Chemometrics monitoring and characterization of heavy metals and physicochemical status of Chanchaga River and Tagwai dam in Minna, Nigeria

Abstract

The deleterious seasonal variation of waterbodies content leaves so much concern for safety of environment. In this study, heavy metals: Pb, Ni, Mn, Zn, Cd, Cu and Cr, as well as physiocochemical parameters: pH, temperature, turbidity, silica, nitrite, nitrate, nitrite as nitrogen and ammonia were determined in 80 samples of sediments and water samples from Chanchaga River and Tagwai Dam in Minna metropolis during dry and rainy seasons. The mean concentrations of the heavy metals in water and sediment samples were ranged as follows respectively: Pb (ND ; ND), Mn (ND - 0.01 mg/dm3;ND – 0.09 mg/dm3), Zn (0.00 – 0.02 mg/dm3 ; ND – 0.12 mg/dm3), Cd (ND ; ND-0.03 mg/dm3), Cu (ND – 0.01 mg/dm3 ;ND – 0.03 mg/dm3) and Cr (ND-0.02 mg/dm3 ; ND-0.02 mg/dm3) for rainy and dry seasons. The concentrations (mg/dm3) of the physicochemical parameters were as follows: pH (6.35 – 7.46 ; 4.41-7.75), temperature (27.64 - 30.570C ; 25.35 – 27.91), silica (ND – 6.09 mg/dm3 ; 1.97 -10.11 mg/dm3) ammonia (0.41- 7.54 ; 4.50 - 14.33 mg/dm3), turbidity (30.87 – 80.86 NTU ; 15.33-66.30 NTU), Conductivity (87.43-115.70 µS/cm ; 209.00 – 421.93 µS/cm), nitrite (ND – 0.12 mg/dm3; 0.05 - 0.41 mg/dm3), nitrite-nitrogen (0.01 – 0.03 mg/dm3 ; 0.03 - 0.13 mg/dm3) and nitrate (ND – 8.13 mg/dm3 ; 2.80 - 21.62mg/dm3). Cd, Zn, Mn, ammonia, turbidity, Cu, pH, and nitrite were above the WHO limit in water and sediment samples and in both seasons. The results of the analysis showed the pollution in Chanchaga River and Tagwai Dam to be above WHO permissible limit.. Principal Component Analysis of the datasets showed nitrite-nitrogen, turbidity and pH as the signature contaminants among the water samples, while nitrate, nitrite-nitrogen, Cd, silica and turbidity characterize the sediment samples. Hierarchical Cluster Analysis (HCA) of the water and sediment samples characterizes the pollution source types. Correlation analysis showed strong positive relationship among conductivity-temperature (0.839), nitrate - nitrite nitrogen (0.806), nitrite – nitrite nitrogen (0.999) in the water samples and strong positive correlation between temperature and silica (0.763mg/dm3), conductivity (0.919µS/cm) and Zn (0.664mg/dm3) in the sediment samples.