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Topic: "Did you know? Mini knowledge about hot springs"
Elements of Hot Spring Classification
Hot springs are said to be "ten springs, ten colors" due to their diverse qualities, and strictly speaking, no two hot springs have the same quality.
By classifying hot springs based on osmotic pressure, pH, and temperature, it helps to understand the characteristics (information) of hot springs.
The order of osmotic pressure, pH, and spring temperature may vary depending on the facility.
Analysis of Hot Springs by Osmotic Pressure
Whether the components of a hot spring are absorbed into the body when bathing (the transfer of substances inside and outside the cells) is greatly influenced by the osmotic pressure of the hot spring. A solution with the same concentration as human cell fluid (body fluid) is called an isotonic solution, and hot springs are classified based on whether their osmotic pressure is higher, lower, or about the same as this.
In other words, hypertonic hot springs have components that easily penetrate the body, enhancing pharmacological effects but also causing hot spring fatigue more easily, whereas hypotonic hot springs are gentle on the body.
| Hypotonic | Total dissolved substances less than 8g/kg |
|---|---|
| Isotonic | Total dissolved substances 8g/kg to less than 10g/kg |
| Hypertonic | Total dissolved substances 10g/kg or more |
Classification of Hot Springs by pH
Hot springs are classified as acidic, weakly acidic, neutral, weakly alkaline, or alkaline based on the hydrogen ion concentration (pH) when they spring forth.
Generally, acidic hot springs tend to be limited to volcanic hot springs in volcanic areas.
Many hot springs known for their "smooth" feel, often called "beauty baths" or "beautiful skin baths," are alkaline or weakly alkaline, influenced by components such as baking soda or sodium carbonate.
| Acidic | pH less than 3 |
|---|---|
| Weakly acidic | pH 3 to less than 6 |
| Neutral | pH 6 to less than 7.5 |
| Weakly alkaline | pH 7.5 to less than 8.5 |
| Alkaline | pH 8.5 or more |
Classification of Hot Springs by Spring Temperature
The temperature of a hot spring when it emerges on the surface or when it is collected is called the spring temperature. Hot springs are classified as follows based on spring temperature.
Hot springs are classified as either broad hot springs or cold mineral springs depending on whether the spring temperature is 25°C or above or below 25°C. Hot springs (broad) above 25°C are further classified into low-temperature, hot springs (narrow), and high-temperature springs, with 34°C and 42°C as boundaries.
| Cold mineral spring | Less than 25°C |
|---|---|
| Hot spring (broad) | 25°C or more |
| Low-temperature spring | 25°C to less than 34°C |
| Hot spring (narrow) | 34°C to less than 42°C |
| High-temperature spring | 42°C or more |