The debuffs are an interesting take on an upgrade system. It fits the limitation really well too. And I liked that you rolled two choices so it feels like you have a bit more control.
I'll note though that it seems as if you can infinitely restore yourself at the pond; i.e. do you even need to kill the enemies? Though I suppose that's better than the futility of having a hard cap on how many shots you can fire.
I was a bit confused as to the goal and the different elements; I originally thought that I was protecting the pool, and that I had separate "health" in the bar, but it looks like those are the same? And why does shooting at pollution make the pollution go up? I do like the idea of pollution just continuously rising even as you do nothing; it reflects the sort of futility of the real world pollution problem as well.
(Also, a quick UX thing: I don't know if it's just me, but I kept getting caught out with the pollution going too high without me knowing -- some kind of more obvious signal when you're getting low might be helpful?)
I'll also add that I really like the soundtrack and simple graphics -- it gives an almost zen feel to an otherwise high-stakes situation. A very interesting mix.
Anyway, I liked this! Nicely done!