The use of hydrochemical and environmental isotopic tracers to understand the functioning of the aquifer system in the Bou Hafna and Haffouz regions, Central Tunisia

Mejri, Hatem El; Moussa, Amor Ben; Zouari, Kamel

doi:10.1016/j.quaint.2014.04.046

Cited by 26 publications

(6 citation statements)

References 12 publications

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“…Figure showed that most samples displayed an excess of Na + over Cl − , and (SO 4 2− + HCO 3 − ) over (Ca 2+ + Mg 2+ ), which may reflect the contribution of cation exchange process to river water mineralisation (Mejri et al, ). Plots of (Ca 2+ + Mg 2+ –HCO 3 − –SO 4 2− ) in function of (Na + –Cl − ) were used to test the possibility that cation exchange affects river water compositions (Zhu et al, ; Han et al, ).…”

Section: Discussionmentioning

confidence: 99%

“…The excess of (Cl À + SO 4 2À ) over (Ca 2+ + Mg 2 + + Na + + K + -HCO 3 À ) in some samples of Wei River and Luo River may indicate their anthropogenic inputs (Figure 4d). Figure 4 showed that most samples displayed an excess of Na + over Cl À , and (SO 4 2À + HCO 3 À ) over (Ca 2+ + Mg 2+ ), which may reflect the contribution of cation exchange process to river water mineralisation (Mejri et al, 2014). Plots of (Ca 2+ + Mg 2+ -HCO 3 À -SO 4 2À ) in function of (Na + -Cl À ) were used to test the possibility that cation exchange affects river water compositions (Zhu et al, 2011;Han et al, 2013).…”

Section: Stoichiometry Of River Watersmentioning

confidence: 97%

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Spatial characteristics and controlling factors of chemical weathering of loess in the dry season in the middle Loess Plateau, China

Xiao

Zhang

Jin

2016

Hydrological Processes

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Hydrochemistry methods were used to decipher the weathering and geochemical processes controlling solute acquisition of river waters in the dry season in the middle Loess Plateau (MLP), one of the most severely eroded areas and turbid riverine systems in the world. River waters were neutral to slightly alkaline with pH varying from 7.6 to 9.6. The total dissolved solids decreased from northwest to southeast with a mean value of 804 mg/l, much higher than the global average and other large rivers in China. Ternary diagram showed that river waters were dominated by Na+, HCO3−, and Cl− with the main water‐type of HCO3−–Cl−–Na+. Saturation index values, Mg2+, Ca2+, and HCO3− analyses indicated the preferential Ca2+ removal by calcite precipitation. Gibbs plots and stoichiometry plots indicated that the dissolved solutes were mainly derived from rock weathering with minor anthropogenic and atmospheric inputs. Samples in the northwestern basin are also influenced by evaporation. A forward model of mass budget calculation showed that, owing to high soluble characteristics, evaporite dissolution was a major feature of river waters and contributed 41% to the total dissolved cations on average, while carbonate and silicate weathering contributed 28%,and 25% on average, respectively. Besides evaporite dissolution, cation exchange is also responsible for the high concentrations of Na+ in river water. Spatial variations showed that evaporite dissolution and silicate weathering were higher in the northern basin, whereas carbonate weathering was higher in the southern basin. Different from most rivers in the world, the physical erosion rates (varying from 117.7 to 4116.6 t/km2y) are much higher than the chemical weathering rates (varying from 3.54 to 6.76 t/km2y) in the MLP because of the loose structure of loess and poor vegetation in the basin. In the future, studies on comparison of water geochemistry in different seasons and on influence of different types of land use and soil salinization on water geochemistry, denudation rates, and water quality should be strengthened in the MLP. These results shed some lights on processes responsible for modern loess weathering and also indicate the importance of time‐series sampling strategy for river water chemistry. Copyright © 2016 John Wiley & Sons, Ltd.

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Section: Discussionmentioning

confidence: 99%

Section: Stoichiometry Of River Watersmentioning

confidence: 97%

Spatial characteristics and controlling factors of chemical weathering of loess in the dry season in the middle Loess Plateau, China

Xiao

Zhang

Jin

2016

Hydrological Processes

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“…According to irrigation standard limit [91], most of the groundwater samples had calcium levels that are very close to or above the threshold. These relatively important concentrations of calcium may be related to the dissolution of gypsum and the incongruent dissolution of dolomite, known as dedolomitization [95,96]. Indeed, when gypsum dissolves, calcium levels increase, resulting in a state of supersaturation compared to calcite and precipitation.…”

Section: Groundwater Hydrochemical Propertiesmentioning

confidence: 99%

Applying Multivariate Analysis and Machine Learning Approaches to Evaluating Groundwater Quality on the Kairouan Plain, Tunisia

Salem,

Gaagai,

Ben Slimene

et al. 2023

Water

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In the Zeroud basin, a diverse array of methodologies were employed to assess, simulate, and predict the quality of groundwater intended for irrigation. These methodologies included the irrigation water quality indices (IWQIs); intricate statistical analysis involving multiple variables, supported with GIS techniques; an artificial neural network (ANN) model; and an XGBoost regression model. Extensive physicochemical examinations were performed on groundwater samples to elucidate their compositional attributes. The results showed that the abundance order of ions was Na+ > Ca2+ > Mg2+ > K+ and SO42− > HCO3− > Cl−. The groundwater facies reflected Ca-Mg-SO4, Na-Cl, and mixed Ca-Mg-Cl/SO4 water types. A cluster analysis (CA) and principal component analysis (PCA), along with ionic ratios, detected three different water characteristics. The mechanisms controlling water chemistry revealed water–rock interaction, dolomite dissolution, evaporation, and ion exchange. The assessment of groundwater quality for agriculture with respect IWQIs, such as the irrigation water quality index (IWQI), sodium adsorption ratio (SAR), sodium percentage (Na%), soluble sodium percentage (SSP), potential salinity (PS), and residual sodium carbonate (RSC), revealed that the domination of the water samples was valuable for agriculture. However, the IWQI and PS fell between high-to-severe restrictions and injurious-to-unsatisfactory. The ANN and XGBoost regression models showed robust results for predicting IWQIs. For example, ANN-HyC-9 emerged as the most precise forecasting framework according to its outcomes, as it showcased the most robust link between prime attributes and IWQI. The nine attributes of this model hold immense significance in IWQI prediction. The R2 values for its training and testing data stood at 0.999 (RMSE = 0.375) and 0.823 (RMSE = 3.168), respectively. These findings indicate that XGB-HyC-3 emerged as the most accurate forecasting model, displaying a stronger connection between IWQI and its exceptional characteristics. When predicting IWQI, approximately three of the model’s attributes played a pivotal role. Notably, the model yielded R2 values of 0.999 (RMSE = 0.001) and 0.913 (RMSE = 2.217) for the training and testing datasets, respectively. Overall, these results offer significant details for decision-makers in managing water quality and can support the long-term use of water resources.

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“…In conclusion, silicate weathering is the dominant process influencing the material source of ions (Na [39,52]. The chloroalkaline index (CAI) of the groundwater samples can be an indicator of the type and the intensity of the ion exchange reactions between the groundwater and the aquifer matrix [53].…”

Section: Dissolution Materials and Dissolution Processmentioning

confidence: 99%

Hydrochemistry and Isotope Hydrology for Groundwater Sustainability of the Coastal Multilayered Aquifer System (Zhanjiang, China)

Zhou

Lu³

2017

Geofluids

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Groundwater sustainability has become a critical issue for Zhanjiang (China) because of serious groundwater level drawdown induced by overexploitation of its coastal multilayered aquifer system. It is necessary to understand the origins, material sources, hydrochemical processes, and dynamics of the coastal groundwater in Zhanjiang to support its sustainable management. To this end, an integrated analysis of hydrochemical and isotopic data of 95 groundwater samples was conducted. Hydrochemical analysis shows that coastal groundwater is fresh; however, relatively high levels of Cl − , Mg 2+ , and total dissolved solid (TDS) imply slight seawater mixing with coastal unconfined groundwater. Stable isotopes ( 18 O and 2 H) values reveal the recharge sources of groundwater in the multilayered aquifer system. The unconfined groundwater originates from local modern precipitation; the confined groundwater in mainland originates from modern precipitation in northwestern mountain area, and the confined groundwater in Donghai and Leizhou is sourced from rainfall recharge during an older period with a colder climate. Ionic relations demonstrate that silicate weathering, carbonate dissolutions, and cation exchange are the primary processes controlling the groundwater chemical composition. Declining trends of groundwater level and increasing trends of TDS of the confined groundwater in islands reveal the landward extending tendency of the freshwater-seawater mixing zone.

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The use of hydrochemical and environmental isotopic tracers to understand the functioning of the aquifer system in the Bou Hafna and Haffouz regions, Central Tunisia

Cited by 26 publications

References 12 publications

Spatial characteristics and controlling factors of chemical weathering of loess in the dry season in the middle Loess Plateau, China

Spatial characteristics and controlling factors of chemical weathering of loess in the dry season in the middle Loess Plateau, China

Applying Multivariate Analysis and Machine Learning Approaches to Evaluating Groundwater Quality on the Kairouan Plain, Tunisia

Hydrochemistry and Isotope Hydrology for Groundwater Sustainability of the Coastal Multilayered Aquifer System (Zhanjiang, China)

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