Accretion of heavy metals in the catfish Bagrus bayad from Taylor Creek, southern Nigeria

Abstract

Heavy metals in the aquatic environment have, to date, come essentially from naturally occurring geochemical resources. However, this has been enhanced by anthropogenic activities such as crude oil exploration and exploitation activities, resulting in pollution in the Taylor Creek aquatic ecosystem. The catfish species Bagrus bayad and other environmental segments were collected from five selected sites along Taylor Creek, southern Nigeria, and total metal concentration determined. The concentration levels of the metals in B. bayad were higher than the values reported in the literature for fresh fish and may lead to a higher risk of harmful effects. The bivariate regression models relating metals in B. bayad and metals in the surface waters were significant (R 2 C 0.9002). The log (bioconcentration factor; BCF) values of Cr and Zn in B. bayad were the highest, whereas the lowest was found for Ni. The ecological distribution of the log (BCF) values was, for all the heavy metals, moderately stable over the creek. All logtransformed bio-magnification factors (BMF) in the creek were positive, which indicates that the metal concentration was greater in B. bayad than in suspended particulate matter (SPM). The absolute log (BMF) values of heavy metals can, therefore, be ranked in order of decreasing magnitude: Cr (3.26) [ Zn (2.99) [ Cd (2.93) [ Fe (2.76) [ Pb (2.66) [ Mn (2.36) [ Ni (2.24). This sequence indicates that toxic metals such as Cd, Cr and Pb are undergoing significant bio-reduction from SPM to B. bayad. The degree of correlation between the metals was different in B. bayad, which suggests that the sources of the metals polluting Taylor Creek were diverse.

Geochemical and environmental assessment of potential effects of trace elements in soils, water, and sediments around abandoned mining sites in the northern Iberian Peninsula (NW Spain)

“…Metals are accumulated in the soil from both natural and anthropogenic sources, making it difficult to identify and determine the origin of the heavy metals present in it, so it can be considered contaminated soil. However, it contains significant levels of As, Cd, Hg, Pb, and Sb in average concentrations of 1.5, 0.2, 0.08, 13, and 0.2 mg/kg, respectively, in the earth's crust [ [7] , [8] , [9] ]. The composition of water resources can be affected by different factors, one of which can be acid mine drainage and leachate, suspended solids, soil erosion, mining waste in surface waters [ 10 ], dispersion in rivers rainfall, and other hydrological processes [ 11 , 12 ].…”