Hydrochemical calculations
Ratios of some components in hot water may have an effect on the
deposition of travertine. The accumulation of bicarbonate content in the
water tends to be limited to the concentration of calcium (Zhou et al.,
2014). The ratios
of\(\ \mathrm{\gamma}\)Ca/\(\mathrm{\gamma}\)HCO3 in the
water samples of the Heinitang hot spring are not significantly
different. The value
of\(\text{\ \ }\mathrm{\gamma}\)Ca/\(\mathrm{\gamma}\)HCO3in the water samples S1, S2, S3, S4 and S6 is 0.44, that in S5 is 0.43
and that in S2* and S4* is 0.35 (Fig. 6a).
Fig. 6. Ratios of\(\mathrm{\gamma}\)Ca/\(\mathrm{\gamma}\)HCO3 (a) and\(\mathrm{\gamma}\)Mg/\(\mathrm{\gamma}\)Ca (b)
This indicates that the value
of\(\text{\ \ }\mathrm{\gamma}\)Ca/\(\mathrm{\gamma}\)HCO3in hot water cannot be used to determine whether the precipitation of
travertine occurs or not. Apart from the value
of\(\text{\ \ }\mathrm{\gamma}\)Ca/\(\mathrm{\gamma}\)HCO3,\(\text{\ \ }\mathrm{\gamma}\)Mg/\(\mathrm{\gamma}\)Ca
of hot springs is one of the important precipitation controlling
factors, and precipitation of aragonite and calcite occurs easily when
the value of\(\text{\ \ }\mathrm{\gamma}\)Mg/\(\mathrm{\gamma}\)Ca
exceeds 1 (Folk, 1994; Rossi and Lozano, 2016). The values
of\(\text{\ \ }\mathrm{\gamma}\)Mg/\(\mathrm{\gamma}\)Ca in S2* and S4*
water samples are 0.46 and 0.47, respectively, and in other water
samples the values are approximate 0.1 (Fig. 6b). They are significantly
lower than 1. In addition, the precipitation of travertine also occurred
near the Alhama-Jaraba hot spring in Spain when the values
of\(\text{\ \ }\mathrm{\gamma}\)Mg/\(\mathrm{\gamma}\)Ca were around 0.7
(Asta et al., 2017). This indicates that the factor
of\(\text{\ \ }\mathrm{\gamma}\)Mg/\(\mathrm{\gamma}\)Ca has little
effect on the precipitation of travertine in the Heinitang and
Alhama-Jaraba hot springs.
Precipitation of travertine easily occurs near the hot springs which are
of HCO3-Ca type (Kpegli et al., 2015, Arenas et al.,
2015). In an attempt to determine water types of the Heinitang hot
springs in this paper, hydrochemical compositions of the water samples
were plotted on the Piper diagrams (Piper, 1944). Concentration of
carbonate is not plotted on the diagrams because of its low
concentration in these water samples. All the water samples display a
unique HCO3-Ca•Na type (Fig. 7). The result shows that
the water types of the travertine-depositing water samples and the water
samples that do not deposit travertine are the same. This indicates that
the water type of hot springs cannot be used to determine whether the
precipitation of travertine occurs or not.
Fig. 7. Piper diagram showing the Heinitang hot spring samples.