1. University of Alabama 2. VIMS, College of William and Mary 3. Ohio State University 4. Florida International University 5. Hokkaido University

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1 Yuehan Lu 1, Elizabeth Canuel 2, James Bauer 3, Youhei Yamashita 5, Randy Chambers 1 Rudolf Jaffe 4, Ed Keesee 2, Erin Ferer 2, Amy Barrett 3 1. University of Alabama 2. VIMS, College of William and Mary 3. Ohio State University 4. Florida International University 5. Hokkaido University

2 Background Land uses have important effects on quantity and quality of DOM (Raymond, 2004; Stern et al., 2004; Longworth et al., 2007; Wilson and Xenopoulos, 2008). Linking DOM with land uses is often difficult due to multiple involving factors (e.g. Gonsior et al., 2008; Raymond and Saiers, 2010) and extensive biogeochemical transformations (e.g. Frost et al., 2006). Objectives Characterize land-use effect on sources and age of DOM Characterize land-use effect on reactivity of DOM

3 First-order streams: Forest Pasture Cropland Urban Development Fluorescence Spectroscopy (excitation emission matrix-parallel factor analysis, EEM- PARAFAC): CDOM Carbon Isotopes: Source & Age Photochemical & Microbial Incubations: Reactivity Nov, 08-Nov, 09

4 80% Urban n= % Forest n= % Pasture n=2 80% Cropland n=1

5 Chesapeake Bay Forest and Agriculture Sites York River % Forest Urban Sites

6 DOC (µm) Forest n=16 Pasture n=12 * p = Urban n=10 Cropland n=6 DOC: Chlorophyll-a (µg/l : µg/l) Forest n=16 Pasture n=12 Urban n=10 * p < Cropland n=6

7 Forest: higher proportions of fluorophores from terrestrial plants Modified land uses: higher proportions of microbial and protein-like fluorophores Relative Abundance of Fluorophores (%) * p < C1 Terrestrial Fulvic-acid type * p < C2 Terrestrial Humic-acid type * p < C3 Microbial Humic-like * p < C4 Protein-like Forest, n=11 Pasture, n=9 Urban, n=9 Cropland, n=4 n.s. p = 0.14 C5 Humic-like

8 % Sources % Sources (C1+C2+C5): (C3 +C4) FI Ter: 79% Ter: 82% Forest n=11 p < Pasture n=9 Urban n=9 Cropland n=4 Ter: 64% Ter: 68% Terrestrial Ter: 63% Ter: 54% Forest n=11 p =0.009 Pasture n=9 Microbial Urban n=9 Cropland n=4 Ter: 74% Ter: 75%

9 Post Bomb Carbon C3 Plants & Freshwater Algae Forest Pasture Urban Cropland 14 C ( ) 14 C age : 1811~ C yr BP Petroleum δ 13 C ( )

10 Post Bomb Carbon Forest Streams Agriculture Streams (Longworth et al., 2007) WWTP (Griffith et al., 2009) 14 C ( ) 14 C age: C yr BP Possible sources of aged C: 1.Fossil fuel C? 2.Carbonate weathering? δ 13 C ( )

11 Forest Pasture Urban Cropland 14 C ( ) 14 C age : C yr BP δ 13 C ( ) Zeng et al., 2010; Raymond et al., 2004

12 Forest Pasture Urban Cropland 14 C ( ) C yr BP OM Respiration Carbonate Weathering δ 13 C ( ) Zeng et al., 2010; Raymond et al., 2004

13 Forest Pasture Urban Cropland 14 C ( ) Ca ++ (µm) 14 C of DIC( ) OM Respiration Carbonate Weathering δ 13 C ( ) Zeng et al., 2010; Raymond et al., 2004

14 Carbonate weathering ( 14 C: -470 ) Terrestrial Plants ( 14 C: +65 ) 53% 37% 63% 47% DIC Carbon fixation increase the age of DOC Remineralization decrease the age of DIC DOC 14 C of DIC ( ) Ter: 54% Non-terrestrial plant DOM: ~45% Terrestrial plant DOM: ~ 55% FI (C 1 +C 2 ): (C 3 +C 4 ) 14 C mass balance Ter: 63% Ter: 47% 14 C of DOC ( )

15 Microbial DOM Forest Pasture Urban Cropland C4% C5% δ 13 C 14 C C1% PC1 (61%) Older & diagenetic DOM Younger DOM PC2 (24%)

16 UVA: 1.41mW cm -2 UVB : 4.17mW cm - 2 Broad Spectrum: 14.0mW cm -2 Incubation time Light days Dark days Combined Photo + Microbial Incubations Microbial-only Incubations 0.7um:remove bacteria predators & 50% bacteria 0.2um: remove bacteria Photo-only Incubations

17 First-order DOC Decomposition Rate Constant k (day -1 ) * p = n.s. p = 0.91 * p = 0.01 Forest Pasture Urban Cropland Photo-only incubations Microbial-only incubations Combined photo + microbial incubations

18 Relative Abundance of Fluorophores (%) C1% R 2 =0.60 C2% R 2 =0.74 First-order DOC Decomposition Rate Constant for Photo-only Incubations k (day -1 ) The relative abundance of fluorophores can predict DOC photoreactivity.

19 Study Area Watershed Land Uses Light sources and Incubation Duration Virginia Forest UVB/UVA/PAR, 15 days Canada Forest UVB/UVA/PAR, 7-12 days % Controlling Factor(s) Photoreactive DOC 51-57% DOM from terrestrial plants 11-50% Light exposure history Sources This study Molot & Dillon, 1997 Northern Great Lake Region Forest UVB/UVA/PAR, 56 hours 6% Not specified, possibly DOM inputs, production and uptake Larson et al, 2007 Colorado Forest and Meadow UVB, 24 hours 10-20% Not specified Clements et al, 2008 New Jersey Forest UVB/UVA/PAR, hours 0% Not specified Wiegner and Seitzinger, 2001 Virginia Agriculture UVB/UVA/PAR, 5-32% DOM from terrestrial This study and Urban lands 15 days plants New Jersey Pasture UVB/UVA/PAR, 38hrs 0% Not specified Wiegner & Seitzinger,

20 Phospholipid Linked Fatty Acid: Neutral Fatty Acid R² = 0.6 Temperature ( C) Temperature R² = 0.45 PLFA:NFA First-order DOC Decomposition Rate Constant for Microbial-only Incubations k (day -1 ) DOC bioreactivity may be related to its diagenetic status.

21 Study Area Watershed Land Uses Incubation Duration % bioreactive DOC Controlling Factor(s) Sources Virginia Forest days 1-15% Diagenetic status This study Canada Forest 7-12 days 0-13% Not specified Molot & Dillon, 1997 Alaska Upland, Wetland, or Forest 30 days 7-38% Protein-rich DOM Fellman et al., 2009 Alaska Forest underlain by permafrost 40 days <20% Protein-rich DOM Balcarczyk et al., 2009 Virginia Agriculture and days % Diagenetic status This study Urban Land Indiana Cropland 6 days Below detection- Not specified Warrner et al., % East-central Illinois Cropland <30 days 18% Not specified Royer & David, 2005 Western Australia Agricultural and Urban Land One month 2-57% Protein-rich DOM Petrone et al 2011 New Jersey Pasture 10 days 9-14% Not specified Wiegner & Seitzinger (2001)

22 To: initial point 100% F T /F T0 (%) Day

23 Day Day Day Day Day Forest Pasture Urban Cropland

24 Initial DOC Residual DOC Reactive DOC Δ 14 C ( ) δ 13 C ( ) 100% 43±10% 57±10% 100% 82±3% 18±3 % 100% 43±10% 57±10% 100% 82±3% 18±3 % 100% 90% 10% 100% 90% 10% 100% 57% 43% 100% 57% 43%

25 Changes in land uses alter sources, age, and reactivity of DOC/DOM in headwater streams Sources: relative abundance of DOM from terrestrial plants: Forest > Modified land uses Photoreactivity: Forest > Modified land uses Age: influenced by inorganic carbon sources Photoreactive DOM pool are similar across the streams: DOM from terrestrial plants, 12 C and 14 C enriched DOC

26 Mellon Postdoctoral Grant, College of William & Mary, VIMS Organic Geochemistry Group, Virginia Institute of Marine Sciences Christina Pondell, Stephanie Salisbury, Sarah Schillawski Environmental Keck Field Lab, College of William & Mary Tim Russell, Charlotte Jackson, Aquatic Ecology/Biogeochemistry group, Ohio State University NSF Chemical Oceanography &Integrated Carbon Cycle Research Program