Saturation index
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The agriculture in Biskra, southeastern Algeria, is based on traditional practices and characterized by small irrigated fields. In the last decades, the increasing demand in water as well as the scarcity of rainfall has forced many... more
The agriculture in Biskra, southeastern Algeria, is based on traditional practices and characterized by small irrigated fields. In the last decades, the increasing demand in water as well as the scarcity of rainfall has forced many farmers to use groundwater of low quality to maintain the profitability of their crops. Unfortunately, this practice seems to be the main harmful factor for soil quality in the region since it is responsible for the salinization of the irrigated areas. Aiming to assess the impact of this phenomenon , the soils of the irrigated perimeter of El Ghrous-a representative rural community located in the west of Biskra-have been analyzed. A set of 82 soil samples was collected from top and subsoil (0-15 and 15-35 cm respectively), on which the following physico-chemical analyzes were performed: Ca 2? , Mg 2? , K ? , Na ? , Cl-, SO 4 2-, HCO 3-, NO 3-, pH, electrical conductivity (EC) and sodium adsorption ratio. A Principal Component Analysis was performed to individuate the geochemical processes that influenced significantly the evolution of soil salinity and its pathways. The results showed a calcium sulfate (CaSO 4) facies with a high risk of salinity and a low to medium risk of alkalinity. The calcite residual alkalinity and generalized residual alkalinity decreased as the solutions became more concentrated. Most of the samples were oversaturated in carbonate minerals (aragonite, calcite, and dolomite) and undersaturated in evaporitic minerals (an-hydrite, gypsum, and halite). Finally, two multiple linear regressions (using cations and anions as independent variables) have been proposed to quantify soil salinity. These equations, with an accuracy of 85 %, can represent a time and money-saving tool for managers and farmers to estimate the EC, in comparison to the traditional estimation methods.
The interaction between surface water and groundwater is a complex process and is considered as an important component for controlling the mining activities. The objective of this study is to understand the interaction between surface... more
The interaction between surface water and groundwater is a complex process and is considered as an important component for controlling the mining activities. The objective of this study is to understand the interaction between surface water and groundwater around a proposed uranium mining site by geochemical modelling. Surface water and groundwater samples along the groundwater flow path were collected from September 2013 to June 2016 across the uranium mineralised region located near Gogi, Karnataka, India. Collected water samples were analysed for major ion and uranium concentrations. This hydrochemical data was used as input in the geochemical modelling code PHREEQC to calculate the uranium speciation and saturation indices. Inverse geochemical modelling was performed along the flow direction by considering the mineralogical composition of host rock. Measurement of surface water and groundwater level indicates that the recharge and discharge of this region were primarily controlled by rainfall. Relation between the temporal variation of rainfall and saturation index of mineral reveals the various scenarios of interaction between surface water and groundwater around the mineralised region. Silicate/carbonate weathering, irrigation return flow and dissolution of evaporites are the major processes indicated by inverse geochemical modelling, which controls the hydrogeochemical evolution of water in this region. Geochemical modelling was effectively used to understand the temporal changes in the interaction between surface water and the groundwater in a uranium mineralised region.
The geochemical analysis was carried out in the center-south portion of the state of Bahia, in the semi-arid region of Bahia, where outcrop the Paramirim Complex, Boquira Unit, Boquira Granite, Veredinha Granite, Serra do Espinhaço,... more
The geochemical analysis was carried out in the center-south portion of the state of Bahia, in the semi-arid region of Bahia, where outcrop the Paramirim Complex, Boquira Unit, Boquira Granite, Veredinha Granite, Serra do Espinhaço, detritus coverings and alluvial deposits. The Boquira Unit is known for lead-zinc mineralization. In this unit operated the Boquira mine, considered the largest lead and zinc mine in Brazil, until it was suddenly abandoned, leaving significant environmental liabilities of toxic metals such as lead, zinc, silver, barium, copper, chromium and nickel. To characterize the groundwater 16 physical-chemical
parameters from 24 wells were used, obtained from the Water and Sanitation Engineering Company of Bahia - CERB. Its classification was made in the Piper Diagram and the ionic relations in meq/L. To evaluate the quality of the water we used the Consolidation Ordinance no 5/2017 of the Ministry of Health and World Health Organization. With the PHREEQC 3.5 hydrochemical model, the saturation index of the analyzed elements was calculated. The results showed predominance of calcium chloride waters (71% of the samples), with ionic relations of type rCa2+>
rMg2+>rNa+ and rCl->rHCO3->rSO42+. Geochemical modeling indicated calcite (CaCO3), dolomite (CaMg(CO3)2) and quartz (SiO2) as the main minerals with a tendency to precipitation. The first two were associated with the dissolution of the Boquira Unit carbonates and the third one with the quartzites of the Serra do Espinhaço Formation. The concentrations of calcium and chloride showed 54% and 25% of the samples above the Maximum Allowable Value for human consumption,
respectively, representing a risk factor to the health of the population in the area.
parameters from 24 wells were used, obtained from the Water and Sanitation Engineering Company of Bahia - CERB. Its classification was made in the Piper Diagram and the ionic relations in meq/L. To evaluate the quality of the water we used the Consolidation Ordinance no 5/2017 of the Ministry of Health and World Health Organization. With the PHREEQC 3.5 hydrochemical model, the saturation index of the analyzed elements was calculated. The results showed predominance of calcium chloride waters (71% of the samples), with ionic relations of type rCa2+>
rMg2+>rNa+ and rCl->rHCO3->rSO42+. Geochemical modeling indicated calcite (CaCO3), dolomite (CaMg(CO3)2) and quartz (SiO2) as the main minerals with a tendency to precipitation. The first two were associated with the dissolution of the Boquira Unit carbonates and the third one with the quartzites of the Serra do Espinhaço Formation. The concentrations of calcium and chloride showed 54% and 25% of the samples above the Maximum Allowable Value for human consumption,
respectively, representing a risk factor to the health of the population in the area.