Measurement of the sand physicochemical property
Sand pH was determined using a pH meter (PT-10, Sartorius, Göttingen, Germany). Sand electrical conductivity (EC) was measured using a conductivity meter (DDSJ-308A, Leici, Shanghai, China). The water content (WC) was calculated based on the moisture difference value. The contents of total carbon (TC), total nitrogen (TN), and total organic carbon (TOC) were detected using an element analyzer (Elementar Vario-EL, Germany). Concentrations of total phosphorus (P), vanadium (V), yttrium (Y), zirconium (Zr), titanium (Ti), manganum (Mn), zinc (Zn), chlorine (Cl) were measured using the wavelength dispersive X-ray fluorescence spectrometer (AXIOS; PANalytical B.V., Netherlands) (Liu et al., 2016; Liang et al., 2019). The content of Cl- was measured by silver nitrate titration method. The contents of Na+, Mg2+, Ca2+were determined by atomic absorption spectrophotometry.