Impacts of Ogbese River Irrigation on Soil and Vegetable (Celosia argentea) Crops Grown in Ogbese with Special Reference to Heavy Metals

摘要

The bank of River Ogbese during the wet and dry season is influenced by anthropogenic activities such as wastes disposal, dumping of sewage, runoffs from an artificial application of fertiliser on farmlands. Runoff of rainwater could carry various ionic species along with heavy metals from top layer of soil due to the soil erosion into the river or leave them as sediments on the farm soils and these ionic species and heavy metals accumulated in River Ogbese irrigated soil, moreover translocate from root to upper parts of vegetables grown on them. This gave the drive to investigate the concentrations of Pb, Cr, Cd, Ni, Zn, Fe, Cu and Mg in the river, soil, and vegetable (Lagos spinach) cultivated along the bank of River Ogbese using AAS (AAS buck scientific 210 vgp). The mean concentrations (mg/kg) of Pb, Cr, Cd, Ni, Zn, Fe, Cu and Mg in water, vegetable, soil, control vegetable, and control soil were observed and recorded respectively. The concentration of lead in Water, Soil and Vegetable leaves were found higher when compared with standards of WHO (2002, 2009). Furthermore, Cr, Cd, Ni, Zn, Fe, Cu and Mg were observed below the prescribed limit of WHO (2002, 2009). The values of the heavy metals were analysed for various samples along with samples along dumpsites which were higher than from the control site thus, suggesting possible mobility of metals from dumpsite to farmlands through leaching and runoffs, but all the control site values were observed below the prescribed limit of WHO (2002, 2009). Hence, the anthropogenic activities on the river bank are not yet controlled; these might influence the heavy metals concentration in future. It was concluded that vegetables grown in River Ogbese irrigated soil were not fit for local population. At such, there will be an urgent need to take important action from local authorities at various levels to ensure adequate waste disposal to prevent indiscriminate dumping of waste into water bodies and the need to increase public awareness in order to protect the river should be encouraged.