亚热带海湾表层沉积物对磷的吸附解析特征研究

磷在沉积物-水界面的吸附解析过程对水体富营养化具有重要影响，目前亚热带海湾沉积物对磷的吸附解析特征并不清楚，其自身的粒度组成和理化性质对沉积物磷吸附解析影响尚不明晰.本研究以3个主要入海河口区采集的表层沉积物为基础，通过吸附动力学和等温吸附试验，研究了不同粒径、pH和盐度等环境因子对磷吸附解析特征的影响规律.采用连续提取(SEDEX)法对沉积物吸附磷前后样品进行磷赋存形态分级，探讨沉积物对磷相应的吸附机制.结果表明：亚热带海湾入海河口区表层沉积物对磷的吸附动力学过程可用准二级动力学模型描述，等温吸附曲线符合Langmuir-交叉型模型.沉积物对磷的最大吸附量(Qm)范围为0.332～0.864 mg/g，沉积物磷的吸附/解吸平衡质量浓度(EPC₀)在0.076～0.150 mg/L之间.粒径较小的沉积物具有较强的磷吸附能力，海水酸碱度和盐度有利于沉积物磷吸附，吸附后的沉积物中可交换态磷(Ex-P)和铁结合态磷(Fe-P)含量明显增加，沉积物对磷的吸附过程同时存在物理吸附和化学吸附，且以物理吸附为主.研究显示，亚热带海湾表层沉积物较高含量的黏土矿物和高分子量的有机质...

Phosphate Adsorption and Desorption Characteristics of Surface Sediments of Subtropical Bay

Phosphate (P) adsorption and desorption processes at the sediment-water interface play a significant role in the eutrophication. At present, the adsorption and desorption characteristics of P in the subtropical bay sediments, and the effects of sediment particle size and physicochemical properties on P adsorption and desorption in sediments are not clear. The surface sediments of the three main estuarine regions in the subtropical bay of the Global Germplasm Resources (Crassostrea rivularis Crould) Reserve were collected to study P adsorption and desorption characteristics of the sediments through adsorption kinetics and isothermal adsorption experiments, and constrain the effects of environmental factors such as sediment particle sizes, pH and salinity on sedimentary P adsorption and desorption. The chemical speciation of P in the sediments before and after adsorption experiments was quantified using the sequential extraction (SEDEX) method, and the binding mechanisms of P in sediments were explored. The results showed that the adsorption kinetics of P in sediments could be described by a pseudo-second order kinetic model, and the adsorption isotherms fitted the modified Langmuir-crossover model. The maximum adsorption capacity (Q_m) of P in sediments and the adsorption/desorption equilibrium mass concentrations (EPC₀) of P ranged from 0.332 to 0.864 mg/g and 0.076 to 0.150 mg/L, respectively. The surface sediments with smaller particle sizes had a high adsorption capacity for P. Seawater pH and salinity in estuarine regions of the subtropical bay were conducive for P adsorption in sediments. The contents of exchangeable P (Ex-P) and iron-bound P (Fe-P) increased significantly in different sediment samples after adsorption. The adsorption processes of P in sediments included physical and chemical adsorptions. This study reveals that higher contents of clay minerals and high molecular weight organic matter promoted the adsorption of P in sediments of the subtropical bay, the pH and salinity of seawater have a certain buffer effect on water eutrophication in this region, but physical adsorption and binding capacity of P in sediments of the subtropical bay are weak, and there may be a risk of P re-release. Therefore, more attention should be paid to endogenous P pollution in this area, which is very important for preventing and controlling eutrophication in the subtropical bay.