Geochemical Speciation and Ecological Risk of Heavy Metals in Estuarine Sediments of the Qua Iboe River, Nigeria
Okpoji, Awajiiroijana U
*
Department of Pure and Industrial Chemistry, University of Port Harcourt, Choba, Nigeria.
Etesin, Monday U
Department of Chemistry, Akwa Ibom State University, Ikot Akpaden, Nigeria.
Ekwere, Ifiok O
Department of Chemistry, Akwa Ibom State University, Ikot Akpaden, Nigeria.
Martins Ndidi P
National Biotechnology Research and Development, Abuja, Nigeria.
Okpanachi, Clifford B
Department of Pure and Industrial Chemistry, Prince Abubakar Audu University, Anyigba, Nigeria.
Adisa Olakunle J
Department of Science Education, Nnamdi Azikiwe University, Awka, Nigeria.
Okonkwo Chidiebere C
Department of Science Education, Nnamdi Azikiwe University, Awka, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
This study investigated the chemical properties of marine sediments and the distribution of heavy metals in a river estuary in Akwa Ibom State. Sediments were collected from 10 geo-referenced points using a standard steel grab sampler. Physical parameters were analysed with standard laboratory instruments, while hydrometer methods determined grain size, metal analysis was performed using were determined using an Inductive Coupled Plasma-Mass Spectrometry and pollution levels were assessed. The sediment pH ranged from 6.32 to 7.88, with a moderate level of organic carbon (1.45 - 3.62%), and fine particles such as salt (42.7%) and clay (20.7%), which favour metal retention. The concentration of heavy metals (mg/kg) followed the order of Fe > Mn > Zn > Cu > Cr > Pb > Ni > Cd. Pollution indices identified Cd and Pb as the major contaminants, with Cd exhibiting a high ecological risk (Er=143). The estuary displays a moderate level of contamination influenced by petroleum activities and domestic discharge.
Keywords: Heavy metals, sediment chemistry, plasma-mass, spectrometry