The use of biological index of pollution (BIP) in assessing quality of rural water sources in Zaria, Nigeria
The biological index of pollution (BIP) which hinges on the responses of aquatic biota to pollution of water sources was used to assess the quality of some water sources in Zaria area, Nigeria. Water samples were collected from 15 stations comprising three open water sources (lakes) and twelve hand-dug wells on a monthly basis for a period of 24 months. Ten liters of the samples from wells were concentrated to 50 ml by filtering through 70 meshes per cm2 plankton net. Collections from the lakes was by means of dragging net over a 3 meter distance in the water. The water was also concentrated to 50 ml. Using the BIP of Horasawa as modified by Palmer, the water quality situation of the sources were classified into betasaprobic and alphasaprobic. Some of the water sources, especially in the rainy season, gradually shifted in quality from betasaprobism to alphasaprobism. The BIP method gave a satisfactory indication of the quality status of each water source especially when the results obtained were compared with the result of physico-chemical analysis of the water sources. However, unless the water sources contain both phytoplankton and zooplankton, which are key variables in the BIP computation, the index proved difficult to apply.