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Результаты 701-710 из 1,955
Composition of in situ burn residue as a function of weathering conditions Полный текст
2013
Fritt-Rasmussen, Janne | Ascanius, Birgit Elkjær | Brandvik, Per Johan | Villumsen, Arne | Stenby, Erling H.
Troll B crude oil was weathered under Arctic conditions with different ice coverage: open water, 50% ice and 90% ice. Samples (100mL) were taken during the experiment and tested for ignitability in a burning cell. From each burning a residue sample was taken for analysis. The burning process removed the light compounds eluting before C13. No effect from the prior weathering time or the different ice coverage was seen in the burn residue composition. The content of selected Poly Aromatic Hydrocarbons (PAHs) was determined and it was noted that the concentration of PAHs with more than 4 rings were increased. The source origin of the PAHs was investigated by use of relative ratios of PAH isomers and indicated that some formation of PAHs was additionally taking place during burning.
Показать больше [+] Меньше [-]Relationships among the abundances of plastic debris in different size classes on beaches in South Korea Полный текст
2013
Lee, Jongmyoung | Hong, Sunwook | Song, Young Kyung | Hong, Sang Hee | Jang, Yong Chang | Jang, Mi | Heo, Nak Won | Han, Gi Myung | Lee, Mi Jeong | Kang, Daeseok | Shim, Won Joon
Plastic debris on six beaches near the Nakdong River Estuary, South Korea, was sampled in May and September 2012 and classified into three size classes, large microplastics (1–5mm), mesoplastics (5–25mm), and macroplastics (>25mm). The relationships among the abundances of the size classes were then examined. The abundances of each size category in May (before rainy season) and in September (after rainy season) were 8205 and 27,606particles/m2 for large microplastics, 238 and 237particles/m2 for mesoplastics, and 0.97 and 1.03particles/m2 for macroplastics, respectively. Styrofoam was the most abundant item both in microplastic and mesoplastic debris, while intact plastics were most common in macroplastic debris. The abundances of meso- and micro-plastics were the most strongly correlated. There was a higher correlation between the abundances of macro- and meso-plastics than between macro- and micro-plastics.
Показать больше [+] Меньше [-]Effects of an oil spill on benthic community production and respiration on subtropical intertidal sandflats Полный текст
2013
Lee, Li-Hua | Lin, Hsing-Juh
This study determined effects of an oil spill on subtropical benthic community production and respiration by monitoring CO2 fluxes in benthic chambers on intertidal sandflats during emersion before and after an accidental spill. The oil spill decreased sediment chlorophyll a concentrations, altered benthic macrofaunal community, and affected ecological functioning by suppressing or even stopping microalgal production, increasing bacterial respiration, and causing a shift from an autotrophic system to a heterotrophic system. Effects of the oil spill on the macrofauna were more severe than on benthic microalgae, and affected sedentary infauna more than motile epifauna. Despite the oil spill’s impact on the benthic community and carbon metabolism, the affected area appeared to return to normal in about 23days. Our results suggest that the prompt response of benthic metabolism to exposure to petroleum hydrocarbons can serve as a useful indicator of the impact of an oil spill.
Показать больше [+] Меньше [-]Critical research needs for identifying future changes in Gulf coral reef ecosystems Полный текст
2013
Feary, David A. | Burt, John A. | Bauman, Andrew G. | Al Hazeem, Shaker | Abdel-Moati, Mohamed A. | Al-Khalifa, Khalifa A. | Anderson, Donald M. | Amos, Carl | Baker, Andrew | Bartholomew, Aaron | Bento, Rita | Cavalcante, Geórgenes H. | Chen, Chaolun Allen | Coles, Steve L. | Dab, Koosha | Fowler, Ashley M. | George, David | Grandcourt, E. M. | Hill, Ross | John, D. M. | Jones, David A. | Keshavmurthy, Shashank | Mahmoud, Huda | Moradi Och Tapeh, Mahdi | Mostafavi, Pargol Ghavam | Naser, Humood | Pichon, Michel | Purkis, Samuel J. | Riegl, Bernhard | Samimi-Namin, Kaveh | Sheppard, Charles | Vajed Samiei, Jahangir | Voolstra, Christian R. | Wiedenmann, Joerg
Expert opinion was assessed to identify current knowledge gaps in determining future changes in Arabian/Persian Gulf (thereafter ‘Gulf’) coral reefs. Thirty-one participants submitted 71 research questions that were peer-assessed in terms of scientific importance (i.e., filled a knowledge gap and was a research priority) and efficiency in resource use (i.e., was highly feasible and ecologically broad). Ten research questions, in six major research areas, were highly important for both understanding Gulf coral reef ecosystems and also an efficient use of limited research resources. These questions mirrored global evaluations of the importance of understanding and evaluating biodiversity, determining the potential impacts of climate change, the role of anthropogenic impacts in structuring coral reef communities, and economically evaluating coral reef communities. These questions provide guidance for future research on coral reef ecosystems within the Gulf, and enhance the potential for assessment and management of future changes in this globally significant region.
Показать больше [+] Меньше [-]Temporal and spatial distribution of red tide outbreaks in the Yangtze River Estuary and adjacent waters, China Полный текст
2013
Liu, Lusan | Zhou, Juan | Zheng, Binghui | Cai, Wenqian | Lin, Kuixuan | Tang, Jingliang
Between 1972 and 2009, evidence of red tide outbreaks in the Yangtze River Estuary and adjacent waters was collected. A geographic information system (GIS) was used to analyze the temporal and spatial distribution of these red tides, and it was subsequently used to map the distribution of these events. The results show that the following findings. (1) There were three red tide-prone areas: outside the Yangtze River Estuary and the eastern coast of Sheshan, the Huaniaoshan–Shengshan–Gouqi waters, and the Zhoushan areas and eastern coast of Zhujiajian. In these areas, red tides occurred 174 total times, 25 of which were larger than 1000 km2 in areal extent. After 2000, the frequency of red tide outbreaks increased significantly. (2) During the months of May and June, the red tide occurrence in these areas was 51% and 20%, respectively. (3) Outbreaks of the dominant red tide plankton species Prorocentrum dong-haiense, Skeletonema costatum, Prorocentrum dantatum, and Noctiluca scientillan occurred 38, 35, 15, and 10 times, respectively, during the study interval.
Показать больше [+] Меньше [-]An integrated microfluidic device in marine microalgae culture for toxicity screening application Полный текст
2013
Zheng, Guoxia | Wang, Yunhua | Wang, Zumin | Zhong, Weiliang | Wang, Hu | Li, Yajie
Algal assay using marine microalgae has emerged as an important method to evaluate the toxicity of chemicals, which is currently undertaken using conventional culture and additional detection of physiological cellular endpoints. While effective, this approach can be labor-intensive and thus could benefit from a more streamlined, integrated approach. Microfluidics offers a way to accomplish this goal. Here, we demonstrate a microfluidic device which consists of a concentration gradient generator (CGG), diffusible culturing module and power-free valve system. It allows the processes of chemical liquid dilution and diffusion, micro-scale microalgal culture (in batch or chemostatic conditions), cell stimulation and on-lined screening to be integrated into a single device. Using the device, marine microalgae were successfully cultured and stressed on-chip. The simple assay provides multi-biological response measurements of cell division rate, autofluorescence and esterase activity. This work showed promising in developing a microfluidic platform for toxicity screening based on marine microalgal culture.
Показать больше [+] Меньше [-]Analysis of temporal and spatial variability of total column ozone over West Africa using daily TOMS measurements Полный текст
2013
Oluleye, Ayodeji | Okogbue, Emmanuel Chilekwu
The aim of this study was to examine the temporal and spatial total column ozone distribution in West Africa using Total Ozone Mapping spectrometer (TOMS) daily data for five years between 2001 and 2005 in fifteen locations. In this study, certain significant observations emerged: weather activity particularly the rainfall producing mechanism (dynamic of the wind systems) was responsible for about 62% ozone distribution in the region. Ozone maximum and minimum concentrations over all the stations were 305 DU and 232 DU respectively producing an average range of 73 DU (only about 27.03% of the mean value). Ozone has a seasonal distribution with minimum occurring during the dry season and maximum occurring during the wet season. A decreasing rate of about –0.6 DU/year was found for the region. Interannual ozone characteristics revealed an oscillating feature similar to Quasi – biennial Oscillation (QBO) footprints which indicated the importance of stratosphere – troposphere exchange to ozone distribution in the region. Furthermore, lag of about one or two months occurs between south (lower latitude) and north (higher latitude) monthly ozone maximums.
Показать больше [+] Меньше [-]Effect of extraction-method, period of incubation and tidal emersion on the viability of haemocytes from oysters Полный текст
2013
Moreira, Fabiana T. | Browne, Mark Anthony | Coleman, Ross A.
The impacts of pollution on marine organisms are often investigated using the viability of their haemocytes. Although this assay is routinely used in monitoring, field and laboratory experimentation, there has been less effort in further optimizing procedures to reduce artefacts and facilitate sampling over large geographic areas.Using the oyster Saccostrea glomerata as a model species, we investigated the effects of different techniques for extracting haemolymph, period of incubation with dye and emersion-time (e.g. tidal-state) on the viability of haemocytes. Collecting haemocytes with a syringe, through a drilled hole in the shell, increased the viability of haemocytes by almost 50%. While emersion-time and incubating haemocytes with the dye for up to 4h did not affect viability.This simple in situ approach provides a less destructive method for extracting haemocytes, allowing their viability to be measured as part of large-scale experiments without jeopardizing the surrounding assemblage of animals and plants.
Показать больше [+] Меньше [-]Biomonitoring of thallium availability in two estuaries of southwest England Полный текст
2013
Turner, Andrew | Turner, Deborah | Braungardt, Charlotte
Thallium is a highly toxic metal whose biogeochemical behaviour in the marine environment is poorly understood. We measured Tl in sediments, macroalgae (Fucus vesiculosus and Fucus ceranoides) and deposit-feeding invertebrates (Hediste diversicolor, Arenicola marina and Scrobicularia plana) from two estuaries of south west England (Plym and Fal) draining mineralised catchments. In the Plym, and for a given sample type, concentrations of Tl were rather invariant between sample locations and averaged about 500μgkg−1 for sediment, 30μgkg−1 for macroalgae and 10μgkg−1 for the invertebrates. In the Fal, respective concentrations were of a similar order of magnitude but exhibited greater variation between sample locations. Normalisation of Tl concentrations to K, the biogeochemical analogue of Tl+, revealed bioenrichment of about 20 for all organisms in the Plym and bioenrichment ranging from about 3 (H. diversicolor) to 170 (F. ceranoides) in the Fal. Despite the low bioaccumulation of Tl relative to other metals measured concurrently, it is recommended that Tl be more closely monitored and better studied in the estuarine environment.
Показать больше [+] Меньше [-]Fractionation, sources and budgets of potential harmful elements in surface sediments of the East China Sea Полный текст
2013
Yu, Yu | Song, Jinming | Li, Xuegang | Yuan, Huamao | Li, Ning
Total concentrations, chemical fractions by BCR procedure and enrichment factors of nine potential harmful elements (V, Cr, Co, Ni, Cu, Zn, Mo, Cd and Pb) in surface sediments of the East China Sea (ECS) were investigated. Spatial distributions illustrated that PHEs (potential harmful elements) were mainly from the Changjiang River and the Jiangsu coastal current, except Pb which was influenced by atmospheric input. Sediments in the ECS were moderately polluted with Cd, Pb, Zn and Cu according to their enrichment factors (EFs). Distributions of EFs and labile fractions revealed that anthropogenic Cd and Cu were mainly input though the Changjiang, Pb pollutant was delivered from the Changjiang and atmosphere, while Zn was impacted by terrestrial pollution from the Changjiang and the Hangzhou Bay. Budget calculation showed that the Changjiang contributed 82–90% of PHE influxes. Thirty-eight to 77% of PHEs were buried in sediment, mainly along the inner shelf.
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