Supplementary Figure 1. Distribution of the study lakes across Sweden.

Transcription

1 Supplementary Figure 1. Distribution of the study lakes across Sweden.

2 Supplementary Figure 2. Multivariate analysis of molecular data and landscape and climatic drivers using non-metric multidimensional scaling. Ordinations are based on either Bray-Curtis (a; stress=0.0966), which utilizes relative peak abundances, or Jaccard distances (b; stress=0.1143), which utilizes presence/absence information. Only landscape and climate variables were fit to the NMDS ordination; for an NMDS including water chemistry variables see Figure 2. Gray shaded circles are DOM compounds, whereas black circles indicate the site. Variables with a significance level of < 0.05 (light blue), < 0.01 (green), and < (purple) are shown. P-values were calculated over 999 permutations. WRT, water residence time; MAP, mean annual precipitation; MAT, mean annual temperature. 2

3 Supplementary Figure 3. Molecular-level DOM dynamics of 981 core molecules across 120 Swedish lakes. Only molecular formulae that occur in at least 90% of the lakes were considered, as opposed to molecular formulae occurring in at least three samples (Figure 3). Significant Spearman rank correlation coefficients (p-value < ) of individual molecules with (a) mean annual precipitation, (b) water residence time, (c) mean annual temperature, and (d) the chemodiversity index. The color indicates molecular-level correlations between the intensity of individual molecules and mean annual precipitation, water residence time, mean annual temperature, and chemodiversity index. Circles and diamonds indicate N-free and N- containing compounds, respectively. The number of positive and negative significant correlations can be found in Supplementary Table 2. 3

4 H/C 1.5 Aliphatic Highly unsaturated and phenolic compounds 1.0 Vascular plantderived polyphenols n 0.5 CHO CHON CHOS Combustio - der i ved polycyclic aromates n= O/C Supplementary Figure 4. Molecular composition of peaks included in Spearman rank correlation coefficient analyses. Molecules were included in the constrained analyses if they were in at least 90% of samples and at least half the samples had a value greater than the dataset detection limit (n = 981). Light blue dots contain nitrogen, and purple dots contain sulphur. 4

5 Variable Median Range Mean annual precipitation (mm) Mean annual temperature ( C) Growing degree days (days) Elevation (m) % Agriculture % Forest % Wetland % Water % Other Slope ( ) Surface area (km 2 ) <1 <1-136 Runoff (l s -1 ) ,000 Water residence time (days) Lake/catchment area Volume (1000 m 3 ) ,200,000 Dissolved organic carbon (mg l -1 ) Total nitrogen (µg l -1 ) Total organic nitrogen (µg l -1 ) NO 2 + NO 3 (µg l -1 ) Total phosphorus (µg l -1 ) Total organic phosphorus (µg l -1 ) < PO 4 (µg l -1 ) NH 4 (µg l -1 ) Chemodiversity index ph Conductivity (ms m -1 ) Alkalinity (meq l -1 ) SO 4 (meq l -1 ) Al (µg l -1 ) As (µg l -1 ) Ca (meq l -1 ) Cd (µg l -1 ) Cl (meq l -1 ) Co (µg l -1 ) Cr (µg l -1 ) Cu (µg l -1 ) F (mg l -1 ) Fe (µg l -1 ) K (meq l -1 ) Mg (meq l -1 ) Mn (µg l -1 ) Na (meq l -1 ) Ni (µg l -1 ) Pb (µg l -1 ) Si (mg l -1 ) V (µg l -1 ) Zn (µg l -1 ) Supplementary Table 1. Medians and ranges of environmental and chemical variables, and molecular diversity in lakes across Sweden. 5

6 Figure 3 Figure 4 (photolabile) Figure 4 (photoresistant) Supplementary Figure 3 Pos/neg Pos/neg Pos/neg Pos/neg Mean annual 507/ /14 28/ /213 precipitation Water residence time 383/657 25/ /21 238/357 Mean annual 698/538 82/127 63/ /292 temperature Chemodiversity index 852/435 N/A N/A 315/406 Supplementary Table 2. Number of significant positive and negative correlations in Figures 3 & 4 and Supplementary Figure 3. 6