||Tréguer P et al., The silica balance in the world ocean: a reestimate. Science. 1995 Apr 21 268(5209):375-9. DOI: 10.1126/science.268.5209.375 AND Laruelle GG, Roubeix V, Sferratore A, Brodherr B, Ciuffa D, et al. 2009. Anthopogenic perturbations of the silicon cycle at the global scale: key role of the land-ocean transition. Glob. Biogeochem. Cycles 23: GB4031 DOI: 10.1029/2008GB003267PubMed ID17746543
||P.478 top paragraph: "Silicon, the seventh-most-abundant element in the universe, is a key nutrient element in the ocean, required for the growth of diatoms and some sponges and utilized by radiolarians, silicoflagellates, several species of choanoflagellates, and potentially some picocyanobacteria. Despite longstanding interest in siliceous organisms and silica sediments (Haeckel 1904, plate 71), only since the late twentieth century have processes controlling the marine biogeochemistry of silicon been quantified (e.g., Nelson et al. 1995, Ragueneau et al. 2000) and silica budgets for the world ocean constructed (Wollast 1974, primary sources Tréguer et al. 1995, Laruelle et al. 2009), showing, for instance, that the silica cycle is strongly intertwined with the inventory of carbon dioxide in the atmosphere
(Pondaven et al. 2000). The resulting estimates for the residence time of silicon in the modern ocean are 15,000 years (primary source Tréguer et al. 1995) to 17,000 years (primary source Laruelle et al. 2009), a timescale over which the silica cycle has been considered to be at steady state (primary sources Tréguer et al. 1995, Laruelle et al. 2009)."