Study On Retaining And Transformation Of N And P In Deganba Riparian In Jiangjin Of The Upper Reaches Of Yangtze River

Nitrogen and phosphorus is the main pollutants of rivers eutrophication.Nitrogen and phosphorus in the Land or farmland by nonpoint source into the water. Riparian zone is a transitional zone between highland and its adjacent water body. And a healthy riparian buffer zone can retain and transform the incoming N and P through physical, biological, and biochemical processes. In this paper, Deganba Riparian zone being the study object.Deganba riparian zone belongs to ChongQing Jiangjin province of The Yangtze upriver. Investigating the topography, climate, hydrology, vegetation features, soil characteristics. The factors governing the N and P retaining and transformation were analyzed.(1) The vegetation in the Deganba riparian zone belongs to22Family,38Genus,44Species. And the uppermost species is Compositae, there have five Genus, six Species. The second more species is Lamiaceae, there have four Genus, four Species. The third more species is Polygonaceae, there have two Genus, four Species. Widely distributed species in Deganba riparian zone is Deyeuxia. arundinacea. Polygonum nepalense. Triglochin palustre. Salix variegate.As the change of seasons that the maximum number of plant species was in May, sum to44Species. And the minimum number of plant species was in November, sum to44Species. The most plant species distribution in B and C transect line. The maximum plant biomass was in May, and the minimum was in November. Transect line A where near farmland that have the maximum plant biomass. More close to the water, the plant biomass more lower. Flood season is June to October, because of the Flood, plant species and biomass reduce to the minimum.The dominant plant distribution in transect line A is Deyeuxia.anmdinacea. Leevsia japonica. Cynodon dactylon. Salix variegata. Transect line B is Cynodon dactylon. Deyeuxia.arundinacea. Polygonum nepalense. Transect line C is Triglochin palustre.Equisetum diffusum. Transect line D is Triglochin palustre.(2)There are significant differences between the soil physical and chemical properties in the different transect line of deganba riparian zone. The soil moisture content A>D>B>C. The soil pH A<B<D<C. The soil OM content A>B>C>D. The soil both TN and AN content are A>B>D>C. The soil both TP and AP content are A>D>B>C. The soil TK content A>C>B>D, AK content A>D>C>B. Water can compensation for soil nitrogen and phosphorus content in the transect line D where is located next to the river.As the change of seasons, soil physical and chemical properties changes. After the flood, soil moisture content have a slight increased, but the soil pH remain stable. The content of soil OM content anniversary show a steady growth trend. The most soil OM content in May, the minimum in November. Anniversary of the soil TN and AN content change is bigger. After a flood,in transect line A and B, the soil N content increased, the other transect line with no big change. Anniversary of the establishment of soil P content change is relatively stable. The soil TK content in after flood more than before. There have a big change in transect line A’s Anniversary of the soil AK content, the others transect line with no big change.In Deganba riparian zone, the moisture content of soil were very significant negative correlation with the soil pH. Soil moisture content and OM content is very significant positive correlation. Soil OM content and N content has a significant positive correlation. Soil TP content were very significant positive correlation with moisture content. Soil TP content were very significant negative correlation with the soil pH.According to the soil nutrient classification standard, in the Deganba riparian zone, the soil TP content is rich and the soil OM, N, AP, K content are poor.(3) The effect on the interception of N and P have a significant difference in different riparian soil of Deganba riparian zone, the interception efficiency of N is A>B>D>C while the interception efficiency of P is A>D>B>C. Compared with the soil in transect line A, the TN reserves of B, C and D decreased by28.65%,49.20%,41.96%, respectively. The AN decreased by24.38%,46.38%,40.99%, respectively. The TP decreased by20.58%,32.98%,20.02%, respectively. The AP decreased by52.67%,58%,40%, respectively.The N and P enrichment of A and B transects is more effective than that in B and C transects. High soil moisture can effectively promote the enrichment of N and P in the soil, the OM content in soil can promote soil N enrichment, higher soil pH can promote soil denitrification and soil phosphatase activity, reduce the enrichment of soil N and P elements.The transformation and absorption effects of nitrogen and phosphorus in different plants of different location also have a significant difference in Deganba riparian zone. The efficiency of TN and TP were A> B> C> D. Compared with the A transect, the TN uptake for the plants in B, C and D decreased by70.12%,97.30%,97.96%, the TP uptake were reduced by74.36%,98.43%,98.69%. With the passing of the seasons.the total reserves of N appeared fluctuations. The TN and AN reserves of A and B increased significant in6-10month while C and D transect do not have. The TP and AP reserves in riparian soil remain relatively stable trend anniversary. The soil N and P absorption efficiency of plants increasing with the plant biomass increases. In May, the N and P transformation effects in soil reaches a maximum, but after flooding of six to ten mouth, the uptake amount of N and P in soil reduced to a minimum in Deganba riparian zone.