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

Triplett, L D; Engstrom, D R; Conley, Daniel LU and Schellhaass, S M (2008) In Biogeochemistry 87(3). p.217-230
Abstract
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... (More)
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. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
River, Mississippi, nutrient cycling, biogenic silica, dissolved silicate, phytolith, riverine lake
in
Biogeochemistry
volume
87
issue
3
pages
217 - 230
publisher
Springer
external identifiers
  • wos:000254360400001
  • scopus:41149117466
ISSN
1573-515X
DOI
10.1007/s10533-008-9178-7
language
English
LU publication?
yes
id
69ceac10-d1ff-482c-8eb6-b5eecf9ea31c (old id 1183049)
date added to LUP
2008-09-02 11:11:12
date last changed
2017-09-24 03:37:20
@article{69ceac10-d1ff-482c-8eb6-b5eecf9ea31c,
  abstract     = {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.},
  author       = {Triplett, L D and Engstrom, D R and Conley, Daniel and Schellhaass, S M},
  issn         = {1573-515X},
  keyword      = {River,Mississippi,nutrient cycling,biogenic silica,dissolved silicate,phytolith,riverine lake},
  language     = {eng},
  number       = {3},
  pages        = {217--230},
  publisher    = {Springer},
  series       = {Biogeochemistry},
  title        = {Silica fluxes and trapping in two contrasting natural impoundments of the upper Mississippi River},
  url          = {http://dx.doi.org/10.1007/s10533-008-9178-7},
  volume       = {87},
  year         = {2008},
}