Hydrochemical variability at the Upper Paraguay Basin and Pantanal wetland

Abstract

Compartmentalization is a prerequisite to understand large wetlands that receive water from several sources. However, it faces the heterogeneity in space and time, resulting from physical, chemical and biological processes that are specific to wetlands. The Pantanal is a vast seasonally flooded continental wetland located in the centre of South America. The chemical makeup of the waters that supply the Pantanal (70 rivers) has been studied in order to establish a compartmentalization of the wetland based on soil-water interactions. A PCA-based EMMA (End-Members Mixing Analysis) procedure shows that the chemistry of the rivers can be regarded as a mixture of 3 end-members, influenced by lithology and land use, and delimiting large regions. Although the chemical composition of the end-members changed between dry and wet seasons, their spatial distribution was maintained. The results were extended to the floodplain by simple tributary mixing calculation according to the hydrographical network and to the areas of influence for each river when in overflow conditions. The resulting document highlights areas of high geochemical contrast on either side of the river Cuiaba in the north, and of the rivers Aquidauana and Abobral located in the south. The PCA-based treatment on a sampling conducted in the Nhecolândia, a large sub region of the Pantanal floodplain, allowed for the identification and prioritization of the processes that control the geochemical variability of the surface waters. Despite an enormous variability in Electrical Conductivity and pH, all data collected were in agreement with an evaporation process of the Taquari River water, which supplies the region. Evaporation and associated saline precipitations (Mg-calcite, Mg-silicates K-silicates) explained more than 77% of the total variability in the chemistry of the regional surface water sampling

Flooding effect on mineralogical and geochemical changes in alkaline‐sodic soil system of northern Pantanal wetlands, Brazil

“…The water chemistry of the São Lourenço River is quite similar to that of rivers originating from sandstone exposed on the whole eastern border of the Pantanal (Rezende Filho et al, ; Rezende‐Filho et al, ). On the one hand they are low‐mineral waters (i.e., able to favour the elimination of any soluble salts in good drainage conditions).…”

“…The lithology of the São Lourenço River Basin mainly consists of Parana Basin sandstones, with some areas of limestones and other carbonate‐rich rocks. However, these carbonate rocks have little influence on the river chemistry (Rezende Filho et al, ; Rezende‐Filho et al, ). Therefore, the São Lourenço River water has low electrical conductivity (20 to 40 μS cm −1 ) but shows positive calcite residual alkalinity (RA calcite ) (i.e., higher alkalinity than calcium (Ca) content) (Barbiero, Valles, & Cheverry, ).…”

“…Similar patterns of alkaline evolution have also been described in wetlands of Europe (Armenteros, Angeles Bustillo, & Blanco, ), southern Africa (Deocampo, ; Humphries et al, ), south‐eastern Australia (Reid & Mosley, ) and California (Graham & O'Geen, ; Lee, Graham, Laurent, & Amrhein, ). However, the chemical composition of water in the Pantanal varies widely, from saline to alkaline (Rezende Filho et al, ), and how this impacts the soil mineralogy of northern Pantanal is not well known.…”

Diversidade taxonômica e funcional de comunidades microbianas em lagoas salino-alcalinas do Pantanal brasileiro

“…O fenômeno de floração é comumente descrito em lagos salino-alcalinos, podendo ser sazonais ou permanentes (GRANT et al, 1990). Esse fenômeno consiste na multiplicação significativa da biomassa devido a um desequilíbrio entre o crescimento do fitoplâncton e os processos de perda (CARSTENSEN et al, 2007) (BARBIÉRO et al, 2007;MARIOT et al, 2007;REZENDE FILHO, 2012…”

“…Tanto a origem como o funcionamento hidro-biogeoquímico dessas lagoas tem sido objeto de muitos estudos (BARBIÉRO et al, 2007;MARIOT et al, 2007;REZENDE FILHO, 2012). Sakamoto (1997)…”