Litter And Residue Of Eichhornia Crassipes(Mart.) Solms And Influence On Water Environment

Eichhornia crassipes(Mart.) Solms has been well recognized on its ability to purify, but it has been disputed for its influence on the eco-environment as external species. Therefore, the research has been one of the hot issues. Although great advances have been made, they lacked systematic research in both depth and extent, especially study on the litter and residue. The litter and residue not only influence the water environment, but also is the important carrier of the physical cycle. So it is of great theoretical and practical significance to study.Under the natural conditions, the paper studied the changes of the plant, the litter and residue and the influence on water environment by the field investigation and laboratory analysis. The conclusions were made as follows.During the initial period of growing, the organic carbon of the plant increased quickly, and got the max value at the end of Sep.. Total phosphorus and total nitrogen had the trend of "increase-decrease-increase", and got the max valuel.08%,4.57% respectively in early January, 2005. There was another peak value 1.04%, 4.55% respectively in early April, 2005.The trend of downward fluxes was "single peak patter", and the peak value appeared in the last period of decomposing. Total nitrogen had also the trend of single peak patter", and reached the max value in mid-March of the following year. But the organic carbon and total phosphorus had the trend of two peaks. The peaks value of the organic carbon appeared in mid-February and early May of the following year respectively, and total phosphorus in early February and April of the following year respectively.During the period of growing, Eichhornia crassipes(Mart.) Solms had a good capability of purification for Permanganate Index, TN, NH₄⁺-N and TP, and had the best effect of purification in mid-September. There was remarkable the influence on DO. During the period of decomposing, they come into being "secondary polluter", and the pollution was the worse in March. The sequential influence lasted to the end of August and early September. After that it had no obvious effects.Furthermore, Eichhornia crassipes(Mart.) Solms restrained the alga. To mid-April, total phosphorus and total nitrogen of sediment increased 2.73%, 19.14% respectively. In comparison to the controlling area, the absolute quantity of total nitrogen and the absolute quantity of total phosphorus increased 3.79%, 1.09%, respectively.