长江南通如皋段江滩长期无钉螺孳生原因的研究

Study on the Reason of No Snail Growing in Long Term in the Marshlands Along Changjiang River,Nantong Rugao Section

目的 探索长江南通如皋段江滩长期无钉螺孽生原因及这一地区的血吸虫病防治对策。方法 采集研究段长江如皋江滩及对照段扬州江滩的水、土样,比较分析两者的理化性质;调查分析两者的气象因子、植被、水文有无差异;用两者的水土室内饲养钉螺,比较分析两者的钉螺半年、1年存活率及雌螺的产卵率、螺卵的孵出率;在研究段及内河环境人工控制现场饲养钉螺,比较分析两者的1年存活率。结果 研究段江水的Ca^(++)、总硬度、Mg^(++)、氯化物和土样的SO_4^(-2)均显著高于对照段;两者钉螺半年、1年存活率及雌螺产卵率均无显著差异;研究段以西有20km江滩基本无植被及有海潮顶托现象。结论 海潮顶托和无植被江滩能阻止钉螺向下游扩散;今后研究段可停止查螺或只花极少量经费监测,以减少卫生资源的浪费。

OBJECTIVE To explore the reason of no snail growing in long team in the marshlands along Changjiang River Nantong Rugao section and to explore the Shistosomiasis control strategies. METHODS Sample of water and soil from Changiiang River Rugao section contrasting Yangzhou section was collected. Physical and chemic character of the two was compared and analyzed. Meteorologic and hydrologic factor and plant was investigated and analyzed. Snails were respectively breeded with water and soil of the two in the room. The snails livability of the two in half a year, in a year was compared. Ratio of trigamous snails laying eggs and ratio of eggs hatching out was analyzed. Snails were breeded respectively in the researched section,in the controlled plot along inland river.The snails livability in a year was analyzed. RESULTS The Ca+ + , Mg+ + , total rigidity and chloride of water and So4-2 of soil from researched section was remarkable higher than that from contrasting section. The snails livability in half a year, in a year and the ratio of trigamous snails laying eggs of the two has no remarkable difference.The 20km - long marshlands to the west of the researched section has little plant and there is tide - topping phenomenon. CONCLUSION Tide - topping and little plant can obstruct snails spreading towards lower reaches of the river. We can stop inspecting snails or cost few to monitor it in the researched section, which will save the health resources.