ABSTRACT
Pollution studies of 14 rivers (Apurogwei, Iyakun, Orogodo, Effurun, Enehren, Udu, Pessu, NPA, Ugbuwangue, Eruemukohwarien, Oha, Ugolo, Agbarho and Osubi) in Delta state Nigeria was carried out based on physico chemical and phytoplankton analysis. Water samples were collected in November, 2020 for both physico-chemical and phytoplankton compositions. Determination of the physico-chemical parameters was done according to standard analytical methods, while phytoplankton composition analysis was done with the aid of a compound microscope to which a digital imager was attached. Results shows that the phytoplankton assemblage was characterized by some pollution tolerant genera and consisted of 164 taxa distributed within the divisions Bacillariophyta (57.31%), Euglenophyta (18.29%), Chlorophyta (12.80%), Cyanophyta (6.73%) and Dinophyta (4.87%). Most frequently occurring species were of the genera Pinnularia, Frustulia, Navicula, and Trachelomonas. Employing the Palmer’s algal pollution index, the sampled rivers were found to be categorized as having no organic pollution (21.42%), moderate organic pollution (57.14%) and confirmed high organic pollution (21.42). For the physico-chemical parameters, water and air temperatures ranged from 28°C – 32°C and 31°C – 38°C respectively, while total dissolved solids, electrical conductivity, total hardness, sulphate, calcium, magnesium, phosphate and nitrate values were I the ranges of 5mg/l – 68mg/l, 10µs/cm – 136µs/cm, 2mg/l – 194mg/l, 4mg/l – 19mg/l, 0.4mg/l – 44.8mg/l, 0.2mg/l – 22.26mg/l, 0.1 mg/l – 1.9 mg/l and 0.1mg/l – 3.0mg/l respectively. In general, the physico-chemical results and algal pollution indices indicated poor water quality status in most of the rivers studied and thus measures to reduce the pollution stress should be carried out regularly.
