Both aluminum and iron atoms are heavy and thus make it into the ocean where they both increase the ocean's carbon sink capacity. https://phys.org/news/2021-05-aluminum-affect-climate-ocean-...

From an energy POV, the chemical launch energy required for orbital insertion is 900GJ per satellite (when amortized) whereas the satellite produces 18,900GJ over its 5-yr lifetime, and far more if it lasts longer.