Distribution and Potential Environmental Risks of Heavy Metals in Riverine Sediments of Maa-Dee-Tai River in Sogho Community, Ogoniland, Rivers State, Nigeria

Abstract

Ecological Risk Assessments are executed to appraise the probability of adverse ecological effects occurring as a consequence of exposure to biological, physical, or chemical factors that causes hostile responses in the environment. Several studies have shown extensive heavy metals and crude oil contamination of soils, sediments, rivers, creeks, and ground waters in Ogoniland, Nigeria. However, the Sogho Community in Ogoniland has not been studied. Hence, this paper evaluates the distribution and ecological risk assessment of heavy metals in riverine sediments of Maa-Dee-Tai River in Sogho Community, Ogoniland, Rivers State, Nigeria using Solaar Thermo Elemental Atomic Absorption Spectrophotometer, Model SN-SG 710960 after total dissolution of riverine sediments by hydrofluoric acid (HF) and aqua regia (HNO 3 : HCl; 1:3, v/v) at a temperature of 100 o C. Distribution of heavy metals in the sampling stations reveal that Werri had the maximum magnitude of nickel (Ni) among the three stations assessed and the mean value for the three stations is 4.21±0.92mg/Kg. The average values recorded for Ni in the three stations were; 3.52±0.58, 4.04±1.04 and 5.07±1.14mg/Kg for Dee-Tai, Barawansah and Werri respectively. The average mean concentration of the sampling stations for each metal (mg/kg) are Ni (4.21), Zn (3.56) Cr (3.35), Pb (3.25), Cu (1.59), Co (0.8), As (0.12) and Cd (0.12). The order of abundance of the metals in the riverine sediments is Ni>Zn>Cr>Pb>Cu>Co>As>Cd. In all the stations examined, Nickel (Ni) was the most abundant metal. The pollution indices revealed that the river was unpolluted with the different heavy metals studied. The potential environmental risks assessment of heavy metals in riverine sediments of the Maa-Dee-Tai River in Sogho Community, Ogoniland reveals that the river poses low risks in terms of pollutants with reference to heavy metals in the sediment. Hence, it is necessary to preserve the natural state of the river.