Pesticide Residue Levels in Soil, Water, and Vegetables: A Comparative Study of Alau and Gongolong Irrigation Sites, Maiduguri, Borno State, Nigeria

The swift surge in population and increasing demand for food security, particularly in developing countries, has led to an upsurge in pesticide use to enhance agricultural productivity and control pests. This trend signals potential environmental contamination. This study aims to determine and compare pesticide residues in soil samples and selected vegetables from Alau and Gongolong irrigation sites. Soil samples were collected from randomly selected farmlands at 20cm depth, with triplicate composite samples (each comprising 13 subsamples) taken from each site for pesticide residue analysis. Composite samples of spinach, sorrel, and okra were collected from Alau and Gongolong irrigation sites, with each composite consisting of 13 subsamples and replicated three times (A, B, and C). Pesticide residue in samples was analyzed using GC-MS, and statistical analysis was performed using SPSS version 24. The results are presented as mean ± standard error of the mean (SEM). One-way analysis of variance (ANOVA) was used to compare means, followed by the Least Significant Difference (LSD) test at P < 0.05. Naphthalene (Gongolong 0.403±0.03 and Alau 1.290±0.13), phenanthrene (Gongolong 0.377±0.06 and Alau 0.000±0.00), dichlorvos (Gongolong 5.347±0.26 and Alau 9.063±0.45), dimethoate (Gongolong 0.000±0.00 and Alau (1.147±0.11), chlorpyrifos (Gongolong 2.930±0.15 and Alau 72.708±3.64), cyhalothrin (Gongolong 0.000±0.00 and Alau 0.447±0.03), 9H-Fluorene (Gongolong 0.030±0.00 and Alau 0.040±0.00) were detected in soil samples from both areas, with higher concentrations mostly detected in Alau. Chlorpyrifos was detected in okra from Alau and Gongolong (12.99 ± 0.65) and (0.305 ± 0.02), respectively. And in spinach at Gongolong (0.203 ± 0.01), while Cypermethrin was detected in okra from Alau (2.012 ±0.10).  On the other hand, Phenanthrene was detected in sorrel at Alau (0.008 ± 0.00). Dichlorvos and Dimethoate in sorrel at Alau (0.020±0.00) and (0.033 ± 0.00), respectively. The results indicate higher pesticide residues in soils and vegetables from Alau compared with Gongolong, highlighting the need for continued monitoring and testing to ensure safety.