Oceans complex formation

Consider complex ion formation in the CdClj-KCl system, and let it be assumed for the moment that a CdCl complex ion is formed. If such complex ions were formed in an aqueous solution of CdClj and KCl, they would exist as little islands separated from other ions by large expanses of water. In fused salts, there are no oceans of solvent separating the ions. Thus, a Cd " ion would constantly be coming into contact on all sides with chloride ions, and yet one singles out three of these CP ions and says that they are part of (or belong to) a CdCIJ complex ion (Fig. 5.54). It appears that in the absence of the separateness possible in aqueous solutions, the concept of complex ions in molten salts is suspect As will be argued later, however, what is dubious turns out to be not the concept but the comparison of complex formation in fused salts with complex formation in aqueous solutions. 

Methylarsines and methylstibines are subject to a number of reactions such as oxidation, quaternization and complex formation, which could facilitate or inhibit their dispersal in the environment . It has been reported that environmentally important concentrations of halocarbons (Mel, MeBr and MeCl) are produced naturally and accumulate in the oceans and the atmosphere. Parris and Brinckman reported quantitative measurements of the rate of quaternization of trimethylstibine and trimethylarsine by alkyl halides in polar solvents. 

Thus the surface chemistry of the ocean consists essentially of the chemistry of that part of the uncharacterised and complex part of the DOM in seawater which is surface active. Apart from other effects, this can lead to the entrainment of trace elements in the surface layer by complex formation with the surface active polymers and their enrichment in the microlayer (Barker and Zeitlin, 1972 Duce et al., 1972 Piotrowicz et al., 1972, Hunter, 1977) and possible enrichment of the atmospheric aerosol (Duce et al., 1972,1976), at least near the ocean surface (Chesselet et al., 1976). 

Fig. 15-5 Comparative adsorption of several metals onto amorphous iron oxyhydroxide systems containing 10 M Fej and 0.1 m NaNOs. (a) Effect of solution pH on sorption of uncomplexed metals, (b) Comparison of binding constants for formation of soluble Me-OH complexes and formation of surface Me-O-Si complexes i.e. sorption onto Si02 particles, (c) Effect of solution pH on sorption of oxyanionic metals. (Figures (a), (c) reprinted with permission from Manzione, M. A. and Merrill, D. T. (1989). "Trace Metal Removal by Iron Coprecipitation Field Evaluation," EPRI report GS-6438, Electric Power Research Institute, California. Figure (b) reprinted with permission from Balistrieri, L. et al. (1981). Scavenging residence times of trace metals and surface chemistry of sinking particles in the deep ocean, Deep-Sea Res. 28A 101-121, Pergamon Press.)...

The geological process of the formation of serpentine from peridotite probably involves the synthesis of carbon compounds under FTT conditions (see Sect. 7.2.3). The hydrogen set free in the serpentinisation process can react with CO2 or CO in various ways. The process must be quite complex, as CO2 and CO flow through the system of clefts and chasms in the oceanic crust and must thus pass by various mineral surfaces, at which catalytic processes as well as adsorption and desorption could occur. 

The complexity and mutual dependence of all the processes in the ocean substantially hinder discovery of the laws of formation of phytoplankton spots and establishing correlations between the various factors that regulate trophic relationship intensity in ocean ecosystems. For instance, many studies revealed a close relationship between primary production and phytoplankton amount. At the same time, this relationship breaks down depending on the combination of synoptic situation and insolation. It turns out that the extent of this breakdown depends much on the combination of groups of phytoplankton (Legendre and Legendre, 1998). 

In the marginal shelves of the ocean, oxygen balance formation is much affected by the run-off from continents. Despite the complexity of this process, the following simple parameterization can be accepted for this case ... 

AuCl2- or even a higher order complex. While it is possible that the enhanced capacity of Au1 for complexation with soft ligands may account for the disparate distributions of Ag and Au, fractionation of Au and Ag may also be caused by a significant Aum chemistry in seawater. The major species of Au111 in seawater are expected to be Au(OH)3 or Au(OH)3C1 (Baes and Mesmer, 1976). Although the analysis ofTumer etal. (1981) indicated that the field of Aum stability is somewhat outside the oxidation-reduction conditions encountered in seawater, a paucity of direct formation-constant observations for both Aum and Au1 creates substantial uncertainties. Furthermore, with respect to thermodynamic predictions of oxidation-reduction behaviour the ocean is not a system at equilibrium. 

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