Dissolved Amazon River estuary

In more recent studies, Feng et al. (1999) calculated a Th water column residence time of 2 to 12 days in the Hudson River estuary. McKee et al (1986b) determined that " Th was removed on a time scale of a day or less in the very particle-rich environment of the Yangtze River estuary. In the Amazon River estuary, another particle-rich environment, McKee et al. (1986a) determined that the residence time of dissolved " Th ranged from 2 to 4 days. McKee et al. (1986a) also calculated apparent distribution... 

Skrabal, S.A. (1995) Distributions of dissolved titanium in Chesapeake Bay and the Amazon River Estuary. Geochim. Cosmochim. Acta 59, 2449-2458. 

Milliman, J. D., and E. A. Boyle. 1975. "Biological uptake of dissolved silica in the Amazon River estuary." Science 189 995-997. 

Fig. 12. Dissolved Nd concentration vs. salinity for the Amazon and Fly (Papua New Guinea) River estuaries. The bottom part is an expanded (> salinity 3) section of the top part. The bottom part also contrasts the surface and deep waters from the Amazon Estuary and shows the concentration of the open ocean Atlantic surface waters which are transported into the Amazon estuary. Amazon data from Sholkovitz (1993) Fly data from...

The Amazon and Fly River (Papua New Guinea) estuaries serve as good examples of the five features outlined above. The salinity distribution of dissolved Nd (<0.22 pm) in fig. 12 is representative of the other bivalent lanthanides. This figure contains data for both surface and deep waters the bottom part B is an expanded scale for S >3 samples. The Fly and Amazon data sets have Nd-salinity distributions for surface waters which are remarkably similar and exhibit the same two major features (1) removal of dissolved lanthanides in the low (0-5) salinity region and (2) desorption in the seaward region. Hence, it appears that the removal process and the release process (desorption) are decoupled. 

The large-scale removal of dissolved lanthanides in the low salinity region is an ubiquitous feature of estuaries (Martin et al. 1976, Goldstein and Jacobsen 1988c, Sholkovitz and Elderfield 1988, Elderfield et al. 1990, Sholkovitz et al. 1992, Sholkovitz 1993, 1995). As illustrated for the Amazon and Fly (fig. 12), the Nd concentrations of surface waters decrease sharply between the river (S 0) and a salinity of 5-7. In the case of the Amazon, Nd removal represents approximately 95% of the river-borne dissolved flux. Of all the trace element distributions reported for estuaries, the lanthanides stand out as being the most similar to dissolved Fe and humic acids, both of which undergo extensive removal in estuaries. Since there is also a strong correlation between... 

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