ADSORPTION CHARACTERISTICS OF PHOSPHORUS ONTO SOILS FROM DIFFERENT LAND USE TYPES IN DANJIANGKOU RESERVOIR AREA

Characteristics of phosphorus adsorption onto soils have been studied in many researches to reveal the adsorption capacities and to explore the mechanism of phosphorus behavior in water-sediment interface. In this study, the land use types in Danjiangkou reservoir riparian area was investigated in April 2013 before the soon-coming impoundment of Danjiangkou reservoir for the first time. The investigation was implemented between 160m and 170m waterlines, and samples of soil in five different land uses (cropland, forest land, abandon cropland, grass land, orange orchard) were taken in the elevations of 160m, 165m and 170m. After the field work, the analysis of chemical components of the soil and the experiments of phosphorus adsorption capacity of these samples were conducted in laboratory. The results showed that: (a) the traditional Langmuir and Freundlich equations can be well fitted to experiment data, the Q(max) obtained ranged from 141.89 similar to 209.96 mg/kg with an average value of 191.61mg/kg; (b) The values of EPC0 ranged from 0.05 similar to 0.59 mg/L, which were higher than the liquid phosphate concentrations. This indicated these samples had a trend of releasing P as a source; (c) the adsorption capacity and isotherm parameters were influenced by sediment components, especially by the content of Fe and Al, while surface area and sample elevation showed no obvious effect in the present system.