Seasonal Variations of Shallow Well Water Quality in Amuwo-Odofin and Ojo LGA’s of Lagos, Nigeria
Keywords: Irrigation, salinity hazard, seasonal variations, shallow well, sodium hazard, water quality index
AbstractWater from fifteen shallow wells used for irrigation was analysed during the wet and dry seasons of 2012 and 2013 respectively from Amuwo-Odofin and Ojo LGAs in Lagos-Nigeria. In situ parameters were measured for electrical conductivity, pH and total dissolved solids using portable metres. Bicarbonate, calcium, carbonate, and chloride were determined using a titrimetry method. Magnesium, potassium and sodium were determined with an Atomic Absorption Spectrophotometer while sulphate was determined using a spectrophotometer. Total hardness was computed using Fournier equation. The study aimed at examining the seasonal variations of shallow well water for irrigation purpose in the study area. Data were analysed using tables, charts, descriptive inferential statistics and irrigation water quality indices. The results show that the mean values of all the parameters were higher in dry season compared to the wet season except for pH. The paired samples T-test indicate significant seasonal variations at p<0.05 for sodium, potassium, bicarbonate and sulphate. The Kelly ratio, magnesium ratio, residual sodium carbonate, percentage sodium and sodium adsorption ratio indices have revealed that the water quality is suitable for irrigation in both seasons. The spatial pattern of sodium and salinity hazard shows that all the samples are suitable for irrigation except for locations G12 and G14; and G9 in dry and wet seasons respectively. It was concluded that the shallow well water is suitable for irrigation. Routine monitoring, appropriate treatment and investigation of soil quality test are recommended for further study.
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