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1.
The separation and simultaneous determination of the traces of U and Th in seawater by IDMS is described. The detection limits of this method are 2.4×10-9 g for Th and 1.1×10-8 g for U. The concentrations of U and Th in seawater nearby Xiamen were measured, which are 3.20 ppb and 7.73 ppt respectively. The precisions fo the method are ±1.7% for U and ±3.6% for Th respectively.  相似文献   

2.
A three-dimensional (3-D) finite volume coastal ocean model (FVCOM) was used for the study of water cir culation and seawater exchange in the Benoa Bay, Bali Island. The M2 tidal component was forced in open boundary and discharge from six rivers was included in the numerical calculation. The M2 tidal elevation produced by the FVCOM has a good agreement with the observation data. The M2 tidal current is also suc cessfully calculated under the ebb tide and flood tide conditions. The non-linear M2 tidal residual current was produced by the coastline geometry, especially surrounding the narrow strait between the Serangan Is- land and the Benoa Peninsula. The tidal residual current also generated two small eddies within the bay and one small eddy in the bay mouth. The salinity distribution influenced by river discharge could be success- fully calculated, where the numerical calculation and the observation results have a good correlation (r2) of 0.75. Finally in order to examine the seawater exchange in the Benoa Bay, the Lagrangian particle tracking method and calculation of residence time are applied. The mechanism of particle transport to the flushing of seawater is depicted clearly by both methods.  相似文献   

3.
An analytical method is proposed for the direct determination of Cd in seawater by differential pulse anodic stripping voltammetry and the derivative technique with a hanging mercury drop electrode. The process of determination is quick, simple and convenient. The concentration of Cd in seawater is only determined by adjusting the acidity of seawater to pH 2 and by taking three minutes' plating time. Sensitivity of the method is about 1×10-10M, and accuracy of that satisfactory. Relative standard deviation is about 12% when the concentration of Cd in seawater is approximately 0.04 ppb. A good agreement was obtained by a standard curve and a standard addition technique respectively from determining Cd in the same seawater. Actual measurement time per sample is about 10 min.  相似文献   

4.
O-phthaldialdehyde is used for the determination of free amino acid in seawater by measuring the fluorescence produced by its reaction with the a-amino group of amino acids. This method is so sensitive that as little as 1-10 nM of amino acids and less than 1 ml of seawater may be sufficient for one test.This method is simple, rapid and accurate and a-amino acids contained in seawater can directly be determined without concentration and extraction. It is free from the interference of large content of inorganic salts and other nitrogenous compounds in seawater.A hundred and fifty-two samples collected at 24 stations in offshore of Zhejiang have been analyzed. The results obtained show that the range of concentration of the total free amino acid is 0.37-4.70 μM. The values are high near shore and low offshore.  相似文献   

5.
The transfer of 137C3, 60Co along Platymonas sp., Brachionus plieatilis Muller and Tilapia mos-sambica Peters was studied by using the tracer methods of both 137C3 and 60Co with Ge (Li) Gamma ray detector and S-80 type multichannel-analyser for measuring the radioactivity of the sample. The experiment was carried out in four groups and the period of the experiment was fifteen days. It was found that 60Co could be transferred along seawater→Platymonas→Brackionus→Tilapia, and that 137C3 could only be transferred from seawater to Platymonas. 137C3 was not accumulated by Brachionus in any group of the experiment. Brachionus ingested 60Co mainly from Platymonas, when 60Co was ingested by Tilapia; Brachionus played an important role in the transfer and the Tilapia ingested 137C3 mainly from seawater.  相似文献   

6.
Hydraulic transport in pipelines is the most promising conveying method for large ore particles in deepsea mining.The dynamic performances of particles during transportation in vertical,inclined and horizontal pipelines are significant for the design of hydraulic transport systems.In the present study,we focus on the statistical characteristics and flow regimes of the mixture composed of ore particles and seawater in the pipelines.Numerical simulations are conducted by using Computational Fluid ...  相似文献   

7.
A computer analysis was performed on experimental results obtained when mine tailings were added to seawater. The Mixed Upper-Layer Ecotrophie Simulation (MULES) model was tested by changing the extinction coefficient and the abundance of heterotrophic zooflagellates. Increasing the extinction coefficient resulted in a delay of phytoplankton growth, an increase in zooplankton standing stock and better growth of autotrophic flagellates compared with diatoms. Zooflagellates in the ecosystem influence the growth of zooplankton; secondary production by zooplankton was markedly depressed at low levels of zooflagellates. These results are believed to be of general significance for the diagnosis of suspended sediment effects on planktonic ecosystems.  相似文献   

8.
The adsorption behaviour for uranium of four kinds of amidoxime resinst RNH, RCH, RAH and RPH in seawater has been investigated. It has been found that all these resins are capable of adsorbing rapidly uranium from U-cnriched seawater with a high uranium uptake.RNH was able to adsorb uranium satisfactorily from natural seawater, and the uranium uptake of RNH with a degree of cross-linking of 3-5 mol % was above 200 μg/g-R (adsorption for 15 days). The uranium uptakes of RCH, RAH and RPH from natural seawater were much lower than the uranium uptake of RNH. The factors which caused the difference between resins RCH, RAH, RPH and resin RNH are discussed.  相似文献   

9.
This paper suggests direct and simultaneous determinations of the reducible species of Zn, Cd, Pb, Cu and Bi in seawater made by the derivative-differential pulse anodic stripping voltammetry with a hung mercury drop electrode. The influence of Cu on the determination of Zn in this experiment condition has been studied, of which both the accuracy and precision are satisfactory. The procedure of determination is so quick, simple and convenient that the background concentration of these five elements in coastal seawaters can be determined only by adjusting the acidity of seawater to pH 2.5 and by taking 10-minutes plating time. Actual measurement time of these five elements for every sample is approximately 25 min.  相似文献   

10.
Transfer rule of 137C3 and 60Co in seawater and an arrificial food web which made up of Platy-monas, Arca, tenaeus and Tilapia were studied.The results showed that the transfer of nuclide could be realized in a longer food chain in which seawater contained radioactivity, the transfer along food chain alone was slight, the pathway of nuclide uptaken by organism was mainly from seawater,but the pressnce of the food was helpful to the transfer of the nuclide, the transfer efficiency of 60Co by every member in the marine food chain was greater than that of 137C3.  相似文献   

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