Liquid Phase Oxidation of S(IV) to S(VI) and pH Lowering

Write the reactions responsible for the LIQUID PHASE oxidation of S(IV) to S(VI), and show how the oxidation can lead to a decrease in pH of rain water.

I think you can help me with this. Please let me know. I've included all details.Thank you Dr. M.

There are two sets of reactions with 3 parts for each set. I'm not sure whether we consider both sets or just one in order to answer the second part of the question (pH). I'm leaning toward the first set though.

First Set: SO2 in Aqueous equillibria
SO2(gas) + H2O(Liq)--->H2OSSO2(aq)
H2OSO2---->Hydrogen ion + HSO3- (aq)
HSO3-ion ---> Hydrogen ion + SO32- ion

Second Set: SO2 oxidation by Ozone in liquid phase
H2OSO2+ O3--->2H+ + SO42(-)ION +O2
HSO3- + O3 -->H+ +SO4(2-) + O2
SO32- + O3 --->SO4(2-) + O2