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Ecological Risks Of Emerging Contaminants In Ikpa River Basin, Nigeria

Congress: 2015
Author(s): Nnanake-Abasi OFFIONG, Edu Inam, Suil Kang, Paul Yang, Joseph Essien
Department of Chemistry, University of Uyo, Uyo, Nigeria1, 2International Environmental Analysis and Education Center, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea2, Applied Chromatography Section, Laboratory Services Branch, Ontario Ministry of the Environment, Canada3, Department of Microbiology, University of Uyo, Uyo, Nigeria4

Keyword(s): Sub-theme 10: Management of water resources,
Abstract

Introduction: Contaminants of emerging concern (CECs) are a class of newly detected compounds in the environment with potential detrimental effects like cell mutation, endocrine disruption, and sexual disruption amongst others. Unlike most well characterised pollutants, CECs are not commonly regulated with challenges of trade-offs due to their uses as active pharmaceutical ingredients (APIs) or personal care products (PCPs). CECs get into the aquatic environment as a result of human activities like wastewater and sewage discharges into nearby water bodies. This class of contaminants have received great attention in developed countries and as such some of them have received priority screening and regulatory guidelines proposed. However, due to the requirements of highly sophisticated analytical instruments research on this subject in developing countries like Nigeria is almost non-existent. The aim of the present study was to determine the occurrence of selected endocrine disrupting compounds (EDCs), pharmaceuticals and personal care products (PPCPs) in water samples of Ikpa River Basin in Southern Nigeria as well as in leachates and storm water of a nearby landfill also used as a hospital dumpsite. The ecological risks of some of the compounds detected were evaluated.

Materials and Methods: Water samples were collected using amber glass bottles. Field grab samples were preserved by adding 250mg/L sodium thiosulphate (Na2SO3S2) and transported to the laboratory in an ice box and stored at 4oC. Sample preparation, extraction followed modified procedure according to Canada method (Hao, 2008). Target compounds were extracted using the solid-phase extraction (SPE) system and analysed by liquid chromatography/tandem mass spectrometry (LC-MS/MS).

Results and Discussion: Seven antibiotic drugs (acetamidophenol, chloramphenicol, ciprofloxacin, erythromycin, lincomycin HCl, roxythromycin, and sulfamethoxazole), three antimicrobial agents or bactericides (sulfathiazole, triclosan and triclocarban), an antiepileptic drug (carbamazepine), an analgesic drug (diclofenac sodium), a resin precursor (bisphenol A), a sunscreen product (oxybenzone), a hormone (equilin), an insect repellent (DEET), and a stimulant (caffeine) were detected at nanogram per litre levels. Bisphenol A, triclosan, triclocarban and oxybenzone were among the most frequently detected compounds (Table 1). In order to evaluate the ecological risk of some of the selected compounds, their predicted no-effect concentrations (PNECs) derived from toxicity data reported for green algae, fish and invertebrate in the literature were compared with the maximum measured environmental concentrations (MECs); MECs/PNECs ratios, to obtain risk quotients (RQs). The potential risk levels (RQs) were low for most of the compounds except bisphenol A and chloramphenicol with RQs (0.044 and 0.07, respectively) approaching medium risk levels. More so, the potential risk level for triclosan and erythromycin reached the medium risk level (HQ>0.1) for the considered organisms. The highest potential risk levels were estimated for triclocarban with RQ values above unity for the aquatic organism --algae, fish and invertebrate. Table 1: Occurrence of emerging contaminants in the study area

Conclusion: The occurrence of contaminants of emerging concern (CECs) in the study area indicates inputs from human activities, presumably from the nearby landfill and hospital dumpsite. Some CECs were frequently detected indicating continuous inputs. Since the water resource of the river basin is used for domestic applications and irrigations, humans may unknowingly be exposed to these contaminants. This is also true for other non-targeted organisms in the aquatic ecosystem. Bisphenol A, triclosan and triclocarban were found to pose high risks to the ecological environment of the study area.

Acknowledgement: This study was supported by the Ministry of Science and Technology in South Korea through the Institute of Science and Technology for Sustainability (UNU & GIST Joint Programme).

Keywords: Ikpa River Basin, Nigeria, endocrine disruptors, pharmaceuticals, hormones, personal care products, risks Hao, C. (2008). The Determination of Emerging Organic Pollutants in Environmental Matrices by LC/MS/MS (EOP-E3454). Ontario Ministry of the Environment, pp. 33-36.

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