Influence of transport parameters and chemical properties of the sediment in experiments to measure reactive transport in seawater intrusion

Abstract

A study of seawater intrusion under controlled laboratory conditions using multicomponent heterovalent 10 chromatography is presented. The aim was to understand the influence of several variables on hydrogeochemical transport, especially on gypsum precipitation and cationic exchange. In addition, the study aimed to provide experimental data on how water composition changes during simulated seawater intrusion. 15The experimental results show that dispersion modifies the shape of the elution curves for the different solutes for processes such as cation exchange and precipitation-dissolution. The maxima and minima of these curves are very smooth, and entirely absent in several instances. Altering the cation exchange capacity of the sediment produced changes in the height of the calcium peak and in the maxima and minima of magnesium. In several experiments the high concentrations of calcium and sulfate during the first stages of 20 the intrusion induced gypsum precipitation. The subsequent dissolution of the gypsum raised the concentration of sulfate higher than that in seawater. Saturation indices (SI) for gypsum in the samples collected were calculated with PHREEQC (version 2). Gypsum SI values are in agreement with experimental observations. 25Piper diagrams demonstrate that the experimental variables of transport parameters and cation exchange capacity (CEC) strongly influence the hydrochemistry of seawater intrusion. The experimental data deviate 2 substantially from the theoretical freshwater-seawater mixing line, and the shape of the pathway between the end members depends on the experimental conditions. The experimental data obtained during column experiments and the physical and chemical parameters determined in each experiment can be used in the validation of multicomponent transport models. These 5 hydrogeochemical models may aid in the interpretation of field data.

Modelling of colloidal particle and heavy metal transfer behaviours during seawater intrusion and refreshing processes

“…Especially, tracer test was conducted after R2 to examine the parameter change. The rate of fluid injection was set to 2.676 g/min, and the Darcy velocity was 8.18 cm/hr to mimic the rate of coastal groundwater interaction (Boluda‐Botella et al, ). The colloid‐scale (10 nm to 10 μm) kinetics in this study were dominated by the interaction energy and gravity (Ikni et al, ; Sen & Khilar, ).…”

“…However, this process largely depends on the pH and redox state in the seawater–freshwater interaction. Extensive studies have focused on regional geophysical characteristics; water and solute behaviour in coastal aquifers, including field investigations of coastal subsurface geological formations and geochemical characterization (Cherubini & Pastore, ; Choudhury, Saha, & Chakraborty, ; Liu et al, ); contaminant migration mechanisms in various porous substrate structures (Liu, Mao, Chen, & Barry, ; Xin, Yu, Lu, & Li, ); steady and transient flow conditions in mixing zones (Llopis‐Albert & Pulido‐Velazquez, ; Lu, Kitanidis, & Luo, ); natural hydrodynamic influences in coastal areas (Bakhtyar, Barry, & Brovelli, ; Chang, Clement, Simpson, & Lee, ; Kuan et al, ; Vallejos, Sola, & Pulido‐Bosch, ); canals, drainage networks construction, and groundwater extraction that influence intruding seawater flow (Antonellini et al, ; Werner, Jakovovic, & Simmons, ); and specific chemical properties that influence seawater intrusion (Boluda‐Botella, Gomis‐Yagues, & Ruiz‐Bevia, ; Boluda‐Botella, Valdes‐Abellan, & Pedraza, ; Fadili et al, ; Lambrakis, ). However, studies regarding the microcosmic mechanisms of coastal groundwater interaction processes are relatively insufficient.…”

Fate of parabens and 4-hydroxybenzoic acid in aquifer materials columns during step experiments with fresh and sea waters

“…In column sorption tests, the determination of the hydrodynamic parameters is necessary to adequately explain the behaviour of the different compounds along a column filled with porous media. Different transport parameters such as dispersion can modify the shape of the elution curves for the different solutes present in waters and therefore affect the chemical composition of the groundwater across the flow path in field studies, as reported in Boluda-Botella et al (2008b).…”

Geochemical variations due to salinization in groundwater along the southeast coast of India

“…The chief geochemical process observed in the coastal sedimentary aquifers with clay is ion exchange [22]. The mixing of seawater-freshwater and the ion exchange process are inferred from the ion ratios [23][24][25]. Further, the geochemical nature of the groundwater and the status of the sea water intrusion have been studied in the sedimentary coastal aquifers by using hydrochemical facies evolution diagram [22,24,26,27].…”