The Contamination Levels of Water and Sediment from Lake Togo by the Persistent Organic Pollutants (Pops)

Gbénonchi Mawussi

doi:10.11648/j.ajep.20160502.11

Abstract

This study was carried out to evaluate the contamination severity of Lake Togo by organochlorinated pesticides historically used in agriculture and in health programs against disease vectors in public health. A total of 48 samples of sediments and 48 samples of water were seasonally collected. For both sediment and water 3 samples per site were collected at 8 sites in the 2014 rainy season and in the 2015 dry season. Water samples were processed using a liquid-liquid method solvent extraction while Soxhlet extraction was used for sediment samples. The sediment and water extractions were cleaned-up and qualitative-quantitative analysis performed on gas chromatograph equipped with electron capture detector (GC-ECD). Pesticides residue levels in water ranged from < 0.001 to 0.093±0.20 µg l-1 (lindane) in rainy season and from < 0.001 to 0.352±0.07 µg l-1 (dieldrin) in dry season. They were lower than that found in sediment which ranged from < 0.001 to 0.98±0.18 µg kg-1 dry weight (pp′-DDE) in rainy season and from < 0.001 to 2.19±0.31 µg kg-1 dry weight (heptachlor epoxide) in dry season. The concentrations of the organochlorinated residues in water and sediment were higher during the dry season. Except pp′-DDE, pp′-DDD, heptachlor and heptachlor epoxide, the others pesticide residues concentrations detected in water samples in dry season were above the maximum acceptable concentration of 0.1 µg l-1 for individual pesticides set by the European Union (EU) for the protection of human health. Pesticide contamination level of Lake Togo is therefore, likely to be harmful to human health in dry season.

Highlights

African countries were considered to be safe from water bodies’ pollution in the past
Such a statement may be subject to debate in our days because more recent studies [24] demonstrate that the high anthropogenic activities have resulted in a remarkable amount of persistent organic pollutants (POPs) such as organochlorine pesticides and diversity of discharges reaching aquatic environment
The pesticide residues concentrations detected in water samples in dry season were generally above the maximum acceptable concentration of 0.1 μg l-1 for individual pesticides set by the European Union (EU) for the protection of human health

Summary

Introduction

African countries were considered to be safe from water bodies’ pollution in the past. Thorslund [1] concluded that the pollution of aquatic environments in African countries was not a concern. Such a statement may be subject to debate in our days because more recent studies [24] demonstrate that the high anthropogenic activities have resulted in a remarkable amount of persistent organic pollutants (POPs) such as organochlorine pesticides and diversity of discharges reaching aquatic environment. Organochlorine pesticides are an important group of persistent organic pollutants (POPs) which are toxic, persistent, bio-accumulative and have the ability of a long-run transport potential [7]. The Stockholm Convention on POPs in 2001 is an outcome of this growing concern about the persistent organic pollutants including organochlorine pesticides. Some of these chemicals are still being used in some

Methods

Results

Conclusion