Study On The Regular Pattern Of Purification And Effect From Eutrophic Water By Preponderant Submerged Plants Of Baiyangdian Lake

The environment of water in Baiyangdian was getting worse, and eutrophication becamed a problem urgent need to solve. Submerged macrophyte were the primary and most important producers in a typical vegetation rich lake, community structure in good condition could respond to the change of water environment promptly,researched on effects of submerged plants on eutrophic water systematic was necessary and had practical significance.This research investigated the submerged macrophytes of Baiyangdian Lake, and made sure Potamogeton pectinatus is the preponderant species,studied purification effects and regular patterns of them on eutrophic water through scientific experiments,combined the research about Potamogeton crispus to provide scientific basis for the governance and control of eutrophic water of Baiyangdian. Around the environmental effects of P. pectinatus on eutrophic water, the paper carried out the following tasks:(1) Study on the removal to nitrogen and phosphorus in the different conditions of water quality by P. pectinatus.Prepared nutrient solutions with different concentrations to simulate different eutrophication levels,cultivated P. pectinatus in laboratory and observd their growth conditions,monitored the changes of water. It showed that P.pectinatus grew well in hyper eutropher water, and removed nitrogen and phosphorus from water by sedimentation and adsorption; the ratio N:P lower the effect better, the highest removal efficiencies of nitrogen and phosphorus were 63%,93%.(2) Study on the purification effects of eutrophic water under natural condition by P. pectinatus. The level and source of contamination in Baiyangdian Lake were different,monitored the dynamic changes of the water at the areas of P. pectinatus growing and non-grass. It showed that:It was the vegetative phase which grew most vigorous from early May to the end of June, the average removal efficiencies of total nitrogen / phosphorus and the average degradation rate of CODcr were 52%,73% and 58% at sampling points ,dissolved oxygen average saturation was 130% ,water quality became the best at the end of June, some can reach the level of class I.(3) Selected P. crispus to do the balance harvest test in order to study the balance of submerged aquatic plants harvesting on lake water quality, and based on it for the mesocosm experiment of P. pectinatu. It showed that the balanced harvest of P.crispus had practical significance to the quality of lake.Harvested P.crispus in late April, control the accumulation and release of the source of nutrients within the lake best with 80% proportion of harvest, and maintained the stability of biological populations of P. crispus well, the removal efficiencies of total nitrogen / phosphorus were 87%,58%.