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Ironing Out the Details

Scientists have long thought the majority of the ocean’s iron—a key biological nutrient—comes from atmospheric dust, with smaller inputs from terrestrial sediment and hydrothermal vent fluids. Although iron is soluble in low-oxygen conditions around vents and along continental margins, it was believed iron remained localized and didn’t contribute much to the overall iron content of the ocean. But a recent study led by WHOI researchers found that deep-ocean vents and sediments are a major source of dissolved iron in the central Pacific Ocean and that iron from these sources can be transported long distances. (Illustration by Jack Cook, Woods Hole Oceanographic Institution)