School of Engineering and Science - Jacobs University

10 -2 hydrothermal fluid
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sample/PAAS
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river water
marine pore water
estuaries
world seawater
La Ce Pr Nd PmSm Eu Gd Tb Dy Y Ho Er Tm Yb Lu
Figure 5. Average REE and REY distributions in natural waters. Seawater and hydrothermal fluid data
are the same as in Fig. 4. River water is an average of 155 filtered (0.2-0.45 μm) samples with pH
between 5-9, and represents complete REY datasets for rivers in Venezuela, Australia, USA, and
Sardinia (Tosiani et al., 2004; Lawrence et al., 2006; Bau et al. 2006; Cidu and Biddau, 2007), as well as
complete REE data for rivers in France and Argentina (Tricca et al., 1999; Gammons et al., 2005b; Stille
et al., 2006). The marine pore water REE pattern is the average of 89 filtered (0.2-0.45 μm) samples
compiled from isotope dilution REE data for the eastern and western margins of North America
(Elderfield and Sholkovitz, 1987; German and Elderfield, 1989; Sholkovitz et al., 1989; Sholkovitz et al.,
1992), as well as complete REE datasets for pore waters from the western margins of North and South
America (Haley and Klinkhammer, 2003; Haley et al., 2004). Estuary water is an average of 134 filtered
(0.2-0.45 μm) samples with salinities between 1-30 ‰ (mean= 13.8 ‰, median= 14.2 ‰) and represents
instrument neutron activation analysis data for samples from France (Martin et al., 1976), as well as
isotope dilution REE data from estuaries along the margins of North America (Sholkovitz and Elderfeld,
1988; Goldstein and Jacobsen, 1988; Elderfeld et al., 1990; Sholkovitz et al., 1992), Great Britain
(Elderfeld et al., 1990), South America (Sholkovitz, 1993), and Papua New Guinea (Sholkovitz and
Szymczak, 2000). Additionally, estuarine water average incorporates complete REY data for estuaries
from Australia (Lawrence and Kamber, 2006) and Germany (Kulaksız and Bau, 2007).
modern seawater. Therefore, some process or processes must exist that effectively
remove REY from these source solutions upon mixing with ambient seawater.
The distinctly lower REY concentrations found in estuaries relative to river water
(Fig. 5) indicate that significant REY removal occurs during the mixing of freshwater
and seawater. This phenomenon has been noted in previous experimental studies (Hoyle
et al., 1984), as well studies of natural systems (e.g., Elderfield et al., 1990). The
removal of REY in estuaries is due to the coagulation and ‘salting-out’ of the major
REY-carrying phases present in river water, which are Fe-organic colloids smaller than
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