玄武湖底泥在不同上覆水位下内源磷释放规律探讨

Discussion on Endogenous Phosphorus Release Law of Sediments at Different Overlying Water Levels in Xuanwu Lake

以南京玄武湖底泥为研究对象,通过室内模拟对照试验探讨玄武湖湖底泥在不同上覆水位下内源磷释放规律和底泥中磷的赋存形态的变化规律。实验结果表明,在有扰动的中性水体中,高水位情况下底泥界面的厌氧状态造成磷的释放量和释放速率高于低水位情况,在碱性环境中,高水位造成的泥水界面厌氧状态不再是内源磷释放的主要因素,[OH]-的存在使得化学溶解作用和物理扩散作用超过微生物的释磷作用;静止的水体的内源磷释放规律和有扰动的相似,但是释放量均大于扰动水体。对底泥中不同形态磷的含量分析表明,底泥内源磷的释放主要是由底泥中的有机磷和铁铝结合态磷(Fe/Al-P)的转化引起的,高上覆水位条件下湖泊底泥中有机磷释放量大于低上覆水位下该值,进一步说明在中性水体底泥内源磷的释放过程中,底泥中的释磷微生物的作用要大于物理和化学释磷作用。在实际湖泊富营养化治理中,可以通过人工方法适当降低湖泊水位以提高水体中的溶解氧来减缓内源磷的释放量。

Taking the sediment in Nanjing Xuanwu Lake as research object, the endogenous phosphorus release law of sediments at different overlying water levels in Xuanwu Lake was discussed through indoor controlled simulation experiment, as well as the variation law of phosphorus＇ existing form in sediments. The experimental results showed that in the neutral water with disturbances, the anaerobic state of sediment interface at high water level caused the release amount and release rate of phosphorus were both higher than that at low water level. In alkaline environment, the anaerobic state of sediment-water interface generated by high water level was no longer the main reason of endogenous phosphorus release, and the existence of [ OH] - made chemical dissolution and physical diffusion exceed the role of microbial phosphorus release. The endogenous phosphorus release law in static water was similar to that in turbulent water, but its average release amount was larger than latter. The content analysis on different forms of phosphorus in sediments showed that the endogenous phosphorus release was mainly caused by the transformation of organic phosphorus and Fe/A1 - P in sediments. The organic phosphorus release a- mount in lake sediments at high overlying water level was larger than that in low overlying water level, which further indicated that in the endogenous phosphorus release process of sediments in neutral water, the role of micro-organisms was greater than chemical and physical phosphorus release effect. In actual treatment of lake eutrophication, the lake water level can be appropriately reduced by artificial means to increase the dissolved oxygen in water, which can slow down the endogenous phosphorus release.