Determination of Selected Heavy Metals and Organochlorine Pesticide Residues in Soil and Crops Cultivated on Farmlands around Dakiri, Girei Local Government Area, Adamawa State, Nigeria

Abstract

This exploratory survey describes seven selected elements (Cd, Ni, Pb, Cu, Zn, As, and Cr) and thirteen organochlorine pesticide (OCP) analytes in surface soils and dried edible portions of spinach, moringa, and okra collected from Dakiri and Labondo, the geographical comparison location, Girei Local Government Area, Adamawa State, Nigeria. Elemental results were reported following aqua-regia digestion and atomic absorption spectrophotometry, while OCP extracts were examined by gas chromatography–mass spectrometry. Soil Cd entries were 4.33 and 6.67 mg/kg dry mass at Labondo and Dakiri, respectively; crop Cd entries ranged from 0.33 to 1.17 mg/kg and crop Pb entries from 0.28 to 2.42 mg/kg. The highest reported soil OCP entry was p,p′-DDE (89.48 mg/kg) in Dakiri, and the highest crop entry was aldrin (19.00 mg/kg) in Labondo spinach. Several apparent crop-to-soil concentration ratios for Cu and Zn exceeded unity. Dietary doses and screening ratios were calculated for an assumed adult single-crop consumption scenario and do not represent observed exposure. The numbers of independent field sampling units and analytical replicates, OCP recovery and identity-confirmation records, analyte-specific reporting limits, and crop moisture fractions were unavailable. Accordingly, the unusually high pesticide entries cannot be independently confirmed, and the measurements do not establish contamination prevalence, regulatory exceedances, or health effects. The findings provide sample-level observations and priorities for further analytical and field confirmation.