ASSESSMENT OF SYNTHETIC PYRETHROIDS RESIDUES IN THE WATERS AND SEDIMENTS FROM THE WEIJA LAKE IN GHANA

Abstract

Abstract: The spectrum and levels of synthetic pyrethroids in the Weija Lake have been investigated using the Lake waters and sediments as a case study. Sampling was done in eight sampling locations along the Lake. Liquid-liquid extraction using hexane and soxhlet extraction using 3:1 hexane/acetone mixture were used for extraction of the pyrethroid from the water and sediment samples respectively. Analysis of the extracts for pyrethroids was done with gas chromatography equipped with electron capture detector. In all, seven synthetic pyrethroids namely, fenpropathrin, cyfluthrin, cypermethrin, fenvalerate, deltamethrin, allethrin, and permethrin were detected in the Lake waters. In addition to the above pyrethroids, bifenthrin and lambda cyhalothrin were detected in the sediments. Cyfluthrin was the most ubiquitous pyrethroid in the Weija water with 100 percent occurrence, while, cyfluthrin, fenvalerate were the most ubiquitous pyrethroids. Both were detected with 87.5 percent occurrence. The concentrations of the detected pyrethroids ranges from 0.10 – 3.50 ng/L and 0.15 – 6.60 ng/g for the water and sediment samples respectively. The concentrations of detected pyrethroids in the Weija waters were far below maximum residue limits set by European Union (EU) and the Japanese Government. The results therefore suggest that pyrethroids residue concentration in the Weija waters may not pose health hazard in terms of synthetic pyrethroid pollution. Key words: synthetic pyrethroid, weija lake, sediment, lake water,