Investigation of Groundwater Contamination from the Use of Fertilizers, Pesticides and Herbicides on Agricultural Lands in Parts of Kaduna State Using Electrical Resistivity Imaging Technique

Fertilizers, pesticides and herbicides contain toxic chemicals which leach into groundwater bodies resulting in the generation of high Biological Oxygen Demand (BOD), and thus contaminating the groundwater system. In order to save the environment from further degradation, a geophysical investigation was carried out across agricultural lands at Kaura Local Government Area (LGA) of Kaduna State, Nigeria where prevalent use of fertilizer, pesticides and herbicides is a norm. The research aims to delineate areas of possible contamination plumes and their migration path. For this purpose, Electrical Resistivity Tomography (ERT) data were acquired along six (6) Traverses and the results were inverted using the RES2DINV Software. Distinct low-resistivity zones adjudged to represent the contamination plumes were obtained from the ERT results. Water samples collected from boreholes, hand-dug wells and river channels were also analyzed. The analyzed water samples results revealed that the total dissolved solids (TDS) ranged between (2.30x101 - 8.20x101) μScm-1 as against the Nigerian Standard for Water Quality (NSDWQ) value of 1x103 μScm-1. Biochemical Oxygen Demand (BOD), chemical oxygen demand (COD) and dissolved oxygen (DO) values ranged between 1-10, <2 - <98 and 0.01 - 0.12 mg/L respectively. The water samples had detectable levels of Cu, Cd, Ni, Mn, Pb and Zn contents which were below the permissible limits, and microbiologically revealed the presence of faecal contamination with bacteria pathogens such as Coliform and Escherichia coli, whose levels were above the acceptable limit while the mould yeast and total aerobic were below the permissible limit. Ultimately, the results obtained showed that the agricultural land constitutes a serious threat to groundwater bodies in the area.