Impact of Three Different Types of Aeration Units on Limnology and Fish Fauna in a Eutrophic Tropical Wetland, Lower Lake, Bhopal, India

摘要

In Bhopal, more than twenty five water bodies are present in and around the city, most of which are under great environmental stress due to multiple anthropogenic activities. The Upper Lake and Lower Lake, jointly known as Bhoj-Wetland (Ramsar Site), are situated in heart of the city and also the lifeline for the citizens of Bhopal. Lower Lake is eutrophicated due to mixing of domestic raw sewage, slums and human intervention in fringe areas, huge growth of aquatic macrophytes, idol immersion and removal of oxygenated surface water through waste weir etc. Due to these anthropogenic activities, sometimes anaerobic conditions were also reported in hypolimnion region causing mass mortality of fish fauna before installation of aeration units. The catchment area of Lower Lake is 9.6 km 2 with water spread area 1.3 km 2 . For improving water quality and oxygenation of lake water three types of aeration units were installed under Bhoj Wetland Conservation and Management Programme: they are (i) Floating Fountain (ii) Ozoniser and (iii) Floating Fountain cum ozoniser. For performance and evaluation of these different types of aeration units various parameters such as pH, alkalinity, free carbon dioxide, dissolved oxygen, biochemical oxygen demand, nitrate and fish fauna were taken. On basis of the observations all three types of aeration units are effective for management of Eutrophication and improving water quality, however, floating fountain cum ozoniser is most effective for over all improvement in water quality of the lake and creating better environment for fish survival and fish growth.