Abstract
The primary objective of this study was to assess the levels of heavy metals, nitrate, and pesticide residues in kale (Brassicaolaracea var. olecephala), a leafy vegetable. The study was conducted in three peri-urban sites in Nairobi, Kenya, where the use of wastewater irrigation is pervasive. The results indicated elevated levels of boron (B), cobalt (Co), chromium (Cr), copper (Cu), lead (Pb), zinc (Zn) and nickel (Ni) in vegetables irrigated with wastewater in two sites. High loadings of the heavy metals Ni, arsenic (As), Pb, Cr, Cu, and Zn into agricultural soils were demonstrated to be from chicken manure. Nitrate levels were within acceptable daily intakes. Residues of diazinon, cypermethrin, biternol, and profenofos pesticides exceeded permissible maximum residue limits in kale at one site. Study findings suggest that consumers of vegetables grown in wastewater-irrigated soils may ingest significant amounts of heavy metals and pesticides. Considering these findings, reducing heavy metal deposits into soils should be a strategic aim of soil protection policies in Kenya.
Highlights
Change in dietary preferences, incomes, and urbanization have increased the demand for leafy vegetables, which has led to increased production of these vegetables in Kenya in the past decade (Onyango, Shibairo, Imungi, & Harbinson, 2008)
The primary objective of this study was to assess the levels of heavy metals, nitrate, and pesticide residues in kale (Brassicaolaracea var. olecephala), a leafy vegetable
We explore pesticide bioaccumulation in the leafy vegetable kale that is grown in peri-urban areas of Nairobi
Summary
Incomes, and urbanization have increased the demand for leafy vegetables, which has led to increased production of these vegetables in Kenya in the past decade (Onyango, Shibairo, Imungi, & Harbinson, 2008). Surface and well waters have been exposed to contamination by industrial effluents and uncontrolled sewage, leading to the accumulation of heavy metals and other toxic materials in soil and crops, leafy vegetables (Abdel-Ghani, Hefny, & ElChaghaby, 2007). Anthropogenic inputs associated with industrialization and agricultural deposition, such as atmospheric deposition, waste disposal, waste incineration, urban effluent, traffic emissions, fertilizer application, and long-term application of wastewater in agricultural land, contribute to heavy metal accumulation (Ensink & Simmons, 2004; Emongor, 2007). Previous studies in Kenya, Uganda, Senegal, Ghana, and Pakistan have shown that use of irrigation water mixed with industrial effluent led to accumulation of toxic metals and excessive nitrates in plants (Keraita et al, 2002; Kar et al, 2007; Karanja et al, 2010)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Journal of Agriculture, Food Systems, and Community Development
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
