The Blocking Effect of Clay in Groundwater Systems: A Case Study in an Inland Plain Area

Abstract

In order to increase understanding of the hydrogeochemical effects that influence changes in the quality of salt water, we investigated the distribution of saline and fresh water in an inland plain area and, in particular, the scarcity of fresh water resources. Taking the inland plain in Jiyang County as a specific case study, samples of undisturbed clay and underground saline water from different depths were collected to examine hydrogeological changes. A wide variety of methods was used to analyze the blocking effect of clay on the chemical characteristics of the groundwater. These include real-time monitoring for field water quality, tests for isothermal adsorption, a factor analysis model, physiochemical analysis, and correlation analysis. Our results show that the optimal adsorption isotherm of clay for Na+, Ca2+ and Mg2+ in groundwater conform to the established Henry and Langmuir equations for adsorption isotherms. The influence of clay mineral types and content on the blockage of Na+, Ca2+ and Mg2+ in groundwater samples were evident at different depths, with the clay adsorption capacity increasing in line with increases in the clay mineral content. Clay at different depths was found to have the strongest blocking effect on Na+ in groundwater, being systematically greater than its effect on Ca2+ and Mg2+. It is believed that the blocking effect of clay has an important influence on the hydrochemical zoning of groundwater in inland plains and the formation of saline water in groundwater systems. This study therefore provides concrete evidence in support of this supposed effect.

Assessing Groundwater Dynamics and Hydrological Processes in the Sand River Deposits of the Limpopo River, Mozambique

“…Due to the meandering nature of the river, the thickness of sand deposits is smallest between two bends, which forces groundwater to flow upwards along the boundary between sands and impermeable clays (see Supplementary Figure 3 and geophysical cross-section in Figure 5A where the sand thickness is shown to reduce toward the southeast) and in this way feeds more permanent reaches inside the river. Xiao et al (2018) and Xing et al (2018), also show that clay layers influence the characteristics of groundwater, confining the groundwater flow, and it may thus contribute significantly to perennial flow. What this further seems to imply is that the sand river aquifer is built up of compartments of larger thickness that may be poorly connected and hence affect the way the sand river responds to groundwater abstractions.…”

Assessment of Groundwater Quality beneath Agriculturally Advanced Region of Northern Alluvial Plain, India

“…Various studies have focused on monitoring and evaluation of the groundwater quality for drinking, irrigation, and industrial purposes using individual parameters (physico-chemical) and various suitable indices (WQI, WAWQI, MCDA, RSC, SAR, PI, %Na, KR, MH, PS, K, and K a ) [10][11][12][13][14][15]. The studies have reported degradation in groundwater quality mainly due to sodium hazard, excessive salt concentration, and nitrate contamination [16][17][18].…”

“…The studies have reported degradation in groundwater quality mainly due to sodium hazard, excessive salt concentration, and nitrate contamination [16][17][18]. Higher sodium concentration in groundwater has been found to limit a plant's healthy growth by decreasing porosity and permeability in clay-dominant soil [11][12][13]. The studies also reported that the concentration of salts impacts agricultural productivity to a large extent [12,14,19].…”