沉水植物与磷细菌的联合对水-沉积物间磷循环的作用规律研究

Eutrophication has been one of the severe water pollution problems in worldwide. Phosphorus is the key factor which leads to occurrence of eutrophication. To control the internal phosphorus loads in the sediment is not only the bottleneck for eutrophic water management, but also a difficulty of in situ remediation of natural water bodies. Satisfactory results of reducing the internal phosphorus loads could not be achieved by only using submerged macrophytes, so one kind of the submerged macrophyte with best phosphorus removal capacity will be screened from Myriophyllum spicatum L., Elodea nuttallii, Potamogeton crispus and Ceratophyllum demersum L in this study. High-efficient phosphorus accumulating/solubilizing bacteria isolated from eutrophic sediment and other environmental samples will be associated together with the screened submerged macrophyte. The sediment samples used in this research will be collected from eutrophic water bodies. The experimental temperature and pH will be set according to the environmental conditions of sampling sites. With the best submerged macrophytes-phosphorus accumulating/solubilizing bacteria association, we are going to investigate how will the phosphorus accumulating/solubilizing bacteria affect the growth and phosphorus assimilation of the submerged macrophyte, and the roles of submerged macrophyte will play on the variability of the rhizophere microbial community compositions. On the basis of this, a set of in situ remediation experiments will be conducted in a eutrophic reservior to prove the phosphorus removal effects of the submerged macrophytes-phosphorus bacteria association optimized from the lab investigations.The results of this study will help to reveal the important roles of both submerged macrophytes and phosphorus accumulating/solubilizing bacteria in the processes of phosphorus migration and the transformation of different phosphorus forms. This research will also provide a basis for comprehensive analysis of phosphorus transfer, transformation and other cycling processes between eutrophic overlying water and sediment. The mechanisms of the phosphorus cycling of eutrophic lake or reservior will be revealed and thus it will be helpful for application of submerged macrophytes and phosphorus accumulating/solubilizing bacteria for water purification and in situ remediation of eutrophication.

水体富营养化已成为亟待解决的环境污染问题之一，磷是引发这一问题的关键因素。减少沉积物内源磷负荷是治理富营养化的根本途径，也是水体生态恢复的难点与重点，而单纯利用沉水植物修复水体时对内源磷的减少效果不够理想。本研究拟以采自富营养化水体的沉积物为研究对象，利用分离自沉积物及其他环境样品的高效磷细菌（包括聚磷菌与解磷菌）在模拟条件下与除磷能力好的沉水植物分别进行组合，确定利于除磷的最佳联合体系。系统考察在磷细菌与沉水植物的联合作用下，水—沉积物间磷的迁移与形态转化特征；探讨磷细菌在沉水植物生长与同化磷过程中发挥的作用以及沉水植物对根际微生物群落结构变化产生的影响，并在此基础上选取最佳组合进行富营养化水体原位修复效果验证。为综合解析生物作用下富营养化水体水-沉积物间磷的迁移转化等复杂的循环过程奠定理论基础，进而为更好地将沉水植物与磷细菌应用于防治水体富营养化与净化水质等原位修复研究提供依据与参考。

针对减少水体沉积物内源磷负荷是治理富营养化的根本途径与生态修复难点这一现实，本研究以采自富营养化水体（太湖）的沉积物为研究对象，利用分离自活性污泥的高效聚磷菌X-24与作物根际土壤样品的高效解磷菌XMT-5在模拟条件下与除磷能力较好的沉水植物（穗状狐尾藻、金鱼藻、菹草和伊乐藻）分别进行组合，确定了利于除磷的最佳联合体系—解磷菌XMT-5与金鱼藻（AMB）以及聚磷菌X-24与金鱼藻（AMC）的组合。系统考察了在磷细菌与金鱼藻的联合作用下模拟体系中上覆水总磷（TP）与可溶性总磷（DTP）含量的变化特征，发现在组合体系AMB与AMC处理中，水体TP与DTP的含量分别明显低于只接种金鱼藻的处理（AM），表明磷细菌的加入可以有效促进金鱼藻对于水体TP含量的降低；探讨磷细菌对金鱼藻P吸收以及金鱼藻对根际细菌群落结构组成的影响，发现磷细菌与金鱼藻的组合可以有效促进沉积物中内源P向金鱼藻中的转移，沉积物中的TP含量分别比只栽种金鱼藻的对照处理减少2.6%与3.9%，而金鱼藻植株中的TP含量分别提高15.2%与11.7%；金鱼藻-磷细菌的组合分别使体系中的细菌多样性增加，优势种群亦有所变化，例如AM处理中沉积物优势细菌种群主要有蓝藻门Cyanobacteria，颤藻属（Limnothrix ），甲基单胞菌属（Methylomonas）和Spirochaetes，解磷菌-金鱼藻组合体系AMB处理中蓝藻门Cyanobacteria的细菌占主要优势，而聚磷菌-金鱼藻组合体系AMC处理中，优势种群主要为拟杆菌门（Bacteroidetes）的细菌；在此基础上利用最佳组合对富营养化水体进行了原位修复效果验证，表明在自然水体条件下磷细菌-金鱼藻的组合亦能够有效促进沉积物内源P负荷的减少。本研究可以为综合解析生物作用下富营养化水体水-沉积物间磷的迁移转化等复杂的循环过程奠定理论基础，进而为更好地将沉水植物与磷细菌应用于防治水体富营养化与净化水质等原位修复研究提供依据与参考。