Interaction Of Organic Matter,Organic Phosphorus And Iron In Lake And Reservoir Sediments And Their Environmental Effects

At present,the study of dissolved organic matter（DOM）,iron（Fe）and organic phosphorus（P_o）in lake and reservoir environments has made great progress,mainly on the individual characteristics of each component and their geochemical processes,as well as on the interaction between DOM and Fe,DOM and P_o,etc.,but little research has been reported on the interaction between the three.The interactions between the three components may play an important role in the migration and transformation of organic matter and organic phosphorus in the basin,as well as in carbon burial,phosphorus bio-effectiveness and its eutrophication effects,and is one of the important links in the further understanding of the biogeochemical processes of organic phosphorus.Therefore,the thesis study selects typical lakes and reservoirs with different organic matter and organic phosphorus sources and eutrophication status,such as Taihu Lake and Xishan Reservoir（with high DOM,Fe and P_o contents）,and tries to use a new method of organic matter and organic phosphorus analysis,FT-ICR-MS,combined with³¹P-NMR to comprehensively characterize the structure,components and contents of organic phosphorus,to elaborate the composition of DOM and P_o in the soil and sediment of the lake and reservoir basin,etc.and its content ratios,and explore the interrelationship between organic matter,iron and organic phosphorus.Based on this,the influence of the interactions between the three components on the transport and transformation of organic phosphorus and their possible contribution to the eutrophication of the lakes and reservoirs are discussed.The following important results and conclusions were obtained:（1）At the basin scale,the interactions of forest-derived DOM with Fe and P_o in Xishan Reservoir may be closely related to the functional groups of tryptophan and tyrosine in organic matter,respectively.The interactions of forest-derived DOM,Fe and P_o are more likely to form Fe-DOM-P_o complexes and promote the transport of forest-derived DOM,Fe and P_o in the basin and their accumulation in the reservoir sediments.（2）The interaction with forest-derived DOM,Fe and P_o is generally consistent,but further studies in different lake areas of Taihu Lake suggest that the interaction may be closely related to the high molecular weight humic fraction and the myo-inositol phosphate in the organic phosphorus fraction,respectively,where the interaction of the three in the algal lake area may be related to the low molecular weight humic fraction and the DNA of the diester phosphorus fraction.The interactions of Taihu DOM,Fe and P_o are more likely to include P_o-Fe-DOM or Fe-DOM-P_o complexes.（3）Differential interaction processes arise between forests,aquatic plants and algal sources of organic matter on organic phosphorus and Fe.Among them,forests and aquatic plants facilitate the interaction and co-precipitation and burial and preservation of organic matter,Fe and organic phosphorus,while the interaction processes of algal sources of organic matter with organic phosphorus and Fe are relatively more complex,and the processes of organic phosphorus recirculation and algal reuse may be more intense under specific conditions,organic phosphorus is both a source of phosphorus and carbon and has important environmental effects on cyanobacterial blooms in processes such as outbreaks.