Webbläsaren som du använder stöds inte av denna webbplats. Alla versioner av Internet Explorer stöds inte längre, av oss eller Microsoft (läs mer här: * https://www.microsoft.com/en-us/microsoft-365/windows/end-of-ie-support).

Var god och använd en modern webbläsare för att ta del av denna webbplats, som t.ex. nyaste versioner av Edge, Chrome, Firefox eller Safari osv.

Daniel Conley

Daniel Conley

Professor

Daniel Conley

Lack of steady-state in the global biogeochemical Si cycle: emerging evidence from lake Si sequestration

Författare

  • Patrick Frings
  • Wim Clymans
  • Erik Jeppesen
  • Torben L. Lauridsen
  • Eric Struyf
  • Daniel Conley

Summary, in English

Weathering of silicate minerals releases dissolved silicate (DSi) to the soil-vegetation system. Accumulation and recycling of this DSi by terrestrial ecosystems creates a pool of reactive Si on the continents that buffers DSi export to the ocean. Human perturbations to the functioning of the buffer have been a recent research focus, yet a common assumption is that the continental Si cycle is at steady-state. However, we have no good idea of the timescales of ecosystem Si pool equilibration with their environments. A review of modelling and geochemical considerations suggests the modern continental Si cycle is in fact characterised in the long-term by an active accumulation of reactive Si, at least partially attributable to lakes and reservoirs. These lentic systems accumulate Si via biological conversion of DSi to biogenic silica (BSi). An analysis of new and published data for nearly 700 systems is presented to assess their contribution to the accumulating continental pool. Surface sediment BSi concentrations (n = 692) vary between zero and > 60 % SiO2 by weight, apparently independently of lake size, location or water chemistry. Using sediment core BSi accumulation rates (n = 109), still no relationships are found with lake or catchment parameters. However, issues associated with single-core accumulation rates should in any case preclude their use in elemental accumulation calculations. Based on lake/reservoir mass-balances (n = 34), our best global-scale estimate of combined lake and reservoir Si retention is 1.53 TMol year(-1), or 21-27 % of river DSi export. Again, no scalable relationships are apparent, suggesting Si retention is a complex process that varies from catchment to catchment. The lake Si sink has implications for estimation of weathering flux generation from river chemistry. The size of the total continental Si pool is poorly constrained, as is its accumulation rate, but lakes clearly contribute substantially. A corollary to this emerging understanding is that the flux and isotopic composition of DSi delivered to the ocean has likely varied over time, partly mediated by a fluctuating continental pool, including in lakes.

Avdelning/ar

  • Kvartärgeologi
  • BECC: Biodiversity and Ecosystem services in a Changing Climate

Publiceringsår

2014

Språk

Engelska

Sidor

255-277

Publikation/Tidskrift/Serie

Biogeochemistry

Volym

117

Issue

2-3

Dokumenttyp

Artikel i tidskrift

Förlag

Springer

Ämne

  • Geology

Nyckelord

  • Silica cycle
  • Biogenic silica
  • Lake retention
  • Silicon isotopes

Status

Published

ISBN/ISSN/Övrigt

  • ISSN: 1573-515X