There are distinct limits on the timing and quantity of volatiles on Mars.

If you want an ocean of condensed volatiles, it has to be gone by the end of the Noachian and in any case cannot be larger than the volume needed to fill the Northern Plains.

Thick atmospheres have to be gone by a similar time or the micrometeorite count goes wrong, and anyway the loss mechanisms don't work well enough to lose it later.

You should read "Mars" University of Arizona Press. 1400pp (!) It is a massive collection of Viking era science about Mars that covers many points. It is beginning to be outdated with the last few missions, but still represents a foundation of knowledge you must start from.

Go read it (borrow from a library via inter-library loan). Peter Cattermole's "Mars, the story of the red planet" is a good intruduction at a less technical level.

Once you've read these, you'll learn how much we know about the timing and degree of atmospheric loss on Mars from N, H isotope depletion. (O is much less depleted, implying that some volatile compound containing O but not H has NOT been depleted - best candidate is CO2).

C isotopes are less useful for atmospheric loss studies because the initial C12/C13 of Mars is not known - it's quite variable across the solar system.