A new approach to determine the ratio of redox active species such as SeIV/SeVI and AsIII/AsV in marine systems

► Relative hydrogen score gives an information on the redox capacity of the marine system. ► rH can be used instead of Eh in this study. ► Ions in solution interact with each other as well as with water molecules. ► Electrostatic activity coefficient can be used instead of activity coefficient. ► We are suggesting a new Nernst equation.