Nickel seawater speciation

If copper interactions were minimized in real seawater, abundant metals of lesser sulfide affinity would take up some of the slack. ITiis is partially evident from analyses of the type in Table III. For example, nickel has mixed layer concentrations on the order of nanomolar (22), and its sulfide equilibria and inorganic seawater speciations may resemble those of zinc (lv-19.31.32). Titration, however, should only lower free sulfide to a Table m SH equivalence point, or, to roughly picomolar. In a follow up to 1Z, Dyrssen and coworkers treat Cu(II) as a variable parameter, and find that in its absence, nickel, zinc and lead can all become sulfides while the bisulfide ion still hovers well above pM (18). Again, it must be emphasized that error margins in the various equilibria remain to be investigated. 

Advantages High analysis rate 3-4 elements per hour Applicable to many more metals than voltammetric methods Superior to voltammetry for mercury and arsenic particularly in ultratrace range Disadvantages Nonspecific absorption Spectral interferences Element losses by molecular distillation before atomisation Limited dynamic range Contamination sensitivity Element specific (or one element per run) Not suitable for speciation studies in seawater Prior separation of sea salts from metals required Suspended particulates need prior digestion About three times as expensive as voltammetric equipment Inferior to voltammetry for cobalt and nickel... 

Donat and Bruland [804] studied the speciation of copper and nickel in seawater by competitive ligand equilibration-cathodic stripping voltammetry, differential pulse ASV, and graphite furnace AAS. 

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