Investigation of Geochemical Characteristics and Controlling Processes of Groundwater in a Typical Long-Term Reclaimed Water Use Area

Yong Xiao,Xingyao Pan,Shiyang Yin,Yali Cui,Xiaomin Gu,Jingli Shao

doi:10.3390/w9100800

Yong Xiao, Xingyao Pan + Show 4 more

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https://doi.org/10.3390/w9100800

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Abstract

The usage of reclaimed water can efficiently mitigate water crises, but it may cause groundwater pollution. To clearly understand the potential influences of long-term reclaimed water usage, a total of 91 samples of shallow and deep groundwater were collected from a typical reclaimed water use area during the dry and rainy seasons. The results suggest both shallow and deep groundwater are mainly naturally alkaline freshwater, which are composed mainly of Ca-HCO3, followed by mixed types such as Ca-Na-HCO3 and Ca-Mg-HCO3. A seasonal desalination trend was observed in both shallow and deep aquifers due to dilution effects in the rainy season. Groundwater chemical compositions in both shallow and deep aquifers are still dominantly controlled by natural processes such as silicate weathering, minerals dissolution and cation exchange. Human activities are also the factors influencing groundwater chemistry. Urbanization has been found responsible for the deterioration of groundwater quality, especially in shallow aquifers, because of the relative thin aquitard. Reclaimed water usage for agricultural irrigation and landscape purposes has nearly no influences on groundwater quality in rural areas due to thick aquitards. Therefore, reclaimed water usage should be encouraged in arid and semiarid areas with proper hydrogeological condition.

Highlights

Water scarcity has been a great threat to socioeconomic development as well as ecology in many parts of the world, especially in arid and semi-arid regions [1,2,3,4]
In order to alleviate shortages, non-conventional water resources such as wastewater and reclaimed water have been widely used for agricultural irrigation and as landscape water for decades [1,8,9]
Wastewater and reclaimed water often have higher concentrations of major ions, heavy metals, nitrogen, phosphorus and other nutrients compared to freshwater [10]

Summary

Introduction

Water scarcity has been a great threat to socioeconomic development as well as ecology in many parts of the world, especially in arid and semi-arid regions [1,2,3,4]. Due to the limited availability of surface water resources and precipitation, groundwater becomes the indispensable source of freshwater for various purposes such as drinking, irrigation and industry [5,6]. Wastewater and reclaimed water often have higher concentrations of major ions, heavy metals, nitrogen, phosphorus and other nutrients compared to freshwater [10]. Their usage may pose risks to environmental quality and human health [1]. Many researches have been conducted to reveal the potential influences of wastewater and reclaimed water usage on plants, soil and groundwater [2,9,10,11,12,13,14,15]

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