The Silicon Cycle in the Ocean

The element silicon is everywhere! In fact, silicon is the second most abundant element in Earth’s crust. Silicon in rocks and minerals breaks down and is transported from rivers and streams into the world’s oceans. Many marine organisms need silicon as it is a crucial nutrient to build their skeletons. Silicon eventually reaches the seafloor, but its journey into the abyss is not straightforward due to biological, physical, and chemical processes. All these processes transport and transform silicon, creating a cycle that we call the marine silicon cycle. The silicon cycle is directly connected to the carbon cycle, making silicon a key player in the regulation of Earth’s climate. In this article, we discuss why we need to understand the marine silicon cycle, explain the steps that happen in the ocean, and demonstrate how the marine silicon cycle affects humans

Silicon isotopes in juvenile and mature Cyperus papyrus from the Okavango Delta, Botswana

The three most abundant stable isotopes of Silicon (Si), 28Si, 29Si, and 30Si, all occur in plants. Isotope studies are a potential tool to explore uptake and function of plant Si, and it is a developing field. However, there is a lack of studies from natural environments, and species from the African continent, and all plant parts including reproductive structures. In this study, naturally grown papyrus plants were sampled from the Okavango Delta and divided into five organs, i.e. umbel, culm, scales, rhizome, and roots. Samples were analysed for TN, TOC, BSi, TP concentrations, and for Si isotopes. Each organ of papyrus is represented by two samples, one from juvenile tissue and one mature (apart from the roots where age is difficult to determine). The study confirms that papyrus is a high Si-accumulating species, with BSi ranging from 0.88 % in rhizomes to 6.61 % in roots. High Si precipitation in the roots leads to an enrichment in heavy Si isotopes in the residual mobile Si pool, as light Si isotopes precipitate in phytoliths in the roots, even though in this study phytoliths were identified for all organs except for roots. In papyrus, shoot organs gradually become enriched in heavy Si isotopes along the transpiration stream, with an increase in heavy isotopes from rhizomes to scales, culm, and umbel, same pattern that has been observed for other plants in literature

Pore water, core incubation, and sponge geochemical data from Greenland margin and the Labrador Sea

The dataset contains pore water and core incubation silicic acid concentration and isotope measurements, sponge silicon isotope measurements, and pore water major and trace elemental concentrations obtained from seven sediment cores collected from the Greenland margin and the Labrador Sea. The samples were collected as part of the European Research Council project ICY-LAB (ERC-2015-STG grant agreement number 678371)