If stars are primarily made of hydrogen, which is then burned to helium, and then on and on and on down the chain until you either reach iron, or in extreme cases much heavier metals, this then implies that as time goes on, more and more heavy elements will disperse into the universe.
Now, the universe is huge, and there's still a lot of hydrogen left to make stars out of. That being said, in denser star-forming regions, much of this gas is available for recycling as the remnants of old stars get turned into new ones.
Doesn't this all this imply that as time goes on, more and more heavy metals will be included within young stars from the start?
It may be a very small percentile, sure, but it I assume it would increase slowly as the generations go by.
Furthermore, I assume many rocks get swallowed up by a star during the formation of the planetary disc, which likely adds to the impurity.
Does any of this have any adverse effect on the lifespan of the sun? Or are we talking quantities so small in objects so huge in time-spans so large, that even a dip of a hundred years is completely meaningless?