DETERMINATION OF RESIDUAL MALATHION IN NATURAL WATER

A method for determination of malathion in natural water by cathodic stripping voltammetry using mercury film electrode is suggested in this paper. The method is based on the quantitativeformation of group generated by malathion as a result of elimination reaction inthe ethanol solution of sodium hydroxide. The group is similar to sulphide in electrochemical properties, and can be determined by cathodic stripping voltammetry. Interference from inorganic sulphide is prevented by the addition of Hg (NO3)2. This method has been applied to the determination of residual malathion in natural water (e. g. the sea, rivers, lakes, etc.). The waveheight is directly proportional to the malathion concentration within the range 5×10-9 - 1×10-7 mol/L. The method is simple and rapid, and the results of water sample determination is quite in accord with those of Gas Chromatograph.     

DIRECT DETERMINATION OP TRACE CADMIUM IN SEAWATER BY DERIVATIVE-VOLTAMMETRY

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.     

SEMIDIFFERENTIAL ELECTROCHEMICAL STRIPPING ANALYSIS FOR THE DETERMINATION OF TRACE HEAVY METALS IN SEAWATER

A new voltammetric technique has been described for the determination of trace Cu, Pb, Cd and Zn in seawater by semidifferential electrochemical stripping analysis, in which the semiderivative, e, of the stripping current, i, is measured as a function of electrode potential, at a rotating thin mercury film glassy carbon electrode formed in situ. The optimun conditions are reported. It is demonstrated that the technique has more merits than that of the ordinary linear sweep anodic stripping voltammetry, greatly enhances the sensitivity and resolution and shortens the time of pre-electrolysis.     

DIRECT DETERMINATION OF TRACE MERCURY IN SEAWATER BY DIFFERENTIAL COLD VAPOR ATOMIC ABSORPTION METHOD

A low-absorbance differential cold vapor atomic absorption method is developed for direct determination of trace mercury in seawater. The sensitivity of the method is good at 1 ng mercury per liter and precision is excellent with a relative standard deviation of 13.9% at 12 ng Hg/1 level and 3.2% at 39 ng Hg/1 level respectively. The method is proved to be rapid and simple, and has been applied to the analysis of mercury in seawater from Xiamen Harbor and the Central Pacific Ocean.     

DIRECT AND SIMULTANEOUS DETERMINATION OF Zn, Cd, Pb, Cu and Bi IN SEAWATER BY DERIVATIVE-VOLTAMMETRY

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.     

RESEARCH ON THE DETERMINATION OF Pb, Cd, Cu AND Zn IN SEAWATER BY STRIPPING VOLTAMMETRY

In this paper, a comparison viral made between the two results of determining Pb, Cd, Cu and Zn in seawater by direct current (tripping voltammetry (DCS) with rotating glass carbon electrode and by differential pulse stripping voltammetry (DPS) with hanging mercury drop electrode (HMDE). By DCS, the range of linear calibration curves obtained was 4×10-3 M-2×10-7M for Cu, Zn and Cd, and 4× 10-9M-2×10-3M for Pb. By using DPS, the range of linear calibration curve was as follows: Cu 0.65-1.9 ppb; Pb 1.0-10 ppb; Zn 0.65-2.0 ppb; Cd 0.02-0.14 ppb. It was found that DCS could be used for determining Pb, Cu, Zn in coastal waters, but it is necessary to add gallium ion to it to eliminate the interference of Cu-Zn inter-metallic compound for determining Zn. The DPS is better for determinig Cd.     

一种新型电镀法制备的Ir/Ir(OH)x pH电极及其在加州纽波特港海域的应用研究

Resulting from the rising levels of atmospheric carbon, ocean acidification has become a global problem. It has significant impacts on the development, survival, growth and physiology of marine organisms. Therefore, a highprecision sensor is urgently needed to measure the pH of sea-water. Iridium wire with a diameter of 0.25 mm is used as the substrate, and an Ir/Ir(OH)_x pH electrode is prepared by a one-step electrochemical method in a Li OH solution at the room temperature. A scanning electron microscope(SEM) observation reveals that it is coated with nanoscale particles. In laboratory tests, the electrode exhibits a very promising pH response, with an ideal Nernst slope(56.14–59.52), fast response, good stability and long life-span in tested pH buffer solutions. For a sea trial,four pH electrodes and one Ag/Ag Cl reference electrode are integrated with a self-made chemical sensor, and a profile detection of nearly 70 m is implemented near Newport Harbor, California on August 3, 2015. The results reflect that the pH value measured by the sensor is very close to the data given by Sea-Bird 911 plus CTD, with a difference value ranging from 0.000 075 to 0.064 719. And the sensor shows a better data matching degree in 0–40m water depth. In addition, the high precision and accuracy of the sensor make it possible to use in the ocean observation field.     

A Moored Underwater Energy Conservation System for Profiling Measurement

There is a need to obtain the hydrologic data including ocean current,wave,temperature and so on in the South China Sea.A new profiling instrument which does not suffer from the damage due to nature forces or incidents caused by passing ships,is under development to acquire data from this area.This device is based on a taut single point mid-water mooring system.It incorporates a small,instrumented vertically profiling float attached via an electromechanical cable to a winch integral with the main subsurface flotation.On a pre-set schedule,the instrument float with sensors is winched up to the surface if there is no ship passing by,which is defined by an on-board miniature sonar.And it can be immediately winched down to a certain depth if the sonar sensor finds something is coming.Since,because of logistics,the area can only be visited once for a long time and a minimum of 10 times per day profiles are desired,energy demands are severe.To respond to these concerns,the system has been designed to conserve a substantial portion of the potential energy lost during the ascent phase of each profile and subsequently use this energy to pull the instrument down.Compared with the previous single-point layered measuring mode,it is advanced and economica1.At last the paper introduces the test in the South China Sea.     

Nonlinear waves in a fluid-filled thin viscoelastic tube

In the present paper the propagation property of nonlinear waves in a thin viscoelastic tube filled with incompressible inviscid fluid is studied. The tube is considered to be made of an incompressible isotropic viscoelastic material described by Kelvin--Voigt model. Using the mass conservation and the momentum theorem of the fluid and radial dynamic equilibrium of an element of the tube wall, a set of nonlinear partial differential equations governing the propagation of nonlinear pressure wave in the solid--liquid coupled system is obtained. In the long-wave approximation the nonlinear far-field equations can be derived employing the reductive perturbation technique (RPT). Selecting the exponent α of the perturbation parameter in Gardner--Morikawa transformation according to the order of viscous coefficient η, three kinds of evolution equations with soliton solution, i.e. Korteweg--de Vries (KdV)--Burgers, KdV and Burgers equations are deduced. By means of the method of traveling-wave solution and numerical calculation, the propagation properties of solitary waves corresponding with these evolution equations are analysed in detail. Finally, as a example of practical application, the propagation of pressure pulses in large blood vessels is discussed.     

Measurements of dissolved organic carbon (DOC) in sea water by high temperature combustion method

Dissolved organic carbon (DOC) is the largest organic carbon reservoir in sea water and plays an imporrant role in the marine carbon cycle and other biogeochemical processes in the ocean. Accurate and precise determinalion of the bOC concentration in sea water is thus a prerequisite for any interpretation of DOC biogeochemistry. A key factor in analytical quality control is an accurate determination of the blank. The assessment and distinction of DOC blanks are essential for the precise measurements of oceanic DOC. The total DOC blank includes instrument and water blanks in the high temperature catalytic oxidation (HTCO) method. DOC can be measured accurately using the HTCO method only when the instrument blank is correctly distinguished from the total DOC blank and corrected in the sample measurements. Low DOC blanks can be achieved by extensive conditioning of new catalysts and the whole instrument system, whereas instrument blanks can be quantified by subtracting the water blank from the total DOC blank. We have been able to produce low carbon nanopure water [≤2μmol/dm³(C)] and have a low instrumental blank [< 5-6 μmol/dm³(C)] when using the HTCO method. Results of concentrations and distributions of DOC in the Gulf of Mexico and the North Atlantic are oceanographically consistent. Results from DOC measurements on samples from the international DOC methods comparison program further confirmed our low values of both nenopure water and the instrument blank.     

ADCP measurements of suspended sediment flux at the entrance to Jiaozhou Bay, western Yellow Sea

The purpose of the present contribution is to explore the technique to use Acoustic Doppler Current Pro- filers （ADCPs） for suspended sediment flux measurements, which may be applied to coastal embayment environments such as estuaries and tidal inlets for sediment exchange and budget studies. Based on tidal cycle measurements from the entrance of ]iaozhou Bay, Shandong Peninsula, eastern China, statistical rela- tionships between the suspended sediment concentration （SSC） and ADCP echo intensity output are estab- lished. Echo intensity data obtained during an ADCP survey along two cross-sections during a spring tidal phase were transformed into SSC data. The ADCP current velocity and SSC data were then used to calculate the flux of fine-grained sediment. The results show that net sediment transport at the entrance is directed towards the open sea, with an order of magnitude of 103 t per spring tidal cycle; hence, although Jiaozhou Bay is a low SSC environment, the tidally induced suspended sediment transport can be intense.     

Response Characteristics of Load on Vessels in Waves

Considering the requirement of direct design and fatigue test for ships and floating structures byuse of FEM technique,a computational procedure of spectral analysis for wave load on the hull surface is de-veloped in this paper.The response of hydrodynamic pressure on the body surface to a designated sea state forships and floating structures is calculated by use of the revised strip method with the hull bound perturbationflow concept.The spectral function of wave load for the defined point on the body surface can be determinedfrom the Wiener-Khinhin theorem and the characteristic load value can be also obtained from spectral mo-ment analysis.A container ship is taken as a computational example and the sample of wave load with a cer-tain probability and corresponding encountered frequency is provided.     

海上溢油极化特征及其探测研究

The SAR(Synthetic Aperture Radar) has the capabilities for all-weather day and night use. In the case of determining the effects of oil spill dumping, the oil spills areas are shown as dark spots in the SAR images.Therefore, using SAR data to detect oil spills is becoming progressively popular in operational monitoring, which is useful for oceanic environmental protection and hazard reduction. Research has been conducted on the polarization decomposition and scattering characteristics of oil spills from a scattering matrix using allpolarization of the SAR data, calculation of the polarization parameters, and utilization of the CPD(Co-polarized Phase Difference) of the oil and the sea, in order to extract the oil spill information. This method proves to be effective by combining polarization parameters with the characteristics of oil spill. The results show that when using Bragg, the oil spill backscattering machine with Enopy and a mean scatter α parameter. The oil spill can be successfully identified. However, the parameter mechanism of the oil spill remains unclear. The use of CPD can easily extract oil spill information from the ocean, and the polarization research provides a base for oil spill remote sensing detection.     

SIMILAR SOLUTIONS TO SHORELINE EVOLUTION DUE TO SPUR DIKES

It is assumed that the angle included between the crest line and the shoreline is variable in the problem of the littoral transport. A nonlinear partial differential equation is derived and the equation is reduced to a nonlinear ordinary differential equation using the method of one-parameter groups of tram-formations. The asymptotic solutions to the problem of a spur dike are obtained. From the results it can be seen that the growth of the shoreline appears fast, which could be explained logically.     

A Lagrangian mean theory on coastal sea circulation with inter-tidal transports I. Fundamentals

A brief review is made on the theory of the Lagrangian residual circulation and inter-tidal transports in a convectively weakly nonlinear system. In the review the emphasis is put on the systematical development of the theory and its weakness of convectively weakly nonlinear approximation. The fundamentals of a Lagrangian tidally-averaged theory on circulation with inter-tidal transport processes have been proposed for a general nonlinear coastal/estuarine system. The Lagrangian residual velocity is strictly de- fined, and it has been verified to be able to embody the velocity field of circulation. A new concept of the concentration for inter- tidal transport processes is presented. The concentration describing the inter-tidal transport processes should be a ＂Lagrangian inter-tidal concentration＂ defined and named, but not the Eulcrian tidally-averaged concentration used traditionally. The circulation described here contains a set of infinite temporal-spatial fields of velocity/concentration, each of which corresponds to a specific value of tidal phases varying continuously over one tidal cycle. When the convectively weakly nonlinear condition（ with a smaller order of eddy diffusion and sources） is approximately satisfied, a set of infinite temporal-spatial fields of velocity/concentration can be reduced to a single one.. the mass transport velocity/the Eulerian tidally averaged concentration as exhibited traditionally.     

A hydraulic hammer corer utilizing hydrostatic energy for hard seafloor sediment coring

The paper presents the design and preliminary test results of a corer used for hard seafloor sediments sampling.Generally the sediment cores are provided by either gravity-type coring or deep-ocean drilling for a range of studies.However,in consideration of the operability and available sample length in collecting hard sediments,these methods exhibit no advantages.In this paper,a new corer which can exploit both hydrostatic energy and gravity energy for hard sediments coring is presented.The hydrostatic energy is provided by pressure differential between ambient seawater pressure and air pressure in an empty cavity.During sampling process,the corer penetrates into the sediment like a gravity corer and then automatically shifts to the percussion mode.The experiments in the laboratory indicate that the corer can complete 40 cycles in the sea with a cycle time of 2.8 seconds in percussion mode and impact the sample tube with the velocity of 0.2 m/s during each cycle.Besides,its adjustable falling velocity can make the corer achieve the maximum efficiency in coring different sediments.     

Extrapolation of upwelling irradiance just beneath the ocean surface from the in-water radiometric profile measurements

Accurate measurements of upwelling irradiance just beneath the ocean surface,E_u(λ,0^-),can be used to calculate ocean optical parameters,and further develop retrieval algorithms for remotely sensing water component concentrations.Due to the effects of sea surface waves,perturbation from instrument platform (ship),and instrument self-shading,E_u(λ,0^-) is often difficult to be accurately measured.This study presents a procedure for extrapolating the E_...     

SPH Numerical Modeling for the Wave-Thin Structure Interaction

In this paper, a numerical model of 2D weakly compressible smoothed particle hydrodynamics (WCSPH) is developed to simulate the interaction between waves and thin structures. A new color domain particle (CDP) technique is proposed to overcome difficulties of applying the ghost particle method to thin structures in dealing with solid boundaries. The new technique can deal with zero-thickness structures. To apply this enforcing technique, the computational fluid domain is divided into sub domains, i.e., boundary domains and internal domains. A color value is assigned to each particle, and contains the information of the domains in which the particle belongs to and the particles can interact with. A particle, nearby a thin boundary, is prevented from interacting with particles, which should not interact with on the other side of the structure. It is possible to model thin structures, or the structures with the thickness negligible with this technique. The proposed WCSPH module is validated for a still water tank, divided by a thin plate at the middle section, with different water levels in the subdomains, and is applied to simulate the interaction between regular waves and a perforated vertical plate. Finally, the computation is carried out for waves and submerged twin-horizontal plate interaction. It is shown that the numerical results agree well with experimental data in terms of the pressure distribution, pressure time series and wave transmission.     

Winter distribution of diatom assemblages along the coastline of R. O. Korea in 2010

Diatoms are a globally successful and eukaryotic photosynthetic organism with an ornamented silica external wall. The relationship between their valve morphology and habitat means that diatoms can be used as bioindicators to characterize the aquatic environment. To estimate the differential distribution and diversity of diatom assemblages along the coastal line, we collected phytoplankton samples from 114 coastal sites of waters of R. O. Korea. We applied the unweighted pair-group technique usin...