Xét về tính hữu ích thực tế khả năng đồng hóa chất thải của dòng suối như một nguồn tài nguyên nước CÓ CƠ SỞ CỦA NÓ Hiện tượng quan tâm đánh giá phức tạp trong dòng tự thanh lọc. Đây là một năng động và hiện tượng thủy văn biologicvariations Phản ánh, và chưa đầy đủ interrelationsare Hiểu về chính xác. Tuy nhiên, không loại trừ này không áp dụng gì được biết đến. Có đủ kiến thức có sẵn để cho phép định nghĩa định lượng trong các điều kiện dẫn dòng Theo dự kiến phạm vi của. | CHAPTER 12 Self-Purification of Streams In terms of practical usefulness the waste assimilation capacity of streams as a water resource has its basis in the complex phenomenon termed stream self-purification. This is a dynamic phenomenon reflecting hydrologic and biologic variations and the interrelations are not yet fully understood in precise terms. However this does not preclude applying what is known. Sufficient knowledge is available to permit quantitative definition of resultant stream conditions under expected ranges of variation to serve as practical guides in decisions dealing with water resource use development and management. c. J. Velz202 BALANCING THE AQUARIUM An outdoor excursion to the local stteam can be a relaxing and enjoyable undertaking. On the other hand when you arrive at the local stream and look upon the stream s flowing mass to discover a parade of waste and discarded rubble bobbing along the stream s course and cluttering the adjacent shoreline and downstream areas any feeling of relaxation or enjoyment is quickly extinguished. Further the sickening sensation the observer feels is made worse as closer scrutiny of the putrid flow is gained. The rainbow-colored shimmer of an oil slick interrupted here and there by dead fish and floating refuse and the slimy fungal growth that prevails are recognized. At the same time the observer s sense of smell is alerted to the noxious conditions. Along with the fouled water and the stench the observer notices signs warning DANGER NO SWIMMING or FISHING. The observer has discovered what ecologists have known and warned about for years. That is contrary to popular belief rivers and streams do not have an infinite capacity for pollution. Before the early 1970s such disgusting occurrences as the one just described were common along the rivers and streams near main metropolitan ar- 202Velz c. J. Applied Stream Sanitation. New York Wiley-Interscience p. 66 1970. 157 Copyright 2001 by Technomic Publishing
