Speciation in seawater

Andreae, M. O. (1979). Arsenic speciation in seawater and interstitial waters the role of biological-chemical interactions on the chemistry of a trace element. Limnol. Oceanog. 24,440-452. 

Garcia-Monco Carra et al. [296] have described a hybrid mercury film electrode for the voltammetric analysis of copper (and lead) in acidified seawater. Mercury plating conditions for preparing a consistently reproducible mercury film electrode on a glassy carbon substrate in acid media are evaluated. It is found that a hybrid electrode , i.e., one preplated with mercury and then replated with mercury in situ with the sample, gives very reproducible results in the analysis of copper in seawater. Consistently reproducible electrode performance allows for the calculation of a cell constant and prediction of the slopes of standard addition plots, useful parameters in the study of copper speciation in seawater. 

Latouche et al. [855] have reviewed trace metal speciation in seawater. 

Table V Lead speciation in seawater corrected and uncorrected for Cl ion-pairs. ...

Although the details of the equilibrium model are still uncertain, the general trends are likely reliable. As shown in Figme 5.16, most of the Fe(III) in seawater is predicted to be in the form of the FeL complex. The equilibrium model also predicts that this degree of complexation should enhance iron solubility such that 10 to 50% of the iron delivered to the ocean as dust will eventually become dissolved if equilibrimn is attained. If this model is a reasonable representation for iron speciation in seawater, uptake of [Fe(III)]jQjgj by phytoplankton should induce a spontaneous dissolution of additional particulate iron so as to drive the dissolved iron concentrations back toward their equilibrium values. 

Table 5.8 Effect of Temperature and Pressure on Sulfate Species Speciation in Seawater. ...

These values can be used to predict redox speciation in seawater as illustrated by the following example. Consider the half-reactions... 

Iron hydrolysis and solubility revisited Observations and comments on iron hydrolyses characterizations. Marine Chem. 70 23—38 Byrne, R.H. Kester, D.R. (1976) Solubility of hydrous ferric oxide and iron speciation in seawater. Marine Chem. 4 255—274 Byrne, R.H. Luo,Y.-R. (2000) Direct observations of nonintegral hydreno ferric oxide solubility products K Sq = [Fe ][H ] Geo-chim. Cosmochim. Acta 64 1873-1877 Cabrera, F. de Arambarri, P. Madrid, L. ... 

The concentrations of the major inorganic ions in seawater are well known in estuarine and coastal areas as well as in interstitial waters anomalies in their constant ratios may occur. The major cations are Na+, Mg2+, Ca2+, K+ and Sr2+, the major anions Cl-, SCty2-, HCO3", B(OH) ", F" and Br". Ion pairs involving these elements and H+, OH", CO32-, POif3- and SiOz -. Under anoxic conditions the S2- - ion and bi- and polysulphides become important. A summary of the major ion speciation in seawater is given by Kester et al. (1975). 

Elderfield, H., 1970. Chromium speciation in seawater. Earth Planet. Sci. Lett., 9 10-16. 

Kester, D.R. (rapporteur), 1975. Chemical speciation in seawater. In E.D. Goldberg (ed.), The Nature of Seawater. Dahlem Conf., Berlin, pp. 17-41. 

Mackey, D.3., 1982. An investigation of the suitability of amberlite XAD-1 resin for studying trace metal speciation in seawater. Mar. Chem., 11 169-181. 

Rohl, R., 1982. Trace metal speciation in seawater - a paper electrophoretic approach. Anal. Chim. Acta, 135 99-110. 

Van den Berg, C.M.G., 1983b. Trace metal speciation in seawater. Anal. Proc., 20 458-460. 

Part II considers speciation in specific compartments of the environment viz. the atmosphere, biological systems, soils, sediments and natural waters, and with particular aspects of the speciation of environmentally important radionuclides. Two new chapters have been added to make the coverage even more comprehensive. These new chapters are Chapter 10, Chemical Speciation in Soib and Related Materials by Selective Chemical Extraction by the editors, and Chapter 12, Speciation in Seawater by R.H. Byrne of the University of South Florida. 

The species distributions shown in Table 12.2 depict results from one of the earliest (Garrels and Thompson, 1962) and one of the most recent (Millero and Schreiber, 1982) seawater ion pairing models. These results and others (Kester, 1975a) are consistent with the following general characteristics of major ion speciation in seawater ... 

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