<p> 1 Supplementary Material</p><p>2 Methods</p><p>3 To quantify watershed characteristics we used ESRI Arc Geographic Information System (GIS) </p><p>4 Desktop, Version 10.1. Geospatial datasets were downloaded from the U.S. Geological Survey: </p><p>5 the National Elevation Dataset (NED, http://ned.usgs.gov), the National Hydrography Dataset </p><p>6 (NHD, http://nhd.usgs.gov), and the National Land Cover Dataset (NLCD 2011, </p><p>7 http://www.mrlc.gov). Wetlands polygons from the National Wetlands Inventory (NWI) were </p><p>8 acquired from U.S. Fish and Wildlife Service (U.S. Fish and Wildlife Service, Division of </p><p>9 Habitat and Resource Conservation, September 26, 2011, Washington D.C., </p><p>10 http://www.fws.gov/wetlands/). We used NWI layers to determine the percentage of wetland </p><p>11 because Johnston et al. (2008) found NWI wetland layers were better predictors of stream DOC </p><p>12 than NLCD wetland layers. </p><p>13 To delineate boundaries and calculate watershed areas for each study site, we used the </p><p>14 Hydrology toolset found in Arc Toolbox under spatial analysis tools. We used sample points </p><p>15 determined with Global Positioning System (GPS) at the downstream end of our sampling reach </p><p>16 and the NED data to delineate the individual watersheds for each of our sample locations. </p><p>17 Therefore, watershed area includes only the area above our sampling locations. Watershed </p><p>18 boundaries were used to clip the NWI data to determine the percent total wetland area and </p><p>19 calculate mean slope for each watershed. Although agriculture is not prevalent in these </p><p>20 watersheds Burtner et al. (2011) found that even a small percent of agriculture within the </p><p>21 watershed can be positively related to DOC concentrations in this region. Therefore, we used the</p><p>22 NLCD data to identify the percent of agriculture present within each of the watersheds. The </p><p>23 length of the polyline in the NHD drainage networks was used to determine the distance from 24 our study sites to Lake Superior. The NHD drainage networks did not include two of our study </p><p>25 streams (Calumet watershed and Black Creek), thus we used flow accumulation data layers </p><p>26 derived from the NED and created as part of the watershed delineation to determine the distance </p><p>27 from these 2 study reaches to Lake Superior. 28 Supplemental Table 1: Stream water chemistry measured on the date of each short term nutrient release including: ammonium </p><p>+ - 29 (NH4 -N), nitrate (NO3 -N) total dissolved nitrogen (TDN), dissolved organic carbon (DOC), soluble reactive phosphate (SRP), total </p><p>- 30 phosphate (TP), chloride (Cl ), sulfate (SO4-S). Organic N was calculated by subtracting the sum of inorganic N from total dissolved </p><p>31 N. Fluoride, phosphate, nitrite, and bromide concentrations were below detection limits, and thus, are not reported herea.</p><p>+ - -1 Site Name Year NH4 (mg NO3 -N TDN (mg N Dissolved DOC (mg SRP (mg P TP (mg P Cl (mg L ) SO4-S (mg N L-1) (mg L- L-1) Organic N C L-1) L-1) L-1) L-1) 1) (mg N L-1) Calumet 2012 0.004 0.04 0.34 0.34 7.92 0.002 0.012 0.72 1.03 Little Huron 2012 0.022 0.16 0.32 0.14 4.68 0.002 0.012 1.28 1.00 Big Pup 2012 0.007 0.29 0.30 0.00 2.14 0.002 0.012 0.40 1.21 Little Garlic 2012 0.002 0.19 0.27 0.08 4.74 0.002 0.012 1.39 1.13 E.Branch Huron 2012 0.005 0.14 0.31 0.16 6.67 0.002 0.012 0.71 1.09 Salmon Trout 2012 0.008 0.04 0.19 0.18 3.29 0.003 0.032 0.49 1.07 Calumet 2013 0.004 0.04 0.37 0.37 8.60 0.002 0.032 0.57 0.62 Little Huron 2013 0.020 0.20 0.33 0.11 4.30 0.004 0.056 0.84 1.02 Big Pup 2013 0.006 0.28 0.33 0.04 2.00 0.004 0.012 0.39 1.12 Little Garlic 2013 0.007 0.04 0.30 0.29 5.10 0.003 0.012 1.29 1.08 Black 2013 0.006 0.04 0.30 0.29 7.25 0.003 0.032 3.60 0.50 Hills 2013 0.002 0.04 0.33 0.33 6.07 0.004 0.047 17.01 0.12 Gratiot 2013 0.002 0.10 0.34 0.24 6.54 0.002 0.042 5.93 0.97 E. Branch Huron 2013 0.007 0.04 0.44 0.43 9.30 0.004 0.012 0.44 0.90 Mountain 2013 0.002 0.04 0.25 0.25 5.94 0.004 0.012 0.48 1.01 Salmon Trout 2013 0.012 0.04 0.21 0.20 3.79 0.003 0.012 0.41 1.06 Pine 2013 0.005 0.12 0.26 0.13 5.89 0.004 0.012 0.68 1.21 a + -1 - -1 -1 -1 - 32 Detection limits were as follows: NH4 : 0.004 mg L , NO3 -N: 0.077 mg L , SRP: 0.003 mg L , Total P: 0.023 mg L , Cl : 0.059 mg </p><p>-1 33 L-1, SO4-S: 0.134 mg L . 34 Supplemental Table 2: Measured stream characteristics on each sampling date. Stream Year Discharge Benthic Canopy Water pH Conductivity Dissolved (L sec-1) chl a (mg cover (%)temperature (mS/cm) oxygen (mg/L) m-2) (°C) Calumet 2012 1.2 2.67 85 17.4 7.87 0.14 9.34 Little Huron 2012 47.2 6.42 74 16.0 7.31 0.13 9.01 Big Pup 2012 78.3 3.32 51 13.8 7.5 0.12 9.81 Little Garlic 2012 97.7 16.16 69 23.9 7.93 0.15 9.01 E. Branch Huron 2012 180.4 8.39 29 19.3 7.44 0.13 9.20 Salmon Trout 2012 755.6 4.56 26 19.0 7.56 0.14 9.05 Calumet 2013 16.3 0.29 90 13.6 7.76 0.13 10.43 Little Huron 2013 75.8 0.97 88 15.1 7.56 0.13 9.16 Big Pup 2013 100.3 2.29 63 14.5 7.94 0.10 10.74 Little Garlic 2013 72.3 5.58 70 20.6 8.03 0.16 9.03 Black 2013 70.7 1.28 67 13.6 7.68 0.23 9.64 Hills 2013 117.9 7.94 42 13.6 7.84 0.20 10.25 Gratiot 2013 180.8 5.13 46 14.8 7.87 0.14 10.25 E. Branch Huron 2013 490.0 2.77 38 19.3 7.74 0.100 9.28 Mountain 2013 636.4 5.05 67 17.9 8.11 0.103 9.10 Salmon Trout 2013 821.4 0.84 25 18.4 7.93 0.147 8.89 Pine 2013 1305.2 2.39 45 20.7 7.87 0.094 8.23 35</p><p>36 37 Supplemental Table 3: Ammonium and soluble reactive phosphate uptake parameters. ns indicates that uptake was undetectable for </p><p>38 that site and date. Enrichment factors are abbreviated as EF.</p><p>+ + + + Year NH4 Vf NH4 SW NH4 U NH4 SRP Vf SRP SRP U SRP EF - -2 - -2 Discharge Velocity Depth (mm min (m) (mg m EF (mm min SW (m) (mg m Site (L s-1) (m s-1) (m) 1) day-1) 1) day-1) Calumet 2012 1.2 0.02 0.09 0.79 128.21 4.57 2.59 ns ns ns 5.33 Little 2012 47.2 0.05 0.15 ns ns ns 1.45 7.15 434.78 21.25 3.91 Huron Big Pup 2012 78.3 0.18 0.15 5.46 294.12 54.80 2.49 3.53 454.55 17.87 0.96 Little 2012 97.7 0.14 0.14 4.54 250.00 21.32 3.75 ns ns ns 5.56 Garlic E. Branch 2012 180.4 0.26 0.22 8.77 384.62 67.38 3.03 ns ns ns 4.73 Huron Salmon 2012 755.6 0.27 0.23 2.96 1250.00 35.46 2.44 1.48 2500.0 5.23 4.25 Trout Calumet 2013 16.3 0.18 0.11 3.74 312.50 19.81 6.71 ns ns ns 8.37 Little 2013 75.8 0.04 0.35 ns ns ns 1.63 ns ns ns 5.12 Huron Big Pup 2013 100.3 0.10 0.17 1.56 666.67 12.57 3.52 0.31 3333.3 1.55 3.99 Little 2013 72.3 0.07 0.21 1.42 588.24 14.59 2.60 0.92 909.09 4.46 3.87 Garlic Black 2013 70.7 0.15 0.11 1.04 909.09 8.49 3.71 1.13 833.33 4.29 5.48 Hills 2013 117.9 0.11 0.21 1.84 714.29 8.68 4.67 1.19 1111.1 3.91 5.27 Gratiot 2013 180.8 0.19 0.17 1.40 1428.60 4.42 6.63 ns ns ns 5.13 E. Branch 2013 490.0 0.16 0.38 10.26 357.14 98.98 5.47 ns ns ns 8.46 Huron Mountain 2013 636.4 0.24 0.21 3.25 666.67 10.30 3.06 ns ns ns 2.37 Salmon 2013 821.4 0.13 0.50 ns ns ns 1.62 ns ns ns 4.01 Trout Pine 2013 1305.2 0.20 0.60 14.61 500.00 107.95 2.02 ns ns ns 3.16 39 References</p><p>40 NRCS Natural Resources conservation Service, soil survey staff, United States Department of </p><p>41 Agriculture. Web Soil Survey. Available online at htt://websoilsurvey.nrcs.usda.gov/. </p><p>42 Accessed [February 2014 ].</p><p>43 Olefeldt D, Teretsky MR, Blodau C. (2013). Altered composition and microbial versus UV-</p><p>44 mediated degradation of dissolved organic matter in boreal soils following wildfire. </p><p>45 Ecosystems 16:1396-1412, doi:10.1007/s10021-013-9691-y</p><p>46 Stedmon CA, Markager S. (2005a) Resolving the variability in dissolved organic matter </p><p>47 fluorescence in a temperate estuary and its catchment using PARAFAC analysis. 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