Biogeochemical characterization of water, plants and soils in the floodplains of the Northern Pantanal of Mato Grosso (Brazil) – A comparison with Central-Amazonian floodplains

Various chemical parameters of water, soils and plants in the savanna wetland Pantanal of Mato Grosso and the elevated plateau Chapada dos Guimaraes in its catchment area were determinded for biogeochemical characterization. In the Pantanal, aquatic, semiaquatic and semiterrestrial soils were analyzed and differences in the content of organic material, total N and P, NO3, NH4, o-PO4 and exchangeable base cations of the soils according to the duration of inundation were obtained. At the semiaquatic site the accumulation of organic material was enhanced by aquatic macrophytes which fix the nutrients of the water and die off during dryness. The soils and herbaceus macrophytes in the catchment area Chapada dos Guimaraes are extremely poor in nutrients. Comparisons with the Central-Amazonian nutrient-rich whitewater floodplain várzea and nutrient-poor blackwater floodplain igapó were done for a general evaluation of the nutrient status. The content of nutrients of the Pantanal waters were similar to the Amazonian whitewater, but poorer in Ca and richer in Mg. In spite of lower contents of exchangeable base cations in the soil of the Pantanal compared to the várzea soil, the sum of base cations in the respective macrophytes was higher. The lower the amounts of exchangeable base cations in the soil, the higher was the uptake efficiency of the respective macrophytes. Some similarities in the composition of the exchangeable base cations between the Pantanal and the várzea soils and between the Chapada dos Guimarães and igapó soils are shown