区域环境与生态
王颖,沈珍瑶,呼丽娟,牛军峰.三峡水库主要支流沉积物的磷吸附/释放特性[J].环境科学学报,2008,28(8):1654-1661
三峡水库主要支流沉积物的磷吸附/释放特性
- Adsorption and release of phosphorus from sediments from the main branches of the Three-Gorges Reservoir
- 基金项目：国家“973”计划课题(No2003CB415204);国家自然科学基金(No50708007);污染环境修复与生态健康教育部重点实验室开放基金(NoEREH0705)
- 作者
- 单位
- 王颖
- 1. 北京师范大学环境学院环境模拟与污染控制国家重点实验室, 北京 100875; 2. 浙江大学环境与资源学院污染环境修复与生态健康教育部重点实验室, 杭州 310029
- 沈珍瑶
- 北京师范大学环境学院环境模拟与污染控制国家重点实验室, 北京 100875
- 呼丽娟
- 北京师范大学环境学院环境模拟与污染控制国家重点实验室, 北京 100875
- 牛军峰
- 北京师范大学环境学院环境模拟与污染控制国家重点实验室, 北京 100875
- 摘要：以三峡水库主要支流寸滩、小江、大宁和香溪表层沉积物为对象,通过连续提取法分析4种沉积物磷的赋存形态,模拟研究了pH和温度对不同沉积物磷吸附/释放的影响.结果表明,寸滩、小江、大宁和香溪表层沉积物磷赋存形态均以无机磷为主(占总磷含量的59.29%～78.82%),其中钙结合态磷(Ca-P)含量大于铁/铝结合态磷(Fe/Al-P).上覆水pH值对沉积物磷释放有明显的影响,中性条件下磷释放量最低,酸性条件下由于占优势的Ca-P大量溶解导致磷释放量大于碱性条件,因此,水体酸化易增加三峡主要支流(寸滩、小江、大宁和香溪)的磷释放风险.pH值变化亦明显影响沉积物对于磷的吸附,pH在6～8范围内,4种沉积物对于磷的吸附量保持在较高的水平,吸附量从大到小的顺序为:小江>大宁>寸滩>香溪.偏酸性条件(pH<6)下过多的H+与固体表面竞争溶解态活性磷(SRP);偏碱性条件(pH>8)下大量的OH-与SRP竞争沉积物表面的吸附位,故这一pH值范围内(pH<6或pH>8)磷的吸附量明显减少.磷在4种沉积物上的吸附为吸热过程,不同温度下(278K、293K、303K)沉积物对P的吸附均符合修正后的Langmuir模型,标准吸附热为18.92～46.63kJ·mol-1,其中,磷从水体分配到大宁河沉积物中的标准吸附热最大.
- Abstract：The effects of pHand temperature on adsorption and release of phosphorus (P) from sediments from the main branches (Cuntan,Xiaojiang,Daning and Xiangxi) of the Three-Gorges Reservoir (China) were investigated. The contents and fractions of Pin the sediments were analyzed by sequential chemical extraction. The results showed that inorganic Pwas the major fraction of total P (accounting for 59.29%～78.82% of total P) for all the samples in this study. The content of calcium-bound P (Ca-P) was higher than that of Fe/Al oxides-bound P (Fe/Al-P). The pH of the overlying water influenced Prelease from the sediments. The least amount of Pwas released under neutral conditions. Higher Prelease was observed in acid than in alkaline conditions due to the dissolution of Ca-Pat lower pH. Thus acidification of the overlying water increases the risk of eutrophication in the main branches of the Three-Gorges Reservoir. Adsorption of Pon the sediments also varied with the pH. The maximum Padsorption capacity of various sediments occurred at pH values between 6 and 8. The adsorption capacity followed the order: Xiaojiang> Daning > Cuntan > Xiangxi. At pH<6,the sediment surfaces compete with H+ to trap soluble reactive P (SRP),whereas at pH>8,high concentrations of free OH- could prevent adsorption of SRP onto sediment surfaces. So the adsorption of Pdecreased rapidly when pH<6 or pH>8. Moreover,the adsorption of Pon the sediments was endothermic. Amodified Langmuir model may describe the Padsorption well for all the samples at different temperatures (278K、293K、303K). The standard heat of adsorption (ΔH0) of Pon the sediments ranged from 18.92 to 46.63 kJ·mol-1,and the highest value was observed in the Daning sediment.
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