Faculty: Physical Sciences
Department: Pure And Industrial Chemistry
Akagha I. Cletus
Ajiwe, V. I. E.
Okoye, P. A. C.
The indiscriminate disposal, discharge and dumping of home wastes and industrial effluents into Aba River can destroy the water quality and environment. Sediment, plant and effluent samples were collected from Nigerian Breweries Limited (NBL), Petterson Zechonis (PZ), Abattoir (ABT), Upstream (USAR) and Downstream (DSAR) stations bi-monthly for twelve months (June 2014-May 2015 inclusive) along the course of the river. These samples were analyzed for concentrations of heavy metals using Atomic Absorption Spectrophotometry. Physico-chemical parameters were determined using standard analytical methods. Horton’s equation was used for the determination of pollution index of the effluents. Dissolved oxygen, electrical conductivity, pH, temperature and turbidity were determined on the industrial effluents using Hannah probe and meters at the collection stations. Statistical analysis were performed on results using ANOVA and SPSS version 20 in correlating geo-accumulation of heavy metals at the stations; potential human health risks of heavy metals on Telferria occidentalis and Talinum triangulare leaves were determined using mathematical models derived by United States Environmental Protection Agency (USEPA, 2015). Physicochemical parameters carried out: BOD (51-69mg/L, dry; 33.6-60.0mg/L, wet); COD(387-179mg/L, dry; 117.3-130mg/L, wet); DO(188-66 mg/L, dry; 92-112mg/L, wet); pH(6.06-5.8 wet;5.3-6.0 dry) and temperature(27.61-27.24oC wet; 27.32-27.63oC dry) in the rain and dry season. The non-cancer risk was estimated using target hazard quotient approach (THQ) on consumption Telferria occidentalis (To) and Talinum triangulare (Tt ) leaves grown at the river side. The THQ results were Cd (57.730To, 27.097Tt); Cr(24.720To, 9.225Tt); Ni(25.12To,4.595Tt); Pb (37.107To, 9.544Tt); Mn (70.073To, 61.222Tt). THQ values for Cu, Zn, and Fe from all the sites were less than one (1.0). The other five heavy metals values being above 1.0 were indicators of possible health risk to the consumers of the leaves. Bio-concentration factors on Eichhnor crassipes Leaf:>> Zn (9930.8-0.113); Fe(3833.4-0.0905); Mn(1157-0.140); Cu (1.173-0.0598); Cd (83.0-0.1538); Pb (9.5-5.7894). Geo-accumulation index investigations indicated positive correlations between heavy metals (Pb, Mn and Cu) and some sites signifying common sources from industrial effluents while the metals Fe, Ni, Cd, Zn and Cr had negative correlations inferring that geo-accumulation was not related to the industrial presence. The pollution index of Aba River water ranged from 1.3206 in June/July 2014 to 4.2313 in Feb/March 2015. These results being greater than one (1.0) confirmed that Aba river was strongly polluted. pH (6.06-5.8wet; 5.3-6.0 dry) and temperature (27.61-27.24oCwet;27.32-27.63oCdry) in the rain and dry season, TDS ranged from 82.3-96.8mg/L against 250mg/L WHO. TSS ranged 45.8-62.3mg/L against 10mg/L WHO. Total Hardness, Electrical conductivity and Chloride had values below WHO set standards ,Chloride at all sites were below WHO set standards of 250mg/L excepting at NBL at of 410mg/L. NO3-1 and PO4-3 were found within (WHO)set limits. Water quality assessment revealed Aba River was affected by the industrial effluents discharged into it. Planting of these plants Telferria occidentalis and Talinum triangulare by the river banks and as standard barriers will serve as plant remediators. The farmers should be educated on the bio-accumulation effects of heavy metals. The river should be monitored by the authorities to regulate the abuse on the water. The water should be treated before use.