Hydro-geochemical analysis and quality evaluation of surface water in the Mamu River basin, southeastern Nigeria

Abstract

Mamu basin is a major tributary of Anambra drainage basin and a reservoir for wastewater from agricultural and runoff processes within the basin. Water quality of the Mamu basin was evaluated to determine its suitability for potable water and agrarian uses. This study utilized 24 water samples collected during the rainy and dry season from the upstream and downstream segments of the sub basins within River Mamu. Hdyro-geochemical analytical results were employed in the evaluation of several water quality criteria such as QWI, SAR, TH, SSP, MAR, PI, KR, Na% and %E of the water from the basin. The results suggested that the surface water is unfit for ingestion when compared with the WHO and Standard Organization of Nigeria (SON) standards. However, the QWI result showed that 66.7% of the water samples are good for consumption in the rainy season, while 75% of the samples are classified unfit for drinking in the dry season. Parameters such as Fe2+, Mn2+, TDS, temperature and total coliform (p < 0.001) exhibited temporal variation unlike pH, EC, Ce, Ca2+, Mg2+, Cl−, K + , NO3, PO43−, Na+, HCO3−, Zn2+, TSS, SO4, DO, BOD and turbidity which showed no response to season. Based on the results of SAR, TH, SSP, PI, KR, Na% and US salinity plots, the surface water is suitable for irrigation. Conversely, the MAR and %E results pointed out that water treatment is vital before use. The basin water is associated with permanent hardness due to CaCl2 coupled with the dominance of Mg2+ and SO42−. Gibbs plots and Stiff diagram showed that geology and dissolution process have an influence on the water chemistry via weathering and rock–mineral interactions, while chemical ratios and correlation coefficients (R2) point on anthropogenic activities.

Hydrogeological and water quality evaluation of parts of River Mamu Sub-Basin, Southeastern Nigeria

“…These indicate that rock weathering is the main contributor of major ionic species in groundwater with minor impute from precipitation. Ayogu et al, (2020), Okogbue (2012), reached similar conclusions. Furthermore, in the ionic ratio plots for surface water, the plot for Ca 2+ +Mg 2+ versus SO4 2-+HCO3shows plotted points are below the 1:1 line (Figure 5ii-a), indicating silicate weathering.…”

“…Cattle and goat markets with abattoirs are also situated in the wet land of Amansea area, which serves as a source of recharge in the hydrologic system. There has been adequate water supply to the area in view of the annual rainfall amount (1750 -2050mm) as noted by Ayogu et al, 2020. However, they observed a decrease in rainfall amount for some of the years in the past 50years.…”

“…The low concentration of major ions may be a result of adsorption ions to clay-rich layers. Elevated concentration of SO 4 2and Clcan be attributed to leaching of salts (NaCl, CaCl 2 and MgCl 2 ), (Ayogu et al, 2020, Dinka et al, 2015, while Okogbue et al (2012) trace their source to anthropogenic activities (agriculture and domestic wastes). High concentration of SO 4 2can be because it more mobile than other ions in water.…”

“…The water quality of an area is influenced by climatic, anthropogenic and geologic processes (Ayogu et al, 2020;Okolo et al, 2020;Nganje et al, 2015;Appelo and Puman, 2005). Rock and mineral weathering, evaporation, precipitation and anthropogenic are the main sources of dissolved ionic species in water (Singh et al, 2005).…”

Mechanisms controlling major ion chemistry and its suitability for irrigation of Narmada River, India

“…The studies on water chemistry emphasizing on ions has been conducted globally for determining water quality and its controlling factors by (Sahoo et al 2019;Ayogu et al 2020;Liu et al 2020;Ogwueleka & Christopher 2020). Similarly in India, physicochemical studies of rivers have been conducted by several researchers (Sharma & Subramanian 2008;Gupta et al 2011;Ghosh et al 2019;Patel et al 2020).…”