Andean Amazon

Klammer, G. (1984). The relief of the extra-Andean Amazon basin. In "The Amazon, Limnology and Landscape Ecology of a Mighty Tropical River and its Basin" (H. Sioli, ed.), pp. 47-83. Dr. W. Junk Publishers, Dordrecht, The Netherlands. 

Klammer, G. 1984. "The relief of the extra-Andean Amazon basin." In The Amazon, ed. H. Sioli... 

Figure 1 Cumulative distributions of major dissolved elements in pristine regions (a) K, (b) Si02, (c) HCO, and (d) Na. A Central and lower Amazon, B Japan, C Andean Amazon Basin, D Thailand, E Mackenzie Basin, F French streams, G temperate stream model, H monolithologic miscellaneous French streams, I major world...

The integrated conceptual model for nutrient transport downstream in the Andean-Amazon transect (Towsend-Small et al, 2005), which may be applied to other tropical mountain systems, is thus as follows Above... 

However, not all the chloride is cyclic, a fact first appreciated in recent years. An example comes from a detailed study of river geochemistry conducted in the Amazon Basin. In the inland regions, rains typically have a chloride content of 10 pM, while major inland tributaries have chloride contents of 20-100 pM. These data suggest that only 25% of the Cl is cyclic, whereas 75% is derived by weathering of evaporites. Indeed, 90% of this 75% can be shown to have its origin in the Andean headwaters, derived from evaporites that make up only 2% of the area of the Amazon Basin (Stallard and Edmond, 1981). As the ratio of sulfate to chloride in evaporite deposits is generally much higher... 

In contrast, mass wasting represents truly episodic inputs of particulate matter to streams, such as in the form of landslides in mountainous regions. Despite their geographic concentration in the Andean portion of the Amazon basin, they codetermine the chemical and mineralogical... 

Andean contributions to the biogeochemistry of the Amazon River system. Bulletin de ITnstimt Franfais des Etudes Andines 24 425-437. 

Three processes primarily control the forms and fluxes of particulate and dissolved materials in the Amazon mainstem input, mixing, and within-reach processing. With respect to the data presented, the CAMREX program has taken the upstream input to the Brazilian Amazon as the measurements made at Vargem Grande (Fig. 15.1). With the notable exception of the Rio Madeira, all the lower tributaries are more dilute in most chemical species than the upstream input. Consequently, the downstream decreases seen in most variables are due primarily to mixing of Andean white water with dilute, less turbid lowland water (Gibbs 1972, Richey and Victoria 1993,... 

The relationship between alkalinity and FSS concentration and Andean source waters was expected because > 80% of suspended materials and dissolved solids in transport in the Amazon are derived from Andean regions (Gibbs 1972, Stallard 1980, Meade et al. 1985). Although the Andes are also the dominant source of CSS, its seasonal cycle is tied more to the river surface slope than the percent Andean water. In fact, the seasonal pattern of river slope has a nearly identical shape to CSS concentration (Devol et al. 1995). Deposition occurs during periods of low slope (low turbulence), whereas resuspension predominates during high slope (Meade et al. 1985). This changing balance would also explain the relationships between coarse particulate... 

The Amazon basin comprises an area of about 6.4 millions km, extending between the Guyana Shield to the north and the Brazilian Shield to the south with the Andean and sub-Andean regions to the west. 

Variations of river chemistry may reflect variations of the sources. As previously noted the "shield" rivers (Negro and Tapajos) have typically depleted concentrations in As, Sr, Ba, Cu, and V as compared with Andean rivets. The increased proportion of waters from these less solute-rich rivers during the high discharge period of the Amazon contributes to the observed decrease of concentrations. 

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).

Virtually nothing is known about cloud or fog contributions to soil geochemistry in tropical and subtropical mountains and it would be desirable to better understand the various contributors to nutrient inputs, especially considering the importance of frequent fire cycles in lowlands upwind from high elevation ranges such as the Amazon and Orinoco basins and the Andean barrier. 

C. Genera with values in the CCA AX2 < -1 (South West Amazon/Andean Piedmont Plots) ... 

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