混凝土护坡通江河道内钉螺迁移扩散规律

STUDY ON REGULAR PATTERNS OF MOVE AND DIFFUSING OF ONCOMELANIA SNAILS IN RIVERS WITH CEMENT BANKS

目的 探讨混凝土护坡通江河道内钉螺迁移扩散规律 ,为制订钉螺防治对策提供依据。方法 以苏南运河“河口至新丰铁路桥”河段为试区 ,开展整治前已灭螺点、混凝土护坡有螺情况、水中障碍物滞螺、水体钉螺、漂浮物携螺和船体携螺调查 ,将调查结果与整治前情况相比较。结果 已灭螺点复查 12处 ,2处查到钉螺 ,距河口分别为 3.2 km和 4 .3km;水中障碍物滞螺调查有螺框出现率为 0 ,与整治前的 87.0 %相比 ,差异有非常显著性 (P<0 .0 1) ;调查水体 4 80 0 m3,捕获活钉螺1只 ,水体钉螺密度 0 .0 2 1只 /m3,较整治前下降了 98.5 % ;调查漂浮物 2 6 0 kg,捕获活钉螺 3只 ,漂浮物携螺量 0 .0 12只 /kg,较整治前下降了 95 .4 %。结论 混凝土护坡通江河道汛期仍存在钉螺迁移扩散 ,以随水流及漂浮物扩散为主要形式 ,但强度明显减弱 。

Objective To probe into regul ar patterns of move and diffusing of Oncomelania s nails in rivers with cement banks and determine the control strategy. [WT5 ”HZ]Methods The part of Sunan Canal from the estuary to Xin feng Railway Bridge was taken as the experimental zone. The revival of snail spo ts destroyed before the canal dredging, snail status on cement banks, snails on obstacles, floaters and ships in the rivers and floating snails were investigate d and compared with the situations before the dredging. Results Twelve destroyed snail spots were investigated and two of them presented snails, apart from the estuary 3.2 km and 4.3 km. The rate with sna il s on obstacles in frame in the rivers was 0, significantly lower than the 87% be fore the dredging(P<0.01). A total of 4800 m3 of water was investigated and only 1 snail caught. The density of f loating snai ls was 0.021/m3, decreasing by 98.5% of that before the dredging. A total of 260 kg of fl oaters were investigated and 3 snails caught. The quantity of snails on floaters was 0.012/kg, decreasing by 95.4% of that before the dredging. Conclusion The move and diffusing of th e snails in the rivers with cement banks still occur in the flood season. The ma inly diffusing forms are floating and clinging to the floaters. However, the in tensity is much weaker and the range obviously smaller. [