In the surface ocean, iron (Fe) is a growth limiting nutrient for microscopic marine life, which impacts their ability to remove carbon from the atmosphere and surface waters. While there are several sources of Fe in the ocean, hydrothermal vents are emerging as a potentially significant source of Fe to the surface ocean, and one that is insensitive to changes in climate. However, it is unknown whether deep ocean Fe can be stabilized long enough to reach sunlit surface waters. Recent geochemical studies have demonstrated multiple mechanisms that allow hydrothermally derived Fe to be protected and transported within the buoyant and non-buoyant plume. However, whether hydrothermal vents impact the global Fe budget, particularly in the surface ocean, has been difficult to constrain, as mechanisms for the sources and sinks of hydrothermal Fe are still poorly understood. For example, low-temperature diffuse flow vents have recently been shown to be another source of hydrothermal Fe to the ocean and under-sampled in global datasets. Our main goal is to understand the physicochemical mechanisms responsible for the stabilization of Fe in hydrothermal plumes, with a focus on the role of organic carbon in stabilizing particulate and colloidal Fe. This talk will focus on field and lab experiments that address how co-precipitation and sorption of organic carbon impacts the mineralogy, aggregation, and longevity of hydrothermal Fe in both low and high temperature vent fluids.
Tuesday 26 February 2019 - 14:00 to 15:00
Other venue (see below for details).
044/11 Ray Beverton
Colleen Hoffman, University of Washington