Temporal and spatial distribution of dissolved copper, lead, zinc and cadmium in the Changjiang Estuary and its adjacent waters

Heavy metal concentrations were measured in the Changjiang Estuary and its adjacent waters. Results from a systematic survey in April 2002 to March 2003 indicate that the ranges of the concentrations of dissolved copper, lead, zinc and cadmium in the study waters are 1.01 - 6.86, 0. 10 - 0.39,3.17 - 9.12 and 0.011 - 0. 049 μg/dm^3 , respectively. Similar to zinc, the behavior of dissolved copper was essentially conservative, but high scatter has been observed for high salinity samples, which can be attributed to the decomposition or mineralization of organic matter by bacteria. Dissolved lead may have active behavior with an addition at high salinity. Overall concentrations of dissolved cadmium increase with salinity. The mean values of these dissolved metals calculated for the surface waters were higher than those for the middle and bottom ones. External inputs of dissolved heavy metals to the surface waters were the likely explanation for these higher values. The maximum seasonal average values of dissolved copper and zinc were found in summer, reflecting higher amounts of riverine input in this season. In contrast, the maximum seasonal average values of dissolved lead and copper were found in winter and the lowest ones in summer, respectively, which might be asso- ciated with a combination of low concentration with heterogeneous scavenging. Concentrations of these dissolved metals found for the Changjiang Estuary fall in the range observed for the other estuaries but are noticeably higher than those from uncontaminated rivers, except for cadmium. Compared with observations for the Changjiang Estuary in the last two decades, it is clear that the Changjiang estuarine waters has been contaminated with copper, lead, zinc and cadmium during China＇ s industrialization, but concentrations of them have decreased in the last few years.     

GEOCHEMISTRY OF ABYSSAL SEDIMENT IN THE PACIFIC OCEAN

The contents of Fe, Mn, Cu, Co, Ni, Pb and Zn in the seaiment associated with manganese nodules from the Northern Central Pacific Ocean and in their acid-soluble fractions were determined and correlations among the elements and between the trace metals and environmental parameters were discussed. It has been found that the contents of Mn, Cu and Ni in the sediment are one order of magnitude higher than those in the common sediment. As shown in the manganese nodules, they may mainly derive from seabed. The contents of all trace metals in the sediment are obviously governed by Fe-and Mn-oxides, organic matter, seawater depth, particle size and Eh. Multi-element correlation equations were developed for all trace metals. The trace metals in acid-soluble fraction of the sediment were also much higher than ihose of common sediment and negatively correlated with water depth, implying the possible influence of carbonate speciation.     

Distribution characteristics of heavy metals in surface sediments and core sediments of the Shenzhen Bay in Guangdong Province, China

The concentration of zinc, chromium, cadmium, nickel, lead and copper was measured on both surface sediments and core sediments in the Shenzhen Bay. The average contents of all metals have exceeded the background values in the coastal zone of Guangdong Province. Cadmium is a heavy pollution matter which indicates a strong pollution level according to the ecological risk coefficient method. The ecological risk index of the whole area is 299 which belongs to middle and strong level. The area with strong pollution level is the near shore area closing to the inside of Shenzhen Bay, Shakou area is in the middle level while the weak pollution level occurs in Shenzhenhe Estuary according to ecological risk index. The four sediment cores can be divided into two parts based on lead-210 dating, sediments size analysis and economic development period in surrounding areas since 1950 with strong human intervention. The sediment size, deposition rate and human activities have positive relationship with the contents of heavy metals which directly impact the pollution level of heavy metals in sediments in Shenzhen Bay.     

Preliminary study on the distribution of nutrients, organic matter, trace metals in sea surface microlayer in Xiamen Bay and Jiulong Estuary

-The enrichment of nutrients (NOa-, NOa-, PO43-), suspended particles, organic matter (POC, PON,DOC) , and trace metals (Cu, Ni, Cd) was determined in the sea surface microlayer of Xiamen Bay and Jiulong Estuary. The mean enrichment factors ([Xi]microlayer/[Xi ]15cm in depth) mostly ranged between 1 . 0 and 2. 0. The dissolved forms were the major forms of the components measured, the enrichment of dissolved organic matter and suspended particles could lead to the changes in the total amount and speciation of nutrients and trace metals. No correlation was observed between sample concentrations, speciation, enrichment factors and sample locations. However, some evidence shows that these parameters are correlated with sea state, indicating the complexity and dynamic nature of the sea surface microlayer.     

Distribution of 9 Principal Tidal Constituents and Tide Prediction for the East China Sea

By use of the hydrodynamic model,the harmonic constants of 8 principal tidal constituents(Q_1,O_1,P_1,K_1,N_2,M_2,S_2andK_2)are obtained for the East China Sea,and the harmonic constant ofS_a is calculated by two-dimensional interpolation.The calculated results agree well with the observed dataaround the sea.The harmonic constants can be used to predict the tide in the East China Sea.The cotidalcharts of the 9 tidal constituents reveal their distribution.     

An Analytic-Numerical Solution of Wave Transformation

An analytic-numerical solution of wave transformation in shoaling water is presented in this paper. The analytical expression for wave heights along the wave rays is derived in consideration of the combined effect of water depth shoaling, the wave refraction and the sea bottom friction. The wave rays (orthogonals) are calculated by a fourth order Runge-Kutta algorithm and the wave crest lines are computed by an iteration procedure. The numerical results are compared with analytical solution for a special case of parallel- straight contour shore and field data, and comparisons show that the proposed mathematical model and computation method are very useful and convenient for engineering application.     

AN ANALYSIS OF THE ASTROMETEOROLOGICAL CONSTITUENTS OF TIDE IN THE BOHAI SEA

Seasonal variations in tidal harmonic constants are found to be significant in shelf seas and can be represented by adding a series of astrometeorological constituents (AMC) to the astronomical constituents (AC). The relation of AMC and corresponding AC to their resultant constituents (RC) is examined and the seasonal variation of RC is described by modulation ellipses. The values of AMC in the Bohai Sea are calculated and the major features of AMC in the Bohai Sea are analyzed. The dynamic factors which cause AMC are examined by means of numerical experiments.     

长江口最大浑浊带潮周期内悬浮物中的重金属

In order to discuss the content distributions and fluxes of heavy metals in suspended matters during a tidal cycle in the turbidity maximum around the Changjiang(Yangtze) Estuary,the contents of heavy metals(Zn,Pb,Cd,Co and Ni) have been analyzed.During a tidal cycle,the average contents of heavy metals are in the order of ZnNiPbCo àCd.The average contents in ebb tide are generally higher than that in flood tide.However,at the inshore Sta.11,influenced by the contamination from the nearby waste treatment plant,the average contents of Zn and Ni in flood tide are higher than those in ebb tide and at the offshore Sta.10,the content of Cd in flood tide higher than that in ebb tide due to marine-derived materials.The five heavy metals,mainly terrigenous,are transported towards east-northeast,and settle down with suspended matters in the area between Sta.11 and Sta.10.Influenced by marine-derived materials,the flux value of Cd does not alter significantly with obviously changing in flux direction towards northwest.The source of heavy metals,the salinity of water and the concentration of suspended matters are the main factors controlling the content distributions of heavy metals during a tidal cycle.There is a positive correlation between the contents of heavy metals(Zn,Pb,Co and Ni) and the salinity of water,while the opposite correlation between the contents and the concentrations of suspended matters.Because of marine-derived materials,the content of Cd is not correlated with the concentration of suspended matters and the salinity of water.     

基于z坐标海洋模式的全球正压潮波数值模拟研究

The performance of a z-level ocean model, the Modular Ocean Model Version 4(MOM4), is evaluated in terms of simulating the global tide with different horizontal resolutions commonly used by climate models. The performance using various sets of model topography is evaluated. The results show that the optimum filter radius can improve the simulated co-tidal phase and that better topography quality can lead to smaller rootmean square(RMS) error in simulated tides. Sensitivity experiments are conducted to test the impact of spatial resolutions. It is shown that the model results are sensitive to horizontal resolutions. The calculated absolute mean errors of the co-tidal phase show that simulations with horizontal resolutions of 0.5° and 0.25° have about 35.5% higher performance compared that with 1° model resolution. An internal tide drag parameterization is adopted to reduce large system errors in the tidal amplitude. The RMS error of the best tuned 0.25° model compared with the satellite-altimetry-constrained model TPXO7.2 is 8.5 cm for M_2. The tidal energy fluxes of M_2 and K_1 are calculated and their patterns are in good agreement with those from the TPXO7.2. The correlation coefficients of the tidal energy fluxes can be used as an important index to evaluate a model skill.     

Dissolved Cu, Pb, Zn and Cd in the South China Sea surface waters

The understanding of the distribution of trace heavy metals in the world ocean has greatlyimProved in the past decades. But most of the data are of vertical profiles of certain stations(Bruland, l980; Paul et al., l992; RObert et al., l990) and large--scale study of temporaland spatial variability of trace heaVy metals in the ocean is rather few. In fact, affected by ver-tical mixing by upwelling or convection, biogenic removal, atmospheric fallout and continentalinput frorn rivers, the dist…     

The pathway and fate of the heavy metal mixture in Xiamen marine experiment enclosures

The pathway and fate of heavy metals were studied in 10m3 enclosures at Xiamen Bay in 1985. The dissolved metals added are removed rather quickly during the first days, and their half-removal times ( t1/2) (d) are as follows: Pb 5. 4-5. 8, Hg 6. 7-14, Zn 11-22, Cu 16 - 29, and Cd 30-89. Zinc is transferred biologically to particles during phytoplankton bloom. The main Fate of added metals after 27 days is as follows; over 80% Cd and 60% Cu remain in dissolved phase, more than 60% Pb and 50% Hg transfer to settling settlement, while Zn is equally distributed in dissolved phase and settling settlement. The wall uptake is less than 2% of the total metals added. Organic materials play an essential role in the partition and the transfer of heavy metals in water column. Terrigenous and autochthonous particles show different affinities to different metals. Most heavy metals associate weakly with zooplankton. The Binding of Cd, Pb, Zn and Cu to the particles shows distinctive features related to the diagenetic     

Nonlinear tidal waves in a kind of estuary with gradually varying cross-section

-Nonlinear tidal waves in a kind of estuary are studied in the paper using one-dimensional nonlinear hydrody-namic equations with friction. The estuary has exponentially varying width B=B0 e-bx and uniform depth h. The one-dimensional hydrodynamic equations are solved by perturbation method. It was found that our solution included two special cases, Pelisenpeki's solution and Airy's solution. The former can be got by letting b=0 in our solutions, and the latter by setting 6 = 0 and f= 0 (f is linear frictional coefficient). In terms of the second-order solution, the physical mechanism of nonlinear tidal waves in estuaries with gradually varying cross-section is explored. It is shown that, under the assumption of linear friction coefficient, shallow water constituent waves consist of two parts, one is produced by shallow water nonlinear effect outside the estuary, the other is generated by shallow water nonlinear effect inside estuary. In addition, the physical mechanism of the residual tidal current and     

Trace metal concentration in marine organisms of Huanghe River estuary and adjacent sea region

The Huanghe River estuary, as one of world-known large river estuary and its adjacent sea re-gion are important aquatic product base with rich marine product resources in North China. The au-thors collected about 60 species of fishes. crustacea. mollusca and polychaeta in this region (119°05′-20′E,37°15′-38°15′N) from Apri1 to May. 1984. The concentration of Zn, Cd, Pb and Cu in eachmarine organisms was measured and concentration factors of trace metals were calculated. The ashingmethods was used for sample treatments. The concentration of trace metals was determined by anti-adsorption physical coating mercury electrode inverse polarography (Davis A1660 Differential CathodRay Polarograph).     

南海风生近惯性能通量的敏感性分析

After validated by the in-situ observation, the slab model is used to study the wind-generated near-inertial energy flux(NIEF) in the South China Sea(SCS) based on satellite-observed wind data, and its dependence on calculation methods and threshold criteria of the mixed layer depth(MLD) is investigated. Results illustrate that the total amount of NIEF in the SCS could be doubled if different threshold criteria of MLD are adopted. The NIEF calculated by the iteration and spectral solutions can lead to a discrepancy of 2.5 GW(1 GW=1×109 W). Results also indicate that the NIEF exhibits spatial and temporal variations, which are significant in the boreal autumn,and in the southern part of the SCS. Typhoons are an important generator of NIEF in the SCS, which could account for approximately 30% of the annual mean NIEF. In addition, deepening of the MLD due to strong winds could lead to a decrease of NIEF by approximately by 10%. We re-estimate the annual mean NIEF in the SCS,which is(10±4) GW and much larger than those reported in previous studies.     

A study on the exchange additivity of zinc in solid mixtures in seawater——Ⅲ. Stepwise isotherms of the mixture

Zinc exchange isotherms in mixtures of hydrous metal oxides and clay minerals have been reported. The relationship between the isotherms of the mixtures and the isotherms of their components is studied. The isotherms of the mixtures are stepwise. And the formation constants for the zinc exchange in the mixtures are calculated. The results show that the stepwise equilibrium formation constants and the saturation exchange capacities for the zinc exchange in kaolinite/ mon-tmorrillonite, amorphous iron oxide/montmorrillonite and γ-AlOOH/montmorrillonite mixtures are equal in weight to those of their components. The interactions between fresh iron oxyhydroxide and δ-MnOz reduce the metal binding sites of the mixtures, while the stepwise equilibrium constants are not affected by the interactions.     

Study of apparent complexing capacities of trace heavy-metals in the Huanghe River Estuary

-By the electroanalysis method combining the complexation titrating technique with the investigation of ip-Ea* characteristic curves, this paper measures apparent complexing capacities of trace heavy-metals in water samples from the Huanghe River Estuary. The results show that the order of apparent complexing capacities of trace heavy-metals in the samples isCu>Cd>Pb,and that apparent complexing capacities of near shore sample are higher than those far from shore. The effect of ultraviolet irradiation on the dissociation of organic ligands and the adsorption effect of cell walls (cells being treated with acid and seawater respectively) are investigated. The reduction (on electrodes) mechanism of species of trace heavy-metals in seawater is approached by ip-Ea* characteristic curves.     

A 2D Mathematical Model for Sediment Transport by Waves and Tidal Currents

In this study, the combined actions of waves and tidal currents in estuarine and coastal areas are considered and a 2D mathematical model for sediment transport by waves and tidal currents has been established in orthogonal curvilinear coordinates. Non-equilibrium transport equations of suspended load and bed load are used in the model. The concept of background concentration is introduced, and the formula of sediment transport capacity of tidal currents for the Oujiang River estuary is obtained. The Dou Guoren formula is employed for the sediment transport capacity of waves. Sediment transport capacity in the form of mud and the intensity of back silting are calculated by use of Luo Zaosen＇ s formula. The calculated tidal stages are in good agreement with the field data, and the calculated velocities and flow directions of 46 vertical lines for 8 cross sections are also in good agreement with the measured data. On such a basis, simulations of back silting after excavation of the waterway with a sand bar under complicated boundary conditions in the navigation channel induced by suspended load, bed load and mud by waves and tidal currents are discussed.     

Fully nonlinear simulations of wave resonance by an array of cylinders in vertical motions

The finite element method(FEM) is employed to analyze the resonant oscillations of the liquid confined within multiple or an array of floating bodies with fully nonlinear boundary conditions on the free surface and the body surface in two dimensions.The velocity potentials at each time step are obtained through the FEM with 8-node quadratic shape functions.The finite element linear system is solved by the conjugate gradient(CG) method with a symmetric successive overelaxlation(SSOR) preconditioner.The waves at the open boundary are absorbed by the combination of the damping zone method and the Sommerfeld-Orlanski equation.Numerical examples are given by an array of floating wedgeshaped cylinders and rectangular cylinders.Results are provided for heave motions including wave elevations,profiles and hydrodynamic forces.Comparisons are made in several cases with the results obtained from the second order solution in the time domain.It is found that the wave amplitude in the middle region of the array is larger than those in other places,and the hydrodynamic force on a cylinder increases with the cylinder closing to the middle of the array.     

有界赤道大洋波包解及其年际年代际变率

Linearized shallow water perturbation equations with approximation in an equatorial β plane are used to obtain the analytical solution of wave packet anomalies in the upper bounded equatorial ocean. The main results are as follows. The wave packet is a superposition of eastward travelling Kelvin waves and westward travelling Rossby waves with the slowest speed, and satisfies the boundary conditions of eastern and western coasts, respectively.The decay coefficient of this solution to the north and south sides of the equator is inversely proportional only to the phase velocity of Kelvin waves in the upper water. The oscillation frequency of the wave packet, which is also the natural frequency of the ocean, is proportional to its mode number and the phase velocity of Kelvin waves and is inversely proportional to the length of the equatorial ocean in the east-west direction. The flow anomalies of the wave packet of Mode 1 most of the time appear as zonal flows with the same direction. They reach the maximum at the center of the equatorial ocean and decay rapidly away from the equator, manifested as equatorially trapped waves. The flow anomalies of the wave packet of Mode 2 appear as the zonal flows with the same direction most of the time in half of the ocean, and are always 0 at the center of the entire ocean which indicates stagnation, while decaying away from the equator with the same speed as that of Mode 1. The spatial structure and oscillation period of the wave packet solution of Mode 1 and Mode 2 are consistent with the changing periods of the surface spatial field and time coefficient of the first and second modes of complex empirical orthogonal function(EOF)analysis of flow anomalies in the actual equatorial ocean. This indicates that the solution does exist in the real ocean, and that El Ni?o-Southern Oscillation(ENSO) and Indian Ocean dipole(IOD) are both related to Mode 2.After considering the Indonesian throughflow, we can obtain the length of bounded equatorial ocean by taking the sum of that of the tropical Indian Ocean and the tropical Pacific Ocean, thus this wave packet can also explain the decadal variability(about 20 a) of the equatorial Pacific and Indian Oceans.     

Reanalysis of the Atmospheric Flux of Nutrient Elements to the Southern Yellow Sea and the East China Sea

Based on the recent research results on dry and wet deposition of nutrient elements and sulphate,we estimate the atmospheric flux of nutrient elements and sulphate to the southern Yellow Sea and the East China Sea in each season.The results suggest that the concentrations of nutrient elements and sulphate in aerosol and precipitation show an apparent seasonal cycle with the maximum values in winter and the minimum values in summer.Depositions of nitrate and sulphate are dominated by wet deposition,while the deposition for phosphate is mainly dry deposition.Moreover,compared with the riverine inputs,the atmospheric deposition may be the main source of dissolved inorganic nutrients in the southern Yellow Sea and the East China Sea.