Abstract:

 According to the WaterFluctuationZone (WFZ)s alternately waterlogged and drained environment, we have carried out the experiment for controlling phosphorous release at both laboratory and insitu flooding conditions at Wanzhou with purple alluvial soil of the WFZ at the Three Gorges Reservoir. This study focused on the environmental effective factor of phosphorous release from soil in the WFZ in periodic inundatingdraining environment. Results showed that there was evident change between each phosphorous fraction in concentration during first 510 days, and then the trend became stable. TP of soil decreased, and there was phosphorous release from soil. After several inundatingdraining processes, the OlsenP of soil decreased after each inundating process and increased after each draining process. There was 167％ lower of OlsenP at last draining process than that at the beginning. OlsenP of the soil increased from 2053 mg·kg-1 to 4323 mg·kg-1, with a 1106％ increase, when the inundating depth increased to 40 m. Phosphorous concentration of overlying water exerted an influence on phosphorous release. Time required to reach adsorption equilibrium was much shorter when phosphorous concentration in overlying water was low (<2 mg/L) than that when phosphorous concentration in overlying water was high (>2 mg/L). It took six weeks to get balance when phosphorous concentration in overlying water was low (<2 mg/L). After adding HgCl2, Phosphorous concentration in overlying water was not changed in first 10 days, and then there was an evident decrease compared to that not adding HgCl2, with 0048 mg/L lower. In addition, the content of OlsenP of soil with plants was higher than that of soil without plantfor soils with Cynodon dactylon and Ficus tikoua  by 215％ and 127％.

Key words:

Key words: Three Gorges Reservoir; WaterFluctuationZone; phosphorous release; effective factor