Several of the small islands that make up the Republic of Cape Verde can be seen beneath the clouds. These volcanic islands lie in the Atlantic Ocean about 570 kilometers (355 miles) off the west coast of Africa, which is on the right. The most striking thing in this image, however, is the dust and sand being carried by the wind toward Cape Verde from the Sahara and an adjacent region. This sand also fertilizes the ocean with nutrients and promotes the growth of phytoplankton, which are microscopic plants that sustain the marine food web. The iron in the dust is particularly important. Without iron mammals cannot make hemoglobin to transport oxygen through the bloodstream, and plants cannot make chlorophyll to photosynthesize. Around 80 percent of iron in samples of water taken across the North Atlantic originates from the Sahara. May 30, 2018.