Study On Phosphorus Absorption And Transformation By Emergent Plants In Yeyahu Wetland

Wetland plants system plays an important role in phosphorus (P) interception and absorption of phosphorus accumulation soil caused by non-points ource pollution, and the emergent plant is the key to the retention of phosphorus, whose roots with large biomass play a crucial role in the purification and removal of phosphorus, so it’s of great significance to study the absorption and transformation by Emergent plants.In this article, the Yeyahu wetland was studied as the carrier,3speices of emergent plants, such as Scirpus planiculmis, Phragmites australis and Zizania aquatic were sampled and under monitored in the field experiments, the circumstances of absorption and the influence on the morphology distribution of different forms of phosphorus by the plant roots were studied; At the same time, laboratory simulation experiments was built to explore the difference between IP and OP absorption and utilization.The results prove that:In the root soil of emergent plant collected on May to October in Yeyahu, the content of total phosphorus (TP) showed a cyclical change with the plants growth:the content of TP decreased from719.84mg/kg to577.60mg/kg on May to August, and then rosed to726.79mg/kg in the two months followed; As TP in the rhizosphere was obviously higher than non-rhizosphere, it shows that the plant roots have a concentration to the phosphorus. The distribution of inorganic phosphorus (IP) and organic phosphorus (OP) in soil show the same trends with TP, the content were down first and then pick up during May to October. The value of TIP/TP is inceased first and decreased then, the range of variation is46.54%-75.69%, but TOP/TP is decreased first then inceased, range from48.23%to25.53%, what indicate that the OP in the root soil will turn to some forms of IP as provision while the plant growing. Besides, the most remarkable change among the content of IP forms is the Ca-P, the value of Ca-P in rhizosphere is10.48%below than non-rhizosphere. In the OP forms, the MR-OP content in rhizosphere is higher than non-rhizosphere, but HR-OP is just the opposite, which shows that the high stability OP forms will convert into low ones that is easily absorbed by plants.Through the hydroponics and soil culture method, the circumstances of absorption towards different phosphorus by Ceratophyllum,Calamus and Phragmites australis were studied, The results showed:Wetland plants can absorb β-Sodium Glycerophosphate directly without microorganisms, and the absorptive capacity is even stronger than KH2PO4; While the Phytic acid can’t be absorbed effectively, Which indicated that some certain OP in the soilcould be absorbed and utilized directly by the wetland plants rather than be mineralized at first.