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Long-term Change of Phosphorus in Acidified and Limed Lakes in comparison to Neutral lakes

Hu, Qian (2013) BIOM35 20122
Degree Projects in Biology
Abstract
Abstract:
Total phosphorus (TP) concentration changes from 1990 to 2012 in acidified and limed lake group in Sweden were investigated and compared to neutral lake group. The Literature study showed that TP concentrations were generally reduced in acidified lakes due to reduced terrestrial losses of P into lakes, increased in-lake P precipitation and burial, and weakened biological P cycling. Although reduced acid deposition started from 1980s and water chemistry recovered in some acidified lakes, watersheds still remain acidified, thus TP concentrations in acidic lakes should be smaller than neutral lakes. Limed lakes are hypothesized to have lower TP concentrations than non-limed lakes because of increased P sediment retention due to... (More)
Abstract:
Total phosphorus (TP) concentration changes from 1990 to 2012 in acidified and limed lake group in Sweden were investigated and compared to neutral lake group. The Literature study showed that TP concentrations were generally reduced in acidified lakes due to reduced terrestrial losses of P into lakes, increased in-lake P precipitation and burial, and weakened biological P cycling. Although reduced acid deposition started from 1980s and water chemistry recovered in some acidified lakes, watersheds still remain acidified, thus TP concentrations in acidic lakes should be smaller than neutral lakes. Limed lakes are hypothesized to have lower TP concentrations than non-limed lakes because of increased P sediment retention due to metal (mainly Al, Fe) precipitation. Data analysis showed no statistical difference for TP between acid and neutral lake groups, whereas limed lakes had a significantly lower mean TP concentration than non-limed lakes. In addition, limed lake group had the highest percentage (85%) of deceasing TP trends and the strongest relative strengths of decreasing TP trends than other lake groups, whereas acidic lake group had the smallest percentage (37%) of decreasing TP trends. Compatibly, limed lake group had the highest P retention potential, whereas acid lake group showed a gradually decreased P retention potential. The result from limed lake agrees with the hypothesis, lowest TP concentration than non-limed lake group is attributed to high P sediment retention. Unexpected similar TP concentration as neutral lake group is considered to result from increasing allochthonous TOC/humic substances after reduction of acid deposition. Export of organic matter into lake is usually accompanied with P and humus can support P in waters due to chelator effects. The decreased P retention potential in acid lake group may be due to the gradual shift of lake status from autotrophy to heterotrophy at the root of increased input of humic substances. Although acidified lakes show recovery of P concentrations compared to neutral lakes, the increased P concentration perhaps will not be helpful for the recovery of biota to pre-acidified conditions, because acidified lakes are becoming more heterotrophic and thus less phytoplankton can be supported. Limed lakes appear to have artificially low P concentration, limiting support of primary producers. Dynamics of DOC or humus and precipitation of metals seems to be the regulating factor for P difference among acidic, limed and neutral lakes.

Popular Science summary:

Long-term Change of Phosphorus in Acidified and Limed Lakes in comparison to Neutral lakes

Total phosphorus (TP) concentration changes from 1990 to 2012 in acidified and limed lake group in Sweden were investigated and compared to neutral lake group. The Literature study showed that TP concentrations were generally reduced in acidified lakes due to reduced terrestrial losses of P into lakes, increased in-lake P precipitation and burial, and weakened biological P cycling. Although reduced acid deposition started from 1980s and water chemistry recovered in some acidified lakes, watersheds still remain acidified, thus TP concentrations in acidic lakes should be smaller than neutral lakes. Limed lakes are hypothesized to have lower TP concentrations than non-limed lakes because of increased P sediment retention due to metal (mainly Al, Fe) precipitation. Data analysis showed no statistical difference for TP between acid and neutral lake groups, whereas limed lakes had a significantly lower mean TP concentration than non-limed lakes. In addition, limed lake group had the highest percentage (85%) of deceasing TP trends and the strongest relative strengths of decreasing TP trends than other lake groups, whereas acidic lake group had the smallest percentage (37%) of decreasing TP trends. Compatibly, limed lake group had the highest P retention potential, whereas acid lake group showed a gradually decreased P retention potential. The result from limed lake agrees with the hypothesis, lowest TP concentration than non-limed lake group is attributed to high P sediment retention. Unexpected similar TP concentration as neutral lake group is considered to result from increasing allochthonous TOC/humic substances after reduction of acid deposition. Export of organic matter into lake is usually accompanied with P and humus can support P in waters due to chelator effects. The decreased P retention potential in acid lake group may be due to the gradual shift of lake status from autotrophy to heterotrophy at the root of increased input of humic substances. Although acidified lakes show recovery of P concentrations compared to neutral lakes, the increased P concentration perhaps will not be helpful for the recovery of biota to pre-acidified conditions, because acidified lakes are becoming more heterotrophic and thus less phytoplankton can be supported. Limed lakes appear to have artificially low P concentration, limiting support of primary producers. Dynamics of DOC or humus and precipitation of metals seems to be the regulating factor for P difference among acidic, limed and neutral lakes.


Advisor: Brian Huser (SLU), Per Carlsson (Lund University)
Master´s Degree Project 30 credits in Aquatic Ecology, 2012
Department of Biology, Lund University (Less)
Please use this url to cite or link to this publication:
author
Hu, Qian
supervisor
organization
course
BIOM35 20122
year
type
H2 - Master's Degree (Two Years)
subject
language
English
id
3567479
date added to LUP
2013-03-15 16:35:09
date last changed
2013-03-26 13:42:55
@misc{3567479,
  abstract     = {Abstract:
Total phosphorus (TP) concentration changes from 1990 to 2012 in acidified and limed lake group in Sweden were investigated and compared to neutral lake group. The Literature study showed that TP concentrations were generally reduced in acidified lakes due to reduced terrestrial losses of P into lakes, increased in-lake P precipitation and burial, and weakened biological P cycling. Although reduced acid deposition started from 1980s and water chemistry recovered in some acidified lakes, watersheds still remain acidified, thus TP concentrations in acidic lakes should be smaller than neutral lakes. Limed lakes are hypothesized to have lower TP concentrations than non-limed lakes because of increased P sediment retention due to metal (mainly Al, Fe) precipitation. Data analysis showed no statistical difference for TP between acid and neutral lake groups, whereas limed lakes had a significantly lower mean TP concentration than non-limed lakes. In addition, limed lake group had the highest percentage (85%) of deceasing TP trends and the strongest relative strengths of decreasing TP trends than other lake groups, whereas acidic lake group had the smallest percentage (37%) of decreasing TP trends. Compatibly, limed lake group had the highest P retention potential, whereas acid lake group showed a gradually decreased P retention potential. The result from limed lake agrees with the hypothesis, lowest TP concentration than non-limed lake group is attributed to high P sediment retention. Unexpected similar TP concentration as neutral lake group is considered to result from increasing allochthonous TOC/humic substances after reduction of acid deposition. Export of organic matter into lake is usually accompanied with P and humus can support P in waters due to chelator effects. The decreased P retention potential in acid lake group may be due to the gradual shift of lake status from autotrophy to heterotrophy at the root of increased input of humic substances. Although acidified lakes show recovery of P concentrations compared to neutral lakes, the increased P concentration perhaps will not be helpful for the recovery of biota to pre-acidified conditions, because acidified lakes are becoming more heterotrophic and thus less phytoplankton can be supported. Limed lakes appear to have artificially low P concentration, limiting support of primary producers. Dynamics of DOC or humus and precipitation of metals seems to be the regulating factor for P difference among acidic, limed and neutral lakes.

Popular Science summary:

Long-term Change of Phosphorus in Acidified and Limed Lakes in comparison to Neutral lakes

Total phosphorus (TP) concentration changes from 1990 to 2012 in acidified and limed lake group in Sweden were investigated and compared to neutral lake group. The Literature study showed that TP concentrations were generally reduced in acidified lakes due to reduced terrestrial losses of P into lakes, increased in-lake P precipitation and burial, and weakened biological P cycling. Although reduced acid deposition started from 1980s and water chemistry recovered in some acidified lakes, watersheds still remain acidified, thus TP concentrations in acidic lakes should be smaller than neutral lakes. Limed lakes are hypothesized to have lower TP concentrations than non-limed lakes because of increased P sediment retention due to metal (mainly Al, Fe) precipitation. Data analysis showed no statistical difference for TP between acid and neutral lake groups, whereas limed lakes had a significantly lower mean TP concentration than non-limed lakes. In addition, limed lake group had the highest percentage (85%) of deceasing TP trends and the strongest relative strengths of decreasing TP trends than other lake groups, whereas acidic lake group had the smallest percentage (37%) of decreasing TP trends. Compatibly, limed lake group had the highest P retention potential, whereas acid lake group showed a gradually decreased P retention potential. The result from limed lake agrees with the hypothesis, lowest TP concentration than non-limed lake group is attributed to high P sediment retention. Unexpected similar TP concentration as neutral lake group is considered to result from increasing allochthonous TOC/humic substances after reduction of acid deposition. Export of organic matter into lake is usually accompanied with P and humus can support P in waters due to chelator effects. The decreased P retention potential in acid lake group may be due to the gradual shift of lake status from autotrophy to heterotrophy at the root of increased input of humic substances. Although acidified lakes show recovery of P concentrations compared to neutral lakes, the increased P concentration perhaps will not be helpful for the recovery of biota to pre-acidified conditions, because acidified lakes are becoming more heterotrophic and thus less phytoplankton can be supported. Limed lakes appear to have artificially low P concentration, limiting support of primary producers. Dynamics of DOC or humus and precipitation of metals seems to be the regulating factor for P difference among acidic, limed and neutral lakes.


Advisor: Brian Huser (SLU), Per Carlsson (Lund University)
Master´s Degree Project 30 credits in Aquatic Ecology, 2012
Department of Biology, Lund University},
  author       = {Hu, Qian},
  language     = {eng},
  note         = {Student Paper},
  title        = {Long-term Change of Phosphorus in Acidified and Limed Lakes in comparison to Neutral lakes},
  year         = {2013},
}