Brian Lutz

PhD Candidate, Duke University

Visiting Researcher, University of Oslo

Investigating interactions between the major biogeochemical cycles

through understanding ecosystem-scale organic matter dynamics

Outline

Research Background and Justification Ch 1: Preliminary Test of Hypotheses

Synoptic Surveys of Stream Chemistry Ch 2: Ecosystem Scale Manipulations

Stream Nutrient Spiraling Ch 3: Geochemical Controls on DON Losses

Soil Sorption Assays Ch 4: DOM Characterization

Fluorescence and PARAFAC Modeling Eutropia Project

Human Domination of the Global N Cycle

Credits: Netherlands Environmental Assessment Agency, www.pbl.nl

Nitrogen Saturation: Environmental Consequences

Credits: Diaz and Rosenberg, Science, 2008

Nitrogen Saturation: Symptoms and Diagnosis

Credits: Aber, BioScience, 1998

What about organic nitrogen?

1%

99%

Inorganic NOrganic N

Credits: Bormann et al., Science, 1977

What about organic nitrogen?

1%

99%

Inorganic NOrganic N

Credits: Bormann et al., Science, 1977

Organic N turnover supports the majority of ecosystem production in most ecosystems

DON Losses from the landscape are important

Credits: Scott et al., Global BGC Cycles, 2007

Nitrogen Saturation: Symptoms and Diagnosis

Credits: Aber, BioScience, 1998

DON??

‘Breaks in the Cycle’: Increased organic N losses?

Anthropogenic N Additions

Saturated Plant Demand

INCREASED ORGANIC N LOSSES

- Neff et al., Frontiers in Ecology, 2003

DON Release Hypothesis: Schematic

DON Release Hypothesis: Predictions

DON

[DIN]

[DO

N]

Outline

Research Background and Justification Ch 1: Preliminary Test of Hypotheses

Synoptic Surveys of Stream Chemistry Ch 2: Ecosystem Scale Manipulations

Stream Nutrient Spiraling Ch 3: Geochemical Controls on DON Losses

Soil Sorption Assays Ch 4: DOM Characterization

Fluorescence and PARAFAC Modeling Eutropia Project

DON Release Hypothesis: Preliminary Test

DON Release Hypothesis: Preliminary Test

DON Release Hypothesis: Preliminary Test

DON Release Hypothesis: Preliminary Test

DON Release Hypothesis: Preliminary Test

DON Release Hypothesis: Preliminary Test

+C +N +CN +DI

Bioavailability Assays

Indirect Carbon Control Hypothesis

Outline

Research Background and Justification Ch 1: Preliminary Test of Hypotheses

Synoptic Surveys of Stream Chemistry Ch 2: Ecosystem Scale C/N Manipulations

Stream Nutrient Spiraling Ch 3: Geochemical Controls on DON Losses

Soil Sorption Assays Ch 4: DOM Characterization

Fluorescence and PARAFAC Modeling Eutropia Project

Ecosystem Scale Experimental ManipulationsNUTRIENT SPIRALING THEORY

Ecosystem Scale Experimental ManipulationsNUTRIENT SPIRALING THEORY

Pump Metering in

C/N

Ecosystem Scale Experimental Manipulations

Day 1: N Enrichment Day 2: C Enrichment

Outline

Research Background and Justification Ch 1: Preliminary Test of Hypotheses

Synoptic Surveys of Stream Chemistry Ch 2: Ecosystem Scale Manipulations

Stream Nutrient Spiraling Ch 3: Geochemical Controls on DON Losses

Soil Sorption Assays Ch 4: DOM Characterization

Fluorescence and PARAFAC Modeling Eutropia Project

The Importance of Geochemical Controls

Large differences in DOM stoichiometry with different parent geology

143.4

36.6

0

20

40

60

80

100

120

140

160

180

200

Dolomite Shale

Parent Mineralogy

DO

M C

:N

Batch incubation soil sorption assays

Removal of Fe/Al

Unprocessed Soil

Removal of Native Organic Matter

Artificial Leachates

Batch incubation soil sorption assays

Credits: Qualls, Forest Ecol. & Managmnt, 2001

Outline

Research Background and Justification Ch 1: Preliminary Test of Hypotheses

Synoptic Surveys of Stream Chemistry Ch 2: Ecosystem Scale Manipulations

Stream Nutrient Spiraling Ch 3: Geochemical Controls on DON Losses

Soil Sorption Assays Ch 4: DOM Characterization

Fluorescence and PARAFAC Modeling Eutropia Project

DOM Characterization: Fluorescence and PARAFAC

Outline

Research Background and Justification Ch 1: Preliminary Test of Hypotheses

Synoptic Surveys of Stream Chemistry Ch 2: Ecosystem Scale Manipulations

Stream Nutrient Spiraling Ch 3: Geochemical Controls on DON Losses

Soil Sorption Assays Ch 4: DOM Characterization

Fluorescence and PARAFAC Modeling Eutropia Project

What am I doing in Norway?

Working with Eutropia Project Flux of Organic N and P from catchment soils to stream Event (storm) export of OM from catchments End Member Mixing Models (EMMA)

X

Y

Z

Acknowledgments

Host: Rolf Vogt UiO Chemistry Department

Funding: Research Council of Norway National Science Foundation

Implications for Ecosystem N Losses

Credits: Schimel and Bennett, Ecology, 2004