Presentation on theme: "The chemistry of two streams draining kaolinitic soils Daniel Markewitz (Univ. of Georgia) Ricardo Figueiredo (EMBRAPA) Eric Davidson (Woods Hole Research."— Presentation transcript:
The chemistry of two streams draining kaolinitic soils Daniel Markewitz (Univ. of Georgia) Ricardo Figueiredo (EMBRAPA) Eric Davidson (Woods Hole Research Center) Mercedes Bustamante, Lucilia Parron, and Julio Resende (Univ. de Brasilia)
Objectives: To develop a biogeochemical understanding of streams draining watersheds comprised of highly weathered soils in the Amazon and Cerrado. Compare seasonal patterns of cation concentrations.
Observation of anomalous patterns of increasing streamwater cation concentrations with increasing stream flow.
Mortatti and Probst 2003, Chemical Geology
Streams (Igarapés): Cq = Igarapé Cinquenta e quatro St = Igarapé do Sete Pj = Igarapé Pajeú Study Area: Fazenda Vitoria, Paragominas, Para
Marques et al., 2003 Geoderma Soilscapes in the Cerrado
Gleissolo Haplico Plintossolo Argiluvico Plintossolo Haplico Latossolo Amarelo Depth cm Clay g/kg Microbasin weir Groundwater well Soil profile description (Tarcísio Ewerton Rodrigues, EMBRAPA) Soilscapes in the Eastern Amazon
Soil chemical components In soils of the Fazenda Vitoria and the IBGE
Stream chemical components in the Fazenda Vitoria and the IBGE Reserve
Stage Ht x Concentration relationship for Ca
Ternary diagram for silicate weathering
Conclusion Soil-stream systems in the IBGE do not present anomalous patterns for cation concentrations. Both soilscapes are in equilibrium will kaolinite and continue to desilicate. Stream cation-anion balances in Fazenda Vitoria are unusually and may be receiving important sea salt inputs.