Spatial and seasonal variations in physico-chemical parameters of the Imo River Estuary, Niger Delta, Nigeria

Variations in the water quality of the Imo River estuary was investigated by measuring values of selected physico-chemical parameters. Samples were collected bi-monthly between April 2015 and March 2016, covering the dry and wet seasons of the year. Three stations were selected: upstream (Kalibiama), midstream (Opobo) and downstream (Queenstown). Analysis of results showed that physico-chemical parameters were affected more on seasonal than spatial scale. Principal component analysis carried out indicated that values of most of the parameters recorded within the stations clustered together. On the other hand, dispersed values were recorded in months and seasons with significant variations at (p≤0.05) among most parameters. The high spatial variations in phosphates, suspended solids and lead could be associated to human activities like laundry and waste disposal within Opobo and Kalibiama stations. While, high seasonal variability in most parameters could be associated with intense sunshine, cloud cover and tidal intrusion/dilution due to runoff. It can be concluded that nutrient fluxes due to nitrogenous fertilizers are not a problem within the estuary. However, chemical factors and biodegradable components which cause fluctuations in biological oxygen demand are more of the challenge. Keywords: Land-use, nutrient flux, water-quality, pollution, coastal wetlands.