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

Silica fluxes and trapping in two contrasting natural impoundments of the upper Mississippi River

Författare

  • L D Triplett
  • D R Engstrom
  • Daniel Conley
  • S M Schellhaass

Summary, in English

Human activities have altered riverine silica cycling and diminished the supply of silica to the oceans, but few rivers have been intensively monitored to evaluate the magnitude of these changes. In this study we measured dissolved silica (DSi) and amorphous silica (ASi) fluxes into and out of two large, culturally-impacted natural impoundments of the upper Mississippi River, Lakes St. Croix and Pepin, USA. ASi sedimentation rates and sediment-water fluxes of DSi were calculated for each lake, and a mass-balance approach was used to determine in-lake ASi production. ASi from terrestrial phytoliths in the lake sediments was determined to be only partially available to biotic recycling, and in-lake ASi dissolution was small relative to the total silica budgets. The river reaches upstream of the two lakes were found to have abundant DSi, and riverine diatom production was found to contribute significant amounts of ASi to each lake. The average total phosphorus concentration in Lake Pepin is four times that in Lake St. Croix but ASi production in Lake Pepin is only 2.3 times higher than in Lake St. Croix, indicating that diatom growth in Pepin is limited by factors such as turbidity. Lake St. Croix currently traps about 10% of the inflowing total bioavailable silica (TSib = DSi + ASi) while Lake Pepin traps closer to 20% of its inflowing TSib, clearly demonstrating the importance of silica retention in lakes and reservoirs along the land-ocean continuum.

Avdelning/ar

  • Kvartärgeologi

Publiceringsår

2008

Språk

Engelska

Sidor

217-230

Publikation/Tidskrift/Serie

Biogeochemistry

Volym

87

Issue

3

Dokumenttyp

Artikel i tidskrift

Förlag

Springer

Ämne

  • Geology

Nyckelord

  • River
  • Mississippi
  • nutrient cycling
  • biogenic silica
  • dissolved silicate
  • phytolith
  • riverine lake

Aktiv

Published

ISBN/ISSN/Övrigt

  • ISSN: 1573-515X