There is no way that a gamma ray source tracks us, more likely there is a lighter-than-air gas such as ethane, methane, etc. (which are used in spark chambers)

There is no way that a gamma ray source tracks us, more likely there is a lighter-than-air gas such as ethane, methane, etc. (which are used in spark chambers) escaping that lake, or somthging else to that effect, making conditions suitable for ionization.