外源磷在三峡库区典型土壤中的活性演变及形态转化  

Variation of Extraneous Phosphorus in Activity and Morphology in Soils Typical of the Three Gorges Reservoir Area

作　　者：冉小萌 蒋珍茂[1,2,3] 何明靖[1,2,3] 魏世强[1,2,3] 

机构地区：[1]西南大学资源环境学院,重庆400716 [2]重庆市农业资源与环境研究重点实验室,重庆400716 [3]三峡库区生态环境教育部重点实验室,重庆400716

出　　处：《土壤学报》2016年第5期1249-1261,共13页Acta Pedologica Sinica

基　　金：国家自然科学基金项目(41171198);水体污染控制与治理科技重大专项(2012ZX07104-003)资助~~

摘　　要：三峡库区消落带土壤周期性淹水—出露对磷素迁移循环和水体负荷具有重要影响。以三峡库区消落带广泛分布的紫色潮土和灰棕紫泥土为对象,通过室内模拟培养实验,探讨不同饱和度外源磷在两种土壤中的活性变化与形态转化特征。结果表明:(1)外源磷进入土壤后,表征土壤磷活性的有效磷(Olsen-P)含量及磷素释放能力呈指数型衰减,可用指数方程C_t=ae^(-kt)+b拟合,拟合度均在94%左右。(2)外源磷在灰棕紫泥土中较在紫色潮土中能够保持更高的活性,同时也具有更高的渗漏淋失与释放风险。50%Q_m(最大吸附量)是两种土壤Olsen-P与磷素平衡解吸量的突变点,当磷素吸持饱和度≥50%时,土壤磷活性与渗漏淋失风险将明显增大。(3)Olsen-P与磷释放量在p<0.01水平上呈显著正相关,两者可用线性方程良好拟合,因此可用Olsen-P含量表征土壤磷素释放潜势。(4)外源磷进入土壤后,主要转化为活性较高的Ca_2-P和Ca_8-P,约占施入量50%~60%;其次是Al-P和Fe-P,约占施入量的30%左右,闭蓄态磷(O-P)和Ca_(10)-P变化不明显。(5)Ca_2-P是决定Olsen-P和磷素解吸能力的主要形态,对两者均起正向直接作用。[Objective]Eutrophi cation of the water body is the main environmental problem the operation of the Three Gorge Reservoir（TGR） has to face.Phosphorus in the water body is considered to be the key restrictive factor of eutrophication.During the operation of TGR,the water level in the reservoir rises and falls periodically,thus causing the formation of a hydro- fluctuation zone,where the soil gets inundated and exposed to air periodically,too.The periodical alternation of exposure amd inundation of the soil significantly affects the circulation and migration of phosphorus in the soil,as well as the P loading of the water body.Parts of the hydro-fluctuation zone are used for agricultural production during the low water level period,resulting in an excess accumulation of phosphorus adsorbed in the soil,which becomes a source of phosphorus loading into the overlying water during the flooding period,thus enhancing eutrophication of the water body.[Method]Therefore,an in- lab incubation experiment was carried out of the purple alluvial soil and grey-brown purple soil,which are widely distributed in the Three Gorges Reservoir area to explore characteristics of the variation of extraneous phosphorous in activity and morphology in the two soiIs as affected by saturation degree of the nutrient.[Result]Results show as follows：,（1） Once extraneous phosphorous entered the soils,the content of Olsen-P,which characterizes soil P availability,and soil P releasing ability declined exponentially,which may be described with the equation of C_t=ae^（-kt）＋b,with fitting degree being as high as about 94%for both soils,and the drop was the sharpest during the first 15 days of incubation,and then leveled off;（2） Extraneous phosphorous in different soils differed in decline of availability,equilibrium concentration and release potential.It remained quite higher in the gray-brown purple soil than in the purple alluvial soil in availability and consequently in risk of leaching loss and releasing;（3） The release potent

关 键 词：三峡库区消落带 土壤无机磷形态 有效磷 释放 临界值 

分 类 号：S153[农业科学—土壤学]