三峡库区消落带土壤对磷的吸附和淹水下磷的形态变化

三峡水库建成后在库区周边形成落差30m的消落带，消落带土壤对磷的吸附固定和磷的去向直接影响到周围的水环境。通过批处理和模拟培养法研究了三峡库区小江流域沿岸消落带的黄壤、紫色土在淹水期间铁的形态变化，磷的吸附及形态转变，结果表明：（1）供试黄壤和紫色土在淹水后，晶形铁氧化物含量明显下降，非晶形铁含量有增加趋势，土壤对磷的吸附量增加；(2)淹水期间土壤Olsen-P含量呈下降趋势，而Fe-P和Al-P含量增加，模拟显示黄壤和紫色土在淹水15d后的磷吸附容量增加70.8%和9.5%；（3）用pH 5和pH 9的0.1mol L-1CaCl2、KCl、NH4Cl溶液培养的黄壤，其Olsen-P、Fe-P、Al-P含量均明显增加，意味着消落带土壤中若施加K、Ca或尿素时，土壤有效磷可能增加，这可导致CaCl2提取磷的增多并影响库区水的含磷量，从而影响库区水质。

Adsorption and transformation of Phosphorus in soils of the tidal zone of the Three Gorges Reservoir region

After the completion of the Three Gorges Reservoir project, a 30-m height tidal zone is formed around the reservoir. Changes in P adsorption and fixation by the soils in the zone and in fate of the phosphorus directly affect the surrounding water environment. Through batch processing and indoor incubation of samples of the yellow soil and purple soil in the tidal zone, changes in form of the iron and adsorption and transformation of P in the soils were studied. Results show that flooding significantly decreased the content of crystalline iron oxides, while increasing the content of noncrystalline iron in both soils; Under flooding the content of Olsen-P in the soils displayed a declining trend, whereas the contents of Fe-P and Al-P turned upwards; Indoor simulation demonstrates that in the two yellow and purple soils under flooding for 15 days, P adsorption capacity increased by 70.8% and 9.5%, respectively; Incubated in 0.1 mol L-1 CaCl2, KCl and NH4Cl solutions at pH 5 and pH 9, separately, for 15 days, the yellow soil increased its contents of Olsen-P, Fe-P and Al-P significantly, indicating that in the soils of the tidal zone, application of K, Ca or urea might increase the content of soil available P, which could eventually lead to increase in CaCl2 extractable P, thus affecting the phosphorus content in the water body and water quality of the reservoir.