Appendix A - Supporting Information
Boreal forest riparian zones regulate stream sulfate and dissolved organic carbon José L. J. Ledesmaa,*, Martyn N. Futtera, Hjalmar Laudonb, Christopher D. Evansa,c, Stephan J. Köhlera a
Department of Aquatic Sciences and Assessment, Swedish University of Agricultural
Sciences (SLU), Lennart Hjelms väg 9, SE-750 07 Uppsala, Sweden b
Department of Forest Ecology and Management, Swedish University of Agricultural
Sciences (SLU), Skogsmarksgränd, SE-901 83 Umeå, Sweden c
Centre for Ecology and Hydrology, Environment Centre Wales, Deiniol Road, Bangor LL57
2UW, United Kingdom *Corresponding author at: Lennart Hjelms väg 9, 750 07 Uppsala, Sweden. E-mail address:
[email protected] (J. L. J. Ledesma).
Table of Contents Figure A1. Measured versus EMEP S-SO42- deposition
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Table A1. Summary of S-SO42- flow-weighted concentrations and fluxes
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Figure A2. Relationship between total S and S-SO42- concentrations
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Figure A3. Relationship between S-SO42- and antecedent hydroclimate
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Figure A4. Outliers from DOC versus S-SO42- relationships in the upslope
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Measured S-SO42- (g/m2)
0.8
0.6
0.4 y = 0.8571x + 0.0073 R² = 0.8849
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0.0 0.0
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0.4 EMEP S-SO42- (g/m2)
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Figure A1. Modelled S deposition data for 1880-2020 were available from the European Monitoring and Evaluation Programme (EMEP). We used forest annual S deposition estimates from the 50 x 50 km grid cell where the catchment is located. Measured S deposition was available for the period 1985-2007. The relationship between EMEP and measured S deposition (R2 = 0.88 for the overlapping period) was used to generate a full time series of data for 1880-2020 to be used, i.e. EMEP values were offset with measured data.
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Table A1. Summary of sulfate sulfur (S-SO42-) annual flow-weighed concentrations (upper table) and fluxes (lower table) in stream (C2), riparian peat (S4), transitional soil (S12), and upslope podzol (S22) waters. Uncertainty boundaries (indicated as “Low” and “Upp”) derived from the groundwater table-discharge regression are also indicated. Coefficients of variation (CV) for every year of the three estimates (Low, Best, and Upp) for each soil profile are also displayed. Year C2 (mg L-1) S4 Best (mg L-1) S4 Low (mg L-1) S4 Upp (mg L-1) S12 Best (mg L-1) S12 Low (mg L-1) S12 Upp (mg L-1) S22 Best (mg L-1) S22 Low (mg L-1) S22 Upp (mg L-1) 1.92 1.48 1.52 1.98 2.09 1.81 3.66 4.03 3.80 2.78 2003 1.49 1.49 1.80 1.81 2.03 1.95 2.30 2.03 2.25 1.70 2004 1.52 2.27 1.74 1.92 1.85 1.91 1.65 1.37 1.56 2005 1.67 1.71 2.01 1.44 2.00 1.81 1.94 2.45 1.68 2.19 2.44 2006 1.32 2.17 1.54 1.46 1.89 1.78 1.82 1.99 1.60 2007 1.98 1.72 2.18 1.41 1.81 1.46 1.64 1.41 1.00 2008 1.52 1.20 2.28 1.51 1.82 1.64 1.34 1.57 1.31 1.07 1.22 2009 1.32 2.29 1.50 1.81 1.56 1.23 1.46 0.95 0.71 1.34 0.84 2010 2.45 1.51 1.81 1.54 1.36 1.01 0.83 1.48 1.56 0.93 2011 1.46 1.55 1.37 1.36 1.42 1.15 1.15 0.61 0.71 0.51 2012 1.45 1.65 2.09 1.79 1.54 1.76 1.71 1.76 1.44 Average 1.66
S4 CV 4.87% 6.44% 9.65% 18.65% 11.10% 17.22% 10.25% 14.04% 9.61% 17.01% 9.91%
S12 CV 7.25% 5.61% 2.02% 5.05% 10.43% 10.80% 10.22% 11.91% 6.28% 10.87% 7.72%
S22 CV 14.79% 11.38% 21.06% 16.60% 27.67% 21.97% 20.61% 21.37% 24.80% 6.36% 18.83%
Year C2 (kg ha-1) S4 Best (kg ha-1) S4 Low (kg ha-1) S4 Upp (kg ha-1) S12 Best (kg ha-1) S12 Low (kg ha-1) S12 Upp (kg ha-1) S22 Best (kg ha-1) S22 Low (kg ha-1) S22 Upp (kg ha-1) 3.29 2.54 3.12 2.61 3.40 3.59 6.51 6.30 2003 4.78 6.92 4.46 3.70 4.52 3.69 5.06 4.85 5.00 5.58 5.69 2004 4.22 3.40 4.16 3.89 5.08 3.06 4.28 4.28 3.50 3.70 2005 3.74 4.60 4.31 5.04 3.63 4.24 4.90 5.02 5.52 6.14 2006 6.16 3.16 4.68 2.85 3.45 3.84 4.08 3.33 3.93 4.30 2007 4.26 3.72 3.85 4.51 5.71 2.63 4.30 4.71 3.98 3.14 3.69 2008 3.77 3.35 4.52 5.64 3.91 4.04 3.04 3.25 2.66 2009 3.29 2.78 4.05 5.11 3.36 1.60 3.27 3.48 2010 3.00 1.88 2.11 2.98 2.64 3.51 4.73 2.93 1.94 1.61 2.85 2011 3.02 1.79 4.35 5.49 5.82 5.18 2.68 1.92 5.10 5.29 2012 4.34 2.30 3.51 3.67 3.97 4.96 3.25 4.07 4.25 Average 4.08 3.76 4.00
S4 CV 4.81% 6.19% 9.43% 18.32% 10.98% 16.78% 9.89% 13.70% 9.48% 16.55% 10.39%
S12 CV 6.93% 5.18% 1.69% 4.48% 10.23% 10.08% 9.66% 11.37% 6.05% 10.17% 7.41%
S22 CV 14.63% 11.16% 20.86% 16.27% 27.58% 21.55% 20.27% 21.04% 24.69% 5.90% 17.82%
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12
10
y = 0.9546x - 0.1617 R² = 0.9283
S-SO42- (mg L-1)
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0 0
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Total S (mg L-1)
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Figure A2. Relationship between total sulfur (S) and sulfate sulfur (S-SO42-) concentrations in all available stream and soil water samples within the period 2003-2012 (N=979).
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Figure A3. Simple linear regressions to predict stream sulfate sulfur (S-SO42-) concentrations from antecedent accumulated annual precipitation (left panel) and S-SO42- concentrations at 45 cm depth in the riparian zone (RZ) from antecedent annual average groundwater table (right panel). Note that the highest S-SO42- concentration in the stream of 7.0 mg L-1 (September 2006) has been omitted for graphical clarity but it is included in the regression. In the case of the RZ, the regression is divided into two periods: 2003-2008 (red dots) and 20092012 (blue dots).
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Figure A4. Relationship (as a power function) between dissolved organic carbon (DOC) and sulfate sulfur (S-SO42-) in soil water samples from the stream and lysimeters at the three soil profiles in the S-transect. A6
