*Article* **An Experimental Study on the Migration of Pb in the Groundwater Table Fluctuation Zone**

**Jihong Qu 1,2,\*, Tiangang Yan 1,2, Yifeng Zhang 1,2, Yuepeng Li 1,2, Ran Tian 1,2, Wei Guo 1,2 and Jueyan Jiang 1,2**


**Abstract:** As a result of fluctuations in the shallow groundwater table, hydrodynamic conditions change alongside environmental conditions and hydrogeochemical processes to affect pollutant migration. The study aimed to investigate the migration, adsorption, and desorption characteristics of Pb on fine, medium, and coarse sand in the water table fluctuation zone by using several laboratory methods, including the kinetic aspects of Pb2+ adsorption/desorption and water table fluctuation experiments. The results showed that the adsorption and desorption curves fit the Elovich equation well at a correlation coefficient above 0.9. In the adsorption and desorption kinetic experiments for fine, medium, and coarse sand collected and from the floodplain, the maximum adsorption capacity of Pb2+ was 2367 mg·kg<sup>−</sup>1, 1848 mg·kg<sup>−</sup>1, and 1544 mg·kg<sup>−</sup>1, respectively. The maximum desorption capacity of Pb2+ was 29.18 mg·kg<sup>−</sup>1, 62.38 mg·kg<sup>−</sup>1, and 81.60 mg·kg<sup>−</sup>1, respectively. In environments with pH greater than 4, the adsorption capacity was proportional to the pH, but the desorption capacity decreased as the pH increased in water. As the water table varied, the lowest pH occurred in the polluted medium we set initially. When the distance between the pollutants and sample solution grew further, pH increased, and the Pb2+ concentration decreased in the sample solution. In the column experiment of water table fluctuations on coarse sand, Pb2+ migrated nearly 5 cm upward from the original pollutant and migrated less than 10 cm downward from that. In our experiments on medium and fine sand, the upward and downward migration distances were <5 cm. The groundwater table fluctuations, pH variation, and Pb concentration currently influence the migration of Pb.

**Keywords:** kinetic adsorption and desorption; groundwater table fluctuations; Pb; migration; experimental study
