Effects of irrigation-induced water table fluctuation on arsenic mobilization in the unsaturated zone of the Datong Basin, northern China

A Critical Review of Groundwater Table Fluctuation: Formation, Effects on Multifields, and Contaminant Behaviors in a Soil and Aquifer System

“…In a field measurement, the groundwater table significantly rises after irrigation, and this increase is found to be related to the leaching rate of irrigation flux (Figure ). , Currently, more people are recycling purified wastewater for agricultural irrigation. Unreasonable introduction of irrigation into surface water can cause a shallow groundwater table to rise and large-scale secondary salinization .…”

“…The presence of GTF zones not only affects the physical structure but also causes a series of chemical changes. Groundwater samples in the early stage turn low pH and high E h into high pH and low E h as irrigation continues in the Datong Basin . Previous studies have shown that oxygen may be trapped in unsaturated soil and saturated aquifers during GTF. − Oxygen-deficient groundwater is carried by the uplift GTF zone to gain the dissolved oxygen (DO) of pores in the upper vadose zone (Figure ).…”

“…The different spatial and temporal distribution of the DO concentration generates a change in E h . The periodic and seasonal variation of the oxidation reduction potential (ORP) at a stated depth is synchronized with the change in the groundwater table. ,, In addition to the changing ORP, a varying groundwater table also changes the redox components in groundwater, such as nitrate (NO 3 – ), manganese (Mn), iron (Fe), and sulfate (SO 4 2– ) . The redox components apparently indicate that the groundwater environment is in exchange with oxidizing and reducing components.…”

“…In addition, increased evaporation and irrigation accelerate rock mineralization, successive saturation, and precipitation of less soluble salts . Excessive exploitation of groundwater leads to the rapid generation of a fluctuation zone and changes in the redox conditions in the vadose zone . Thus, transformation of the redox environment affects the growth and reproduction of microorganisms, because it provides donors and favorable environments.…”

“…2,20−22 Fe(II) and Fe(III) play important roles in determining the transformation and redistribution of Cr 140,168 and As. 64,142,145 Environmental Science & Technology addition, researchers found that higher emission of nitrous oxide (N 2 O) appeared during the period with a low water table in the Tibetan Plateau, because the variation of the water level changed the oxygen content and induced nitrification and denitrification to redistribute N. 134 In conclusion, the transformation of various nitrogenous compounds (NO 3 − , NH 4 + , and NO 2 − ) caused by variation of the hydrodynamic field and biochemical field during GTF and the identification of dominant nitrogenous components need to be studied further. Additionally, the fixation and transformation of nitrogenous compounds caused by dynamic changes in environmental factors (such as E h , soil respiration, dry and wet distribution, temperature variation, and microbial nitrogen fixation) under the effect of multiple scenarios (such as rainfall, tide, water recharge and drainage, and human activities) have not been sufficiently examined.…”