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ENCYCLOPEDIA OF ENVIRONMENTAL SCIENCE AND ENGINEERING - EUTROPHICATION

Trong một thời gian đáng kể, các nhà khoa học đã nhận thức được sự lão hóa tự nhiên của hồ, một quá trình chậm như vậy nó được coi là vô hạn trong vòng đời của con người. Trong những năm gần đây, tuy nhiên, phần của chương trình làm giàu chất dinh dưỡng hoặc hiện tượng phú dưỡng của các cơ quan tự nhiên khác của nước đó đóng góp do con người tạo ra nguồn đã trở thành một vấn đề quan tâm. Nhiều cơ quan của nước cuối có biểu hiện phiền hà sinh học như. | EUTROPHICATION INTRODUCTION For a considerable time scientists have been aware of the natural aging of lakes a process so slow that it was considered immeasurable within the lifetime of human beings. In recent years however that portion of the nutrient enrichment or eutrophication of these and other natural bodies of water contributed by man-made sources have become a matter of concern. Many bodies of water of late have exhibited biological nuisances such as dense algal and aquatic weed growths whereas in the past they supported only incidental populations of these plants. Excessive nutrients are most often blamed in the scientific literature for the creation of the plant nuisances. Among the nutrients dominant roles have been assigned by most researchers to nitrogen and phosphorus. These elements can be found in natural waters in soils in plants and animals and in precipitation. Man-made sources for these nutrients are in domestic wastes and often in industrial wastes. This chapter concerns itself with the nature of algae the environmental factors affecting their growth the nature of the entrophication problem sources relative quantities of nutrients contributed by these sources threshold limits for the growth of aquatic plants and various techniques for the removal of those nutrients usually associated with the eutrophication problem. THE PHYSICAL NATURE OF ALGAE Most bodies of water which can be considered eutrophic exhibit various predominant forms of algae at different times of the year. Algae that are important to investigators concerned with the eutrophication problem may be classified into four groups which exclude all but a few miscellaneous forms. The four groups are 1 Blue-green algae Myxophyceae 2 Green algae Chlorophyceae 3 Diatoms Bacillariophyceae 4 Pigmented flagellates Chrysophyceae Euglenophyceae The basis for this classification is the color of the organism. Blue-green and green algae are self descriptive whereas diatoms are brown or .