Journal Highlights

Accounting for the Missing Silica in the Marine Sediment Cycle

Research Spotlight—

Cosmogenic silicon-based estimates of the amount of biogenic silica stored in clays along continental margins could explain the large discrepancy in the nutrient’s global marine budget.

During the past few decades scientists have increasingly realized that the cycling of silica in the world’s oceans is entwined with other key biogeochemical cycles, including those of carbon and nitrogen. And even though this coupling means silicon plays an important role in primary production and the amount of carbon dioxide in the atmosphere, a large mismatch in our estimates of the amount of this nutrient entering the oceans versus the amount that’s being removed remains.

One of the least understood pathways in the marine silica budget is the burial of biologically derived silica along continental margins with high sedimentation rates. In contrast to standard assumptions that much of the biogenic silica dissolves following burial, researchers have recently discovered that some of this silica is being converted to clay. Although this conversion would help explain where some of the silica is going, current estimates of this process account for just one quarter of the “missing” material.

To better constrain this pathway, Rahman et al. used cosmogenic silica...more

-- Terri Cook, Freelance Writer,