不同生物量苦草在生命周期的不同阶段对水体水质的影响

The effects of submerged macrophyte (Vallisneria natans) at different biomass levels in one-year life cycle on water quality

在玻璃温室大棚内,模拟太湖的水、土、植物情况,研究了不同生物量苦草在1年内生命周期中不同阶段对水体水质的影响.研究结果表明,不同生物量的苦草在对水体水质的影响有较大的差异,此差异受苦草生长状况的影响显著.通过单因素方差分析得出从整个生命周期看,苦草生物量为992.00g时,对水体pH值影响最大,不利于苦草吸收NH4+-N和ρ(TOC)的降低;为496.00g时,水体ρ(DO)的周年平均值处于较高水平,约8.65mg/L;为228.00g时,有利于ρ(TP)的降低,不利于其吸收NO3--N和ρ(TN)的降低.其中,生长期,苦草对水体营养盐的去除率随生物量的增加不断增大,当生物量达到2380.00g时,去除率放缓;衰亡期,苦草生物量为168.00g时,水体TN去除率取得极大值,为784.00g时,水体TP去除率取得极小值.最终确定214.00g的苦草残余生物量为最佳滞留量,此时苦草密度为118.00g/m2.

The effects of submerged macrophyte at different biomass levels in one-year life cycle on water quality were studied. Vallisneria natans, which was planted in greenhouse, was used in the present study. The sediment was collected from Taihu Lake and water was prepared according to the water quality of Taihu Lake. The experimental results showed that, the effects of submerged macrophyte on water quality had significant differences under different biomass levels, which were mainly influenced by Vallisneria natans from the different period in life cycle. Data were analyzed by one-way ANOVA, the results showed that, from the view of whole life cycle in one year, the treatment with biomass level of 992.00g had the highest effective on pH value of water column and adversely affected on the absorbed amount of NH4＋-N and TOC. When the biomass was 496.00g, ρ（DO） always maintained a high level （approximately 8.65mg/L）. The biomass of 228.00g was beneficial to the reduction of ρ（TP） in water column, but unbeneficial to the reduction of ρ（TN） and ρ（NO3--N）.During the growing season, the removal rate of water nutrients kept increasing with biomass increasing until the biomass reached 2380.00g. Then, the removal rate reduced gradually. During the decomposing season, the removal rate of ρ（TN） reached maximum value when the biomass was 168.00g, while the removal rate of ρ（TP） reached minimum value when the biomass was 784.00g. In summary, 214.00g was the optimum biomass in terms of water quality, which was corresponding to the density of 118.00g/m2.