Modern Chemistry 2018; 6(4): 44-49 http://www.sciencepublishinggroup.com/j/mc doi: 10.11648/j.mc.20180604.11 ISSN: 2329-1818 (Print); ISSN: 2329-180X (Online) Environmental Effect of Dredging and Geochemical Fractionation of Heavy METALS in Sediments Removed from River Ogbu Victor, Osu Charles Ikenna * , Iwuoha Godson Ndubuisi Department of Pure and Industrial Chemistry, Faculty of Science, University of Port Harcourt, Port Harcourt, Nigeria Email address: * Corresponding author To cite this article: Ogbu Victor, Osu Charles Ikenna, Iwuoha Godson Ndubuisi. Environmental Effect of Dredging and Geochemical Fractionation of Heavy METALS in Sediments Removed from River. Modern Chemistry. Vol. 6, No. 4, 2018, pp. 44-49. doi: 10.11648/j.mc.20180604.11 Received: August 5, 2018; Accepted: September 6, 2018; Published: January 10, 2019 Abstract: Geochemical fractionation of six heavy metals; Zn, Pb, Cd, Cu, Cr, and Ni in soil from two dredging sites at Chokocho and Umuechem communities in Etche Local Government Area of Rivers State, Nigeria, which is characterized by domestic, oil exploration and other industrial activities. The heavy metal concentration determined were 26.30 ± 0.38 mg/kg, Pb; 10.60 ± 0.04 mg/kg, Cd; 486.00 ± 1.20 mg/kg, Zn; 35.50 ± 0.30 mg/kg, Cr; 43.50 ± 0.40 mg/kg, Ni and 37.70 ± 0.10 mg/kg, Cu for Chokocho site. For Umuechem site, the concentration of the metals revealed were 18.40 ± 0.10 mg/kg, Pb; 6.80 ± 0.70 mg/kg, Cd; 437.00 ± 0.60 mg/kg, Zn; 29.30 ± 0.20 mg/kg, Cr; 36.40 ± 0.10 mg/kg, Ni; and 28.30 ± 0.20 mg/kg, Cu. Results from umuechem site was greater than Chokocho site. Heavy metal fractionation using conventional method was adopted for sequential extraction which was accomplished in five steps. Results revealed that Cd and Pb were dispersed more at exchangeable phase in the sample; Cu and Zn were the least bioavailable. Cd, Pb, and Cr show health risks because of high percent in the exchangeable or dissolved fraction. The results of the analysis also revealed that the bioavailablity and mobility of the heavy metals were in order; Cd > Pb > Cr > Ni > Zn > Cu. Keywords: Dredging, Geochemical Fraction, Contamination, Pollution 1. Introduction Dredging is a worldwide excavation activity that involves removing sediment from a sea, river, or lakebed and depositing it at a new location. Uses are vast and include construction of ports, waterways, dykes, and other marine infrastructure, land reclamation, flood and storm protection, extraction of mineral resources to provide material for the construction industry (e.g. for road construction), and in environmental remediation of contaminated sediments [1, 2, 3, 4]. Dredging can also be described as the process of removing part of the seabed or its overlying sediments with the aim of deepening the area commonly for the purpose of navigation or associated with construction projects. Dredging is an excavation activity usually carried out underwater, in shallow seas or freshwater areas with the purpose of gathering up bottom sediments and widening. This technique is often used to keep waterways navigable and creates an anti-sludge pathway for boats. It is also used as a way to replenish sand on some public beaches, where sand has been lost because of coastal erosion. Fishing dredges are used as a technique for catching certain species of edible clams and crabs. A variety of harmful substances, including heavy metals can be effectively locked into the seabed sediments. The dredging and disposal processes can release these contaminants into the water column, making them available to be taken up by animals and plants. These contaminants can often be of historic origin and from distant sources. The dredging and disposal processes can release these contaminants into the water column, making them available to be taken up by animals and plants, with the potential to cause contamination and/or poisoning. Some portion of the total quantity of pollutant present in soil is potentially available for uptake by organisms. This