Lanthanide interelement fractionation

Fig. 25. Histograms showing lanthanide interelement fractionation for the Atlantic, Indian, and Pacific oceans (data as in fig. 24) (a) Sm/Nd ratio (b) Er/Nd ratio and (c) Ce anomaly. From Bertram and Elderfield (1993).

Figures 23 and 24 (from Bertram and Elderfield 1993) illustrate interelement fractionations. There is a clear regional variation between oceans [fig. 23]. Surface water concentrations of both Er and Nd increase in the following sequence Atlantic > Indian > Pacific. .. This is the reverse of the situation in the deep waters of the oceans.. .. deep waters concentration of the REEs increase in the following sequence Atlantic < Indian < Pacific. The oceanwide trend in surface waters REE concentrations suggests that the primary control is that of REE input from the continents rather than scavenging efficiency for REE removal. Studies of Nd isotopes confirm this key point -continents as the dominant source of lanthanides to oceans (sect. 5.1).

Interelement lanthanide fractionation in the oceans allow insights into basic processes controlling the concentrations and relative abundance of trace elements. The best synthesis of lanthanide fractionation in the oceans appears in Bertram and Elderfield (1993). This subsection relies heavily on this paper and focuses on strictly trivalent elements. 

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