Effects of Aquatic Plants in Different Growth Stages on Nutrient Contents in Wetland Sediments
GUAN Xiu-ting;ZHOU Lin-fei;CHENG Qian;College of Water Conservancy, Shenyang Agriculture University;
In order to study the effects of aquatic plants on the changes of organic matter, nitrogen and phosphorus in wetland sediments at different growth stages, samples of sediment were taken in designated area which belongs to the four different plant regions(including lotus area, reed area, cattial plant areas, the mixing area of submerged and floating plants) of Shifosi artificial wetland in 2013-2015 for determining the content of OM, TN and TP in sediment. The average of the three years' data for some comparative analysis was calculated. The results showed that the contents of the three nutrients in wetland sediments were all reduced for the reason of plant fast growth in germination period. In blooming and fruit stage, the content of organic matter in wetland sediments was reduced for the reason of storm water, and the changes of N and P contents were unstable. In fruit maturity stage, due to the plant decomposition, the variation tendency of three nutrient contents in wetland sediments increased but the total contents were the lowest. In decaying stage, the contents of nutrient contents in wetland sediments increased. The influence of temperature on the changes of nutrient contents in sediments were mainly reflected to the growth of aquatic plants,microbial activities in sediments and microbial reaction. Plant decay was a long process, not only existed in the decaying stage.Lotus was the best for the purifying effect of the three nutrient substances in wetland sediments and the highest purifying rate for the organic matter, nitrogen and phosphorus were 77.3%, 64.8% and 47.5%. Cattial was undesirable, the lowest purifying rate for phosphorus was 39.1%. In conclusion, aquatic plants plays a very important part for the purifying effect of the three nutrient substances in wetland sediments.