Speciation estuaries

Dyrssen D, Wedborg M (1980) Major and minor elements, chemical speciation in estuarine waters. In Olausson E, Cato I (eds) Chemistry and biogeochemistry of estuaries. Wiley, New York, pp 71-119... 

Batley [28] examined the techniques available for the in situ electrodeposition of lead and cadmium in estuary water. These included anodic stripping voltammetry at a glass carbon thin film electrode and the hanging drop mercury electrode in the presence of oxygen and in situ electrodeposition on mercury coated graphite tubes. Batley [28] found that in situ deposition of lead and cadmium on a mercury coated tube was the more versatile technique. The mercury film, deposited in the laboratory, is stable on the dried tubes which are used later for field electrodeposition. The deposited metals were then determined by electrothermal atomic absorption spectrometry, Hasle and Abdullah [29] used differential pulse anodic stripping voltammetry in speciation studies on dissolved copper, lead, and cadmium in coastal sea water. 

The solubilized metals form complexes with organic and inorganic anions. The chemical speciation of these complexes changes as the metal moves seaward through the estuary due to increasing salinity. These shifts can be predicted from equilibrium speciation calculations as described in Chapter 5.7. Two examples are shown in Figure 28.23 for... 

Howard, A.G., Apte, S.C., Comber, S.D.W. and Morris, RJ. (1988) Biogeochemical control of the summer distribution and speciation of arsenic in the Tamar estuary. Estuarine Coastal and Shelf Science, 27(4), 427-43. 

To illustrate one type of speciation research, i.e. the determination of the apparent complexation capacity for copper (CCqu) and the conditional stability constant (K1), examples are given for three marine areas, viz. the Scheldt estuary, the Southern Bight of the North Sea and the open north Atlantic Ocean. A hypothetical model is presented giving the complexation capacity across the land-sea boundery from river to ocean. 

Dyrssen, D. and Wedborg, M., 1980. Chemical speciation of some constituents in estuarine waters. In E. Olausson and I. Cato (eds), Chemistry and Biogeochemistry of Estuaries. Wiley, New York, pp. 71-119. 

Baeyens, W., C. Meuleman, B. Muhaya, and M. Leermakers. 1998. Behaviour and speciation of mercury in the Scheldt estuary (water, sediments and benthic organisms). Hydrobiologia 366 63-79. 

Leermakers, M., C. Meuleman, and W. Baeyens. 1995. Mercury speciation in the Scheldt estuary. Water Air Soil Pollut. 80 641-652. 

The solubility of mineral salts may be enhanced with the formation of ion pairs, a salting-in effect, requiring the inclusion of ion speciation effects. Conversely, there is commonly a salting-out effect of dissolved constituents across a salinity gradient. This can be particularly important when examining more hydrophobic organic compounds (HOC), such as aromatic hydrocarbons in estuaries. 

The cycling and availability of P in estuaries is largely dependent upon P speciation. Consequently, total P (TP) has traditionally been divided into total dissolved P (TDP) and total particulate P (TPP) fractions (Juday et al., 1927), which can further be divided... 

The distribution and speciation of trace metals in estuaries will depend on their concentrations as well as the concentrations of dissolved complexing ligands and the associated coordination sites on colloids and particulates. 

Coelho, J.P., Flindt, M.R., Jensen, H.S., Lillebo, A.I., and Pardal, M.A. (2004) Phosphorus speciation and availability in intertidal sediments of a temperate estuary relation to eutrophication and annual P-fluxes. Estuar. Coastal Shelf Sci. 61, 583-590. 

Stordal, M.C., Gill, G.A., Wen, L.S., and Santschi, P.H. (1996) Mercury phase speciation in the surface waters of three Texas estuaries importance of colloidal forms. Limnol. 

Tseng, C.M., Amouroux, D., Abril, G, Tessier, E., Etcheber, H., and Donard, O.F.X. (2001) Speciation of mercury in a fluid mud profile of a highly turbid macrotidal estuary (Gironde, France). Environ. Sci. Technol. 35, 2627-2633. 

Riedel GF, Sanders JG. 1998. Trace element speciation and behavior in the tidal Delaware River. Estuaries 21(l) 78-90. 

O Day, P.A. et al., Metal speciation and bioavailability in contaminated estuary sediments, Alameda Naval Air Station, California, Environ. Sci. Technol., 34, 3665, 2000. 

A component can undergo considerable physico-chemical speciation alterations in an estuary. With respect to dissolved constituents, the composition and concentration of available ligands changes. Depending upon the initial pH of the riverine water, OH may become markedly more important down the estuary. Similarly, chlorocomplexes for metals such as Cd, Hg and Zn become more prevalent as the salinity increases. Conversely, the competitive influence of seawater derived Ca and Mg for organic material decreases the relative importance of humic complexation for Mn and Zn. 

Estuaries are the major pathway of materials from the rivers to the marine environment. In order to understand how dissolved and particulate organic matter v/ithin the estuary affect the speciation of cations within this environment, the ion exchange parameters as a function of ionic strength must be studied. In addition to the physical transfer of material between the dissolved and particulate forms, the salinity variations also affect the ion exchange abilities of these organic molecules. These two major processes can affect the organic material distribution and ability to bind metals, and hence the overall distribution of a given trace metal. 

The relative proportions of arsenic species in estuarine waters are more variable because of changes in redox, salinity, and terrestrial inputs (Abdullah et al., 1995 Howard et al., 1988). Arsenic(V) tends to dominate, although M. O. Andreae and T. W. Andreae (1989) found increased proportions of As(III) in the Schelde Estuary of Belgium. The highest values occur in anoxic zones near sources of industrial effluent. Increased proportions of As(III) also occur near sources of mine effluent (M. O. Andreae and T. W. Andreae, 1989). Seasonal variations in concentration and speciation have been reported in seasonally anoxic waters (Riedel, 1993). Peterson and Carpenter (1983) reported a clear crossover in the proportions of the two species with increasing depth in the Saanich Inlet of British Columbia. Arsenic(III) represented only 5% (0.10 p,g L ) of the dissolved arsenic above the redox front but 87% (1.58p,gL ) below it. In marine and estuarine waters, organic forms of arsenic are... 

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