Predictive Modelling of Heavy Metal-Metal Interactions in Environmental Setting: Laboratory Simulative Approach

Abstract

Aquatic ecosystem pollution by heavy metals is a global problem and requires proactive measures and techniques in tackling the scourge. Exposure to multiple contaminants in water environment now displaces the single action of pollutants and creates a challenge for complex mixture contact management. Heavy metals at individual low acting concentrations can elicit higher toxicity on interactions with other environmental toxicants. In this study, Clarias gariepinus was exposed to the mixture of zinc and copper at predetermined ratio of 1:1 and 1:2 based on 96hLC₅₀ index and binary interactive dynamics of the two metals calculated using the synergistic ratio model. Following the exposure, the 9hLC₅₀ values were 84.683 mg/l and 45.875 mg/L for ratios 1:1 and 1:2, respectively. Physiological responses such as rapid opercula movement, frequent gulping of air and neurological symptoms like jerking movements, frightening and loss of balance were observed throughout the experimental period. There were antagonistic and synergistic reactions between the metals at the two combinatorial ratios. Antagonism occurs when the metals were mixed at the ratio of 1:1 and synergism at the ratio of 1:2. We therefore recommend that joint action toxicity of metals should be taken into consideration in fixing environmental safe limits for heavy metals in order to have a complete protection of aquatic ecosystems.