Showing papers by "Ocean University of China published in 2000"
TL;DR: In this paper, a two-layer model with weak vertical shear was proposed to investigate the interaction between baroclinic planetary-scale dipole soliton (weak incipient dipole block) and a train of synoptic-scale waves (eddies) upstream.
58 citations
TL;DR: In this article, a new substrate for peroxidase-mediated voltammetric enzyme immunoassay was investigated by electrochemical methods and used for the detection of plant virus.
43 citations
TL;DR: In this article, a planar Ni(OH) 2 composite electrode was devised for cyclic voltammetry and stationary polarization to investigate the electrochemical properties of spherical Ni( OH) 2 rapidly.
32 citations
TL;DR: Major concentration of the polyunsaturated fatty acid 20∶5n−3 (eicosapentaenoic acid) was present in each strain, with the highest proportion in B222 (19.5%).
Abstract: Fatty acid composition and total lipid content of 8 strains of marine diatoms (Nitzschia frustrula, Nitzschia closterium, Nitzschia incerta, Navicula pelliculosa, Phaeodactylum tricornutum, Synedra fragilaroides) were examined. The microalgae were grown under defined conditions and harvested at the late exponential phase. The major fatty acids in most strains were 14∶0 (1.0%–6.3%), 16∶0 (13.5–26.4%), 16∶1n−7 (21.1%–46.3%) and 20∶5n−3 (6.5%–19.5%). The polyunsaturated fatty acids 16∶2n−4, 16∶3n−4, 16∶4n−1 and 20∶4n−6 also comprised a significant proportion of the total fatty acids in some strains. The characteristic fatty acid composition of diatoms is readily distinguishable from those of other microalgal groups. Significant concentration of the polyunsaturated fatty acid 20∶5n−3 (eicosapentaenoic acid) was present in each strain, with the highest proportion in B222 (19.5%).
23 citations
TL;DR: In this article, the photochemical oxidation of benzothiophene in seawater was investigated, and it was shown that photo-oxidation rates were influenced by the medium, pH, heavy metal ion, dissolved oxygen, and light intensity.
Abstract: Kinetic investigation into the photochemical oxidation of benzothiophene in seawater showed that photo-oxidation rates of benzothiophene were influenced by the medium, pH, heavy metal ion, dissolved oxygen, and light intensity. The photo-oxidation of benzothiophene followed the first order reaction law, with the rate constants ranging from 1.21×10−5/s to 5.38×10−5/s. An interesting observation was that the presence of Hg2+ could markedly enhance the photo-oxidation rate of benzothiophene in seawater; and that the photo-oxidation rate of benzothiophene increased with light intensity. The effect of oxygen on the rate constant for benzothiophene photolysis was also observed. Compared with purging with nitrogen, purging seawater with oxygen evidently increased the photolysis rate of benzothiophene. Based on this observation, a benzothiophene photo-oxidation mechanism including singlet oxygen (O21Δg) was suggested. Two photolysis products of benzothiophene were identified. The photolysis of benzothiophene is considered to be important in the removal of this compound in seawater.
8 citations
TL;DR: In this paper, measurements of surface seawater and vertical profiles at sixteen stations in the Nansha Islands waters of the South China Sea were taken, and it was found that surface seawaters DMS concentrations ranged from S 52 to 122 ng/L, average of 82 n/L. The sea-to-air DMS flux from this sea area was estimated to be 5.95 μmol/(m2·d).
Abstract: Measurements of dimethylsulfide (DMS) concentrations in surface seawater and vertical profiles at sixteen stations in the Nansha Islands waters of the South China Sea showed that surface seawater DMS concentrations ranged from S 52 to 122 ng/L, average of 82 ng/L. DMS distribution tendency coincided with that of primary productivity observed during the same cruise. In vertical profiles, the DMS distribution was influenced by factors such as algal biomass, as indicated by chlorophyll a, particular algal species, consumption by photochemical oxidation, etc. Maximal DMS concentrations appeared at 30–75 m depths. DMS concentration was significantly correlated to seawater temperature. The sea-to-air DMS flux from this sea area was estimated to be 5.95 μmol/(m2·d).
6 citations
TL;DR: The correlation between the colloidal fraction and the so-called dissolved fraction suggests the significant role of colloidal material in the biogeochemistry of trace metals as mentioned in this paper, thus, past studies overestimate the dissolved trace-metal concentration.
Abstract: This paper discusses the measured concentrations of trace metals in different size fractions at Daya Bay, and describes the features of distribution and variation of lead, copper and cadmium there. On average, 16% of Pb, 10% of Cu and 8% of Cd which previously would have been considered in the dissolved phase are actually associated with colloidal material. Thus, past studies overestimate the dissolved trace-metal concentration. The correlation between the colloidal fraction and the so-called dissolved fraction suggests the significant role of colloidal material in the biogeochemistry of trace metals.
3 citations
TL;DR: In this paper, the application of cross-flow ultrafiltration (CFF) techniques to separate colloidal organic carbon (COC) from truly dissolved organic carbon(TDOC) was investigated; COC and TDOC were determined by the high-temperature combustion method(HTC) and UV/persulphate method.
Abstract: The application of cross-flow ultrafiltration (CFF) techniques to separate colloidal organic carbon (COC) from truly dissolved organic carbon(TDOC) was investigated; COC and TDOC were determined by the high-temperature combustion method(HTC) and UV/persulphate method. It was found that CFF can quantitatively separate COC from seawater. The determination results by the HTC and UV/persulphate method for COC and TDOC showed little difference, which suggested that the oxidation efficiency of the two methods are identical. Colloidal particles have no remarkable influence on the oxidation efficiency of the UV/persulphate method.
2 citations
01 Jan 2000
TL;DR: In this paper, the adsorption of dissolved organic carbon (DOC) onto goethite in seawater and its possible affects on distribution of DOC on goedrite were investigated.
Abstract: The adsorption of dissolved organic matter onto goethite in seawater and its possible affects on distribution of dissolved organic carbon (DOC) were investigated. The seawater was collected at Xiaomaidao in Qingdao in March, 1996. Goethite was synthesized at the same time. Adsorption equilibrium was achieved by shaking and UV/persulphate method was used to determine adsorption percentage-pH curves and isotherm of DOC on goethite. Sorption of DOC onto goedrite occurred very rapidly, implying that mineral surfaces in seawater would not remain uncoated by natural organic matter for long. The isotherm of DOC on goethite showed Langmuir-type. The saturated adsorption amount is 1245.3μmol·g-1 goethute. It was calculated that an area of around 12.8A is available to each organic carbon atom over the goethite surface. On the basis of the radius of carbon atom, the amount of area actually required for each carbon atom would be approximately 22A. Therefore, a monolayer of sorbed natural organic matter exists over the goethite surface as adsorption maximum values are achieved. The adsorption of DOC on goethite were affected by solution pH. Adsorption percentage was high at pH5-6 and decreased with an increasing pH value. The adsorptions percentage of natural organic matter also appears to decrease as initial the DOC concentration increases. Over 50% of DOC was adsorbed by goethite at pH of natural seawater (pH8.1). This indicated that adsorption of DOC would affect the distribution of DOC in seawater. The mechanism of DOC adsorption on goethite is a combination of special adsorption and electrostatic interaction.
1 citations
01 Jan 2000
TL;DR: It can be found from the multi-limitation model that the nutrient concentrations of the culture medium is the dominating limit factor of the growth rate of phytoplankton.
Abstract: The effects of nutrients on the growth rates and the cell composition of nitrogen and phosphorus of Skeletonema costatum and Nitzschia closterium were studied in June 1995 to Mar 1996 by batch culture. The effects of nitrate and phosphate concentration of the culture medium on the algal growth rates of the two species in batch culture can be described using the Monod equation. The halfsaturation constants for the growth of Skeletonema costatum and Nitzschia closterium influenced by nitrate (K) are 0.54 and 0.50μmol /L, respechvely. Those for the growth of the two species influenced by phosphate (Kμ(P)) are 4.0 and 14.6μmol /L respectively. Nitzschia closterium is easily limited by nitrogen shortcoming compared with Skeletonema costatum. The multi-limitation model can be arrived by expanding the Monod equation. The degree of the nutrient limitation can be expressed using the limitation effecting coefficient represents nitrogen or phosphorus). It can be found from the multi-limitation model that the nutrient concentrations of the culture medium is the dominating limit factor of the growth rate of phytoplankton. The growth rate of phytoplankton will be mainly limited by nitrogen when CN/Cp K/K, and it will be limited mainly by phosphorus when CN/CPK/K. The concentrations of nitrogen and phosphorus in the algal cell vary with and . When 0.80, the concentrations of nitrogen in the algal cell is low, and the concentration of phosphorus increases highly because of storage. When 0.80, the concentrations of phosphorus in the algal cell decrease, and the concentration of nitrogen increases slightly =0.80 or =0.80 can be considered as the boundary of nitrogen or phosphorus limitation.
1 citations
TL;DR: In this article, the Tyndall effect was used to show that both Fe(naph)2Al(i-Bu)3CH2˭ CHCH2Cl catalyst and FeCl3Al (i-bu)3Phen catalyst were colloidal disperse systems in butadiene, and contained hy-drogenated gasoline solvent.
Abstract: By the Tyndall effect, the observation of electronic microscope and ultrafiltering experiment proved that both Fe(naph)2Al(i-Bu)3CH2˭ CHCH2Cl catalyst and FeCl3Al(i-Bu)3Phen catalyst were colloidal disperse systems in butadiene, and contained hy-drogenated gasoline solvent. Catalytic activity sites were located on the surface of colloidal particles. Therefore, both the catalysts were colloidal catalysts. The catalyst particles were amorphous. The ratio of catalyst components affected the shape of colloidal particles, among which the colloidal particles of the optimal ratio were small in size, even distributed, and with high catalytic activity. The transition metal iron compound has been used to catalyze butadiene to polymerize since 1960. People have continuously researched the iron system mainly including the choice of the iron compound 1-10, the finding of the right matching 11-16, the stabilization of the active sites, the improvement of the catalytic activity [2], 13-16, and the synthesis of the high ...
TL;DR: In this article, a model for describing the behavior of macromolecules in adsorbed layers is developed by introducing a concept of distribution density of layer thickness U based on stochastic process and probabilistic statistics.
Abstract: A model for describing the behavior of macromolecules in adsorbed layers is developed by introducing a concept of distribution density of layer thickness U based on stochastic process and probabilistic statistics. The molecular behavior of layers adsorbed on clay particle surfaces is discussed; the random distribution and its statistics of the layer thickness are given by incorporating experimental results with an ionic polyelectrolyte with the molecular weight of 1.08×10 6 and chain charged density of 0.254.