Pesticide and Nutrient Loads of Lake Bosomtwe in the Ashanti Region of Ghana

Abstract

Pollution of Lake Bosomtwe is a major concern in Ghana due to its derived socio-economic benefits such as employment, ecotourism and major protein source to the people in the basin. Besides these benefits, the lake water is used for domestic purposes and has since served as the drinking water source to the people. However, the use of agrochemicals within the basin has intensified within the last decade. The problems associated with fertilizer and pesticide use in the Bosomtwe basin seem to carry with it a higher price, which, if not identified and checked, will overshadow the desired benefits of the lake. This study assesses pesticide and nutrient loads of Lake Bosomtwe in the Ashanti Region of Ghana. Fifty-four (54) lake water samples were collected from September 2016 to February 2017. Pesticide samples were extracted using the solid phase extraction method and GCMS to identify the pesticides present in the water samples and determine their loads. The data obtained were analyzed using Statistical Product Service Solutions (SPSS version 20) for descriptive statistics. The concentration of dichlorvos was a bit lower when compared with the WHO/USEPA guidelines of 5 ppb for surface water. Diazinon had a mean concentration of 0.28 ± 0.03 ppb which was higher than the WHO 0.05 ppb and USEPA 0.04 ppb for surface water bodies. The detection of diazinon confirms the findings from the field survey, which revealed that diazinon, is an active ingredient of a pesticide with a trade name "Akate suro", which was extensively used by cocoa farmers along the banks of the lake. The mean concentration recorded for nitrate and phosphate were 0.15 ± 0.05 mg/L and 0.40 ± 0.12 mg/L respectively. The pesticides application inventory and implications of pesticide and nutrient loads on the lake are discussed in the paper.