底泥营养释放对城市景观水质影响的模拟研究

Simulations of the effects of sediment nutrient release on urban landscape water quality

通过对天津市卫津河夏末底泥开展室内模拟,探讨重度富营养化河道底泥的氮、磷释放以及与上覆水浮游藻类种群变动的相互关联。结果表明:(1)以富营养湖水为上覆水较之蒸馏水能更快促进底泥氮、磷的释放。以湖水、蒸馏水为上覆水的处理组氨氮极大值分别为4.36、3.61mg/L;溶解性正磷酸盐极大值分别为110.3、81.9μg/L。(2)湖水样品室内培养后,优势蓝、绿藻门的细胞密度与生物量都成倍增长。添加底泥开展培养,蓝藻门和硅藻门快速增殖,绿藻门的生长因溶解性正磷酸盐的竞争与消耗而受到抑制。底泥营养释放导致上覆水层富营养化程度加剧,硅藻门的梅尼小环藻(Cyclotella meneghiniana)被大量检出且增殖迅速。(3)上覆水为蒸馏水时,氮、磷营养自底泥的持续释放,促使绿藻门的土生绿球藻(Chlorococcum humicola)成为绝对优势种,藻类总生物量最高。

The study aimed to find the correlations between the sediment nutrient releases and the variations of phytoplankton community in a hypertrophic river. Indoor simulations were carried out with the sediment collected from the Weijin River,Tianjin in late summer. The results showed that： （1） It accelerated the nitrogen and phosphor- us release from the sediment when covered by the natural eutrophic lake water compared to the distilled water. During the experiments,the maximum concentrations of ammonia nitrogen were 4.36 mg/L in the sediment-lake water group （Group B） and 3.61 mg/L in the sediment-distilled water group （Group C）. The maximum concentrations of soluble orthophosphate were 110.3,81.9 /~g/L in the two groups respectively. （2） During the indoor culture, both the cell abundance and biomass of the dominant cyanobacteria and chlorophytes in the lake water （Group A） almost doubled. Adding the sediment to the lake water, the cyanobacteria and diatoms rapidly became the dominant phyla. The growth of chlorophytes was greatly restrained because of the depletion of soluble orthophosphate in the competition. The nutrients from the sediment caused more serious eutrophication in the overlying water. The Cyclotella meneghiniana was detected and it grew rapidly. （3） In Group C, the Chlorococcum hurn icola becamed the most abundant species and the total algal biomass was significantly greater than the other groups for the sustained release of nitrogen and phos- phorus from the sediment.