Reseatch On Distribution And Influencing Factors Of Phosphorus In Surficial Sediments Of Wetland

Study of the relationship between phosphorus fractionations in sediment and the eutrophication of lakes is significant. This research was conducted in the northern section of Qixinghu Wetland receiving water from Chenghe River. Water samples and surfical sediments were collected in seven sections including no-plant area, reeds and cattails communities (October2012and May2013). The sediments were evaluated on the basis of phosphorus (P) fractionation by sequential extraction scheme, which explored the transportation and transformation regularity of various forms of phosphorus in the sediment. The study also provided the basic theory for the evolution of eutrophication. The results showed that:In the sediments of wetland, TP content of no-plant area was maximal, followed by phragmites communis, cattail communities was minimum. In three areas, sedimentary TP had different trends along the flow direction, while the trend of no-plant area increased firstly, then decreased, changed smoothly in the end; in the phragmites communis TP decreased firstly, then increased, finally decreased; TP increased from the front of the cattail communities, then decreased. In the wetland, the rank order according to the content of P-fractions was Ca-P> Org-P> Al-P/Fe-P> Ex-P> BD-P. inorganic phosphorus dominated TP, spring had high inorganic phosphorus ratio, In no-plant area, Ca-P, Ex-P, Al-P, Fe-P were associated with TP has a very significant positive correlation, only Ca-P was significantly associated with TP in the phragmites communis and cattail communities.OM had greater impact on TP, Org-P, Ex-P, Al-P, Fe-P, Ca-P in the no-plant area, which also impacted Org-P, Ex-P, Al-P in the phragmites communis, while in the cattail communities OM had no significant relationship with TP, phosphorus forms. Alkaline phosphatase consistented with the trends of Ex-P, Al-P, Fe-P, TP in the no-plant area, while in the phragmites communis only consistented with Org-P, in the cattail communities only consistented with Ex-P. Active Al, Fe content determined the content of Al-P, Fe-P in the no-plant area, while in the plant areas active Al did not significantly affect Al-P, Fe-P content and the active Fe was a significant positive correlation in the cattail communities.Generally the surface water of wetland mainly contained SRP, which gradually decreased along the flow direction, while PP changed more gentlely. Wetland sediment phosphorus to permanent phosphorus dominated, semi-permanent phosphorus content. Secondly, containing a very small amount of reactive phosphorus, and the pH range was not conducive to the release of phosphorus, so TP removal process was mainly dependent on the decrease of the SRP, the risk of sediment phosphorus re-releasing was low. This study revealed that in the case of external sources of phosphorus load, the distribution of phosphorus and influencing factors, which could provide a theoretical basis and data support for the wetland construction and management of eutrophication wetland ecological engineering.