Redox zonation for different groundwater flow paths during bank filtration: a case study at Liao River, Shenyang, northeastern China

Su, Xiaosi; Lu, Shuai; Yuan, Wenzhen; Woo, Nam Chil; Dai, Zhenxue; Dong, Weihong; Du, Shanghai; Zhang, Xinyue

Redox zonation for different groundwater flow paths during bank filtration: a case study at Liao River, Shenyang, northeastern China | Zonation d’oxydoréduction pour différentes voies d’écoulement d’eaux souterraines lors du processus de filtration par Berge: une étude de cas Sur la rivière Liao, Shenyang, Nord-Est de la Chine Zonificación redox para diferentes trayectorias de flujo de aguas subterráneas durante la filtración de banco: un estudio de Caso en el río Liao, Shenyang, noreste de China 河岸入渗期间不同地下水流通道的氧化还原反应成带现象:中国东北沈阳辽河的一个研究案例 Zona redox em diferentes caminhos do fluxo de água subterrânea durante a filtração em margem: um estudo de Caso no rio Liao, Shenyang, nordeste da China

2018

The spatial and temporal distribution of redox zones in an aquifer is important when designing groundwater supply systems. Redox zonation can have direct or indirect control of the biological and chemical reactions and mobility of pollutants. In this study, redox conditions are characterized by interpreting the hydrogeological conditions and water chemistry in groundwater during bank infiltration at a site in Shenyang, northeast China. The relevant redox processes and zonal differences in a shallow flow path and deeper flow path at the field scale were revealed by monitoring the redox parameters and chemistry of groundwater near the Liao River. The results show obvious horizontal and vertical components of redox zones during bank filtration. Variations in the horizontal extent of the redox zone were controlled by the different permeabilities of the riverbed sediments and aquifer with depth. Horizontally, the redox zone was situated within 17 m of the riverbank for the shallow flow path and within 200 m for the deep flow path. The vertical extent of the redox zone was affected by precipitation and seasonal river floods and extended to 10 m below the surface. During bank filtration, iron and manganese oxides or hydroxides were reductively dissolved, and arsenic that was adsorbed onto the medium surface or coprecipitated is released into the groundwater. This leads to increased arsenic content in groundwater, which poses a serious threat to water supply security.

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