Plateau typeE(%)- pH curves of interfacial exchange between liquid and solid in seawater

A study on the curves of the exchange ratioE(%)- pH on the liquid-solid interface of the systems Zn (II) with clay minerals, (Kaolinite, illite and montmorillonite), Zn (II) with hydrous ferric oxides (amorphous ferric oxide, geothite and hematite), Zn (II) with hydrous manganese oxide (γ-MnOOH, manganite and δ-MnO₂) etc. in seawater resulted in the discovery of new plateau type exchange ratioE(%)-pH curves not yet reported in literature. The two factors that decide the growth, decline and the change of the “plateau type” curve are: (1) the inherent characteristics of systems, which can be explained by the exchange constants (i=1, 2, 3, etc.) of interfacial stepwise ion/coordination particle exchange between liquid and solid; and (2) . The theory of interfacial stepwise ion/coordination particle exchange in seawater was applied to explain the experimental results of the above study and a general formula was derived for the plateau type exchange ratioE(%)-pH curves. The theoretically simulated and calculated curves coincided well with the experimental results. This paper provides new and powerful experimental basis to support the theory of interfacial stepwise ion/coordination particle exchange in seawater. The project was supported by the National Natural Science Foundation of China.     

Physical and interfacial chemistry of Huanghe estuary

Summarized results of studies on the physical and interfacial chemistry of the Huanghe estuary are presented as follows: 1. The relationship between the exchange ratio (%) and pH for the Cu (II)-Sedi.ments of the Huanghe Estuary and that of the Cu (II)-illite system were observed to be very similar. 2. A stepwise ion/coordination particle exchange isotherm of trace metal in Huanghe estuary sediment was derived. 3. The ion/coordination particle exchange between trace metal and Huanghe Estuary sediment is analogous to the interfacial chemical characteristic of illite.     

Fourier-transform infrared spectroscopic studies on the interaction among marine trace metal ions,solid particles and organics

IR spectra of Cu (II)-marine solid particle systems show that Cu(II)-marine solid particle ion exchange causes a stepwise change in the surface H-bonding hydroxyl groups on illite, montmorillonite, CaCO₃, γ-AlOOH and goethite, but that this does not affect the surface free hydroxyl groups on illite, montmorillonite and CaCO₃, and framework hydroxyl group on goethite and on γ-AlOOH. Over the range of Cu (II) exchange amounts in the present experiment, four stepwise changes were discovered for the surface H-bonding hydroxyl group on illite, while two stepwise changes were observed on the other marine solids. The interfacial stepwise ion exchange theory was first demonstrated by the above experimental evidence.     

STUDY ON THE ISOTHERMS OF THE INTERACTION BETWEEN SUSPENDED PARTICLES AND Cu (Ⅱ) IN THE HUANGHE RIVER

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Interfacial stepwise ion/coordination particle exchange isotherm and isotherm equation on suspended marine particles

This article deals with a new type of isotherm discovered in sea water systems. The characteristics of this type of isotherm are the non-linear exponential relationship in the low concentration region and the isotherm composed of two or three “S” curves with one or two plateaus in the middle. This isotherm cannot be expressed by the isotherm equation used in marine chemistry at present.[⁷] Besides, there has been no report in literature about this type of isotherm in so far as the reaction of minor elements on hydrous oxides is concerned. In order to explain theoretically this type of isotherm, this article suggests the use of the theory of interfacial stepwise ion/coordination particle exchange (for simplicity, ion exchange is used herein-after) of suspended particles to deduce a corresponding isotherm equation. Proceeding from the isotherm of this article, we made theoretical analyses of these two characteristics as well as experiments in verification thereof. Twenty-four systems of experiments on this new type of isotherm and isotherm equation were designed and conducted. Experiment results agree with the theory reported here. Project supported by the Science Fund of the Chinese Academy of Sciences.     

The effect of amino acids on copper (II)-goethite ion exchange in seawater

In seawater, aside from metal elements and suspended particles, organic substances amount to about 500–2,000 ug carbon/l^[8], which is not neglegible in comparison with that of minor metal elements. But in the study of the interaction of the three constituents (metal elements, organics, and suspended particles), the effect of organics in seawater on the surface reaction of metal element—suspended particles has usually been neglected. Recent theoretical research^{[1, 11]} confirmed the importance of the effect of organics in seawater on the surface reaction of metal element—suspended particles. Generally, the effect of organics on the reaction of metal ions, especially Cu(II), on a solid surface is either promotive^[2] or inhibitive^{[7, 9]}. So far the fact that organics cannot affect the surface reaction of Cu(II) ions on solids has not been reported in literature. Our experimental results showed that none of the amino acids in seawater affect Cu(II)-goethite ion exchange under certain experimental condition (such as amino acid of lower concentration and lower pH). It was known that the metal ion-organics complex in a liquid competing with solids for metal ions may inhibit the surface reaction of metal ions on solids, but the mechanism of the complex reaction of metal ions competing with solids is not known yet. In fact, the decrease of surface site-exchanging due to the surface reaction of organics on solids is also inhibitive. It is also explained by the ion exchange isotherm of the “amino acid-Cu(II)-geothite” system. This result further demonstrates that the theory of interfacial stepwise ion exchange is applicable to the metal ion exchange isotherm with the presence of organic substances in the system. Projects supported by the Science Fund of the Chinese Academy of Sciences     

Study on the isotherms of the interaction between suspended particles and Cu (II) in the Huanghe River

The isotherms of the interaction between the suspended particles and Cu²⁺, and the effects of lysine and asparaginic acid on the isotherms in the Huanghe (Yellow) River were studied by applying the theory and method of interfacial stepwise ion/coordination particle exchange. We obtained a new stepped river isotherm, formed by two curves joined together with a “plateau” in the middle. The adsorption equilibrium constantsK ₁ andK ₂ were calculated by using the isothermal equation of surface stepwise ion exchange. Amino acid in small amount promotes exchange adsorption of the suspended particles with Cu²⁺. The degree of promotive action relates to the isoelectric point of amino acid. The promotive effect of lysine is bigger than that of asparaginic acid. Project 29361001 supported by NSFC.     

The stepwise exchange action and steric hindrance effect of organic phenols on clays in seawater

The exchange action of six types of organic phenols on clay surfaces in seawater is systematically studied in this work. The following significant conclusions are drawn from the experiments. (1) The interaction of organic phenols with montmorillonite, illite and kaolinite in seawater is monovalent anion exchage.(2) Their isotherms of stepwise exchage on clay surfaces belong to the Langmuir type or stepwise type.(3) The discovery of the"steric hindrance effects of stepwise exchange of organic phenols on clays surfaces", and revelation of an exchange mechanisrn diffeient from that in references are the greatest achieverments in this work.     

A new type of isotherm for zinc liquid-solid partitioning on δ−MnO2, γ−MnOOH and manganite in seawater

This article deals with the interaction of zinc with δ−MnO₂, γ−MnOOH and manganite existing in natural water systems. The mechanism of the reaction has been studied in detail. From the fact that the “ratio of ion exchange(%)-pH” graph is an “S shaped” curve, it is possible to deduce that the chemical reaction is of the nature of cation exchange. And since the pH range of ion exchange=4, it is possible to further deduce that the reaction can be explained by the mechanism of monovalence cation exchange. The main result of this article is the discovery of a new type of isotherm which has not been mentioned in previous literature here and abroad. This isotherm cannot be represented by any presently available adsorption isotherm equations in marine chemistry. The characteristics of this new type of isotherm are as follows: the isotherm has two “knees” and three “plateaus”, the heights of these three “plateaus” are in the ratio 1:2:3. In order to explain theoretically our new isotherm, this article suggests the application of the principle of interfacial stepwise ion exchange for liquid-solid distribution of minor elements on suspended particulate matter. The corresponding isotherm equation was derived from this theory. The results obtained in this article will be of theoretical guiding significance in the study of the marine geochemistry of zinc. Projects supported by the Science Fund of the Chinese Academy of Sciences.     

THE INTRINSIC ACIDITY CONSTANTS AND SPECIFIC SURFACE AREA OF MARINE SOLID PARTICLESII. THE RELATIONSHIP BETWEEN THE INTRINSIC ACIDITY CONSTANT AND THE TERNARY SURFACE COMPLEX

This paper deals with the infrared spectra of " amino acid- clay , calcium carbonate and y-AlOOH" and " Cu (II )-clay-amino acid" model systems, and shows that the model of the ternary surface complex is M-OHLCu (L = amino acid) for marine solid particle-Cu (II)-amino acid. Study of the formation mechanism of the ternary surface complex shows that the specific surface area , and especially the intrinsic acidity constant, determine whether the ternary surface complex is easily formed, and that factor, FTSC,quantifies the relationship between the promoting effect of organics on Mt-marine solid particle ion exchange and the intrinsic acidity constant and specific surface area.     

The surface reaction on liquid-solid interface of “amino acid-Cu(II)−MnO2” system in seawater

The results obtained from the Cu(II)%-pH curve of the system in the presence of added amino acid indicated that the added amino acids of higher concentration can inhibit the Cu(II)-σ-MnO₂ ion exchange and that their inhibiting effects decrease in the following sequence when the initial amino acid concentrations are 20.00 ppm: histidine > cystine > glutamic acid > proline > alanine > glycine. The determination of amino acid in solution performed with an amino acid analyser showed that added amino acids react chemically on the surface of the σ-MnO₂ According to thermodynamic equilibria relations in the system, amino acids can be changed to amines because of their decarboxylation on the surface of the σ-MnO₂. Considering (1) the effect-inhibiting factor of amine F_A(β, K_a, pH) representing the complex potential of amine with Cu(II) in solution and (2) the acidic constant of −NH ₃ ⁺ group in the amine molecule representing the ability of cation exchange of the amine with σ-MnO₂, the inhibiting seqence of added amino acid of 20.00 ppm (Eq.(1)) is reasonable. Thus added amino acids do inhibit Cu(II)-σ-MnO₂ ion exchange because (1) the amino acid and/ or amine, which is the decarboxylate of the corresponding amino acid, complex with Cu(II) in solution and compete with σ-MnO₂ for Cu(II); (2) the cation exchange of the amino acid and/or amine reduce the exchange site on the surface of the σ-MnO₂. The results obtained from the isotherms indicated that the theory of interfacial stepwise ion exchange can be extended to the Cu(II) σ-MnO₂ ion exchange system in the presence of added amino acid.     

The intrinsic acidity constants and specific surface area of marine solid particles

This paper deals with the infrared spectra of “amino acid-clay, calcium carbonate and γ-AlOOH” and “Cu(II)-clay-amino acid” model systems, and shows that the model of the ternary surface complex is M-OHLCu (L=amino acid) for marine solid particle-Cu (II)-amino acid. Study of the formation mechanism of the ternary surface complex shows that the specific surface area, and especially the intrinsic acidity constant, determine whether the ternary surface complex is easily formed, and that factor,F _TSC, quantifies the relationship between the promoting effect of organics on M_t-marine solid particle ion exchange and the intrinsic acidity constant and specific surface area.     

Determination of butyltin in seawater by gas chromatography with flame photometric detector

INTRODUCTIONTheincreasinglydiverseuseofbutyltininindustry ,agricultureandaquaculturehasledtocon cernregardingtheimpactanddangerofthesealkyltincompoundsonenvironment.Muchattentionhasbeenpaidbyworldscientistsinthelastthirtyyearstotheproblemsoforganotincontamination .Theuseoforganotin ,particularlytributyltinbiocides,asshippaintcomponentcausescontaminationofharbourandcoastalaquaticbiota.Tributyltinandbutyltinareveryeffectiveagainstmarinefoulingorganismsbutalsopollutethemarineenvironmentandar…     

沸石去除地下水中氨氮的影响因素分析及作用机理探讨

对改性沸石去除氨氮的条件及机理进行了实验探讨。结果表明 ,沸石经过活化剂处理后具有降低水中氨氮的作用。影响沸石去除氨氮的主要因素包括沸石与含氨氮溶液作用时间、沸石用量、溶液中氨氮浓度、沸石的粒度和溶液的温度等 ,探讨了沸石去除氨氮的机理 ,初步认为主要是由于离子交换作用和吸附作用共同完成的。     

Some trace metal ions in natural waters of Tianshan Mountains and Qinghai-Tibet plateau

The concentrations of Zn, Cd, Pb, Cu ions are shown to be similar in natural waters of Tianshan Mountains and Qinghai-Tibet plateau and to be similar in those of the sea water. The average and variability of concentraions of trace metal ions in fresh water are Zn 5.7±1.5, Cd 0.092±0.038, Pb 0.048±0.011, and Cu 1.1±0.20 ppb. The average concentrations in the East China Sea are Zn 7.3 (5.5 in 1976), Cd 0.12, Pb 0.036, and Cu 0.94 ppb. It proves that the homogeneous distribution of trace metal ions (free ion and unstable complexes) in natural waters is present in the nature as a rule. Contribution No. 985 from the Institute of Oceanology, Academia Sinica.     

Controlling mechanisms for the trace metals, (Cu,Zn, Cd,Fe, Co and Ni) in anoxic sea water in Saanich Inlet,British Columbia,Canada

A study was conducted on Cu, Zn, Cd, Fe, Co and Ni levels in Saanich Inlet anoxic seawater. Data on the concentration of these trace metals and H₂S, and other oceanographic parameters were obtained in four cruises. Equilibrium models are presented together with in situ data. The results strongly support the assumption that the solubilities of Cu, Zn, Cd, Fe, Co and Ni are controlled by bisulfide and/or polysulfide complexes. The species of Cu, Zn, Cd and Ni are shown to be Cu(S₄) ₂ ³⁻ and Cu(Sn₄S₅)³⁻, Zn(HS) ₂ ⁰ and ZnHS ₂ ⁻ , Cd(HS) ₂ ⁰ and Ni(HS) ₂ ⁰ , respectively. The solid species controlling Fe²⁺ and Co²⁺ are respectively the pyrohotites FeS and CoS. The data illustrates that thermodynamic equilibrium has been established in the H₂S-controlled seawater of Saanich Inlet, and that equilibrium has not been established in the H₂S−O₂-coexisted seawater of Saanich Inlet. The lack of equilibrium in the H₂S−O₂-coexisted seawater is a result of the flushing or mixing of oxygenated seawater with anoxic water. The new species of trace metals are still in the processes of reduction and precipitation. Contribution No. 1428 from Institute of Oceanology, Academia Sinica     

Three tropical seagrasses as potential bio-indicators to trace metals in Xincun Bay, Hainan Island, South China

Concentrations of the trace metals Cu,Cd,Pb,and Zn were measured in seawater,rhizosphere sediments,interstitial water,and the tissues of three tropical species of seagrasses (Thalassia hemprichii,Enhalus acoroides and Cymodocea rotundata) from Xincun Bay of Hainan Island,South China.We analyzed different environmental compartments and the highest concentrations of Pb and Zn were found in the interstitial and seawater.The concentrations of Cd and Zn were significantly higher in blades compared with roots or rhizomes in T.hemprichii and E.acoroides,respectively.A metal pollution index (MPI) demonstrated that sediment,interstitial water,and seagrasses in the sites located nearest anthropogenic sources of pollution had the most abundant metal concentrations.There was obvious seasonal variation of these metals in the three seagrasses with higher concentrations of Cu,Pb and Zn in January and Cd in July.Furthermore,the relationships between metal concentrations in seagrasses and environmental compartments were positively correlated significantly.The bioconcentration factors (BCF) demonstrated that Cd from the tissues of the three seagrasses might be absorbed from the sediment by the roots.However,for C.rotundata,Zn is likely to be derived from the seawater through its blades.Therefore,the blades of T.hemprichii,E.acoroides and C.rotundata are potential bio-indicators to Cd content in sediment,and additionally Zn content (C.rotundata only) in seawater.     

Research on the critical conditions for clay particle release during saline aquifer freshening process

Water sensitivity phenomenon occurs during saline aquifer freshening process in seawater intrusion area, and clay particles released in the phenomenon can damage the infiltration capacity of the aquifer. In order to find out the factors and mechanisms for clay particle release, laboratory column infiltration experiments simulating saline aquifer freshening process were designed to measure the critical conditions(critical flow velocity, critical salt concentration and critical ionic strength) and force analysis for clay particle according to DLVO electric double layer theory was employed to illustrate the mechanisms for particle release. The research results showed that critical flow velocity for clay particle release is influenced by salt concentration of injecting solution. When salt concentration of injecting solution is very high, clay particles are not released, indicating that there does not exist a critical flow velocity in this situation. As salt concentration of injecting solution decreases, particles start to be released. The critical salt concentration for clay particle release is 0.052 mol L-1 in our work, which was determined by a constant-flux experiment for stepwise displacement of high concentration Na Cl solution. The critical ionic strength for clay particle release decreases as Ca2+ molar content percentage of the mixed solution of Na Cl and Ca Cl2 increases following the first-order exponential decay equation y = 0.0391e-0.266 x + 0.0015.     

DISTRIBUTION OF DISSOLVED AND PARTICULATE TRACE METALS IN ANOXIC SEAWATER, SAANICH INLET, B . C. CANADA

This paper discusses the spatial and seasonal distribution character of dissolved and paniculate trace metals in the anoxic seawater of Saanich Inlet, B.C., Canada. The study showed that concentration of dissolved and paniculate trace metals in anoxic seawater is closely related to (1) the concentration of H2S and the depth of the O2-H2S interface, (2) the exchange of seawater in Saanich Inlet with outside seawater, (3) biotic action, and (4) the flushing event. The study was based in part on the ratio between trace metals and nutrients. There was a steep change in the concentration of dissolved trace metals at the O2-H2S interface. The concentration of dissolved trace metals in the H2S-controlled zone was dependent on the H2S there. The suspended matter in Saanich Inlet comes from the Hero Strait seawater, phytoplankton production and resuspension of flushed-up sediments. The concentration of particulate trace metals was rather low in Saanich Inlet and tended to increase with depth. The total concentra     

Benthic nutrient recycling in shallow coastal waters of the Bohai Sea

Sediment-water fluxes of N and P species in the Bohai Sea were investigated in September-October 1998 and April-May 1999. The benthic fluxes of nutrient species were determined by incubating sediment core samples with bottom seawater bubbled with air or nitrogen. NO^-2,NH4, dissolved organic nitrogen (DON) and phosphorus (DOP), total dissolved nitrogen (TDN) and phosphorus (TDP), and PO4^3- showed a net exchange flux from seawater to sediment, while NO^-3, dissolved inorganic nitrogen (DIN) and SiO3^2- were released from sediment to seawater in the Bohai Sea. Sediment-water nutrient exchange increases DIN and reduces the phosphorus load in the Bohai Sea. The release of silicate from sediment to overlying seawater reduces potential silicate limitation of primary production resulted from decrease of riverine discharge.The exchange flux of nutrients showed no obvious seasonal variation. The present study showed that the concentrations and composition of nutrients in the water column were affected by suspended sediment, and that not all the exchangeable phosphate in sediment could be released via sediment resuspension.