Earth Surface Science Institute seminar: Glaciers, icebergs and silicon - The biogeochemical fingerprint of melting ice

This event is part of the Earth Surface Science Institute seminar series.

Speaker: Dr Kate Hendry, University of Bristol


The supply and distribution of dissolved silicon (Si) in the oceans is a key factor in the growth of marine diatoms, which precipitate biogenic silica (or opal, hydrated SiO2). Rivers and groundwater have long been considered the major inputs of dissolved Si, which is released during the weathering of silicate rocks. Glaciers are known sources of both dissolved and particulate phases of Si, but the impact on oceanic systems needs further quantification to produce a more robust global budget. The aim of the ICY-LAB project is to investigate the role of high-latitude processes on the Si marine cycle. Observations from two expeditions focused on characterising the physical and chemical properties of the fjord, shelf and slope waters off Southwest Greenland, and shed light on the impact of meltwater dynamics and circulation on biological production and ecosystems. Whilst biological uptake in fjords and strong diatom activity in coastal waters maintains low dissolved Si concentrations in surface waters, we find important but spatially heterogeneous additions of particulates into the system, which are transported rapidly away from the shore. We expect the glacially-derived particles – together with diatom tests – to be cycled rapidly through shallow sediments, resulting in a strong benthic flux of dissolved Si. Our findings improve the understanding of the Si cycling between terrestrial sediments, shelf processes and seawater in glaciated regions, which represents an important but understudied component of internal cycling as well as a key input into the oceanic Si budget.