Hydro-chemical evolution of groundwater and mixing between aquifers: a statistical approach based on major ions

Linhua Sun,Herong Gui

doi:10.1007/s13201-014-0169-7

Linhua Sun, Herong Gui

Open Access

https://doi.org/10.1007/s13201-014-0169-7

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Abstract

Geochemical analysis is a useful tool in hydrogeological assessment, particularly in constructing a conceptual model of a hydrogeological system. In this study, major ion concentrations of 53 groundwater samples from the coal-bearing aquifer in the Qidong coal mine, northern Anhui Province of China have been processed by statistical analysis for understanding either hydro-chemical characteristics or hydrological evolution, which will be useful for the safety of coal mining. The results suggest that most of the samples are Na–SO4 and Na–HCO3 types, and their hydro-chemical compositions are mainly controlled by dissolution of more soluble minerals (e.g. calcite) and weathering of silicate minerals (e.g. plagioclase). Two groups of samples have been subdivided by quantile and scatter plots of factor scores, one is related to different degrees of water–rock interactions and another is related to groundwater mixing. Moreover, four end members have been identified and the mixing calculation suggests that the groundwater samples affected by mixing have 20–100 % contribution from the loose layer aquifer (LA), and therefore, groundwater from the LA in the coal mine should be taken seriously during coal mining. The study demonstrated that statistical analysis is useful for connecting the hydrochemistry of groundwater with hydrological evolution of the aquifer.

Highlights

IntroductionUnderstanding the mixing between groundwater and other water bodies is an important work for groundwater management, because it is a common phenomenon and important process governing groundwater chemistry in many natural systems, and a large number of studies have been processed (Schramke et al 1996; Johannesson et al 1997; Laaksoharju et al 1999, 2008; Rueedi et al 2005; Long and Valder 2011; Valder et al 2012; Morales-Casique 2012)
Major ion concentrations of 53 groundwater samples from the coal-bearing aquifer in the Qidong coal mine, northern Anhui Province of China have been processed by statistical analysis for understanding either hydro-chemical characteristics or hydrological evolution, which will be useful for the safety of coal mining
The results suggest that most of the samples are Na–SO4 and Na–HCO3 types, and their hydro-chemical compositions are mainly controlled by dissolution of more soluble minerals and weathering of silicate minerals

Summary

Introduction

Understanding the mixing between groundwater and other water bodies is an important work for groundwater management, because it is a common phenomenon and important process governing groundwater chemistry in many natural systems, and a large number of studies have been processed (Schramke et al 1996; Johannesson et al 1997; Laaksoharju et al 1999, 2008; Rueedi et al 2005; Long and Valder 2011; Valder et al 2012; Morales-Casique 2012). These studies demonstrated that the concentration of solutes of mixtures between two end members follows a linear relation, while chemical reactions of reactive constituents introduce significant nonlinear effects (Wigley and Plummer 1976)

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