Abstract
This study investigated the interactions of essential and non-essential trace elements when present in binary mixtures and resultant effects on acute toxicity in fish. The effects of four essential trace elements; Zn, Ni, Co and Cr respectively on the acute toxicities of three non-essential trace elements; Cd, Hg and Pb against Clarias gariepinus and Sarotherodon melanotheron were assessed using laboratory bioassays. The patterns of interaction of the elements affecting toxicity via antagonistic, synergistic or additive reactions were determined using the Synergistic Ratio (RA) and Concentration Addition (CA) joint action toxicity models. Single action toxicity indices showed that Hg was the most toxic element with a 96hr LC50 value of 0.0004 and 0.0003 mmol/l and Co the least toxic element with a 96hr LC50 value of 0.86 and 1.00 mmol/l, against the two fish species respectively. The SR and CA toxicity models showed that the essential trace elements (Zn, Ni, Cr and Co) reduced the toxicity of Pb against C.gariepinus as indicated by SR and RTU values < 1. Both models also showed that Zn reduced the toxicity of Pb and Hg respectively against S.melanotheron. However, the SR model showed that only Co reduced the toxicity of Cd against C.gariepinus. This study has established the possible beneficial interactions among essential trace elements and hazardous non-essential trace elements. Factors influencing such beneficial interactions including physiological processes in fish species, trace element concentrations and physicochemical parameters of exposure medium should be explored in future studies.Keywords: Essential Trace Elements; Non-essential Trace Elements; Antagonism; Toxicity
Highlights
Trace elements are a group of inorganic pollutants that are commonly detected in polluted aquatic ecosystems
Ramakritinan et al (2012) have reported Hg to be the most toxic element when compared to other elements they tested against aquatic species
This study showed beneficial antagonistic interactions among essential trace elements and some non-essential trace elements
Summary
Trace elements are a group of inorganic pollutants that are commonly detected in polluted aquatic ecosystems. Trace element pollution in aquatic ecosystems is a recurrent global environmental problem because they are not degradable by natural processes and are toxic to biological systems at low concentrations (Jiang et al, 2012) They occur naturally in rocks and soils, their use as raw materials in many industrial processes have resulted in elevated concentrations in the environment especially in aquatic ecosystems. The pattern of toxic interaction among trace elements when present in mixtures may be antagonistic, synergistic or additive (Otitoloju, 2002) These interactions may affect the uptake or excretion rates in exposed organisms (Franklin et al, 2002) and subsequently manifestation of toxic effects in the organism, final consumers and ecosystem at large. The objective of this study was to evaluate the single and joint action toxicity of selected essential and non-essential trace elements in binary mixtures against Clarias gariepinus and Sarotherodon melanotheron as well as to assess the influence of the essential trace elements on the toxicity of nonessential trace elements by defining patterns of interaction via antagonistic, synergistic or additive actions using two mixture toxicity models
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Journal of Applied Sciences and Environmental Management
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
