The influence of water/rock − water/clay interactions and mixing in the salinization processes of groundwater

Journal of Hydrology: Regional Studies

卷:13

Damien Gaboury¹  Romain Chesnaux¹  Julien Walter¹  Vincent Cloutier² 

[1] Centre d’études sur les ressources minérales, Groupe de recherche R2eau, Département des sciences appliquées, Université du Québec à Chicoutimi, Saguenay, Québec, Canada, Canada;

[2] Groundwater Research Group, Institut de recherche en mines et en environnement, Université du Québec en Abitibi-Témiscamingue, Campus d’Amos, Amos, Québec, Canada;

关键词: Hydrogeochemistry;    Groundwater salinization;    Precambrian shield;    Granular deposits;    Multivariate analysis;   

DOI  :  10.1016/j.ejrh.2017.07.004

来源: DOAJ

【 摘 要 】

Study region: Groundwater from the Precambrian Shield rock and Pleistocene deposit aquifers in Saguenay-Lac-Saint-Jean region ( >13 000 km2) in the province of Quebec, Canada.Study focus: Interpretations are based on the combination of hierarchical cluster analysis (HCA) results, principal component analysis (PCA), binary plots investigations ([Na+, Ca2+, Br−] vs. Cl−; Ca2+ vs. HCO3−; Ca2+ vs. Na+) and Piper diagram investigations. The HCA and PCA was applied on 321 samples to specifically enable the identification of two very distinct salinization paths that produce the brackish groundwater in the study area.New hydrological insights for the region: The results show that each of the two salinization paths exerts a major and different influence on the chemical signature of groundwater. Groundwater present in the crystalline bedrock naturally evolve from a recharge-type groundwater (Ca-HCO3-dominant) to a type of brackish groundwater (Ca-(Na)-Cl-dominant) due to water/rock interactions (plagioclase weathering and mixing with deep basement fluids). Groundwater evolution in confined aquifers is dominated by water/clay interactions. The term water/clay interactions was introduced in this paper to account for a combination of processes: ion exchange and/or leaching of salt water trapped in the regional aquitard. Mixing with fossil seawater might also increase the groundwater salinity. PCA revealed that Ca2+, Sr2+, Ba2+ are highly correlated with groundwater from bedrock aquifers, while Mg2+, SiO2, K+, SO42−and HCO3− are more representative of the regional confining conditions.

【 授权许可】

Unknown