Hannah Whitby

Identifying the sources of marine humic substances

PostDoctoral Fellow: Dr Hannah Whitby
Scientific Sponsors: Dr Géraldine Sarthou, Dr Hélène Planquette and Dr Eva Bucciarelli (LEMAR)
LabexMER Research Axis: Axis 2: Efficiency of the biological pump

Trace metals, essential elements to life          

My research centres on the nutrient properties and toxicity of dissolved metals. Currently this involves iron – a key micronutrients to marine life. Due to the poor solubility of iron in seawater, it is often the limiting nutrient, regulating primary production in up to 40% of the ocean. Complexation with organic ligands is essential to the global iron cycle, enhancing its solubility and influencing its bioavailability to support phytoplankton growth (i.e. availability to be taken up by cells). Without iron, photosynthesis cannot occur, but without ligands (organic compounds that bind metals) there would be no dissolved iron in surface waters. Humic substances are one of the main ligands for iron, leading to growing interest in oceanic humic measurements. My current project involves identifying the sources of humic substances and the role they play in the global iron cycle, from open ocean waters to algal culture exudates and hydrothermal systems.