The important role of the Southern Ocean in global biological processes and the carbon cycle has been confirmed anew by a study published in Science that, for the first time based on field evidence, reveals the underappreciated role of inorganic zinc (Zn) particles in these cycles.
This article has been reviewed according to Science X's editorial process and policies . Editors have highlighted the following attributes while ensuring the content's credibility: Team South Africa getting ready to board South Africa's polar research vessle, the SA Agulhas II, for the 2019 expedition to Antarctica. Credit: Wiida Fourie-Basson The Southern Ocean plays the greatest role in global phytoplankton productivity, which is responsible for absorbing atmospheric carbon dioxide. In these processes, Zn, present in trace quantities in seawater, is an essential micronutrient critical to many biochemical processes in marine organisms and particularly for polar phytoplankton blooms. When phytoplankton blooms perish, Zn is released. But to date, scientists have been puzzled as there was an observed disjunct between Zn and phosphorus, another nutrient essential for life in the oceans, even though both nutrients are co-located in similar regions in phytoplankton. Instead, a strong (but inexplicable) coupling between Zn and dissolved Silica is often seen. Prof. Alakendra Roychoudhury, a specialist in environmental and marine biogeochemistry at Stellenbosch University (SU) and a co-author on the article, says they can now, for the first time, explain with confidence the biogeochemical processes driving the oceans' Zn cycle. Since 2013, Roychoudhury's research group in SU's Department of Earth Sciences have joined three expeditions of South Africa's polar research vessel, the SA Agulhas II. Crossing the vast Southern Ocean on its way to Antarctica in both summer and winter, the team collected sea water samples from the surface and deep ocean, as well as sediments. Dr. Ryan Cloete, co-first author on the paper and currently a postdoctoral fellow at the Laboratory of Environmental Marine Sciences…