| 摘要 |
PURPOSE:To prevent the turbid condition of river as well as obtain fish attraction effects by providing an obstacle having a shape such as to disturb water current and covered with a natural stone substance on the bed of the river. CONSTITUTION:An obstacle having a shape such as to disturb the current of water and covered with a powdery granular natural stone substance, e.g., tetrapot, etc., is set on the bed of river. Also, natural stones housed in a net may be placed on the outside of the tetrapot to cover each tetrapot with the natural stones. The apposition growth of protozoa can thus be promoted, the decomposition of organics can be attained, and the turbid condition of river can be prevented. |
