**Table 3.**

*REE (Rare earth elements) concentration in Pidong volcanic crater Lake (may 2013–April 2015). NB- All element concentration in parts per billion.*

*Hydrogeochemistry of the Pidong Crater Lake, Jos Plateau Volcanic Province, Nigeria… DOI: http://dx.doi.org/10.5772/intechopen.99720*

lake color change activities pH were observed to have decrease from 7.39 to 6.71, 7.15 to 6.83 and 7.18 to 6.20 in November 2014, October 2015, and September 2016 respectively.


**Table 4.**

*Oxygen and hydrogen isotope composition of Pidong crater Lake, Bwonpe volcanic spring and rainfall.*

δ*2H versus* δ*18O diagram for Pidong crater Lake, Bwonpe volcanic spring, rainfall and standard mean ocean water (SMOW).*

**Figure 6.** *Radio carbon (14C) age of Pidong crater Lake.*

#### **Figure 7.**

*(a) Natural bluish water color of Pidong crater Lake; (b) Pidong crater Lake water color change activities in November 2014, October 2015 and September 2016.*

### **4.4 Lake water types and sources of major ions**

The Piper Trilinear diagram (**Figure 8**) for the lake water plots predominantly in the Mg-Ca-HCO3 segment. The minor water types which constitutes only about 10–20% and include Na-K-Cl and Na-K-SO4 water types.

The major element concentration abundance of the lake is in the order of Mg2+ > Ca2+ > K+ > Na+ . Similarly, the major element oxide distribution order for the volcanic ejecta materials (Basalts, pyroclastic, ash) for the Pidong volcanic rocks is in order of MgO > CaO > Na2O > K2O [12, 13]. The major cation concentration order *Hydrogeochemistry of the Pidong Crater Lake, Jos Plateau Volcanic Province, Nigeria… DOI: http://dx.doi.org/10.5772/intechopen.99720*

**Figure 8.** *Piper trilinear diagram for Pidong crater Lake.*

of the lake water and that major oxides of the Pidong volcanic rocks show similarity in the concentration abundance.

The Gibbs diagram is an illustration of the mechanism controlling the chemistry of groundwater samples in crystalline aquifers. The plot is that of the ratios of *Na Na Ca* + <sup>+</sup> + vs. Total Dissolved Solids and \_ \_ 3 *Cl Cl HCO* + vs. Total Dissolved Solids. The Gibbs diagrammatic plot for the Pidong Crater Lake water shows it is controlled predominantly by water-rock dominance processes (**Figure 9**).
