خيارات البحث
النتائج 631 - 640 من 2,512
Community-level destruction of hard corals by the sea urchin Diadema setosum النص الكامل
2014
Qiu, Jian-Wen | Lau, Dickey C.C. | Cheang, Chi-chiu | Chow, Wing-kuen
Sea urchins are common herbivores and bioeroders of coral ecosystems, but rarely have they been reported as corallivores. We determined the spatial pattern of hard coral damage due to corallivory and bioerosion by the sea urchin Diadema setosum Leske in Hong Kong waters. Coral damage was common at the northeastern sites, with 23.7 – 90.3% colonies being either collapsed or severely damaged with >25% tissue loss. Many genera of corals were impacted by the sea urchin but the damage was most obvious for the structure forming genus Platygyra. The percentage of severely damaged and collapsed coral had significant positive correlation with the abundance of D. setosum, which ranged from 0.01 to 5.2 individuals per coral head or 0.1 – 21.1 individuals m−2 across the study sites. Remedial management actions such as sea urchin removal are urgently needed to save these fringing coral communities.
اظهر المزيد [+] اقل [-]Distribution of surfactants along the estuarine area of Selangor River, Malaysia النص الكامل
2014
Alsalahi, Murad Ali | Latif, Mohd Talib | Ali, Masni Mohd | Magam, Sami Muhsen | Wahid, Nurul Bahiyah Abd | Khan, Md Firoz | Suratman, Suhaimi
This study aims to determine the levels of methylene blue active substances (MBAS) and ethyl violet active substances (EVAS) as anionic surfactants and of disulphine blue active substances (DBAS) as cationic surfactants in the surface microlayer (SML) around an estuarine area using colorimetric methods. The results show that the concentrations of surfactants around the estuarine area were dominated by anionic surfactants (MBAS and EVAS) with average concentrations of 0.39 and 0.51μmolL−1, respectively. There were significant between-station differences in surfactant concentrations (p<0.05) with higher concentrations found at the stations near the sea. The concentration of surfactants was higher during the rainy season than the dry season due to the influence of runoff water. Further investigation using total organic carbon (TOC) and total organic nitrogen (TON) shows that there is a significant correlation (p<0.05) between both anionic and cationic surfactants and the TON concentration.
اظهر المزيد [+] اقل [-]The 2013 severe haze over the Southern Hebei, China: PM2.5 composition and source apportionment النص الكامل
2014
Wei, Zhe | Wang, Li–Tao | Chen, Ming–Zhang | Zheng, Yan
PM2.5 samples were collected and analyzed for the first time in Handan City, which was listed in the top 4 polluted cities in China, during December 2012 to January 2013 when the record–breaking severe haze pollution happened. Positive Matrix Factorization method (PMF) was applied to understand major sources to the severe haze pollution over this city. The daily average concentration of PM2.5 was 160.1μg m–3, which was 2.1 times of the National Ambient Air Quality Standards of China (Class II, Annual Average Level) for daily average PM2.5 of 75μg m–3. SO42– was the most abundant ion (15.4%), followed by NH4+ and NO3–. They accounted for 39.5% of PM2.5. Eight factors were identified by positive matrix factorization (PMF) model. The major sources were coal combustion source (25.9%), secondary source (21.8%), industry source (16.2%), Ba, Mn and Zn source (12.7%), motor vehicle source (7.7%), road dust source (10.9%), K+, As and V source (6.3%) and fuel oil combustion source (2.5%).The mean value of extinction coefficient (Bext) was 682.1Mm–1 and the largest contributor to Bext was ammonium sulfate with the mean value of 221.0Mm–1, accounted for 32.4% of the Bext.
اظهر المزيد [+] اقل [-]Analysis of the spatial representativeness of rural background monitoring stations in Spain النص الكامل
2014
Martín, Fernando | Fileni, Lorenzo | Palomino, Inmaculada | Vivanco, Marta G. | Garrido, Juan L.
The spatial representativeness of rural background air quality stations was estimated using the spatial distribution of air pollutants computed by the combinations of the results of annual WRF–CHIMERE model simulations and data measured at stations of the Iberian Peninsula in 2008, 2009 and 2010 for NO2, SO2, O3 and PM10. The advantage of using validated models combined with measurements is that effects of the emission sources distribution and atmospheric pollutant processes are both taken into account and that the model bias and errors are corrected. This methodology provides a considerably realistic spatial view of air pollutant concentration distribution around the rural background stations. The criteria for delimiting the representativeness area are based on the assumptions that: (1) concentration does not differ by more than a certain percentage from the concentration at the station; and (2) the air quality in the station and in the representativeness area should have the same status regarding the legal standard. The results showed that there is a large variability in the size and shape of the representativeness area of rural background stations in Spain, also depending on the pollutant and the limit or target value. In addition, the interannual variability of the representativeness areas, station redundancy and network coverage have been analyzed. A high interannual variability of spatial representativeness areas was found, except for daily and hourly SO2, hourly O3 and annual NO2. Roughly 50% of rural background stations measured O3 overlap with other stations in at least 80% of their spatial representativeness area, denoting a high percentage of station redundancy. Concerning network coverage, there are zones that are not covered by stations, the worst coverage being for PM10. The proposed methodology seems to be useful for determining the spatial representativeness of air quality stations.
اظهر المزيد [+] اقل [-]Macrobenthic diversity in protected, disturbed, and newly formed intertidal wetlands of a subtropical estuary in China النص الكامل
2014
Lv, Weiwei | Ma, Chang-an | Huang, Youhui | Yang, Yang | Yu, Ji | Zhang, Mingqing | Zhao, Yunlong
In this study, intertidal macrobenthic diversity in protected, disturbed, and newly formed wetlands of Yangtze estuary was assessed using PRIMER 5.2 based on species diversity and species relatedness. We observed high diversity in nature reserves and low diversity in adjacent disturbed and newly formed wetlands. These diversity data were then integrated with historical data to detect the variation in macrobenthic diversity over the past two decades. The integrated data indicated that the intertidal macrobenthic diversity sharply decreased in heavy reclamation tidal flats whereas markedly increased in non-disturbed nature reserve and newly formed wetland. Benthic health was observed with the departure degree of average taxonomic distinctness (Δ+) and variation in taxonomic distinctness (Λ+) from the simulated 95% confidence funnel. All the habitats were subjected to different levels of human interference, except Jiuduansha and Beigangbeisha. The degradation of intertidal wetland in Yangtze estuary was mainly attributed to land reclamation, overgrazing, and overfishing.
اظهر المزيد [+] اقل [-]Microbial release from seeded beach sediments during wave conditions النص الكامل
2014
Phillips, Matthew C. | Feng, Zhixuan | Vogel, Laura J. | Reniers, Ad J.H.M. | Haus, Brian K. | Enns, Amber A. | Zhang, Yifan | Hernandez, David B. | Solo-Gabriele, Helena M.
Beach sands can sustain indigenous and introduced populations of enterococci. The objective of this study was to evaluate wave action in promoting the release of introduced bacteria. To accomplish this objective this study developed a method to assess attachment and identified conditions under which introduced bacteria are integrated into the sand. A new “shearing assay” showed that attachment of the introduced spike mimicked that of the natural sand when the spike was allowed to integrate into the sand for 24h at room temperature at a sand moisture content of 20%. Experiments in a wave flume showed that waves were capable of releasing about 60% of the total bacteria added. This suggests that for the range of wave conditions evaluated (height: 1.9–10.5cm, period:1–2.7s), waves were incapable of releasing all of the bacteria. Further study is needed to evaluate bacteria attachment mechanisms.
اظهر المزيد [+] اقل [-]The interaction between organic phosphate ester and p53: An integrated experimental and in silico approach النص الكامل
2014
Li, Fei | Li, Renmin | Yang, Xianhai | You, Liping | Zhao, Jianmin | Wu, Huifeng
Concerns have been raised in regards to the environmental impact of the more used organophosphate flame retardants (OPFRs). In this study, to better understand the relationship between molecular structural features of OPFRs and binding affinity for the tumor suppressor p53, an integrated experimental and in silico approach was used. From docking analysis, hydrogen bonding and hydrophobic interactions were found to be the dominant interactions, which implied the binding affinities of the compounds. The binding constants of 5 OPFRs were determined by surface plasmon resonance technology (SPR). Based on the observed interactions, appropriate molecular structural parameters were adopted to develop a quantitative structure-activity relationship (QSAR) model. The developed QSAR model had good robustness, predictive ability and mechanism interpretability. The interactions between the OPFRs and p53 (Ebinding) and the partition ability of the OPFRs into the bio-phase are main factors governing the binding affinities.
اظهر المزيد [+] اقل [-]Marine mammals and ocean noise: Future directions and information needs with respect to science, policy and law in Canada النص الكامل
2014
Williams, Rob | Ashe, Erin | Blight, Louise | Jasny, Michael | Nowlan, Linda
Marine mammals are ecologically and culturally important species, and various countries have specific legislation to protect the welfare of individual marine mammals and the conservation of their populations. Anthropogenic noise represents a particular challenge for conservation and management. There is a large and growing body of research to support the conclusion that anthropogenic noise can affect marine mammal behavior, energetics, and physiology. The legal, policy, and management issues surrounding marine mammals and noise are similarly complex. Our objective is twofold. First, we discuss how policy and legal frameworks in Canada have some important differences from other jurisdictions covered in previous reviews, and provide a useful general case study. Secondly, we highlight some priority research areas that will improve marine mammal conservation and management. Our examples focus on the research needed to meet stated conservation objectives for marine mammal species in waters under Canadian jurisdiction.
اظهر المزيد [+] اقل [-]Community change and evidence for variable warm-water temperature adaptation of corals in Northern Male Atoll, Maldives النص الكامل
2014
McClanahan, T.R. | Muthiga, N.A.
This study provides a descriptive analysis of the North Male, Maldives seven years after the 1998 bleaching disturbance to determine the state of the coral community composition, the recruitment community, evidence for recovery, and adaptation to thermal stress. Overall, hard coral cover recovered at a rate commonly reported in the literature but with high spatial variability and shifts in taxonomic composition. Massive Porites, Pavona, Synarea, and Goniopora were unusually common in both the recruit and adult communities. Coral recruitment was low and some coral taxa, namely Tubipora, Seriatopora, and Stylophora, were rarer than expected. A study of the bleaching response to a thermal anomaly in 2005 indicated that some taxa, including Leptoria, Platygyra, Favites, Fungia, Hydnophora, and Galaxea astreata, bleached as predicted while others, including Acropora, Pocillopora, branching Porites, Montipora, Stylophora, and Alveopora, bleached less than predicted. This indicates variable-adaptation potentials among the taxa and considerable potential for ecological reorganization of the coral community.
اظهر المزيد [+] اقل [-]Carbonyl concentrations from sites affected by emission from different fuels and vehicles النص الكامل
2014
Concentrations of carbonyl compounds were evaluated on places impacted by emissions from different fuels and vehicles. In order to evaluate the concentrations, four campaigns during the winter and summer of 2011 and 2012 were performed, inside a covered parking area in a commercial establishment where mainly gasohol and ethanol vehicles are in circulation. Also, measurements were done inside a semi–closed bus station, which is the direct source of emissions from heavy duty vehicles (i.e. buses) burning B3–diesel (3% biodiesel and 97% diesel). The results indicated that acetaldehyde is the main aldehyde emitted by light vehicles due to large use of ethanol in Brazil by these vehicles. In addition, the concentrations found in the bus station revealed that B3–diesel fuel increases the emissions of carbonyl compounds and that of acetaldehyde when compared with results from B0–diesel at same bus station. Possible impacts of changing diesel to B3–diesel indicate an increase of ozone formation. In terms of health, a lower impact was estimated considering only the changes in formaldehyde concentrations.
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