Amazon River dissolved loads

Fig. 9-8 Histogram of dissolved solids of samples from the Orinoco and Amazon River basins and corresponding denudation rates for morpho-tectonic regions in the humid tropics of South America (Stal-lard, 1985). The approximate denudation scale is calculated as the product of dissolved solids concentrations, mean armual runoff (1 m/yr), and a correction factor to account for large ratios of suspended load in rivers that drain mountain belts and for the greater than average annual precipitation in the lowlands close to the equator. The correction factor was treated as a linear function of dissolved solids and ranged from 2 for the most dilute rivers (dissolved solids less than lOmg/L) to 4 for the most concentrated rivers (dissolved solids more than 1000 mg/L). Bedrock density is assumed to be 2.65 g/cm. (Reproduced with permission from R. F. Stallard (1988). Weathering and erosion in the humid tropics. In A. Lerman and M. Meybeck, Physical and Chemical Weathering in Geochemical Cycles," pp. 225-246, Kluwer Academic Publishers, Dordrecht, The Netherlands.)...

The species distribution (Table 6.9) calculated for the brine differs from that of seawater and Amazon River water in the large molalities predicted and the predominance of ion pairs such as NaCl, CaCl+, and MgCl+. The complex species make up a considerable portion of the brine s dissolved load. 

Figure 5 Downstream evolution of vanadium, nickel, and manganese concentrations measured in the dissolved load of the Amazon river showing different possible behaviors of trace elements in river systems. Major solutes and TDS follow the similar pattern to that of vanadium and correspond to a dilution of Andean waters by waters from the Amazonian lowlands (source Seyler and Boaventura, 2002).

Gibb, R.J., Amazon River Environmentai factors that control its dissolved and suspended load. Science, 1967, 156, 1734-37. 

In order to compare the dissolved and suspended trace elements loads of the different types of rivers of the Amazon basin, we computed the mass of each element in one liter of river water. Several observations are apparent from Fig. 16.8. 

Figure 10.18. Effect of pH on residual metal concentration in fresh waters. Dissolved zinc is plotted against pH. (a) Zinc in relatively undisturbed major rivers including the Yangtze (Chiang Jiang) and tributaries of the Amazon and Orinoco, (b) Zinc normalized to total dissolved solids for the same set of major rivers, (c) Zinc in pH-adjusted aliquots of Mississippi River water (April 1984, 103 mg liter suspended load, pH 7.7) the adjusted aliquots were allowed to equilibrate overnight before filtration and analysis. (From Shiller and Boyle, 1985.) (d) Zinc in different mountain lakes in the southern parts of the Swiss Alps. These lakes are less than 10 km apait, so that the atmospheric inputs can be considered to be uniform over this scale, but their water composition (pH) is influenced by different bedrocks in their catchments. A similar dependence on pH has also been observed for Cd and Pb but this dependence is less pronounced with Cu(II) when solute complex formation counteracts adsorption (data 1983-1992). (From Sigg et al., 1995, in press.)...

The data (Table I, Figures 2 and 3) clearly show that the majorities of the Cu, Cd, Zn, and Ni were present in the dissolved phase most of the Fe was found in the solid phase. Dissolved and solid phases were equally important for Mn content in these systems. These trends were consistent with the transport of metals in watersheds in eastern Tennessee (24), Maryland (25), and Australia (26) as well as earlier work (27) on the Upper Three Runs Creek and Steel Creek watersheds. However this data does not support the previous work (11) on the transport of metals by the Amazon and Yukon Rivers where most of the Fe as well as the other trace elements were associated with the various components of the solid phase. These differences may be resolved by considering the TSS load which was much higher in the Amazon and... 

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