Chemical Speciation, Contamination Assessment, and Ecological Risk Indices of Trace Metals in Estuarine Sediments

International Journal of Chemistry | Vol. 5, No. 3, March 2014 | pp. 17–24

DOI: 10.46882/2014/IJC/000066

Article Type: Original Research Paper

Title: Chemical Speciation, Contamination Assessment, and Ecological Risk Indices of Trace Metals in Estuarine Sediments

Names of Authors: C. I. Obi¹, K. H. Kim²*

Authors’ Affiliations:
¹Department of Pure and Industrial Chemistry, University of Port Harcourt, Port Harcourt, Nigeria.
²Department of Civil and Environmental Engineering, Hanyang University, Seoul, South Korea.

Abstract: Monitoring total heavy metal loads in coastal aquatic systems is inadequate for evaluating ecotoxicity because the mobility and environmental risks of contaminants depend heavily on their chemical fractions. This study assesses the total concentrations and geochemical binding forms of cadmium (Cd), chromium (Cr), lead (Pb), and copper (Cu) in estuarine surface sediments exposed to industrial effluents. Metal quantification was performed via Inductively Coupled Plasma Mass Spectrometry (ICP-MS) following the modified BCR three-step sequential extraction protocol. Total metal concentrations followed the sequence: Cr > Pb > Cu > Cd. Spatial mapping revealed heavy metal accumulation downstream from active petrochemical and manufacturing points. Speciation analysis showed that a substantial portion of cadmium (45.8%) and lead (32.4%) existed within the water-soluble and exchangeable fractions, suggesting high structural instability and bioavailable risk to benthic fauna. Conversely, chromium and copper were primarily locked within residual and organic crystal lattices, indicating low immediate mobility under baseline pH conditions. The Potential Ecological Risk Index (RI) calculated for cadmium showed a very high hazard rating, requiring urgent regional remediation actions.

Keywords: Estuarine sediments; Trace metals; BCR protocol; Geochemical speciation; Bioavailability; Ecological risk index

Manuscript Timeline: Received: April 02, 2013; Revised: May 20, 2013; Accepted: June 15, 2013; Published: March 11, 2014.

Citation: Obi, C. I., & Kim., K. H. (2014). Chemical Speciation, Contamination Assessment, and Ecological Risk Indices of Trace Metals in Estuarine Sediments. International Journal of Chemistry, 5(3), 17–24.

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