Geochemical Fractions, Spatial Distribution, and Bioavailability of Copper and Zinc in Coastal Lagoon Sediments

International Journal of Chemistry | Vol. 6, No. 11, November 2015 | pp. 81–88

DOI: 10.46882/2015/IJC/000086

Article Type: Original Research Paper

Title: Geochemical Fractions, Spatial Distribution, and Bioavailability of Copper and Zinc in Coastal Lagoon Sediments

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

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

Abstract: Total concentrations of heavy metals are insufficient to assess ecological risk in coastal bodies because environmental mobility and bioavailability depend heavily on specific chemical binding forms. This study evaluates the total concentration and geochemical speciation fractions of copper (Cu) and zinc (Zn) in surface sediments collected from an urban coastal lagoon exposed to municipal and industrial waste discharges. Quantitative analysis was performed using Atomic Absorption Spectrophotometry (AAS) following the modified BCR three-step sequential extraction procedure. The total metal concentrations followed the sequence: Zn > Cu across all sampling locations. Spatial mapping revealed significant pollutant accumulation near storm-water discharge channels. Speciation patterns demonstrated that a high proportion of zinc (42.5%) was associated with the acid-soluble and exchangeable fractions, suggesting high structural instability and bioavailable risks to benthic organisms. Conversely, copper was primarily bound within the organic and reducible matrices, indicating low immediate mobility under baseline pH conditions. The Risk Assessment Code (RAC) calculated for zinc indicated a high environmental hazard rating, highlighting a strong need for local effluent regulatory frameworks.

Keywords: Coastal lagoon; Sediments; Trace metals; BCR protocol; Geochemical speciation; Bioavailability

Manuscript Timeline: Received: April 02, 2015; Revised: May 22, 2015; Accepted: June 15, 2015; Published: November 02, 2015.

Citation: Obi, C. I., & Kim, S. H. (2015). Geochemical Fractions, Spatial Distribution, and Bioavailability of Copper and Zinc in Coastal Lagoon Sediments. International Journal of Chemistry, 6(11), 81–88.

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