Diurnal variations of certain chemical characteristics in Qua Iboe river in south eastern Nigeria

Abstract

The diurnal variations in certain physico-chemical characteristics in Qua Iboe River (Nigeria) as investigated between Feb.–Dec. 2000 at three stations. Measurements were made for pH, conductivity, free CO2, dissolved oxygen, total alkalinity and salinity. The diel pattern of pH changes showed lower levels in the mornings and night and higher levels during the day. Conductivity did not show any particular diel variation and diel range varied within narrow limits except at the estuary. The pattern of diel variation in DO was similar to that of pH with minimum levels recorded during early morning hours (4.00–8.00am). Seasonal pattern in DO was higher at surface than bottom which exhibited narrow differences. Free CO₂ exhibited wide variation over diel periods with minimum levels during day light hours. Total alkalinity exhibited narrow variation over diel periods and bottom levels were higher than surface. The pattern of diel variation in salinity was more remarkable than other parameters particularly at the estuary and also higher at the bottom than surface due to tidal regime and salt intrussion. Diurnal changes in these parameters are attributed to influence of precipitation, evapo-crystalisation process, photosynthetic activity and episodic events.

Keywords: diel variation, chemical parameters, river

Global Journal of Pure and Applied Sciences Vol. 11(4) 2005: 481-486