the influence of watershed land use on the composition of dissolved organic matter ... ·...
TRANSCRIPT
TheInfluenceofWatershedLandUseontheCompositionof
DissolvedOrganicMatterEnteringConesusLake,NY
Morgan R. Bida, Todd Pagano, A. Christina Tyler Program in Environmental Sciences
School of Life SciencesRochester Institute of Technology
College of Science85 Lomb Memorial DriveRochester, NY 14623‐5603
WhatisDissolvedOrganicMatter?• Dissolved Organic Matter (DOM) is a complex mixture of soluble molecules supplied to aquatic ecosystems from the decomposition of living organisms.
• DOM represents the largest, most bioavailable pool of carbon supplied to aquatic ecosystems (Battin, T. J. et al., 2008).
Credit: NASA (2011) http://disc.sci.gsfc.nasa.gov/oceancolor/additional/science‐focus/ocean‐color/black_water.shtml
DOMSources• Allochthonous DOM consists of partially decomposed organic residues from plants, animals, and microbes (Aitkenhead‐Peterson et al., 2003)• High molecular weight humic / fulvic acids
• Aromatic compounds
• Recalcitrance provides ecosystem aquatic food web stability (Wetzel 2003)
• Autochthonous DOM comes from internal photosynthetic production (Persson, 1997 and Vanni & Layne, 1997)
• Labile, colorless compounds, low molecular weight
• Rapidly consumed by microbes and algae
• Make up small proportion of total DOM pool
RoleofDOMinAquaticSystems
• DOM forms the base of aquatic food webs
• Facilitates trophic energy exchanges
• Modifies the optical properties of water (Findlay et al., 2003, Gergel et al. 1999).
• ~700 Gt C in the form of DOC
• Potentially responsive to climate change (Stedmon et al., 2003, Findlay et al., 2003).
MeasuresofDOM• DOC, DON, DOP concentrations
• UV‐Visible Spectroscopy
• SUVA254: Aromaticity
• E2/E3 (A254/A365): Average molecular weight
• Florescence EEM spectroscopy
• Fluorescence Index: Autochthonous vs. allochthonous
• β/α ratio (Freshness Ratio): New DOM vs. aged DOM
• Humification Index (HIX): DOM humification
MeasuresofDOM:FluorescenceEEMs• Excitation Emission Matrices (EEMs) provide a 3‐D intensity landscape based on fluorophores in DOM
• Key fluorescence peaks (Coble, 1990)• B: tyrosine‐like
• T: tryptophan‐like
• A: Humic‐like
• C: Humic or fulvic likeCredit: Pagano, 2010
RelatingDOMtoLandUse• Wilson & Xenopoulos. (2008)
• Found that the structural complexity of dissolved organic matter decreases as the amount of continuous cropland increases.
• Autochthonous derived DOM signature increases as continuous cropland increases.
• Williams et al. (2010)
• Found increased microbial activity in streams draining areas of high anthropogenic land use
• DOM from agriculturally dominated watersheds supported higher microbial activity than those with more natural land cover
ConesusLake• Western‐most of 11 Finger Lakes• Mean depth: 11.6 m.• Max depth: 20 m• Area: 1,384 ha• Length: 13 km• Max width: 1.61 km
Cred
it: N
YS DEC
2011h
ttp://www.dec.ny.gov/
Sub‐WatershedLandUse• GIS generated subwatersheds
Landuse Type Long Point
Agriculture 78 %
Forest 13 %
Wetland 0 %
Developed 5 %
Other 3 %
Total Area (ha) 540
Landuse Type North McMillan
Agriculture 27 %
Forest 51 %
Wetland 1 %
Developed 7 %
Other 6 %
Total Area (ha) 2034
ConesusLakeResearch• Conesus Lake Watershed Project, lead by Dr. Joseph Makarewicz of SUNY Brockport
• Evaluated implementation of agricultural best management practices (BMPs) from 2002‐2007
• Conesus Lake Watershed Management Plan
• Increased citizen participation in maintaining watershed.
Credit: Makarewicz (2009)
Credit: Makarewicz (2009) Credit: Makarewicz (2007)
Objectives1. Determine DOM concentration and composition in
stream water entering Conesus Lake in terms of DOC, DON, and DOP concentrations
2. Describe optical characteristics of DOM in streams using UV‐visible and fluorescence EEM spectroscopy
3. Distinguish significant relationships between stream subwatershed land use and DOM composition derived from optical properties and C,N,P concentrations.
Hypotheses• DOC concentrations will be greater in subwatersheds with the highest proportions of wetland and forested land covers.
• Experimental subwatersheds with higher % agricultural land cover will show a greater autochthonous signature.
• DOM in streams that have subwatersheds dominated by wetland and forested land cover types will consist of higher molecular weight, more humified and aromatic compounds.
PreliminaryResults
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Total N
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Mean Total Nitrogen by Stream
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Totoal Pho
spho
rous (µ
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Mean Total Phosphorous by Stream
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DOC (m
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Mean Summer 2011 DOC Concentrations
Summer2011DOCConcentrations• The best predictor of stream DOC concentration was the proportion of wetland land cover in watershed
• Stepwise regression gives the model: • DOC = 4.09 + 77.1 Wetland – 17.5 Other
• Explains 61.9% of the variation in DOC concentration (α=0.05) for the Summer 2011 in relation to stream watershed landuse.
y = 51.346x + 3.349R² = 0.4208
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DOC (m
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Wetland Land Cover in Watershed
Mean TOC vs. Wetland Area
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Dissolved
Organ
ic Carbo
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Dissolved Organic Carbon by Season
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Dissolved
Organ
ic Carbo
n (m
g C/L)
Seasonal Dissolved Organic Carbon by Stream
Conclusions• The best predictor of stream DOC concentration was the proportion of wetland land cover in watershed
• Seasonal fluctuations in DOC are consistent with growing season
• Fluorescence EEMs from agricultural and forested watersheds show distinct difference in the humic region.
• Work continues….• Nutrients: TN, TP, NO3
‐, PO4
3‐, NH4+
• DOC• Phenolic content• Fluorescence analysis
• In‐stream processing of DOM
• Storm‐event DOM characteristics
• Riparian buffer land use?
Acknowledgements
• The Finger Lakes Institute
• Funding provided by RIT/NTID Innovation Grant
• Advisors: Dr. Todd Pagano and Dr. A. Christy Tyler
• Undergraduates: Matthew Forsythe, James Macisco, Ryan Spector, and Gloria Wink
References• Agren, A. I., Berggren, K., Bishop, M., Jansson, M., & Laudon, H. (2008). Dissolved organic carbon characteristics in boreal
streams in a forest‐wetland gradient during the transition between winter and summer. Journal of Geophysical Research ‐Biogeosciences , 113.
• Aitkenhead‐Peterson, J. A., McDowell, W. H., & Neff, J. C. (2003). Sources, Production, and Regulation of Allochthonous Dissolved Organic Matter Inputs to Surface Waters. In Findlay, & Sinsabaugh, Aquatic Ecosystems: Interactivity of Dissolved Organic Matter (pp. 25‐70). New York: Academic Press.
• Battin, T. J., et al. (2008), Biophysical controls on organic carbon fluxes in fluvial networks, Nat. Geosci., 1, 95‐100, doi:10.1038/ngeo101
• Bertilsson, S., & Jones, Jr., J. B. (2003). Supply of Dissolved Organic Matter to Aquatic Ecosystems: Autochthonous Sources. In S. E. Findlay, & R. L. Sinsabaugh (Eds.), Aquatic Ecosystems: Interactivity of Dissolved Organic Matter (pp. 3‐19). Burlington, MA, USA: Academic Press.
• Cory, R. M., & McKnight, D. M. (2005). Fluorescence spectroscopy reveals ubiquitous presence of oxidized and reduced quinones in DOM. Environmental Science and Technology , 39, 8142‐8149.
• Fellman, J., Hood, E., Edwards, R., & D’Amore, D. (2009). Changes in the concentration, biodegradability, and fluorescent properties of dissolved organic matter during stormflows in coastal temperate watersheds. J. Geophys. Res , 114.
• Foley, J. A., Defries, R., Asner, G. P., Barford, C., Bonan, G., Carpenter, S. R., et al. (2005). Global Consequences of Land Use. Science , 309, 570‐574.
• Forest, H. S., Wade, J. Q., & Maxwell, T. F. (1978) The limnology of Conesus Lake, Lakes of New York State: Ecology of the Finger Lakes (pp. 122‐225). New York: Academic Press.
• Hua, B., Veum, K., Yang, J., Jones, J., & Deng, B. (2010). Parallel factor analysis of fluorescence EEM spectra to identify THM precursors in lake waters. Environmental monitoring and assessment , 161 (1), 71‐81.
• Makarewicz et al. (2007). Elevated Nutrient Levels from Agriculturally Dominated Watersheds Stimulate Metaphyton Growth. J. Great Lakes Res, 33, 437‐448.
• Makarewicz. (2009). Nonpoint Source Reduction to the Nearshore Zone Via Watershed Management Practices: Nutrient Fluxes, Fate, Transport and Biotic Responses‐Background and Objectives. Journal of Great Lakes Research , 35 (sp1), 3‐9.
• McKnight, D. M., Boyer, E. W., Westerhoff, P. K., Doran, P. T., Kulbe, T., & Andersen, D. T. (2001). Spectrofluorometric characterization of DOM for indication of precursor material and aromaticity. Liminol. Oceanogr. , 46, 38‐48.
• Nollet, L. M. L. (2007), Handbook of Water Analysis, 2nd Edition. CRC Press, Boca Raton, Florida.• Roulet, N., & Moore, T. (2006). Environmental chemistry: Browning the waters. Nature , 444, 283‐284.• Stedmon, C. A., Markager, S., Bro, R. (2003) Tracing dissolved organic matter in aquatic environments using a new
approach to fluorescence spectroscopy. Marine Chemistry, 82, 239‐254. • Wetzel, R. G. (2003). Dissolved Organic Carbon: Detrital Energetics, Metabolic Regulators, and Drivers of Ecosystem
Stability of Aquatic Ecosystems. In S. E. Findlay, & R. L. Sinsabaugh (Eds.), Aquatic Ecosystems: Interactivity of Dissolved Organic Matter (pp. 455‐477). Burlington, MA: Academic Press.
• Wilson, H., & Xenopoulos, M. (2008). Effects of agricultural land use on the composition of fluvial dissolved organic matter. Nature Geoscience , 2 (1), 37‐41.
Questions?
AllochthonousDOM• Allochthonous DOM consists of partially decomposed organic residues from plants, animals, and microbes (Aitkenhead‐Peterson et al., 2003)
• High molecular weight humic / fulvic acids• Aromatic compounds• Recalcitrance provides ecosystem stability
Credit: Roulet, Nigel and Tim R. Moore. "Environmental Chemistry: Browning the waters." Nature 444 (2006): 283‐284.
WaterSampling• Seasonal sampling
• Summer 2010 – Winter 2012• Will help to understand seasonal DOM dynamics in watershed
• Monthly sampling • June – October, 2011• 14 experimental subwatersheds• Varied proportions of land use types (i.e. Ag: 79 – 1 %)
• Triplicate collection• Samples filtered using 0.45µm cellulose membranes
• Stored frozen
NorthMcMillanSubwatershed
Landuse Type North McMillan
Agriculture 27 %
Forest 51 %
Wetland 1 %
Developed 7 %
Other 6 %
Total Area (ha) 2034
LongPointSubwatershed
Landuse Type Long Point
Agriculture 78 %
Forest 13 %
Wetland 0 %
Developed 5 %
Other 3 %
Total Area (ha) 540
ParallelFactorAnalysis(PARAFAC)• PARAFAC is a way to mathematically separate fluorescence EEM spectra into classes of fluorophoric constituents(Stedmon, C. A., et al., 2003).
• Multiple component model is generated
• Each component represents different groups of fluorophores present.
• PARAFAC provides greater resolution that allows for EEMs to be decomposed further as compared to “peak picking”techniques.
ParallelFactorAnalysis(PARAFAC)
Credit: Markager et al., 2007