Impacts of Lithological and Anthropogenic Factors Affecting Water Chemistry in the Upper Paraguay River Basin (original) (raw)
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Hydrochemical variability at the Upper Paraguay Basin and Pantanal wetland
Hydrology and Earth System Sciences, 2012
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 composition 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 viewed as a mixture of 3 endmembers, 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 map highlights areas of high geochemical contrast on either side of the river Cuiaba in the north, and of the rivers Aquidauana and Abobral in the south. The PCAbased treatment on a sampling conducted in the Nhecolândia, a large sub region of the Pantanal, allowed the identification and ordering 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 Ksilicates) explained more than 77 % of the total variability in the chemistry of the regional surface water sampling.
Geochemistry of the Upper Paraná River floodplain: study of the Garças Pond and Patos Pond
Journal of Radioanalytical and Nuclear Chemistry, 2015
The aim of this study was to investigate the temporal evolution of the supply of chemical elements to the Upper Paraná River floodplain and identify trends in the geochemistry of its drainage basin. The primary factor that regulates the supply of chemical elements of the Upper Paraná River floodplain is the flood pulse, which can be magnified by the El Niño-Southern Oscillation. Garças Pond is affected by agriculture, urbanization, discharge of industrial effluents and hydroelectric power production activities. Patos Pond is affected by sugarcane burning, gold mining, agriculture and urbanization.
Environmental Geology, 2008
The main ions were measured seasonally during two years at 13 sampling stations in the Salado River and its main tributaries. The importance of each ion was assessed by standard methods used to examine ionic composition and by multivariate methods. The K-means clustering and Principal Component Analysis were applied to the percentages of the major ions. The concentration of the major cations are in the order Na + > Mg 2+ > Ca 2+ > K + and the major anions, Cl-> SO 4 2-> HCO 3-> CO 3 2-, and the salinity was high (mean TDS 2,691 mg l-1) due to sodium chloride. Using the proportions of the ions was possible to identify seven types of water within the basin related to discharges of different river sub-catchments and from endorheic catchments (in a sand dune region) actually connected with the basin by canals. The chemical composition of the basin is consequence of surface waters receiving salts from groundwater, evaporation and weathering of Post-Pampeano materials, and of anthropogenic impact by diversion between subcatchments for flood control. These results allowed us to test the marked effects on the ionic balance of basin at the base of a diversion management from endorheic catchments characterized by high salinity waters.
Remote Sensing of Environment, 2003
Amazônia is one of the most important ecosystems of the planet, containing the largest extent of contiguous tropical rain forest on earth, over 5 million square kilometers. While most of the region remains forested, rapid development has led, over the past two decades, to the destruction of over 589,000 km 2 of forests in Brazil alone. Forest clearing can alter the transport of sediments, organic matter and associated nutrients to the rivers. In this article, we present the results of an integrated analysis of the landscape characteristics, including soil properties, river network, topography, and land use/cover of a tropical meso-scale river. This physical template was developed as a comprehensive tool, based on Remote Sensing and GIS, to support the understanding of the biogeochemistry of surface waters of the Ji-Paraná river basin, State of Rondônia, Western Amazônia. Our primary objective was to demonstrate how this tool can help the understanding of complex environmental questions, such as the effects of land-use changes in the biogeochemistry of riverine systems. River sites and basin characteristics were calculated using the data sets compiled as layers in Arc-Info GIS. A land-use/cover map for 1999 was produced from a digital classification of Landsat 7-ETM + images. To test the effects of the landscape characteristics on river water chemistry, we performed a multiple linear regression analysis. Average slope, river network density, effective cation exchange capacity (ECEC), and proportion of pasture were treated as independent variables. River water electrical conductivity (EC) and Na + , Ca 2 + , Mg 2 + , K + , Cl À and PO 4 3 À concentrations were the dependent variables. Spatially, higher values of all ions were associated with areas dominated by pasture, with the highest concentrations found in the central part of the basin, where pasture areas are at a maximum. As the river enters the lower reaches, forests dominate the landscape, and the concentrations drop. The percentage of the basin area covered by pasture was consistently the best predictor of EC (r 2 = 0.872), PO 4 3 À (r 2 = 0.794), Na + (r 2 = 0.754), Cl À (r 2 = 0.692) and K + (r 2 = 0.626). For Ca 2 + , both ECEC (r 2 = 0.538) and pasture (r 2 = 0.502) explained most of the observed variability. The same pattern was found for Mg 2 + (r 2 = 0.498 and 0.502, respectively).
RBRH, 2019
In the upper Paraguay River basin, which includes the Pantanal, one of the largest wetlands in the world, rivers connection the surrounding upland plateaus with lowland floodplains. Agriculture, erosion, urban effluent, and hydropower in the uplands can alter the transport of materials by rivers to the Pantanal. Information about material transport, particularly nutrients, is still insufficient to evaluate changes. In this study we estimated rates of dissolved and suspended material transport from the upland watersheds into the Pantanal, and through the Paraguay River, and calculated mass balances of these flows to reveal net losses and gains inside the Pantanal. We sampled fifteen tributaries and the Paraguay River for seven years. The annual water balance in the basin was almost complete, with a deficit of only 11%. Predicted:Observed ratios close to one indicated a near balance between inputs and outputs for dissolved solutes and nutrients, however sedimentation losses of suspend...
Environmental Earth Sciences, 2016
In coastal wetlands, the interaction between groundwater, surface water and marine or estuarine water determines the water chemistry; variations in the water balance may be of influence as well. The objective of this work was to assess how the rainfall regime affects the hydrological and geochemical processes that regulate the quality of surface and groundwater in the Samborombón Bay coastal wetland. We analyzed the water balances and chemical data of surface and groundwater during a dry and a wet period. Results show that the rainfall regime regulates water quality in the three hydrological units defined for the region (i.e., groundwater in the coastal plain, groundwater in the shell ridges and surface water in the coastal plain). In the water balance corresponding to a dry period, real evapotranspiration is similar to precipitation. In such conditions, in the coastal plain, the halite and gypsum salts precipitate. Subsequently, the rain or the tidal flow dissolves them, and they enter the water table by infiltration. The lowering of the water table favors the oxidation of sedimentary pyrite and the contribution of sulfates. The oversaturation of calcium carbonates in groundwater causes their precipitation, both in the coastal plain and in the shell ridges. The chemistry of surface water depends on the influence generated by the tidal inflow and groundwater discharge. During the wet periods, precipitation is higher than real evapotranspiration, leading to the infiltration of water excess toward the water table and the increase in surface runoff; this causes a decrease in the concentration of ions dissolved by dilution. This rainfall regime hinders the formation of evaporite salts (gypsum and halite) and leads to the undersaturation of groundwater with respect to calcite, allowing the dissolution of carbonates. As regards the chemical composition of the surface water in the coastal plain, the surface runoff in the drainage basin is more significant than the groundwater discharge and the tidal inflow. It can be concluded that the alternation of dry and wet periods in the Samborombón Bay wetland causes the rainfall regime to be a determining factor in the different hydrological and geochemical processes affecting the quality of surface and groundwater.
Geomorphology, 2009
The relationship between geomorphological features and water geochemistry was studied for a group of mountainous rivers (from~900 to~2200 m a.s.l.) with similar geology and climate, in the Sierras Pampeanas of Córdoba (Argentina, 31°30′, 32°00′S, and 64°30′, 65°10′W). A multivariate approach was used to identify three morphological domains that describe the set of sampled rivers, namely "size" dominance, slope dominance, and drainage density dominance. The links between physicochemical and geomorphological variables show that "size" dominance is mostly related to major ions, conductivity, and pH, which tend to increase downstream. Slope dominance is associated with the total concentration of heavy metal (i.e., high heavy metal concentrations are associated with relatively flat areas with slightly acid to circumneutral pH, which promotes desorption). The drainage density dominance results in an association between well-drained catchments and low Cl − concentration (i.e., preserving the chemical signature of atmospheric precipitation).
Rainwater chemestry at the western savannah region of the Lake Maracaibo Basin, Venezuela
Water, Air, & Soil Pollution, 1995
The major part of Venezuela oil production is located in and around the Lake Maracaibo Basin. The samples were collected over a 1-year period at Catatumbo and La Esperanza sites. The rainwater was acidic, with a VWA-pH of 4.6 for Catatumbo and 4.2 for La Esperanza. This acidity is made up in 93% by inorganic + acids (mainl~ H2SO4) , and NH 4 is the major cation which buffer the acidity of precipitation. An excess of sulfa:e (SO 4) > 96% was obtained in both sites. Correlation analysis shows that H + is strongly correlated with SO 4. Anthropogenic air pollution from oil fields (H2S) and the burning of sulphur-bearing fuels (SO2) are probably the dominant sources; however, the lack of correlation between the H + and NO 3-levels would appear to indicate that the SO 4 is also of biogenic origin (H2S-DMS from Sinamaica Lagoon-Lake Maracaibo-and the Caribbean). Statistical analysis of the pooled data indicated that the concentration differences between Catatumbo and La Esperanza sites are not significant at 99% confidence level.