I am geochemist who is interested in the biogeochemical couplings between oceans and climate. I measure the stocks and flows of nutrient- and trace-elements (e.g. iron) that are washed from the continents and cycled within the ocean, because the supply of these elements from the Earth’s crust may ultimately determine the fertility – and potential toxicity – of the oceans for marine life. Many such solid-aqueous exchanges occur at the ocean floor as precursor reactions to the formation of marine sedimentary rocks; in particle-suspensions carried from ocean-continental margins; or in hydrothermal plumes erupting in the ocean interior. These settings may critically determine the balance of nutrition available for primary producers and the strength of the ocean’s biological carbon pump – which plays such a crucial role in the removal carbon dioxide from the atmosphere.
I aim to find the mechanisms and quantify the rates of trace element exchanges between rocks, and the ocean, so that we may more accurately evaluate their impact on ocean life and climate. I use stable- and radio-isotope observations (e.g. iron and radium) and studies across the soluble-colloidal-particulate size spectrum. This draws me to many parts of the oceans, from shallow coasts to deep basins, and the riverine, glacial and volcanic ocean interfaces. Presently, I am exploring the use of short-lived radium as a tracer in the ocean, in combination with autonomous sampling technology, to quantify rates of sediment-water exchanges.
I have further collaborative interests at the seafloor too: the assessment of ecosystem services to support governance of the seabed, and proxy calibrations to strengthen palaeoenvornmental interpretation. For example, chemical signals preserved in sediments might be useful proxies to interpret past ocean productivity (e.g. cadmium and barium isotopes), but their utility depends on our knowledge of signal preservation processes that we see occurring at the ocean floor today.
The Carbon Cycle (2nd yr)
Topics in Oceanography (4th yr)
Geochemical Proxies of Modern Ocean Processes (DTP-Env Sci)
View Selected Publications
Bridgestock, L., Hsieh, Y-T, Porcelli, D., Homoky, W.B., Bryan, A., Henderson, G.M., (2018) Controls on the barium isotope compositions of marine sediments. Earth and Planetary Science Letters. 481:101-10.
Homoky, W.B. (2017) Deep ocean iron balance. Nature Geosci. 10(3):162-3.
Klar, J.K., Homoky, W.B., Statham, P.J., Birchill, A.J., Harris, E.L., Woodward, E.M.S., et al. (2017) Stability of dissolved and soluble Fe(II) in shelf sediment pore waters and release to an oxic water column. Biogeochemistry 135(1):49-67.
Lough, A.J.M., Klar, J.K., Homoky, W.B., Comer-Warner, S.A., Milton, J.A., Connelly D.P., et al. (2017) Opposing authigenic controls on the isotopic signature of dissolved iron in hydrothermal plumes. Geochim Cosmochim Acta. 202(Supplement C):1-20.
Schlosser, C., Schmidt, K., Aquilina, A., Homoky, W.B., Castrillejo, M., Mills, R.A., et al. (2017) Mechanisms of dissolved and labile particulate iron supply to shelf waters and phytoplankton blooms off South Georgia, Southern Ocean. Biogeosciences Discuss. 2017:1-49.
Thompson, C.E.L., Silburn, B., Williams, M.E., Hull, T., Sivyer, D.… Homoky, W.B., et al. (2017) An approach for the identification of exemplar sites for scaling up targeted field observations of benthic biogeochemistry in heterogeneous environments. Biogeochemistry. 135(1):1-34.
Homoky W.B., Weber, T., Berelson, W.M., Conway, T.M., Henderson, G.M., van Hulten, M., Jeandel, C., Severmann, S., Tagliabue, A. (2016) Quantifying trace element and isotope fluxes at the ocean–sediment boundary: a review. Phil. Trans. R. Soc. A 374: 20160246