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1.
Nicholas Friligos 《Marine pollution bulletin》1985,16(11):435-439
The Euboikos Gulf is a restricted embayment on the eastern coast of Greece, having a significant, unusual tidal phenomenon, and receiving some industrial and domestic wates. The South Euboikos Gulf has only slightly greater concentrations of nutrients than background, while the North Euboikos Gulf tends to accumulate nutrients, in particular nitrate and silicate. Also a comparison is made with the nutrient concentrations in polluted coastal gulfs of the Aegean. The different nutrient levels are due to the different sources of nutrients, as well as the morphology of each area and the circulation of the waters. 相似文献
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Abstract. The changes in the concentrations of silicate, phosphate, and inorganic nitrogen in Eiefsis Bay. an intermittently anoxic basin, arc described and related to the changes in the physical properties of the water. Winter convection resulted in a very small vertical gradient of temperature, salinity, oxygen, and nutrients. Stratification started to develop in May and persisted for about 6 months. High values of silicate, phosphate, and ammonia occurred during the anoxic conditions prevailing in summer. The vertical transport of particulate organic matter and decomposition of abundant pelagic and benthic organic matter during the summer produced a low oxygen level in the bottom layer below the pycnoclinc. A high sea water temperature and vertical stability contributed to the development of anoxic conditions during the summer in the near bottom layer and to mass mortality of benthic macrofauna. Also the Eiefsis Bay anoxia appears to have had significant ecological effects on many other marine species, including several of economic importance. 相似文献
3.
Nikolaos Friligos 《Estuarine, Coastal and Shelf Science》1985,21(6):879-894
The Western Gulf is a basin in the Saronikos Gulf. Below about 100 m the water is almost stagnant, essentially isothermal (around 14°C) and it has practically uniform salinity. The level and the mechanism of enrichment in nutrients is discussed. The age of the water estimated from nutrient budget calculations is between one and eight years. The replacement time of water is similar to that found in the Santa Barbara basin, but different from those of the Cariaco Trench and the Black Sea. 相似文献
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This paper concerns the enrichment by nutrients and the oxygen utilization rates of an intermittently anoxic basin. The concentration of nutrients and dissolved oxygen have been determined during seasonal surveys of water characteristics. The oxygen utilization rates ranged between 1.3 and 1.8 ml l.−1 month−1 from March to June and were considerably higher than those reported for oceanic waters. The nutrients enrichment appears to be considerably influenced by eutrophication and human activity. During anoxic conditions in summer, the mineralization of organic matter was associated with consequent accumulation of enormous amounts of nitrogen (ammonia), phosphates and silicates. Nutrient ratios underwent great fluctuation mainly due to anoxic conditions. 相似文献
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Analysis of quantitative and qualitative composition of rare phytoplankton species was performed using a data set collected over a large geographic area (four eutrophic gulfs of the Aegean Sea, E. Mediterranean Sea) during 2002–2003. We examined the effects of excluding rare species on comparisons of species richness, diversity, similarity and niche breadth as well as the regional and seasonal contribution of rare species to cell abundance and carbon biomass. Overall, the total of 401 species included 182 rare species contributing 45.1% of the total species number. However, there was a considerable variation in this relationship among the other parameters, as rare species contributed only 6.4% of total cell abundance, 13.1% of total species diversity, 21.2% of total cell biovolume and 16.6% of total carbon biomass. The results showed that rarity may be a significant issue in studies detecting and quantifying phytoplankton community structure. 相似文献
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The scope of this study is to investigate the effect of the direction of seismic excitation on the fragility of an already constructed, 99‐m‐long, three‐span highway overpass. First, the investigation is performed at a component level, quantifying the sensitivity of local damage modes of individual bridge components (namely, piers, bearings, abutments, and footings) to the direction of earthquake excitation. The global vulnerability at the system level is then assessed for a given angle of incidence of the earthquake ground motion to provide a single‐angle, multi‐damage probabilistic estimate of the bridge overall performance. A multi‐angle, multi‐damage, vulnerability assessment methodology is then followed, assuming uniform distribution for the angle of incidence of seismic waves with respect to the bridge axis. The above three levels of investigation highlight that the directivity of ground motion excitation may have a significant impact on the fragility of the individual bridge components, which shall not be a priori neglected. Most importantly, depending on the assumptions made for the component to the system level transition, this local sensitivity is often suppressed. It may be therefore necessary, based on the ultimate purpose of the vulnerability or the life cycle analysis, to obtain a comprehensive insight on the multiple damage potential of all individual structural and foundation components under multi‐angle excitation, to quantify the statistical correlation among the distinct damage modes and to identify the components that are both most critical and sensitive to the direction of ground motion and carefully define their limit states which control the predicted bridge fragility. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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N. Friligos 《Marine pollution bulletin》1985,16(5):208-209
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Nikolaos Friligos 《Marine pollution bulletin》1982,13(3):103-106
Observations in Elefsis Bay, an anoxic basin in the Saronikos Gulf, indicate that the large accumulation of ammonia, phosphates and silicates in the deep water are the result of the decomposition of organic matter during the anoxic period. The processes of denitrification, nitrate reduction and organic decomposition are also evident. Ammonia predominates in the inorganic fraction within the whole water column. 相似文献
10.
N. Friligos 《Marine pollution bulletin》1981,12(3):96-100
A method is investigated for monitoring the urban pollution in the Saronikos Gulf. In this research, measurements of nutrients and salinity were carried out. In this phase, the correlations between dilution relating to salinity and diminution coefficients relating to nutrients were defined by classical sampling methods. A wide variability of the pollution level of the. environment is occurring and the continuous analysis of phosphates is proposed in order to monitor the pollution. 相似文献