Spatio-Temporal Assessment of Surface Water Quality in an Agrarian Community, SW Nigeria Using Globe Protocol

Abstract. This study was undertaken to assess some physical parameters (pH, dissolved oxygen, total dissolved solids, salinity, conductivity and oxidation-reduction potential) of stream water within the Ilara–Mokin community Ondo State, Nigeria, using standard GLOBE protocol. The data were subjected to descriptive statistics and crossplot analyses to explore the relationships among the parameters and compare the measured parameters to Nigerian and international standards. Based on these parameters, we determined the portability of stream water, evaluated and discussed the impact of these parameters on the quality of surface water of Ilara–Mokin. Parameter values were higher in the dry season compared to the wet season. Parameter concentrations correlate well with population density. Parameters' values were predominantly higher or lower than national and international standards both in dry and wet seasons. A positive association exists between TDS-salinity, TDS-EC and EC-salinity in the dry season. TDS and salinity's correlation suggests that the dissolve solids emanate from municipal wastes. The Salinity-EC relationship was strong and only held in the dry season due to high insolation and the consequent very high evaporation rate and reduced water discharge, which in turn led to increased concentration of dissolved salts in the stream water. Only TDS and Salinity exhibited positively associated in the wet season. Regardless of the season, we observed that TDS, Salinity and EC values are defiant with Nigeria and WHO standards; hence, the water is unsuitable for human consumption. Nevertheless, the studied watershed's surface water resources can meet the domestic water demand of the Ilara-Mokin community if remediated.