Adsorption Characteristics of Phosphorus onto Soils from Water Level Fluctuation Zones of the Danjiangkou Reservoir

A comparative study was conducted to investigate the adsorption characteristics of phosphorus (P) on two soil samples collected from a typical subtropical reservoir and to reveal the possible influence of alternating exposure and inundation on the P adsorption onto soil in a water level fluctuation zone. Short-term batch experiments were performed, and characterization methods, such as scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) spectroscopy, were also used. The P adsorption kinetics for both soils was best described by a pseudo-second order model (R-2 > 0.99). A modified Langmuir model described the P adsorption on both samples well, and low temperature increased the risk of releasing soil P into the overlying water. Low pH values were not conducive to the P adsorption process. It appeared that alternating exposure and inundation had no significant impact on the adsorption capacity of P onto soil from water level fluctuation zones in this research. pH, SEM, and FT-IR analyses demonstrated that Fe, Al, and Ca contained in the clay minerals of the soil played an important role in the adsorption of P onto soil from water level fluctuation zone.