长江河口潮滩表层沉积物对磷酸盐的吸附特征

Phosphate Adsorption Characteristics of Tidal Flat Surface Sediments and Its Environmental Effect from the Yangtze Estuary

实验研究了长江口滨岸潮滩表层沉积物对上覆水体中磷酸盐(PO4-P)的吸附特性,结果表明,沉积物吸磷过程主要发生在0～10小时(h)内,尔后基本上达到一种动态平衡过程,但在0～0.5 h内沉积物对PO4-P的吸附速率最大,达到10.40～56.40 mg/kg h,且其吸附速率受细颗粒物含量影响明显.沉积物对PO4-P等温吸附曲线符合Langmuir等温吸附方程.据Langmuir方程计算,PO4-P的吸附容量达26.32～204.08 mg/kg,且吸附容量与Fe3+和总有机碳(TOC)含量有较好的正相关关系;PO4-P的吸附效率达21.55～248.30 L/kg,且吸附效率主要取决于TOC含量.此外,环境因子(温度、pH和盐度等)对沉积物吸磷作用影响显著.

Adsorption of phosphate (PO 4 -P) on sediments taken from the Yangtze estuarine and coastal tidal flats were determined in laboratory. The results indicate that the process of phosphorus adsorption onto sediments mainly occurs within 0-10 h, and then attends to a dynamic equilibrium. Maximum adsorption rates occurred within 0-0.5 h, ranging from 10.40 to 56.40 mg/kgh. The adsorption rates were obviously influenced by the concentration levels of fine particles. Adsorption isotherm curves were fitted to modified Langmuir's equation. Adsorption capacities varied from 26.32 to 204.08 mg/kg, showing good affinities for Fe 3+ and total organic carbon (TOC) concentrations. The adsorption efficiency of phosphate on sediments ranged from 21.55 to 248.30 L/kg, showing close correlation with TOC concentrations. Furthermore, the correlation between environmental factors and phosphate adsorption was presented in this experiment, indicating that temperature, pH and salinity have obvious effects on phosphate adsorption.