水葫芦生态工程措施对太湖竺山湖水环境修复效果的研究

采取以水葫芦(Eichhornia crassipes Solms)等为代表的生态工程措施净化污染水体,成为污染水体治理的发展趋势。在太湖流域,虽然已有多年的工程措施经验,但尚无针对该种生态工程措施实施过程中对水质改善影响的系统性研究,为此对2011年太湖竺山湖种养66.7 hm2水葫芦期间水体营养盐吸收和水质净化效果进行了调查研究,结果表明:受风浪扰动等水文气象条件的影响,工程区内外水体交换强烈,水体透明度、p H等基本理化指标变化不明显,水葫芦种养区内未出现厌氧现象,水葫芦工程措施对颗粒物及蓝藻具有滞留效果,使得水葫芦种养区水体TN、TP含量较高,其变化幅度分别为1.13~3.30、0.085~0.165 mg·L-1,低于外围水体中TN、TP含量;受气温及水流等影响,水体中蓝藻密度在8月份达到高峰,放养区内叶绿素含量为77.97 mg·m-3,同期边缘和外围含量分别为84.40、86.84 mg·m-3,植物根部叶绿素含量较高,表明水葫芦根须对蓝藻细胞具有较强的拦截作用。全年收获20000 t水葫芦,从水体中共带出N、P、K的量分别为19.8、2.4、44.5 t,表明规模化种养以水葫芦等为代表的生态工程措施具有较好的水体净化功能,为扩大利用水葫芦等速生漂浮植物建立的"移动湿地式"生态工程措施治理较大面积富营养化水体提供了依据。

Purification of Water in Zhushan Bay of Taihu Lake with Water Hyacinth Ecological Engineering

Ecological engineering measures, using fast-growing floating plants to purify polluted water, have become efficient and effective methods to restore water environment. Here, effects of water hyacinth on nutrient absorption and purification of water in Zhushan Bay, Taihu Lake, were investigated in 2011. Results showed that transparency, pH and oxygen deficit of water in hyacinth areas were not significantly different from those in no- hyacinth area, due to wave disturbance and strong water exchange. However, water hyacinth roots had a strong ability to absorb suspended solids and algae, and to reduce concentrations of TN and TP in water. Chlorophyll content of water was 77.97 mg·m^-3 in August in the water hyacinth areas, while it was 84.40 mg·m^-3 and 86.84 mg·m^-3 at the edge of and in the area outside water hyacinth, respectively. Total biomass of water hyacinth was 20, 000 tons throughout the year, implying that a total of 19.8, 2.4, and 44.5 tons of N, P, and K were removed from the water, respectively. These results suggest using ecological engineering such as floating wetland planted with water hyacinth could remediate water in large area.