Уточнить поиск
Результаты 861-870 из 2,512
Intercomparison of tropospheric nitrogen dioxide retrieved from Ozone Monitoring Instrument over China Полный текст
2014
Zheng, Fengjie | Yu, Tao | Cheng, Tianhai | Gu, Xingfa | Guo, Hong
Tropospheric NO2 columns observed from the Ozone Monitoring Instrument (OMI) were evaluated and the seasonal characteristics were analyzed at eastern China with surface measurements. A comparison between the DP (DOMINO) and SP (Standard Product) tropospheric NO2 products from OMI different algorithms shows similar spatial and temporal variability, but DP is generally higher than SP by 13% in wintertime and lower 9% in summertime on average over East China. Larger differences occur on the significantly contaminated regions. The differences in seasonality are associated with emissions sources. In order to investigate and monitor the air pollution monitoring over east China, the relative contributions of the stratosphere–troposphere separation and air mass factors calculations to the observed difference between DP and SP tropospheric NO2 columns were compared. The seasonal difference due to stratosphere–troposphere separation is opposite in sign to the tropospheric vertical columns. Air mass factors (AMFs) of DP are smaller than SP AMFs, leading to higher DP tropospheric columns. Impacts induced by different AMFs calculation are crucial. Then, the differences of four cities in significant polluted areas were compared. The results showed apparent discrepancies between two products in local region with irregular monthly variation, however the seasonal mean columns demonstrated that basically DP is larger than SP. Overall, this study analyses the discrepancies in DP and SP, as well as the seasonal variations over East China which is an important implication for the control of nitrogen oxides.
Показать больше [+] Меньше [-]Study of landscape patterns of variation and optimization based on non-point source pollution control in an estuary Полный текст
2014
Jiang, Mengzhen | Chen, Haiying | Chen, Qinghui | Wu, Haiyan
Appropriate increases in the “sink” of a landscape can reduce the risk of non-point source pollution (NPSP) to the sea at relatively lower costs and at a higher efficiency. Based on high-resolution remote sensing image data taken between 2003 and 2008, we analyzed the “source” and “sink” landscape pattern variations of nitrogen and phosphorus pollutants in the Jiulongjiang estuary region. The contribution to the sea and distribution of each pollutant in the region was calculated using the LCI and mGLCI models. The results indicated that an increased amount of pollutants was contributed to the sea, and the “source” area of the nitrogen NPSP in the study area increased by 32.75km2. We also propose a landscape pattern optimization to reduce pollution in the Jiulongjiang estuary in 2008 through the conversion of cultivated land with slopes greater than 15° and paddy fields near rivers, and an increase in mangrove areas.
Показать больше [+] Меньше [-]ALien Biotic IndEX (ALEX) – A new index for assessing impacts of alien species on benthic communities Полный текст
2014
Çinar, Melih Ertan | Bakir, Kerem
Biotic indices are mainly aimed at assessing levels of deterioration caused by chemical or organic pollution. However, no biotic index to date has been developed to detect impacts of alien species on benthic communities. In this paper, a new biotic index, namely ALEX, is proposed to address the objectives of the Water Framework Directive and was tested in Mersin Bay (Levantine Sea, Turkey). Species were divided into four biogeographic groups, namely native species, casual species, established species and invasive species, and the metric considers the relative importance of these groups in samples. The index classified the ecological status of some stations which are shallow, and close to harbor and river mouths as bad or poor in February and October. The ALEX values were positively and significantly correlated with total nitrogen, silicate and silt percentage in sediment, and negatively correlated with depth and the distance from the harbor.
Показать больше [+] Меньше [-]The invasive kelp Undaria pinnatifida (Laminariales, Ochrophyta) along the north coast of Portugal: Distribution model versus field observations Полный текст
2014
Veiga, P. | Torres, A.C. | Rubal, M. | Troncoso, J. | Sousa-Pinto, I.
After the first report of Undaria pinnatifida in north Portugal (between 1999 and 2007), a rapid spread of this species could be expected due to the presence of a stable population and the favourable environmental conditions proposed by distribution models. However, field surveys showed that U. pinnatifida was not present in most of the rocky shores in north Portugal. It seems that U. pinnatifida cannot outcompete native species outside of marinas in north Portugal. The only population in natural rocky shores was found in Buarcos, where this species was frequent. This study provides density data of U. pinnatifida that will be useful in the future to monitor changes on its abundance and distribution in the centre and south of Portugal.
Показать больше [+] Меньше [-]Quantifying and modelling the carbon sequestration capacity of seagrass meadows – A critical assessment Полный текст
2014
Macreadie, P.I. | Baird, M.E. | Trevathan-Tackett, S.M. | Larkum, A.W.D. | Ralph, P.J.
Seagrasses are among the planet’s most effective natural ecosystems for sequestering (capturing and storing) carbon (C); but if degraded, they could leak stored C into the atmosphere and accelerate global warming. Quantifying and modelling the C sequestration capacity is therefore critical for successfully managing seagrass ecosystems to maintain their substantial abatement potential. At present, there is no mechanism to support carbon financing linked to seagrass. For seagrasses to be recognised by the IPCC and the voluntary C market, standard stock assessment methodologies and inventories of seagrass C stocks are required. Developing accurate C budgets for seagrass meadows is indeed complex; we discuss these complexities, and, in addition, we review techniques and methodologies that will aid development of C budgets. We also consider a simple process-based data assimilation model for predicting how seagrasses will respond to future change, accompanied by a practical list of research priorities.
Показать больше [+] Меньше [-]Isolation of 12 microsatellite markers following a pyrosequencing procedure and cross-priming in two invasive cryptic species, Alexandrium catenella (group IV) and A. tamarense (group III) (Dinophyceae) Полный текст
2014
Laporte, Martin | Shao, Zhaojun | Berrebi, Patrick | Laabir, Mohamed | Abadie, Eric | Faivre, Nicolas | Rieuvilleneuve, Fabien | Masseret, Estelle
Isolation of 12 microsatellite markers following a pyrosequencing procedure and cross-priming in two invasive cryptic species, Alexandrium catenella (group IV) and A. tamarense (group III) (Dinophyceae) Полный текст
2014
Laporte, Martin | Shao, Zhaojun | Berrebi, Patrick | Laabir, Mohamed | Abadie, Eric | Faivre, Nicolas | Rieuvilleneuve, Fabien | Masseret, Estelle
Alexandrium catenella (group IV) and Alexandrium tamarense (group III) (Dinophyceae) are two cryptic invasive phytoplankton species belonging to the A. tamarense species complex. Their worldwide spread is favored by the human activities, transportation and climate change. In order to describe their diversity in the Mediterranean Sea and understand their settlements and maintenances in this area, new microsatellite markers were developed based on Thau lagoon (France) samples of A. catenella and A. tamarense strains. In this study twelve new microsatellite markers are proposed. Five of these microsatellite markers show amplifications on A. tamarense and ten on A. catenella. Three of these 12 microsatellite markers allowed amplifications on both cryptic species. Finally, the haplotypic diversity ranged from 0.000 to 0.791 and 0.000 to 0.942 for A. catenella and A. tamarense respectively.
Показать больше [+] Меньше [-]Isolation of 12 microsatellite markers following a pyrosequencing procedure and cross-priming in two invasive cryptic species, Alexandrium catenella (group IV) and A. tamarense (group III) (Dinophyceae) Полный текст
2014
Laporte, Martin | Shao, Zhaojun | Berrebi, Patrick | Laabir, Mohamed | Abadie, Eric | Faivre, Nicolas | Rieuvilleneuve, Fabien | Masseret, Estelle
Alexandrium catenella (group IV) and Alexandrium tamarense (group III) (Dinophyceae) are two cryptic invasive phytoplankton species belonging to the A. tamarense species complex. Their worldwide spread is favored by the human activities, transportation and climate change. In order to describe their diversity in the Mediterranean Sea and understand their settlements and maintenances in this area, new microsatellite markers were developed based on Thau lagoon (France) samples of A. catenella and A. tamarense strains. In this study twelve new microsatellite markers are proposed. Five of these microsatellite markers show amplifications on A. tamarense and ten on A. catenella. Three of these 12 microsatellite markers allowed amplifications on both cryptic species. Finally, the haplotypic diversity ranged from 0.000 to 0.791 and 0.000 to 0.942 for A. catenella and A. tamarense respectively.
Показать больше [+] Меньше [-]Trace element concentrations in barramundi (Lates calcarifer) collected along the coast of Vietnam Полный текст
2014
Tu, Nguyen Phuc Cam | Ha, Nguyen Ngoc | Haruta, Shinsuke | Takeuchi, Ichirō
We determined concentrations of 23 trace elements (TEs), and stable carbon and nitrogen isotope (δ13C and δ15N) signatures in barramundi (Lates calcarifer) specimens collected along the coast of Vietnam in the Northern (NCZ), Central (CCZ) and Southern (SCZ) zones in the period 2007–2010. A combination of δ13C and δ15N signatures provided insight into ontogenetic shifts in barramundi foraging choices. There were clear zone-dependent differences in Mn, As, Sr and Tl concentrations; levels of Tl were highest in the NCZ, As in the CCZ, and Mn and Sr in the SCZ. Lowest concentrations of Rb occurred in the NCZ, Bi was lowest in the CCZ, and Cd and Cs were lowest in the SCZ. δ15N values significantly increased with increasing Zn, Se, Sn and Cs. Concentrations of TEs in barramundi from Vietnam were below worldwide guidelines for human consumption.
Показать больше [+] Меньше [-]Heavy metals in surface sediments from nine estuaries along the coast of Bohai Bay, Northern China Полный текст
2014
Wu, Guanghong | Shang, Jingmin | Pan, Ling | Wang, Zhongliang
Concentrations of heavy metals in river water and sediment were investigated in nine estuaries along the coast of Bohai Bay, Northern China. Multivariate statistical techniques such as principal component analysis and cluster analysis, in combination with metal concentration analysis and correlation analysis, were used to identify the possible sources of the metals and the pollution pattern in nine estuaries along the coast of Bohai Bay. The environmental risks of metals, evaluated by sediment quality guidelines and background values, revealed Hg contamination in the estuaries. However, levels of Cd in estuarine sediments were low, and they were less than those levels in river sediments, partly due to the high mobility and dilution of river or seawater. Cd did not contribute to sediment deposits in estuaries. High organic matter from effluents from large municipal sewage treatment plants was predominantly responsible for restricting Hg mobility from the river to Bohai Bay.
Показать больше [+] Меньше [-]Impacts of recreational motorboats on fishes: A review Полный текст
2014
Whitfield, A.K. | Becker, A.
A considerable amount of research has been conducted on the impacts of recreational boating activities on fishes but little or no synthesis of the information has been undertaken. This review shows that motor boats impact on the biology and ecology of fishes but the effects vary according to the species and even particular size classes. Direct hits on fishes by propellers are an obvious impact but this aspect has been poorly documented. Alterations in the wave climate and water turbidity may also influence fishes and their habitats, especially submerged and emergent plant beds. Sound generated by boat motors can also influence the communication and behaviour of certain species. Pollution arising from fuel spillages, exhaust emissions and antifouling paints all have detrimental effects on fishes. Finally, the use of recreational boats as vectors of aquatic invasive organisms is very real and has created major problems to the ecology of aquatic systems.
Показать больше [+] Меньше [-]Partitioning behavior of perfluorinated compounds between sediment and biota in the Pearl River Delta of South China Полный текст
2014
Zhao, Y.G. | Wan, H.T. | Wong, M.H. | Wong, Chris K.C.
Surface sediment and biota were collected from 12 sampling sites – seven along the Pearl River Delta and five along the Hong Kong coastline. Perfluorinated compound (PFC) concentrations were detected using a high-performance-liquid-chromatogram–tandem-mass-spectrometry system. Analytical results indicated that the total PFC concentrations were in the range of 0.15–3.11ng/g dry weight in sediments, while the total PFC concentrations in oyster and mussel samples were between 0.46–1.96 and 0.66–3.43ng/g wet weight, respectively. The major types of PFCs detected in the sediment samples were perfluorooctanesulfonic acid (PFOS) and perfluorobutanoic acid (PFBA), with concentrations ranging from low limits of quantification to 0.86±0.12ng/g dry weight and 1.50±0.26ng/g dry weight, respectively. In bivalve samples, PFOS was the dominant contaminant with concentrations ranging from 0.25±0.09 to 0.83±0.12ng/g wet weight in oysters and 0.41±0.14 to 1.47±0.25ng/g wet weight in mussels. An increase in PFC concentration was found to be correlated with increased human population density in the study areas.
Показать больше [+] Меньше [-]