不同固磷方式对巢湖沉积物磷吸附行为的影响

EFFECTS OF DIFFERENT PHOSPHORUS IMMOBILIZATION WAYS ON PHOSPHORUS SORPTION BEHAVIORS IN SEDIMENT OF LAKE CHAOHU

内源磷负荷将严重阻碍富营养化湖泊的恢复,其控制技术的关键在于有效增强沉积物吸附磷的能力,而相关研究相对较少。研究以典型富营养化湖泊(巢湖)严重污染区域的沉积物为实验对象,系统比较了常规固磷方式(施用CaCl2、FeCl3、AlCl3与曝气)对沉积物磷吸附行为和间隙水溶解态可反应磷(SRP)浓度的影响。结果表明:施用不同剂量的CaCl2之后,沉积物磷最大吸附量和吸附能均无显著变化,间隙水SRP浓度和沉积物磷平衡浓度(EPC0)仅有较小幅度的下降;FeCl3和AlCl3的施用可明显增加沉积物磷的最大吸附量和吸附能,同时有效降低间隙水SRP浓度和EPC0值,即沉积物显示更强的从水中吸附磷的能力。当同处低剂量水平时,铁能更有效地降低沉积物EPC0值;反之,曝气对沉积物最大吸附量和吸附能均无显著影响,却明显提高了间隙水SRP浓度和沉积物EPC0值,进而导致更强的磷释放风险。故建议将适量铁的施用作为富营养化湖泊沉积物修复的有效技术,且慎用曝气处理。

Internal phosphorus loading in sediment will exert negative effects on restoration of eutrophic lakes,whose control is dependent on the effective enhancement of phosphorus sorption on sediments,but relevant works are scare.In this study,the sediments from the seriously polluted areas in a Chinese eutrophic lake（Lake Chaohu） were obtained,and the effects of the routine technologies such as dosing salts of calcium,iron,aluminium and aeration,on sediments phosphorus sorption behavior and interstitial water soluble reactive phosphorus（SRP） concentration were compared with the application of calcium salt,no significant changes in phosphorus sorption maximum and the bonding energy were observed,together with the slight decrease in SRP concentration in interstitial water and zero equilibrium phos-phorus concentration（EPC0） in sediment;furthermore,the application of salts of iron and aluminium not only significant enhanced phosphorus sorption maximum and the bonding energy,but also decreased SRP concentration in interstitial water and EPC0 in sediments,leading to a stronger ability to adsorb phosphate from aqueous phase into sediment.With the lowest dosage,iron salt could reduce sediment EPC0 more effective relative to aluminium salt;on the other hand,aeration had no significant effects on phosphorus sorption maximum and the bonding energy,and what is worse,it substantially gave rise to SRP concentration in interstitial water and sediment EPC0 value,thereby increasing risk of phosphorus release.Overall,iron salt application with optimal dosage can be taken as a suitable technology for sediment remediation of eutrophic lakes,while the benthic aeration must be cautiously used.