利用湿地植物控制长江泥沙的示范研究

The demonstration research of the sediment control of the Yangtse River by wetland plants

根据自然水体湿生植物(挺水植物)、浮叶植物以及沉水植物的空间分布规律,利用水生高等植物构建由挺水植物、浮叶植物到沉水植物的野外示范研究区,面积为9 048 m2.模拟长江潮汐规律每天调长江水4 320 m3流经试验区,试验共进行100 h,进水量18 000 m3,试验区平均水力负荷0.477 5 m/d.结果表明:(1)湿地植被对水体透明度的改善与维持具有重要作用,即使外界环境有强烈干扰,只要不危及到湿地植被的存活,水体的透明度很快就可以提高到一定程度;(2)湿地植物对长江水体N、P等具有良好的净化作用;(3)湿地植物可降低泥沙含量,加速泥沙沉降.输入挺水植物长江水泥沙含量为130.87 mg/L,而流出挺水植物区的泥沙含量仅为32.66 mg/L,降低了75%,试验100 h的最终沉降量达到402 g/m2;输入浮叶植物长江水泥沙含量为32.66 mg/L,而流出浮叶植物区的泥沙含量仅为20.30 mg/L,试验100 h的最终沉降量达到271 g/m2.输入沉水植物泥沙浓度平均为20.30 mg/L,流经沉水植物群落后泥沙浓度平均18.65 mg/L,在沉水植物区的沉降量为0.011 5 g/m2,明显低于挺水和浮叶植物区;(4)示范研究的结果充分验证了由挺水、浮叶、沉水等水生高等植物组成的串连湿地系统对挟沙水体中的悬浮泥沙的截留效果,因此在长江泥沙控制与水质改善上具有较好的可应用性,是长江泥沙控制、水质改善的重要措施之一.

The out door demonstration research region of emerging plants, floating-leaved plants and submerged plants which was based on spatial distribution of natural layer body was constructed and the area was 9 048 m^2. Simulate the law of the tide of the Yangtse River： transfer 4 320 m^3 water of the Yangtse River flow through the experiment region every day. The experiment lasted 100 hours. The input water quantity was 18 000 m^3. The average hydraulic loading was 0. 477 5 m/d. The results were as follows： （1） the wetland plants play an important role in improving and keeping the water transparency. Although there is intense disturbances in surroundings, water transparency will improve soon as long as it doesn＇t endanger the survival of the wetland plants; （2） the wetland plants are able to purify the N, P of the Yangtse River water; （3） the wetland plants can decrease the silt content and increase the silt deposition. The input silt concentration of the emerging plants is 130.87 mg/L and the output is just 32.66 mg/L, decreasing by 75%. The deposition of the experiment comes to 402 g/m^2. The input silt concentration of the floating-leaved plants is 32. 66 mg/L and the output is just 20.30 mg/L. The deposition comes to 271 g/m^2. The input silt concentration of the submerging plants is 20.30 mg/L and the output is 18.65 mg/L. The deposition comes to 0. 011 5 g/m^2 , obviously lower than the emerging plant region and the floating-leaved plant region; （4） the results of the demonstration research prove the effects of the concatenated wetland system which is made up of emerging plants, floating-leaved plants and submerged plants on suspended sediment interception. Thus it is practical in the silt control of the Yangtse River and the improvement of water quality. It is one of the best measures in the silt control of the Yangtse River and the improvement of water quality.