Where does this dust end up? Into the oceans? Because iron-rich dust entering the oceans helps create nutrition for algae which can absorb CO2

Believe it or not at least 40 million tons of it ends up in the Amazon basin each year where it does have an effect on the plants there: https://iopscience.iop.org/article/10.1088/1748-9326/1/1/014...

It goes elsewhere too, as expected.