EFFECTS OF AGROCHEMICALS ON SOIL AND WATER QUALITY IN PARTS OF RIVERS NIGER AND KADUNA CATCHMENTS, NORTH CENTRAL NIGERIA

Abstract

Contamination of soil and surface water due to unsustainable use of pesticides and fertilisers by farmers and subsequent socioeconomic effects on communities’ livelihoods is a major problem in the study area. Comprehensive data on this problem is of great interest as the existing ones are scanty. The objectives are to investigate the patterns of pesticides and fertilisers use; determine the spatial concentrations of physicochemical properties of sediment and water samples; determine the spatial concentrations of plant minerals and the extent of occurrence of organochlorine pesticide residues in water and soil; investigate the socioeconomic challenges; and appraise the effectiveness of relevant environmental laws and extant regulations on agrochemical use in the study area. An extensive field survey was conducted using various participatory appraisal techniques, namely, questionnaires, scheduled interviews, and village-level group discussions. Subsequently, seasonal water and sediment samples was collected, analysed in-situ (for water only) and in the laboratory for physico-chemical properties, plant minerals and pesticide residue concentrations. Collated data were analysed using descriptive statistical methods (frequency percentage), spatial analysis and non-parametric analysis. Survey results indicated that a significant percentage of the study population (97.5%) used synthetic fertilizers in their farming. Percentage volume of fertilizers and pesticide application per hectare indicated that the study population uses high quantities of agrochemicals across the zones. Physico-chemical properties identified in this study showed that the value of pH range (5.2 to 7.4), salinity (28.0 to 76.0 PSU), temperature (22.1 to 28.1 °C), EC (10.0 to 43.0 μs/cm), DO (5.3 to 8.6 ppm), TDS (6.7 to 23.60 ppm), turbidity (12 to 47 0 NTU), COD (13.80 to 45.06 ppm), BOD (7.05 to 18.15 ppm), TSS (15.8 to 54.0 ppm), Mn (0.08 to 2.86 ppm), TH (3.55 to 10.52 ppm), chloride (16.08 to 106.5 ppm), sulphate (0.447 to 22.68 ppm) and potassium (0.13 to 62.75 ppm). Plant mineral concentrations were detected and spatially distributed across the study zones in surface water and sediment samples during rainy and dry seasons, with concentrations ranging from NO3- (0.02 to 3.147 ppm), NO2- (0.02 to 1.16 ppm) and PO4- (0.228 to 5.771 ppm). Organochlorine pesticide compounds which include endosulfan, alpha endosulfan, endosulfan ether, delta endosulfan, endosulfan sulfate, mehoxychlor, alpha lindane, delta lindane, endrin ketone, dieldrin, DDT, DDMU, mitotane and heptachlor epoxide were detected and quantified with concentrations ranging from 0.01 ppm to 15.97 ppm in water and sediment samples analysed. Conclusively, it can be stated that there exist unsustainable patterns of agrochemical use which has obviously led to contamination of water, sediments and socioeconomic effects in the study area owing to weak regulations. Thus, it is recommended that visible and effective environmental management policies in respect of agrochemical use in the study area be put in place. Also, Green chemistry technology should be adapted for agrochemical formulations, organic farming and the use of biobased products should be encouraged and promoted among farmers to minimize or prevent the use of environmental unfriendly agrochemicals. This will guarantee cleaner and healthier environment for all.