原位覆盖对异龙湖底泥氮磷释放抑制效果的实验研究

Experimental Study on the Inhibition Effect of in-Situ Capping on Nitrogen and Phosphorus Release from the Sediment of Yilong Lake

底泥中埋藏的氮磷等营养物质二次释放作用是导致浅水湖泊富营养化难以根治的主要过程,因此,抑制底泥氮磷释放控制技术对于湖泊生态修复具有重要的现实意义.本研究以重度富营养高原浅水湖泊异龙湖为对象,通过开展为期36d的底泥覆盖抑制氮磷释放试验,对比了生石灰+石膏(2∶1)、生石灰+石膏+红壤(2∶1∶1)、三氯化铁改性高岭土(1∶4)、无覆盖4种覆盖处理对氮磷释放的抑制效果,以期筛选出有效削减异龙湖内源负荷的覆盖材料与最优方案.试验结果表明:与无覆盖组相比,3种材料覆盖都可抑制底泥磷的释放,加入生石灰处理组的水体pH大幅上升,会破坏湖泊自然生境,不宜用于湖泊底泥生态修复;三氯化铁改性高岭土覆盖处理的抑磷效果达75.9%,可作为抑磷释放覆盖材料.同时相比无覆盖组,只有三氯化铁改性高岭土覆盖能抑制氮的释放,抑氮效果达64.1%,而其它两组处理对氮释放的抑制效果均不明显.因此,从抑制氮磷释放效果及其生态环境效应角度综合考虑,三氯化铁改性高岭土是最佳的覆盖材料,可为高原浅水富营养化湖泊的氮磷内源控制提供工程修复技术参考.

The release of nitrogen and phosphorus from sediment is one of the main processes promoting eutrophication of shallow lakes.Therefore,inhibition of internal loading is of great importance for lake restoration.In this study,the shallow eutrophic Yilong Lake was selected as the study site.The inhibitory effects of quicklime+gypsum(2∶1),quicklime+gypsum+red soil(2∶1∶1),iron trichloride modified kaolin(1∶4)and non-covering treatments on nitrogen and phosphorus release were studied for 36 d,in order to screen out the capping material which can effectively reduce the internal load in Yilong Lake.The results shows that all the three treatments reduce phosphorus flux from sediment.But quicklime-treated groups are unsuitable for lake restoration as quicklime addition increases pH in lake water substantially.Iron trichlorid-emodified kaolin can be used as capping material with 75.9%phosphorus reduction effect.It is also found that only iron trichloride modified kaolin could inhibit the release of nitrogen by 64.1%compared with the control group.Therefore,the iron trichloride-modified kaolin is the best capping material by considering its inhibitory effects and its ecological and environmental effects.The results of this study will provide a technical reference for endogenous control of nitrogen and phosphorus in large plateau eutrophic lakes,especially in Yilong Lake.