*2.2. Experimental Equipment*

The following devices were employed for the adsorption and desorption kinetic aspects of Pb2+: a digital water bath oscillator, high-speed desktop centrifuge, and microwave.

The experimental devices for water table fluctuations include a 90 cm long column, water tank with 25 L volume, peristaltic pump with 100 rpm speed, piezometer tube, and soil solution sampler. We set eight openings for sampling in every column at heights of 20, 30, 35, 40, 45, 50, 55, and 60 cm. The experimental devices are shown in Figure 1.

**Figure 1.** Experimental devices for the water table fluctuations. (**a**) The schematic diagram. (**b**) The field experiment diagram.
