Abstract
Surveys of five rivers in a hot-humid zone of a tropical country (Nigeria) were carried out over 3 years by obtaining samples for physical, chemical and bacteriological analyses. The main characteristics monitored were temperature, turbidity, total, dissolved and suspended solids, pH, dissolved oxygen, BOD, ammonia-nitrogen and the coliform counts. In addition, the main characteristics of the liquid waste being discharged into the rivers were determined. During the dry season, the highest mean temperature is 29 C with a range of 5 C and the lowest is 26 C with a range of 3 C. In the wet season, the highest mean temperature is 27.3 C with a range of 2 C while the lowest is 24.5 C with a range of 1 C. The other characteristics vary more widely with seasons. The high temperature in these rivers all the year round encourages pollution by human activities. During the dry season, pollution causes prolific algae boom, which causes oxygen supersaturation during periods of high temperature and abundant sunlight. The physical, chemical and biological characteristics of the rivers deteriorate sharply as they flow through towns annd other human communities. (Author 's abstract)