Sorption and degradation of neonicotinoid insecticides in tropical soils |
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Authors: | Enock Dankyi Chris Gordon Derick Carboo Vitus A. Apalangya Inge S. Fomsgaard |
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Affiliation: | 1. Department of Chemistry, College of Basic and Applied Science, University of Ghana, Legon, Accra, Ghanaedankyi@ug.edu.gh endankyi@gmail.com;3. Institute for Environment and Sanitation Studies, College of Basic and Applied Sciences, University of Ghana, Legon, Accra, Ghana;4. Department of Chemistry, College of Basic and Applied Science, University of Ghana, Legon, Accra, Ghana;5. Department of Food Process Engineering, College of Basic and Applied Sciences, University of Ghana, Legon, Accra, Ghana;6. Department of Agroecology-Crop Health, Aarhus University, Slagelse, Denmark |
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Abstract: | ABSTRACTNeonicotinoids are the most widely applied class of insecticides in cocoa farming in Ghana. Despite the intensive application of these insecticides, knowledge of their fate in the Ghanaian and sub-Saharan African environment remains low. This study examined the behavior of neonicotinoids in soils from cocoa plantations in Ghana by estimating their sorption and degradation using established kinetic models and isotherms. Studies of sorption were conducted using the batch equilibrium method on imidacloprid, thiamethoxam, clothianidin, acetamiprid and thiacloprid, while degradation of imidacloprid, thiamethoxam and their respective deuterated counterparts was studied using models proposed by the European forum for coordination of pesticide fate and their use (FOCUS). Analytes were extracted using the quick, easy, cheap, effective, rugged and safe (QuEChERS) procedure and quantified by liquid chromatography-tandem mass spectrometry (LC–MS/MS). Average recoveries were high (≥ 85%) for all analytes. The findings from the study suggest that neonicotinoid insecticides may be persistent in the soils studied based on estimated half-lives > 150 days. The study also revealed generally low-sorption coefficients for neonicotinoids in soils, largely influenced by soil organic carbon. |
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Keywords: | Neonicotinoids tropical soil sorption persistence dissipation degradation |
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