Hydrogeochemical characteristics of coastal aquifers from Port Harcourt, southern Nigeria
2017
Onwuka, O.S. | Omonona, O.V.
This study presents the hydrogeochemical characteristics and quality assessment of groundwater from Port Harcourt, an oil-rich, densely populated town in southern Nigeria. Twenty (20) groundwater samples and 2 rainwater samples were analyzed for their physicochemical parameters (pH, EC and TDS), cations (Ca, Na, Mg and K), anions (Cl, HCO₃, NO₃ and SO₄) and trace metals (B, Co, Cr, Fe, Mn, Ti and Zn). All the groundwater is acidic in nature, with pH values ranging from 4.04 to 6.2. Only one groundwater belongs to brackish water type, while the others classified as freshwater, based on their TDS values. About 50% of the groundwater is not acceptable for drinking and domestic purposes. Three hydrochemical facies were identified, namely Ca–Mg–HCO₃ (18.2%), Na–K–Cl–SO₄ (36.4%) and Ca–Mg–Cl–SO₄ (45.4%). The presence of Na–K–Cl–SO₄ hydrochemical facies and the high concentrations of TDS, EC, Na, Cl and the other major ions revealed the effects of salinization in the area. Salinization processes and trace metals contamination were observed to be the main processes controlling the groundwater hydrochemical characteristics. The concentrations of SO₄, Fe, Cu, Cr, Co and Mn in the groundwater were observed to be significantly (p < 0.05) influenced by seasons, while only SO₄ and Zn were significantly (p < 0.05) influenced by location. Only SO₄ (from anthropogenic sources) and Cu (from geogenic weathering and rock–water interactions) were seen to be significantly (p < 0.05) influenced by both season and location. These results showed that both geogenic and anthropogenic factors shape the groundwater chemistry.
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