title: The impact of river infiltration on the chemistry of shallow groundwater in a reclaimed water irrigation area.
abstract: Reclaimed water reuse is an effective method of alleviating agricultural water shortages, which entails some potential risks for groundwater. In this study, the impacts of wastewater reuse on groundwater were evaluated by combination of groundwater chemistry and isotopes. In reclaimed water infiltration, salt composition was affected not only by ion exchange and dissolution equilibrium but also by carbonic acid equilibrium. The dissolution and precipitation of calcites and dolomites as well as exchange and adsorption between Na and Ca/Mg were simultaneous, leading to significant changes in Na/Cl, (Ca+Mg)/Cl, electrical conductivity (EC) and sodium adsorption ratio (SAR). The reclaimed water was of the Na-Mg-Ca-HCO3-Cl type, and groundwater recharged by reclaimed water was of the Na-Mg-HCO3and Mg-Na-HCO3types. The hydrogeological conditions characterized by sand-clay alternation led to both total nitrogen (TN) and total phosphorus (TP) removal efficiencies >95%, and there was no significant difference in those contents between aquifers recharged by precipitation and reclamation water. >40years of long-term infiltration and recharge from sewage and reclaimed water did not cause groundwater contamination by nitrogen, phosphorus and heavy metals. These results indicate that characteristics of the study area, such as the lithologic structure with sand-clay alternation, relatively thick clay layer, and relatively large groundwater depth have a significant role in the high vulnerability.
authors: China University of Geosciences, Beijing 100083, China.
authors: Shiyang
authors: S
authors: Yin
authors: State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of Water Resources and Hydropower Research, Beijing 100048, China; Engineering Technique Research Center for the Exploration and Utilization of Non-Conventional Water Resources and Water Use Efficiency, Beijing 100048, China. Electronic address: wenyongwu@126.com.
authors: Wenyong
authors: W
authors: Wu
authors: Engineering Technique Research Center for the Exploration and Utilization of Non-Conventional Water Resources and Water Use Efficiency, Beijing 100048, China.
authors: Honglu
authors: H
authors: Liu
authors: Rural Energy and Environment Agency, Ministry of Agriculture, PRC, Beijing 100125, China.
authors: Zhe
authors: Z
authors: Bao
mesh_terms: D000383:Agriculture; D003247:Conservation of Natural Resources / Q000379:methods*; D004784:Environmental Monitoring / Q000379:methods; D004787:Environmental Pollution / Q000032:analysis*; D060587:Groundwater / Q000737:chemistry*; D007474:Ion Exchange; D045483:Rivers / Q000737:chemistry*; D012987:Soil / Q000737:chemistry; D062065:Wastewater / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D012987:Soil; D062065:Wastewater; D014874:Water Pollutants, Chemical
keywords: Groundwater chemistry; Irrigation; Isotope; Reclaimed water; Vulnerability