西湖引水工程絮凝剂余铝对菹草生长及水质的影响

为分析杭州西湖引水工程絮凝剂残余铝盐对水质和沉水植物的影响,研究采用室外模拟试验,考察了连续投加不同浓度梯度的明矾(KAlSO412H2O)絮凝剂对菹草(Potamogeton crispus)的生理影响和对水质的影响。试验设置了4个处理: 对照组、低剂量组(35050) g/L、中剂量组(65070) g/L、高剂量组(1100150) g/L。结果表明: (1)低、中剂量投加对水中铝盐含量无显著影响,高剂量投加导致水中铝盐含量显著上升; (2)水中铝盐含量呈先升高后降低的趋势,pH随铝盐含量升高而降低,总磷(TP)随之有所下降,各处理组水中总氮(TN)、浮游植物密度、浊度均明显下降; (3)3个剂量组菹草各生化指标较对照组几乎无显著变化,试验浓度的铝盐投加对菹草的生长没有造成明显损害,在菹草耐受范围内,建议在西湖引水工程入水口附近水中铝盐含量约(25050) g/L]可选用菹草进行植被恢复。

EFFECT OF RESIDUAL ALUMINUM FLOCCULANT OF WEST LAKE DIVERSION PROJECT ON THE GROWTH OF SUBMERGED MACROPHYTE POTAMOGETON CRISPUS AND WATER QUALITY

To investigate effects of residual aluminum flocculant on the growth of submerged macrophyte Potamogeton crispus and water quality of the West Lake diversion project, the method of outdoor simulation was utilized with four different treatment groups: the control group (no addition), low-dose group (35050) g/L, middle-dose group (65070) g/L and high-dose group (1100150) g/L. The results showed that: (1) high-dose addition increased significantly the concentration of aluminum salt in water, while low and medium-dose addition had little effect. (2) The concentration of aluminum salt in water increased first then decreased latterly and pH had a little change conversely, and total phosphorus decreased accordingly; Total nitrogen, phytoplankton density and turbidity in water of every group had a clear decline. (3) Three treatment groups of P. crispus had almost no significant changes in the biochemical indi-cators compared with the control group. On experimental concentration of alum flocculant dosing, P. crispus was growing with no obvious damage, and the concentration was in the tolerance range of P. crispus. Hence we suggest that P. crispus can be selected planting near the water inlet districts of diversion project for submerged macrophyte restoration in West Lake, Hangzhou.