2.1.1. Experimental Materials

The experimental soil samples were collected on the floodplain of the Yellow River in Mengjin District, Luoyang City, Henan Province (Figure 1). The groundwater level in this area fluctuates frequently. Sample collection and processing were carried out by the requirements of the "Technical Specifications for Soil Environmental Monitoring" (HJ/T 166-2004). Sampling was performed using the quarter method, followed by drying, crushing and sieving, delineating three media, namely coarse sand, medium sand and fine sand. The pH value of the sand was between 8.5 and 9.3, and the organic matter content was between 0.241 and 1.070 g·kg−1. The basic physical and chemical properties of the soil are shown in Table 1. The water used in the laboratory is ultrapure water made by the German Millipore ultrapure water machine.
