Migration characteristics of atrazine in porous media during managed aquifer recharge

Xiuxiu Sun,Weidong Zhao,Shisong Qu,Qingyang Zheng,Weiping Wang

doi:10.2166/ws.2021.204

Abstract

Abstract To study the influences of sand and gravel layer and groundwater velocity of Yufuhe River on atrazine migration, adsorption-desorption and sand column experiments were carried out. Results show that the adsorption capacity of montmorillonite, raw sand and washed sand to atrazine sequentially weakens. In different media, the time for atrazine concentrations to peak in washed sand with montmorillonite (WSM), raw sand and washed sand is 60, 135 and 105 minutes respectively, and the peak concentration accounts for 84, 90 and 95% of the initial concentrations. Under different flow rates, the peak time in washed sand at flow rates of 100, 150 and 200 mL/min is 135, 105 and 75 minutes, and the peak time in WSM is 90, 60 and 45 minutes, respectively. Results from this study indicate that increasing flow velocity and suspended colloids concentrations can promote the migration of atrazine in aquifers, while the presence of clay minerals in sand and gravel layers can reduce atrazine migration. Thus, during Yellow River water recharging, the sand and gravel layer of Yufuhe River is helpful to protect the aquifer, but the colloids-associated migration of atrazine can contaminate groundwater in underlying karst aquifer.

Highlights

Yellow River water is the main source of water supply for most cities in Shandong province (Gao et al 2015)
Based on the work of Zheng et al (2018), this study further explored the effects of clay minerals and groundwater flow velocity on atrazine migration, so as to provide references for recharge projects
The raw sand of the sand-gravel layer from Yufuhe River is selected, with low organic matter content, so clay minerals play an important role in the adsorption of atrazine

Summary

Introduction

Yellow River water is the main source of water supply for most cities in Shandong province (Gao et al 2015). 85% of the suspended particles in Yellow River water are removed, and the turbidity is 3–5 NTU, but fine suspended particles (including clay minerals colloids) with particle size less than 74 μm, trace organic matters and odorous substances still remained (Chien et al 2018; Hou et al 2021). As one of the main water sources of Yufuhe River recharge project, the Yellow River water stored by the Yellow River Diversion Reservoir is transported to the upper reaches of Yufuhe River by pumping station to recharge karst groundwater. The effects of the contents and characteristics of colloids on the migration of atrazine and the adsorption-desorption characteristics of atrazine in different porous media and different flow rates are studied, which is of great significance to maintain the long-term operation of the MAR project and protect the karst groundwater

Methods

Results

Conclusion