input. Results showed that nitrogen additions significantly increased 4 kinds of enzyme activities (Urease, Nitrate reductase, Nitrite reductase and hydroxylamine reductase). The pH value increased to 7.1 under ammonium addition, but decreased to 6.9 under nitrate addition. Potential Nitrification Intensity (PNI) increased 200–1500% compared with control under ammonium addition, and Potential Denitrification Intensity (PDI) increased more than 200% under nitrate addition. Ten types of organic acids were detected from root exudates, which mainly included oxalic acid, tartaric acid, formic acid, acetic acid, and citric acid. The abundance of 5 kinds of microbial functional groups (nifH, AOA, AOB, nirS, nirK) responded differently. Total nitrogen in organs of K. obovata increased more than 200%. This indicated that nitrogen additions accelerated the transformation of nitrogen directly and stimulated the exudation of root exudates and 5 kinds of genes indirectly.
Показать больше [+] Меньше [-]Characteristics of gas–phase nitric acid and ammonium–nitrate– sulfate aerosol, and their gas–phase precursors in a suburban area in Cairo, Egypt Полный текст
2013
Hassan, Salwa K. | El–Abssawy, Ahmed A. | Khoder, Mamdouh I.
Simultaneous measurements of gaseous SO2, NO2, HNO3, NH3 and particulate SO42–, NO3– and NH4+ were carried out in a suburban area in Cairo during summer 2009 and winter 2009–2010. PTFE membrane filters were used to collect particulate SO42–, NH4+ and NO3–, followed by the impregnated filter to collect HNO3. Colorimetric methods were used for determination of NO2, SO2, NH3, SO42–, NH4+ NO3–, and HNO3 levels. The mean concentrations of NO2, SO2 and NH3 were 75.0, 40.1 and 29.1 µg/m3 in winter and 54.1, 25.1 and 44.9 µg/m3 in summer, respectively. The daytime/nighttime concentration ratios were 1.3 and 1.2 for NO2, 1.3 and 1.2 for SO2 and 0.6, and 0.8 for NH3 during the winter and summer, respectively. The mean values of NH4+, SO42–, NO3–, HNO3 and total NO3– were 4.4, 19.0, 3.4, 1.1 and 4.5 µg/m3 in winter and 7.5, 28.0, 4.2, 3.1 and 7.3 µg/m3 in summer, respectively. The levels of NH4+, SO42–, NO3– and HNO3 were relatively higher in daytime than in nighttime. Sulfur conversion (Fs) and nitrogen conversion ratios (Fn) in summer were about 1.78 and 2.15 times higher than in winter, respectively. Fs and Fn were higher in daytime than in nighttime. Significant positive correlation was found between Fs and relative humidity. The positive correlation between Fn and relative humidity was insignificant. The correlation between the concentration of NH4+ and NO3– indicates that NO3– may be found in fine mode (NH4NO3) in winter and it may be present predominantly as a coarse mode, such as Ca(NO3)2, Mg(NO3)2 and NaNO3 in summer. The concentration of SO42– was significantly correlated with NH4+ concentration, suggesting neutralization by NH3 and indicating that the forms of (NH4)2SO4 and/or NH4HSO4 exist in the aerosol. The NH4+/SO42– molar ratio indicates that SO42– in aerosol may be present as (NH4)2SO4, (NH4)2SO4.CaSO4.2H2O and CaSO4.
Показать больше [+] Меньше [-]Chemical composition, diurnal variation and sources of PM2.5 at two industrial sites of South China Полный текст
2013
Huang, Bo | Liu, Ming | Ren, Zhaofang | Bi, Xinhui | Zhang, Guohua | Sheng, Guoying | Fu, Jiamo
Diurnal PM2.5 samples were collected during summer and winter at an industrial complex site (site A) and an electronic waste (e–waste) recycling site (site B) in Qingyuan, South China. The concentration of organic carbon (OC), elemental carbon (EC), water soluble ions (WSI) and elements were investigated for their seasonal and diurnal variations. Organic matter (OM) was the most abundant specie in winter, accounting for 40.2% and 48.8% of PM2.5 in sites A and B, respectively; while in summer, excluding the elemental portion, WSI was the biggest part, which accounted for 37% and 49.4% of PM2.5 mass in sites A and B, respectively. Significantly higher concentrations were observed for most of the analyzed chemical species in winter. Average acidity of PM2.5 at both sites was significantly higher in summer. Diurnal variation with elevated concentrations of PM2.5 in nighttime samples was found at site B. Secondary inorganic aerosols (NH4+, NO3− and SO42−) exhibited clear day–to–night variation. Concentration of SO42− was about 15% higher in daytime samples. NH4+ and NO3− co–varied in winter, but were weakly associated with each other in summer. Sites A and B samples were almost all ammonium–rich in winter, whereas the summer samples were ammonium–poor during the daytime but ammonium–rich in the night. Positive matrix factorization (PMF) model analysis showed that secondary formation, biomass burning, regional industries, coal combustion and dust had significant contribution to PM2.5. Among them, secondary formation and biomass burning together contributed approximately 50% of PM2.5 mass at both sites. Additionally e–waste recycling activities resulted in high pollution of Cu at Site B.
Показать больше [+] Меньше [-]Development of aerosol wind tunnel and its application for evaluating the performance of ambient PM10 inlets Полный текст
2013
Lee, Sangil | Yu, Miae | Kim, Hun H.
Size selective particulate matter (PM) sampling inlets play an important role in ambient PM measurement. Improper design of the sampling inlets results in collecting of PM with undesired size, which leads to significant errors in the measurement of ambient PM concentrations. Therefore, the performance of PM inlets should be carefully evaluated in a proper environment prior to their field of applications. In this study, a new aerosol wind tunnel system was designed to evaluate the performance of ambient PM10 inlets and evaluated for the uniformity of wind speed distribution and aerosol concentration. In addition, a custom–made PM10 inlet was tested in the aerosol wind tunnel to determine its 50% cutoff diameter. Results of the wind speed distributions show that the percentage deviations from the mean wind speeds at any measurement point are less than 10% with turbulence intensity of less than 5% for three different wind speed levels (0.57m/s, 2.22m/s, and 6.67m/s). Results from the aerosol concentration measurements show that the percentage deviations from the mean aerosol concentrations at any measurement point are less than 10% for three different wind speed levels, which meets the aerosol wind tunnel performance specifications specified by the U.S. Environmental Protection Agency (EPA). Results from PM10 inlet performance tests show that the 50% cutoff diameters of the PM10 inlet are 10.0 μm, 10.3 μm, and 10.0 μm at wind speeds of 0.57m/s, 2.22m/s, and 6.67m/s, respectively. The PM10 inlet is characterized to meet the performance specifications for PM10 inlets, 10.0±0.5 µm, specified by the U.S. EPA. The results indicate that the newly developed aerosol wind tunnel meets the performance requirements for evaluating the performance of PM10 size selective inlets.
Показать больше [+] Меньше [-]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 Полный текст
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.
Показать больше [+] Меньше [-]Thermal tolerances of reef corals in the Gulf: A review of the potential for increasing coral survival and adaptation to climate change through assisted translocation Полный текст
2013
Coles, Steve L. | Riegl, Bernhard M.
Corals in the Gulf 1Although virtually all standard maps use the term “Persian Gulf”, the term “Arabian Gulf” has become commonly used in publications of studies conducted in the waters of Arabian Peninsula countries. The nonpolitical generic term “Gulf” is therefore used here for this marine area.1 withstand summer temperatures up to 10°C higher than corals elsewhere and have recovered from extreme temperature events in 10years or less. This heat-tolerance of Gulf corals has positive implications for the world’s coral populations to adapt to increasing water temperatures. However, survival of Gulf corals has been severely tested by 35–37°C temperatures five times in the last 15years, each time causing extensive coral bleaching and mortality. Anticipated future temperature increases may therefore challenge survival of already highly stressed Gulf corals. Previously proposed translocation of Gulf corals to introduce temperature-adapted corals outside of the Gulf is assessed and determined to be problematical, and to be considered a tool of last resort. Coral culture and transplantation within the Gulf is feasible for helping maintain coral species populations and preserving genomes and adaptive capacities of Gulf corals that are endangered by future thermal stress events.
Показать больше [+] Меньше [-]Concentration of organic sun-blocking agents in seawater of beaches and coral reefs of Okinawa Island, Japan Полный текст
2013
Tashiro, Yutaka | Kameda, Yutaka
The concentration of UV filters (UVFs) and UV light stabilizers (UVLSs) were measured in seawater and river water collected from sites at four beaches, two reefs, and one river on Okinawa Island, Japan. UVFs and/or UVLSs of 8–10 types were detected in beaches samples and 6–9 types were detected in reef samples. The total UVF concentrations at the beach sites were highest either in July or August with a maximum of 1.4μgL−1. The concentrations at the reef sites did not show peaks in summer and the maximum values were close to 10ngL−1. The detected UVF profiles reflected the ingredients of sunscreens used in each region. The highest UVLS concentrations at the reefs were observed not only in summer but also in June and September. The UVLS concentrations at the reefs were similar to or even higher than that at the beaches or in the river.
Показать больше [+] Меньше [-]Enhancement of the diesel oil degradation ability of a marine bacterial strain by immobilization on a novel compound carrier material Полный текст
2013
Hou, Dengyong | Shen, Xianrong | Luo, Qun | He, Ying | Wang, Qingrong | Liu, Qiong
A novel floatable and biodegradable carrier material was made by coating puffed foxtail millet (PFM) with a calcium alginate (CA)-chitosan compound membrane. A diesel oil-degrading marine bacterial strain, Acinetobacter sp. F9, was immobilized on the carrier material. The number of viable F9 cells immobilized on the carrier material reached approximately 5×109CFU/g. This formulation could be stored at −20°C and 4°C for 10weeks without a significant decrease in the number of viable immobilized cells. SEM results showed that the coating membrane was porous and that F9 cells were immobilized on the walls of the pores. The immobilized F9 cells were able to remove more than 90% of the diesel oil by the second day, while free F9 cells did not remove 90% of the diesel oil until the seventh day. GC–MS analysis indicated that the immobilized F9 cells could remove diesel oil more completely than free cells. The immobilization of the F9 cells enhanced their ability to biodegrade diesel oil.
Показать больше [+] Меньше [-]