高磷含量湖泊表层沉积物对磷吸附特征研究

Characterization of Phosphorus Sorption by Surface Sediments in Lakes with High Phosphorus Content

该文以黄石市青山湖为研究对象,对表层沉积物进行磷的吸附动力学与等温吸附实验,分析了表层沉积物对磷的吸附特征及其影响因素,以此探究城市小型浅水湖泊沉积物的“汇”“源”性质,为同类型湖泊的生态环境治理提供参考依据。结果表明:(1)青山湖沉积物对磷吸附的动力学拟合符合Lagergren准一级动力学模型,30 min内沉积物对磷酸盐的吸附速率最快,在15 min时各样点吸附速率达到最大值,为17.31~26.99 mg/(kg·h),48 h时基本达到动态平衡。(2)低磷浓度(0~0.5 mg/L)下,表层沉积物对磷的吸附符合Linear模型,沉积物对磷的吸附(解吸)平衡浓度为0.153~0.167 mg/L,青山湖沉积物处于释放状态,是上覆水体营养盐的“源”;高磷浓度(0~20 mg/L),表层沉积物对磷的吸附更符合Langmuir模型,对磷的最大吸附量为606.60~647.44 mg/kg。(3)沉积物总磷的含量范围为1838.28~2260.66 mg/kg,以无机磷为主,沉积物不同形态磷含量为TP>IP>NaOH-P>OP>HCl-P,IP占TP含量的83.26%~96.08%,IP以NaOH-P为主(48.78%~64.32%)。各样点磷的单因子评价指数均>1,说明沉积物总磷释放风险较大;沉积物风险评价指数ERI在11.99%~12.77%之间,3个采样点的ERI均在10%以上,表明青山湖沉积物呈现中等营养化风险。

The objective of this paper was to analyze the adsorption characteristics and the phosphorus of the surface sediments of the Qingshan Lake.The phosphorus adsorption kinetics and isothermal adsorption experiments were carried out on the surface sediments,to investigate the“sink”and“source”nature in the sediments of small shallow urban lakes,and provide a reference for the ecological management of similar lakes.The results show that:(1)Kinetic fitting of phosphorus sorption by sediments in Castle Peak Lake is consistent with the Lagergren quasi-level kinetic model.The sediment adsorption rate of phosphate was the fastest within 30 min,and the maximum adsorption rate was 17.31~26.99 mg/(kg·h)at 15 min,and the adsorption came to the equilibrium stat at 48 h.(2)Low phosphorus concentrations(0~0.5 mg/L),the sorption of phosphorus by the surface sediments was in accordance with the Linear model,with the equilibrium concentration of phosphorus sorption(desorption)by the sediments being 0.153~0.167 mg/L,indicating that the sediments in Qingshan Lake were in a release state and were a“source”of nutrients to the overlying water.High phosphorus concentrations(0~20 mg/L),the adsorption isotherm curve were fitted to Langmuir model,the maximum P adsorption capacity ranged from 606.60 to 647.44 mg/kg.(3)The TP content of the sediment was 1838.28 to 2260.66 mg/kg,with inorganic IP being dominant.The phosphorus content of the different forms of sediment was:TP>IP>NaOH-P>OP>HCl-P.IP accounted for 83.26%~96.08%of TP content and IP was dominated by NaOH-P(48.78%to 64.32%).The sediment single factor evaluation indices are all greater than 1,indicating a high risk of total phosphorus release from the sediment.The eutrophication risk index of sediments varied from 11.99%to 12.77%,and the ERI of all three sampling sites was above 10%,indicating that the sediment of Qingshan Lake showed moderate nutrient risk.