Speciation freshwater

Meylan S, Behra R, Sigg L (2003) Accumulation of Cu and Zn in periphyton in response to dynamic variations of metal speciation in freshwater. Environ Sci Technol 37 5204... 

Meylan S, Odzak N, Behra R, Sigg L (2004) Speciation of copper and zinc in natural freshwater comparison of voltammetric measurements, diffusive gradients in thin Aims (DGT) and chemical equilibrium models. An Chim Acta 510 91... 

Gill GA, Bmland KW. 1990. Mercury speciation in surface freshwater systems in California and other areas. Environ Sci Technol 24 1392-1400. 

Luther et al. [92] have described a procedure for the direct determination of iodide in seawater. By use of a cathodic stripping square-wave voltammetry, it is possible to determine low and sub-nanomolar levels of iodide in seawater, freshwater, and brackish water. Precision is typically 5% (la). The minimum detection limit is 0.1 - 0.2 nM (12 parts per trillion) at 180 sec deposition time. Data obtained on Atlantic Ocean samples show similar trends to previously reported iodine speciation data. This method is more sensitive than previous methods by 1-2 orders of magnitude. Triton X-100 added to the sample enhances the mercury electrode s sensitivity to iodine. 

Sibley TH, Morgan JJ (1975) Equilibrium speciation of trace metals in freshwater-seawater mixtures. In Hutchinson HC (ed) Proceedings of international conference on heavy metals in the environment, University of Toronto, Toronto, Ontario pp 310-338... 

Metal speciation is discussed here from the perspective of the speciation occurring in natural freshwater environments. This speciation is relevant for interactions of metals with aquatic organisms. 

Xue, H.-B. and Sigg, L. (1998). Cd speciation and complexation by natural organic ligands in freshwater, Anal. Chim. Acta, 363, 249-259. 

Although the abundance of silver in the Earth s crust is comparatively low (0.07 pgg-1), it is considered an environmental contaminant and is toxic at the nanomolar level. As an environmental pollutant it is derived from mining and smelting wastes and, because of its use in the electrical and photographic industries, there are considerable discharges into the aquatic environment. Consequently, there have been studies on the geochemistry and structure of silver-sulfur compounds [31]. Silver, either bound to large molecules or adsorbed on to particles, is found in the colloidal phase in freshwater. In anoxic sediments Ag(I) can bind to amorphous FeS, but dissolved silver compounds are not uncommon. A more detailed study of silver speciation in wastewater effluent, surface and pore waters concluded that 33-35% was colloidal and ca. 15-20% was in the dissolved phases [32]. 

In freshwater, Mn(II) oxidation is slightly slower than in 0.1M NaClO. The difference between the Mn(II) oxidation rate in freshwater and 0.1M NaCIO, is greatest at pH 8.5, at this pH the rate of Mn(II) oxidation is only 40% lower in the freshwater than in 0.1M NaClO. In the estuarine-water at pH 8.5 the rate of Mn(II) oxidation is 20 times slower than in 0.1M NaCIO,. The speciation calculations indicate why the model predicts the oxidation is slower than in natural waters (see, for example Table VII). 

Table VII. Calculated speciation in freshwater, estuarine-water and ...

The aqua Zn ion is dominant in organic matter-free freshwater while the free Zrf+ ion and chloride complexes dominate in seawater (Stanley and Byrne 1990 Millero 1996). The free Cu + ion is dominant in freshwater, while the carbonate complexes CuCO, and [Cu(C03)2] are preponderant in seawater. Speciation and solubility of Zn in Cl-rich hydrothermal solutions has been investigated by Wesolowski et al. (1998). Speciation and solubility of Cu have been investigated by Mountain and Seward (1999) for hydrothermal solutions dominated by sulfides and by Xiao et al. (1998), Liu et al. (2002), and Archibald et al. (2002) for solutions dominated by chlorides. 

A full imderstanding of the speciation of dissolved iron requires consideration of ligands other than water and hydroxide. The most important ones are listed in Table 5.6 along with their concentration ranges in seawater and freshwater. For Fe(III) in seawater at pH > 4, the formation of complexes with hydroxide is most important, but at pH <4, sulfete, chloride, and fluoride pairing predominates (Figure 5.15b). To predict the equilibrimn speciation at low pH, these anions need to be added to the mass balance equation fiar Fe(III) (Eq. 5.20). Seawater with low pH tends to have low O2 concentrations. Under these conditions, most of the dissolved iron is present as Fe( II), which undergoes complexation with sulfide and carbonate. 

For the determination of organotin compounds (tributyltin, triphenyltin, triethyltin, and tetra-ethyltin) a MAE is proposed before the normal phase (NP) HPLC/UV analysis [35], In organotin and arsenic speciation studies, hydride generation is the most popular derivatization method, combined with atomic absorption and fluorescence spectroscopy or ICP techniques [25,36], Both atmospheric pressure chemical ionization (APCI)-MS and electrospray ionization ESI-MS are employed in the determination of butyltin, phenyltin, triphenyltin, and tributyltin in waters and sediments [37], A micro LC/ESI-ion trap MS method has been recently chosen as the official EPA (Environmental Protection Agency) method (8323) [38] it permits the determination of mono-, di-, and tri- butyltin, and mono-, di-, and tri-phenyltin at concentration levels of a subnanogram per liter and has been successfully applied in the analysis of freshwaters and fish [39], Tributyltin in waters has been also quantified through an automated sensitive SPME LC/ESI-MS method [40],... 

H202 affects metal speciation in marine environments (21, 24, 29-31) however, little work has been reported for freshwater systems. A study by Sturzenegger (15) showed decomposition of H202 with both y-MnOOH and (3-Mn02, in phosphate-buffered distilled water. Additional studies are necessary to determine the significance of these pathways of H202 in fresh waters. 

Hart, B.T. and Davies, S.H.R., 1981. Trace metal speciation in the freshwater and estuarine regions of the Yarra river, Victoria. Est. Coast. Shelf Sci., 12 353-374. 

Sibley, T.H. and Morgan, 3.3., 1975. Equilibrium speciation of trace metals in freshwater -seawater mixtures. In T. Hutchinson (ed.), Proc. Int. Conf. Heavy Metals in the Environment. Univ. of Toronto, Ontario, p. 319. 

Petersen, R., 1982. Influence of copper and zinc on the growth of a freshwater alga, Scenedesmus quadricauda the significance of chemical speciation. Environ. Sci. Technol., 16 443-447. 

The New Hampshire Department of Health and Human Services is determining blood mercury concentrations and related freshwater fish consumption, studying speciated arsenic in urine, and analyzing phthalates in urine and PBDEs in serum and breast milk (APHL 2004, 2006). In 2004, New Hampshire received about 300,000 to support its biomonitoring program (APHL 2004). 

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