Gabrielle (Gabi) is a PhD student from the University of Hawaii in Chris Measures’ lab. She is interested in the cycling of trace elements and isotopes in the oceans. During this cruise she will be working with Dr. Mariko Hatta to measure shipboard aluminum (Al), manganese (Mn), and iron (Fe). Trace metals such as aluminum and manganese in seawater indicate the relative influence of dust deposition and sediment contact on the water mass, respectively. Other trace elements such as iron come from dust deposition and shelf sediments, but are also necessary micronutrients for phytoplankton (the small plants in the surface ocean).
Large areas of the surface ocean have plenty of major nutrients that plants like phytoplankton need to grow; however, unlike land plants that grow in relatively iron rich soil, phytoplankton must remove iron from the seawater in their immediate environment for use. Without iron, these phytoplankton effectively become anemic and cannot efficiently grow or remove carbon dioxide from the atmosphere or seawater for growth (photosynthesis). Therefore, the distribution and processes that control the distribution of iron in the ocean must be investigated to fully understand the distribution of phytoplankton as well as the role that limiting nutrients and therefore phytoplankton play in the CO2 cycle.
However, properly sampling seawater for these trace elements is extremely challenging, as concentrations in the ocean are extremely low. However, elements such as iron and aluminum are ubiquitous in ships and sampling equipment. Therefore, measuring the concentrations of trace elements such as iron and aluminum in near real-time while at sea provides essential information on potential contamination issues with our sampling platform. Alternatively, the real time sample data also provides the ability to amend sampling plans if an interesting feature is found from the data.