Fig. 6

Concentration (mg/kg) of various ions in volcanic ash from Cotopaxi-2015 and Tungurahua-2016 eruptions in gram per 500 ml of deionized water a calcium (Ca2 +), potassium (K +) and magnesium (Mg2 +) leached from the minerals inside the ash particles, b chloride (Cl-) and sulfate (SO42-) leached from adsorbed volatiles onto ash particles during gas-particle interaction and/or volatilization of a hydrothermal system, c Cl/SO4 ratio. Note that figures a and b are in logarithmic scale