Grant: Discovery Grants Program - Individual
York University
$15,400.00
Particulate organic carbon formation and phosphorus/iron supply ratios along pH and trophic gradients in lakes
FY 2008-09
Summary
Globally, lake sediments store a very large amount of carbon. The presence of algal remains in sediments such as pigments, cell walls, etc indicates that sediment carbon is partially derived from algae. However, evidence shows that algal carbon is readily mineralized by the microbial community so it appears that there must be a major non-biological source of sediment carbon. During the last grant cycle, work in my laboratory demonstrated that irradiation of acidic stream waters with artificial sunlight resulted in formation of particulate organic carbon (POC) from dissolved organic carbon (DOC) and that formation of particulate iron played a major role, probably because DOC adheres to the surface of newly formed particulate iron. We hypothesize that this mechanism plays a major role in transferring DOC to sediments. The first part of this proposal seeks to extend this work by examining the extent of POC formation in acidic and non-acidic waters in the absence of UVB.
In the second part of this proposal, I propose to examine the relationship between the production of 'labile' iron in freshwaters and the algal species that dominate phytoplankton communities. Benign eukaryotic species typically co-exist with very small cyanobacteria in nutrient-poor oligotrophic lakes where productivity is usually by low levels of phosphorus. Nutrient-rich eutrophic waters are typically dominated by large cyanobacteria. It is not clear how more benign eucaryotic species are displaced by toxic cyanobacteria. I developed a conceptual model in which the ratio of labile iron supply rate to phosphate supply rate is critical in determining the relative abundance of cyanobacteria. The primary goal of my proposed research is to compare supply rates of phosphate and labile iron using a method that captures labile iron and phosphate over a 24 hour period to algal species composition. This will help determine whether variation in the phosphorus/iron supply ratio affects the composition of the algal community.
Program
Discovery Grants Program - Individual
Recipient
Location
Ontario, Canada
Recipient Type
Academia
Type
Grant
Source
NSERC's Awards Data
As published
Application id
238800-2007
Name nom
Molot, Lewis
Department département
Environmental Studies, Faculty of
Organization id
38
Institution établissement
York University
Province en
Ontario
Province fr
Ontario
Country en
CANADA
Country fr
CANADA
Fiscal year exercice financier
2008
Competition year année de concours
2007
Award amount
15400
Program id
RGPIN
Program nane en
Discovery Grants Program - Individual
Program name fr
Programme de subventions à la découverte - individuelles
Group en
Discovery grants programs
Group fr
Programmes de subventions à la découverte
Committee code
18
Committee name en
Evolution & Ecology
Committee name fr
Évolution et écologie
Area of application code
400
Area of application group en
Environment
Area of application group fr
Environnement
Area of application en
Environment
Area of application fr
Environnement
Research subject code
4713
Research subject group en
Evolution and ecology
Research subject group fr
Évolution et écologie
Research subject en
Chemical ecology
Research subject fr
Écologie chimique
Partie
2
Nb partie
5
Application title
Particulate organic carbon formation and phosphorus/iron supply ratios along pH and trophic gradients in lakes
Keyword
NA
Application summary
Globally, lake sediments store a very large amount of carbon. The presence of algal remains in sediments such as pigments, cell walls, etc indicates that sediment carbon is partially derived from algae. However, evidence shows that algal carbon is readily mineralized by the microbial community so it appears that there must be a major non-biological source of sediment carbon. During the last grant cycle, work in my laboratory demonstrated that irradiation of acidic stream waters with artificial sunlight resulted in formation of particulate organic carbon (POC) from dissolved organic carbon (DOC) and that formation of particulate iron played a major role, probably because DOC adheres to the surface of newly formed particulate iron. We hypothesize that this mechanism plays a major role in transferring DOC to sediments. The first part of this proposal seeks to extend this work by examining the extent of POC formation in acidic and non-acidic waters in the absence of UVB.
In the second part of this proposal, I propose to examine the relationship between the production of 'labile' iron in freshwaters and the algal species that dominate phytoplankton communities. Benign eukaryotic species typically co-exist with very small cyanobacteria in nutrient-poor oligotrophic lakes where productivity is usually by low levels of phosphorus. Nutrient-rich eutrophic waters are typically dominated by large cyanobacteria. It is not clear how more benign eucaryotic species are displaced by toxic cyanobacteria. I developed a conceptual model in which the ratio of labile iron supply rate to phosphate supply rate is critical in determining the relative abundance of cyanobacteria. The primary goal of my proposed research is to compare supply rates of phosphate and labile iron using a method that captures labile iron and phosphate over a 24 hour period to algal species composition. This will help determine whether variation in the phosphorus/iron supply ratio affects the composition of the algal community.
