Understanding variability in dissolved organic matter:

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Understanding variability in dissolved organic
matter
A proposal for additional work in the National
Parks.
C. M. OReilly P. D. Brooks
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Why DOM is important?

• Buffer against acidification.
• Acid-base chemistry/ metal transport.
• Supports microbial production.
• Influences predator-prey interactions/ food web
  structure.
• Lake transparency/ stratification.
• Absorbs UV radiation.

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Coarse breakdown of DOC

• Total DOC labile DOC fulvic acids

food and nutrients aquatic
UV protection soil OM
primary source
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Patterns seen in Rocky Mountain NP. Total DOC

• Higher altitude lakes have lower total DOC
  (plt.0041).

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Labile DOC

• Higher altitude lakes have lower labile DOC
  (plt.0135).

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Fulvic acid concentration

• Higher altitude lakes have lower fulvic acid
  (plt.0053).

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fulvic acid

• fulvic acid is not related to altitude.
• fulvic acid is related to year (plt.0339).
• Most lakes are gt 50 fulvic acid.

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BUT . . . . . . lots of variability!!
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Temporal patterns differ spatially.

• Different ponds have different patterns of fulvic
  acid concentration.

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DOC model
VEGETATION Spatial control on soil organic matter.
CLIMATE Temporal control on hydrologic flow paths.
SOIL organic matter
hydrologic transport
WATER DOM
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Which ecosystem characteristics are important in
controlling DOM?
2. What is the temporal variability of DOM in
different vegetation communities?
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1. Which ecosystem characteristics are important
in controlling DOM?

• Landscape position
• headwater lakes vs. lakes lower in the catchment
• Climate/ snowmelt
• Vegetation patterns
• both watershed scale and riparian
• Soil type and chemistry