Questions concerning residence time in a reservoir

Hey ,
I'm really interested in oceanoraphy, and I had some questions about residence time, but I'm not sure if I'm right :

1st-Let's consider a substance that chemically decompose in freshwater , would it lead to the amount of runoff to ocean to increase or decrease ?

* I would say it increases it , as chemcial decomposition decreases residence time which leads to outflow to increase.

2nd-Still concerning the freshwater reservoir, What does the residence time calculated for freshwater(including lakes and rivers and glaciers) tell us about the time the water spends on land ?

* I think we can conclude that water spends more time on land , as we know the residence time of ocean reservoir is the biggest !