岱海沉积物内源磷释放特征的研究

Release Characteristics of Phosphorus in Sediment from Daihai Lake

岱海沉积物及水体营养盐浓度较高,内源污染释放风险大,水体营养盐浓度逐年上升.通过分析岱海西南湖区、东北湖区及中心湖区沉积物磷吸附动力学特征和吸附等温特征,计算沉积物NAP(native adsorbed phosphorus,吸附解吸态磷)浓度和EPC 0(equilibrium phosphorus concentration,平衡磷浓度),明确岱海各湖区沉积物磷的“源-汇”转换机制.结果表明:①准二级动力学模型能够较好地描述沉积物样品对磷的吸附动力学行为,且沉积物吸附磷的速率较快,最高吸附速率达11.45 g/(mg·min),在8 h内沉积物对磷的吸附可趋于平衡状态.②修正后的Langmuir等温吸附模型(R 2为0.9076~0.9742)能较好地描述沉积物对磷的吸附等温行为,且通过参数计算发现,岱海中心湖区的沉积物具有较高的磷吸附量,最大值为0.867 mg/g.③通过对比NAP含量、沉积物EPC 0与间隙水中SRP(soluble reactive phosphorus,可溶性活性磷)浓度,发现岱海中心湖区沉积物有较大的磷释放风险,西南湖区和东北湖区磷释放风险较小.④岱海中心湖区沉积物较高的NAP含量及pH导致该区内源磷释放风险加大.根据岱海沉积物磷释放呈现的区域性特征,在内源磷释放控制方面,可采取轻重结合的防控方式对岱海湖区进行重点防控.

The nutrient content in water and sediment are high in Daihai Lake,and the trophic status is increasing in recent years,as well as the high release risk of endogenous pollutants.The phosphorus sorption kinetic and sorption isotherm characterization of the sediments from southwest,northeast,and center regions in Daihai Lake was analyzed,and the role of‘source-sink’in sediment from three regions was clarified according to the calculation of native adsorbed phosphorus(NAP)and equilibrium phosphorus concentration(EPC 0).The results indicated that:(1)The pseudo-second order could better describe the phosphorus sorption kinetic characterization,and the sediments had the sorption equilibrium within 8 h with the high sorption rate(the highest value of 11.45 g/(mg·min)).(2)The sediments in the center region of Daihai Lake had the high sorption capacities(0.867 mg/ g),and the modified Langmuir sorption isotherm model could describe the phosphorus sorption well(R 2 was 0.9076-0.9742).(3)Comparing the NAP content,the sediment EPC 0 and the value of soluble reactive phosphorus(SRP)in the interstitial water,the sediments form the center region of Daihai Lake had the high Phosphorus release risk,while the sediments from the southwest or northeast regions of Daihai Lake had the low Phosphorus release risk.(4)The release risk of endogenous phosphorus was high because of the high NAP content and pH values in sediments from the center region of Daihai Lake.According to the regional characteristic of phosphorus release in Daihai Lake,the weight combination method could be used for the endogenous phosphorus prevention and control.The center region of Daihai Lake with high phosphorus release risk should be prevented and controlled focally.