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81.
82.
Organic matter origin and distribution in suspended particulate materials and surficial sediments from the western Adriatic Sea (Italy) 总被引:5,自引:2,他引:5
T. Tesi S. Miserocchi M.A. Goi L. Langone A. Boldrin M. Turchetto 《Estuarine, Coastal and Shelf Science》2007,73(3-4):431-446
In this study, organic carbon (OC), total nitrogen (TN), stable carbon isotopic (δ13COC) and CuO reaction product compositions were used to identify the sources of organic matter (OM) and to quantify the relative importance of allochthonous and autochthonous contributions to the western Adriatic Sea, Italy. Suspended particulate material (195 samples) and surficial sediments (0–1 cm, 70 samples) from shallow cross-shelf transects were collected in February and May 2003, respectively. Vertical water column profiles were acquired along the same transects. Data include depth, potential temperature, salinity, density and chlorophyll fluorimetry.Along the western Adriatic shelf in the near-shore region, the phytoplankton growth was influenced by dynamics of the buoyant plumes from the Po and Appennine rivers. A small amount of very fine terrigenous material remained suspended within the coastal current and was exported southward along the shelf to the slope. High variability in the bulk composition was detected in the Po prodelta surficial sediments, whereas the western Adriatic shelf, although a larger area, exhibited a narrower range of values.A significant decoupling was observed between suspended particles in the water column and surficial deposits. The organic material collected in the water column was compositionally heterogeneous, with contributions from marine phytoplankton, riverine–estuarine phytoplankton and soil-derived OM. Frequent physical reworking of surficial sediments likely leads to the efficient oxidation of marine OC, resulting in the observed accumulation and preservation of refractory soil-derived OC delivered by the Po and Appennine rivers. 相似文献
83.
固定化鲅鱼乙酰胆碱酯酶的制备及部分性质测定 总被引:3,自引:0,他引:3
酶的固定化是酶传感器制备过程中重要的1个环节.研究采用直接共价法固定鲅鱼乙酰胆碱酯酶(AChE).制备方法为:0.1g CNBr活化的Sepharose 4B凝胶用1mmol/L的HCl充分溶胀后,与活力为10U的AChE溶液混合,于4℃下150r/min振荡8h.所制备的固定化酶活力回收率较高(96%),对pH值和温度变化的适应能力均优于非固定化酶;在3个月保存期内,前者的活力损失13%,而后者的活力则下降89%.这说明固定过程能够大大提高AChE的抗逆性和保持酶活力的稳定,有利于酶传感器的制备. 相似文献
84.
《Marine Policy》2005,29(5):391-405
Integrated oceans management (IOM) is emerging in the international arena as a tool in meeting requirements for sustainable use of ocean space and marine resources. Australia and Canada are at the forefront of these developments and, being without set precedents, each state has adopted quite different strategies to implement IOM—Australia adopting a policy-driven approach delivered through Regional Marine Plans and Canada developing legislation that provided a framework for policy implementation delivered through an Integrated Management Framework. Despite these significant differences, examination of initiatives in both states indicates that there are also significant commonalities and shared experiences, providing important lessons for implementing IOM. 相似文献
85.
86.
Abstract. Boonea (= Odostomia) impressa is a common ectoparasite of oysters. In the laboratory, small oysters (Crassostrea virginica) parasitized by natural densities of B. impressa produced 75 % less new shell than unparasitized oysters. Shell deposition rates of previously parasitized oysters increased significantly after all B. impressa were removed. Thus, the decrease in growth rate, although significant, apparently was not permanent. B. impressa preferentially parasitized small, living oysters (≤2.5cm) in the field, even though a higher percentage of large, living oysters (>2.5cm) was available. The snails maintained an aggregated distribution on the oyster reef. The number of B. impressa per oyster clump was positively correlated with the number of living oysters per clump, however some clumps with few or no living oysters had many B. impressa. Thus, food availability only partially explained the pattern of distribution. B. impressa was very mobile. About 50 % of the population moved in one week. Reproduction occurred throughout the year with a peak period in May. Recruitment was greatest in July, however new recruits were observed throughout the year. The reduction in growth rate of parasitized oysters, the snaiľs propensity towards parasitizing small oysters and the snail's tendency to be contagiously distributed suggests that B. impressa potentially exerts a significant influence on the population structure and health of oyster populations. 相似文献
87.
Cadmium and zinc concentrations were determined in 10 species of pelagic zooplankton collected in the northern North Pacific,
the Bering Sea, the Okhotsk Sea and off Hokkaid?, during the summers of 1974–1976. The mean cadmium contents in euphausiids,
copepods, and amphipods were 1.16μg/g dry wt (range: 0.36–2.17μg/g), 6.63μg/g (1.66–14.55μg/g), and 8.28μg/g (2.83–14.50μg/g), respectively. Cadmium in euphausiids was significantly lower in concentration than in the other two crustacean groups.
The difference in cadmium levels among the crustacean groups is discussed on the basis of feeding habits and physiological
characteristics of the zooplankton. Zinc levels in the crustaceans were similar, with values around 100μg/g (range: 59–195μg/g). Both cadmium and zinc concentrations in euphausiids taken from coastal waters off Hokkaid? were significantly higher
than those from the Bering Sea and the northern North Pacific. This trend may reflect coastal pollution rather than characteristics
of the species.
Contribution No. 117 from the Research Institute of North Pacific Fisheries, Faculty of Fisheries, Hokkaido University 相似文献
88.
A nutrient dynamic model coupled with a 3D physical model has been developed to study the annual cycle of phytoplankton production in the Yellow Sea. The biological model involves interactions between inorganic nitrogen (nitrate and ammonium), phosphate and phytoplankton biomass. The model successfully reproduces the main features of phytoplankton-nutrient variation and dynamics of production. 1. The well-mixed coastal water is characterized by high primary production, as well as high new production. 2. In summer, the convergence of tidal front is an important hydrodynamic process, which contributes to high biomass at frontal areas. 3. The evolution of phytoplankton blooms and thermocline in the central region demonstrate that mixing is a dominant factor to the production in the Yellow Sea. In this simulation, nitrate- and ammonium-based productions are estimated regionally and temporally. The northern Yellow Sea is one of the highly ranked regions in the Yellow Sea for the capability of fixing carbon and nitrogen. The annual averaged f-ratio of 0.37 indicates that regenerated production prevails over the Yellow Sea. The result also shows that phosphate is the major nutrient, limiting phytoplankton growth throughout the year and it can be an indicator to predict the bloom magnitude. Finally, the relative roles of external nutrient sources have been evaluated, and benthic fluxes might play a significant role in compensating 54.6% of new nitrogen for new production consumption. 相似文献
89.
《Marine Geology》2005,216(4):239-247
The Ayeyarwady continental shelf is a complex sedimentary system characterized by large sediment influx (> 360 million ton/yr), a wide shelf (> 170 km), a strong tidal regime (7 m maximum tidal range), and incised by the Martaban Canyon. Grain size distribution on the Ayeyarwady shelf reveals three distinct areas in terms of sediment texture (i) a near-shore mud belt in the Gulf of Martaban and adjacent inner shelf (ii) outer shelf relict sands and (iii) mixed sediments with varying proportions of relict sand and modern mud in the Martaban Canyon. The bulk of the terrigenous sediment discharged by the Ayeyarwady River is displaced eastwards by a combination of tidal currents and clockwise flowing SW monsoon current and deposited in the Gulf of Martaban resulting in shoaling of its water depths. Part of the sediment discharge reaches the deep Andaman Sea via the Martaban Canyon and the rest is transported westward into the Bay of Bengal by the counter-clockwise flowing NE monsoon currents. 相似文献
90.
The probability of fractal determination of coastal types based on GIS is preliminarily discussed with China as an example. Finally, some significant conclusions are drawn: (1) The fractal dimension of coastline of the bedrock coast is larger than that of the plain coast on the same scale map; (2) As far as the bedrock coast is concerned, the larger fractal dimension of coastline of the bedrock coast on the same scale map indicates that the bedrock coast is probably not typical; (3) As far as the plain coast is concerned, the smaller fractal dimension of coastline of the plain coast on the same scale map indicates that it is probably the silt plain coast; (4) The different substantial compositions affect the fractal dimensions of coastlines of different coastal types. In general, the coast which lies in the north of the Hangzhou Bay consists of sand mainly, its surface is flat, and it is connected with the coastal plain, its landform is broad shoal, its total change is comparatively homogenous in the tidal dynamic process, and thus, the relatively smaller fractal dimension of coastline results from this. For the bedrock coast, there is more bedrock, the coastline is comparatively smooth and straight, being affected by the faults and ocean dynamic process, which result in the larger fractal dimension. 相似文献