Abstract
Boreal watersheds contain a vast quantity of terrestrially derived dissolved organic matter (DOM) originating from wetland and forest soils, yet variation in the potential for photochemical transformation of boreal aquatic DOM sources remains poorly understood. Laboratory solar radiation exposure experiments were conducted on DOM samples collected in three seasons, across nine sites, representing contrasting catchment composition and watershed position to assess variation in the photochemical lability of boreal DOM source and stable carbon isotopic signature (δ13C) of photomineralized DOM. Dissolved organic carbon (DOC) loss rates during laboratory exposure were lowest in summer, suggesting that DOM may have been more photo-degraded during summer. DOM from upstream portions of forested stream sites and wetland-influenced sites was more photolabile relative to downstream portions and the river DOM, suggesting potential losses in photolabile DOM downstream and in the lower reaches of the watershed. Increased a254:a350 and spectral slope following sample exposure suggest photoproduction of low molecular weight (LMW) CDOM and/or a higher photoreactivity of high molecular weight versus LMW compounds. Photomineralization of nitrogen was regulated by organic nitrogen concentration and resulted in NH4 +-photoproduction rates between 0.01 and 0.3 µM N h−1 and ecologically significant increases in NH4 + for these waters. The δ13C of the photomineralized DOM was positively correlated to initial DOC concentration and generally lower when initial DOC concentrations were lower, suggesting variation in photomineralized DOM δ13C may be a result of kinetic isotope fractionation. Results from this study demonstrate significant variation in the photochemical lability of boreal watershed sources of DOM. Such variation suggests landscape and environmental change has the potential to alter the biogeochemical role photochemical transformations play in downstream portions of boreal watersheds.
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References
Aiken GR, Malcolm RL (1987) Molecular weight of aquatic fulvic acids by vapor pressure osmometry. Geochim Cosmochim Acta 51:2177–2184
Aitkenhead-Peterson JA, Dowell WH, Neff JC (2003) Sources, production, and regulation of allochthonous dissolved organic matter inputs to surface waters. In: Findlay SE, Sinsabaugh RL (eds) Aquatic ecosystems: interactivity of dissolved organic matter. Elsevier Science, Amsterdam, pp 25–70
Alexander RB, Boyer EW, Smith RA, Schwarz GE, Moore RB (2007) The role of headwater streams in downstream water quality. J Am Water Resour Assoc 43:41–59
Algesten G, Sobek S, Bergstrom AK, Agren A, Tranvik LJ, Jansson M (2004) Role of lakes for organic carbon cycling in the boreal zone. Glob Change Biol 10:141–147
Anesio AM, Granéli W (2003) Increased photoreactivity of DOC by acidification: Implications for the carbon cycle in humic lakes. J Limnol Oceanogr 48:735–744
Arango CP, Tank JL (2008) Land use influences the spatiotemporal controls on nitrification and denitrification in headwater streams. J N Am Bentholog Soc 27:90–107
Benner R, Kaiser K (2011) Biological and photochemical transformations of amino acids and lignin phenols in riverine dissolved organic matter. Biogeochemistry 102:209–222
Benner R, Fogel ML, Sprague EK, Hodson RE (1987) Depletion of 13C in lignin: implications for stable carbon isotope studies. Nature 329:708–710
Bertilsson S, Tranvik LJ (2000) Photochemical transformation of dissolved organic matter in lakes. Limnol Oceanogr 45:753–762
Bertilsson S, Stepanauskas R, Cuadros-Hansson R, Graneli W, Wikner J, Tranvik L (1999) Photochemically induced changes in bioavailable carbon and nitrogen pools in a boreal watershed. Aquat Microb Ecol 19:47–56
Bigeleisen J, Allen TL (1951) Fractionation of the carbon isotopes in decarboxylation reactions. IV. The relative rates of decomposition of 1-C12 and 1-C13 trichloracetate ions. J Chem Phys 19:760–764
Bjorkvald L, Buffam I, Laudon H, Morth CM (2008) Hydrogeochemistry of Fe and Mn in small boreal streams: the role of seasonality, landscape type and scale. Geochim Cosmochim Acta 72:2789–2804
Brisco S, Ziegler S (2004) Effects of solar radiation on the utilization of dissolved organic matter (DOM) from two headwater streams. Aquat Microb Ecol 37:197–208
Brown M (1977) Transmission spectroscopy examinations of natural waters: C. Ultraviolet spectral characteristics of the transition from terrestrial humus to marine yellow substance. Estuar Coast Mar Sci 5:309–317
Buffam I, Laudon H, Temnerud J, Morth CM, Bishop K (2007) Landscape-scale variability of acidity and dissolved organic carbon during spring flood in a boreal stream network. J Geophys Res Biogeosci 112:G01022
Bushaw KL, Zepp RG, Tarr MA, SchulzJander D, Bourbonniere RA, Hodson RE, Miller WL, Bronk DA, Moran MA (1996) Photochemical release of biologically available nitrogen from aquatic dissolved organic matter. Nature 381:404–407
Clair TA, Ehrman JM (1996) Variations in discharge and dissolved organic carbon and nitrogen export from terrestrial basins with changes in climate: a neural network approach. Limnol Oceanogr 41:921–927
Clair TA, Sayer BG (1997) Environmental variability in the reactivity of freshwater dissolved organic carbon to UV-B. Biogeochemistry 36:89–97
Clair TA, Sayer BG, Kramer JR, Eaton DR (1996) Seasonal variation in the composition of aquatic organic matter in some Nova Scotian brownwaters: a nuclear magnetic resonance approach. Hydrobiologia 317:141–150
Clair TA, Arp P, Moore TR, Dalva M, Meng FR (2002) Gaseous carbon dioxide and methane, as well as dissolved organic carbon losses from a small temperate wetland under a changing climate. Environ Pollut 116:143–148
Cole JJ, Prairie YT, Caraco NF, McDowell WH, Tranvik LJ, Striegl RG, Duarte CM, Kortelainen P, Downing JA, Middelburg JJ, Melack J (2007) Plumbing the global carbon cycle: integrating inland waters into the terrestrial carbon budget. Ecosystems 10:171–184
Dodds WK, Priscu JC, Ellis BK (1991) Seasonal uptake and regeneration of inorganic nitrogen and phosphorus in a large oligotrophic lake—size-fractionation and antibiotic-treatment. J Plankton Res 13:1339–1358
Faust BC, Zepp RG (1993) Photochemistry of aqueous iron(Iii) polycarboxylate complexes—roles in the chemistry of atmospheric and surface waters. Environ Sci Technol 27:2517–2522
Fellman JB, D’Amore DV, Hood E (2008) An evaluation of freezing as a preservation technique for analyzing dissolved organic C, N and P in surface water samples. Sci Total Environ 392:305–312
Fellman JB, Hood E, Edwards RT, Jones JB (2009) Uptake of allochthonous dissolved organic matter from soil and salmon in coastal temperate rainforest streams. Ecosystems 12:747–759
Fellows CS, Valett HM, Dahm CN, Mulholland PJ, Thomas SA (2006) Coupling nutrient uptake and energy flow in headwater streams. Ecosystems 9:788–804
Findlay S, Sinsabaugh RL (1999) Unravelling the sources and bioavailability of dissolved organic matter in lotic aquatic ecosystems. Mar Freshw Res 50:781–790
Findlay S, Quinn JM, Hickey CW, Burrell G, Downes M (2001) Effects of land use and riparian flowpath on delivery of dissolved organic carbon to streams. Limnol Oceanogr 46:345–355
Fisher SG, Likens GE (1973) Energy flow in Bear Brook, New Hampshire—integrative approach to stream ecosystem metabolism. Ecol Monogr 43:421–439
Francko DA, Heath RT (1982) UV-sensitive complex phosphorus: association with dissolved humic material and iron in a bog lake. Limnol Oceanogr (United States) 27(3):564–569
Freeman C, Fenner N, Ostle NJ, Kang H, Dowrick DJ, Reynolds B, Lock MA, Sleep D, Hughes S, Hudson J (2004) Export of dissolved organic carbon from peatlands under elevated carbon dioxide levels. Nature 430:195–198
Freeman MC, Pringle CM, Jackson CR (2007) Hydrologic connectivity and the contribution of stream headwaters to ecological integrity at regional scales. J Am Water Resour Assoc 43:5–14
Gao HZ, Zepp RG (1998) Factors influencing photoreactions of dissolved organic matter in a coastal river of the southeastern United States. Environ Sci Technol 32:2940–2946
Gennings C, Molot L, Dillon P (2001) Enhanced photochemical loss of organic carbon in acidic waters. Biogeochemistry 52:339–354
Green SA, Blough NV (1994) Optical absorption and fluorescence properties of chromophoric dissolved organic matter in natural waters. Limnol Oceanogr 39:1903–1916
Guéguen C, Granskog MA, McCullough G, Barber DG (2011) Characterisation of colored dissolved organic matter in Hudson Bay and Hudson Strait using parallel factor analysis. J Mar Syst 88:423–433
Hayes JM (2001) Fractionation of carbon and hydrogen isotopes in biosynthetic processes. Stable Isot Geochem 43:225–277
Hedges JI (1992) Global biogeochemical cycles—progress and problems. Mar Chem 39:67–93
Hedges JI, Mann DC (1979) The characterization of plant tissues by their lignin oxidation products. Geochim Cosmochim Acta 43:1803–1807
Hedges JI, Clark WA, Cowie GL (1988) Organic-matter sources to the water column and surficial sediments of a Marine Bay. Limnol Oceanogr 33:1116–1136
Hedges JI, Keil RG, Benner R (1997) What happens to terrestrial organic matter in the ocean? Org Geochem 27:195–212
Helms JR, Stubbins A, Ritchie JD, Minor EC, Kieber DJ, Mopper K (2008) Absorption spectral slopes and slope ratios as indicators of molecular weight, source, and photobleaching of chromophoric dissolved organic matter. Limnol Oceanogr 53:955–969
Inamdar S, Singh S, Dutta S, Levia D, Mitchell M, Scott D, Bais H, McHale P (2011) Fluorescence characteristics and sources of dissolved organic matter for stream water during storm events in a forested mid-Atlantic watershed. J Geophys Res 116:G03043
Johannessen SC, Miller WL (2001) Quantum yield for the photochemical production of dissolved inorganic carbon in seawater. Mar Chem 76:271–283
Jonsson A, Meili M, Bergstrom AK, Jansson M (2001) Whole-lake mineralization of allochthonous and autochthonous organic carbon in a large humic lake (Ortrasket, N. Sweden). Limnol Oceanogr 46:1691–1700
Keller W, Paterson AM, Somers KM, Dillon PJ, Heneberry J, Ford A (2008) Relationships between dissolved organic carbon concentrations, weather, and acidification in small Boreal Shield lakes. Can J Fish Aquat Sci 65:786–795
Kelton N, Molot LA, Dillon PJ (2007) Effect of ultraviolet and visible radiation on iron lability in boreal and artificial waters. Aquat Sci 69:86–95
Koehler S, Buffam I, Jonsson A, Bishop K (2002) Photochemical and microbial processing of stream and soil water dissolved organic matter in a boreal forested catchment in northern Sweden. Aquat Sci Res Across Bound 64:269–281
Kortelainen P, Mattsson T, Finer L, Ahtiainen M, Saukkonen S, Sallantaus T (2006) Controls on the export of C, N, P and Fe from undisturbed boreal catchments, Finland. Aquat Sci 68:453–468
Lamontagne S, Carignan R, D’Arcy P, Prairie YT, Pare D (2000) Element export in runoff from eastern Canadian Boreal Shield drainage basins following forest harvesting and wildfires. Can J Fish Aquat Sci 57:118–128
Laudon H, Köhler S, Buffam I (2004) Seasonal TOC export from seven boreal catchments in northern Sweden. Aquat Sci Res Across Bound 66:223–230
Lindell MJ, Graneli H, Bertilsson S (2000) Seasonal photoreactivity of dissolved organic matter from lakes with contrasting humic content. Can J Fish Aquat Sci 57:875–885
Lindsey JK (1997) Applying generalized linear models. Springer, New York. ISBN: 0387982183
Madronich S, McKenzie RL, Bjorn LO, Caldwell MM (1998) Changes in biologically active ultraviolet radiation reaching the Earth’s surface. J Photochem Photobiol 46:5–19
Maranger R, Canham CD, Pace ML, Papaik MJ (2006) A spatially explicit model of iron loading to lakes. Limnol Oceanogr 51:247–256
Miller WL (1994) Recent advances in the photochemistry of natural dissolved organic matter. In: Helz GR, Zepp RG, Crosby DG (eds) Aquatic and surface photochemistry. A. F. Lewis, New York, pp 111–127
Minor EC, Dalzell BL, Stubbins A, Mopper K (2007) Evaluating the photoalteration of estuarine dissolved organic matter using direct temperature-resolved mass spectrometry and UV–visible spectroscopy. Aquat Sci 69:440–455
Molot LA, Dillon PJ (1996) Storage of terrestrial carbon in boreal lake sediments and evasion to the atmosphere. Global Biogeochem Cycles 10:483–492
Molot LA, Dillon PJ (1997) Colour—mass balances and colour—dissolved organic carbon relationships in lakes and streams in central Ontario. Can J Fish Aquat Sci 54:2789–2795
Molot LA, Dillon PJ (2003) Variation in iron, aluminum and dissolved organic carbon mass transfer coefficients in lakes. Water Res 37:1759–1768
Moore TR, Matos L, Roulet NT (2003) Dynamics and chemistry of dissolved organic carbon in precambrian shield catchments and an impounded wetland. Can J Fish Aquat Sci 60:612–623
Moran MA, Zepp RG (1997) Role of photoreactions in the formation of biologically labile compounds from dissolved organic matter. Limnol Oceanogr 42:1307–1316
Moran MA, Wicks RJ, Hodson RE (1991) Export of dissolved organic-matter from a mangrove swamp ecosystem—evidence from natural fluorescence, dissolved lignin phenols, and bacterial secondary production. Mar Ecol Prog Ser 76:175–184
Obernosterer I, Benner R (2004) Competition between biological and photochemical processes in the mineralization of dissolved organic carbon. Limnol Oceanogr 49:117–124
Opsahl S, Benner R (1998) Photochemical reactivity of dissolved lignin in river and ocean waters. Limnol Oceanogr 43:1297–1304
Opsahl SP, Zepp RG (2001) Photochemically induced alteration of stable carbon isotope ratios (delta C-13) in terrigenous dissolved organic carbon. Geophys Res Lett 28:2417–2420
Osburn CL, Morris DP, Thorn KA, Moeller RE (2001) Chemical and optical changes in freshwater dissolved organic matter exposed to solar radiation. Biogeochemistry 54:251–278
Osburn CL, O’Sullivan DW, Boyd TJ (2009) Increases in the longwave photobleaching of chromophoric dissolved organic matter in coastal waters. Limnol Oceanogr 54:145–159
Pastor J, Solin J, Bridgham SD, Updegraff K, Harth C, Weishampel P, Dewey B (2003) Global warming and the export of dissolved organic carbon from boreal peatlands. Oikos 100:380–386
Pelster D, Burke JM, Couling K, Luke SH, Smith DW, Prepas EE (2008) Water and nutrient inputs, outputs, and storage in Canadian boreal forest wetlands: a review. J Environ Eng Sci 7:35–50
Peterson BJ, Wollheim WM, Mulholland PJ, Webster JR, Meyer JL, Tank JL, Marti E, Bowden WB, Valett HM, Hershey AE, McDowell WH, Dodds WK, Hamilton SK, Gregory S, Morrall DD (2001) Control of nitrogen export from watersheds by headwater streams. Science 292:86–90
Piirainen S, Finer L, Mannerkoski H, Starr M (2002) Effects of forest clear-cutting on the carbon and nitrogen fluxes through podzolic soil horizons. Plant Soil 239:301–311
Rantakari M, Kortelainen P (2005) Interannual variation and climatic regulation of the CO2 emission from large boreal lakes. Glob Change Biol 11:1368–1380
Richardson JS, Naiman RJ, Swanson FJ, Hibbs DE (2005) Riparian communities associated with Pacific Northwest headwater streams: assemblages, processes, and uniqueness. J Am Water Resour Assoc 41:935–947
Sarpal RS, Mopper K, Kieber DJ (1995) Absorbance properties of dissolved organic matter in antarctic sea water. Antarct J U. S. 30:139–140
Schiff SL, Aravena R, Trumbore SE, Hinton MJ, Elgood R, Dillon PJ (1997) Export of DOC from forested catchments on the Precambrian Shield of Central Ontario: Clues from C-13 and C-14. Biogeochemistry 36:43–65
Schiff S, Aravena R, Mewhinney E, Elgood R, Warner B, Dillon P, Trumbore S (1998) Precambrian shield wetlands: hydrologic control of the sources and export of dissolved organic matter. Climatic Change 40:167–188
Schindler DW, Curtis PJ, Bayley SE, Parker BR, Beaty KG, Stainton MP (1997) Climate-induced changes in the dissolved organic carbon budgets of boreal lakes. Biogeochemistry 36:9–28
Schumacher M, Christl I, Vogt RD, Barmettler K, Jacobsen C, Kretzschmar R (2006) Chemical composition of aquatic dissolved organic matter in five boreal forest catchments sampled in spring and fall seasons. Biogeochemistry 80:263–275
Smith EM, Benner R (2005) Photochemical transformations of riverine dissolved organic matter: effects on estuarine bacterial metabolism and nutrient demand. Aquat Microb Ecol 40:37–50
Sobek S, Tranvik LJ, Cole JJ (2005) Temperature independence of carbon dioxide supersaturation in global lakes. Global Biogeochem Cycles 19:GB2003
Sobek S, Tranvik LJ, Prairie YT, Kortelainen P, Cole JJ (2007) Patterns and regulation of dissolved organic carbon: an analysis of 7,500 widely distributed lakes. Limnol Oceanogr 52:1208–1219
Soumis N, Lucotte M, Larose C, Veillette F, Canuel R (2007) Photomineralization in a boreal hydroelectric reservoir: a comparison with natural aquatic ecosystems. Biogeochemistry 86:123–135
Southwell MW, Mead RN, Luquire CM, Barbera A, Avery GB, Kieber RJ, Skrabal SA (2011) Influence of organic matter source and diagenetic state on photochemical release of dissolved organic matter and nutrients from resuspendable estuarine sediments. Mar Chem (in press)
Spencer RGM, Bolton L, Baker A (2007) Freeze/thaw and pH effects on freshwater dissolved organic matter fluorescence and absorbance properties from a number of UK locations. Water Res 41:2941–2950
Spencer RGM, Stubbins A, Hernes PJ, Baker A, Mopper K, Aufdenkampe AK, Dyda RY, Mwamba VL, Mangangu AM, Wabakanghanzi JN, Six J (2009) Photochemical degradation of dissolved organic matter and dissolved lignin phenols from the Congo River. J Geophys Res Biogeosci 114:G03010
Sulzberger B, Durisch-Kaiser E (2009) Chemical characterization of dissolved organic matter (DOM): a prerequisite for understanding UV-induced changes of DOM absorption properties and bioavailability. Aquat Sci 71:104–126
Sulzman EW (2007) Stable isotope chemistry and measurement: a primer. In: Stable isotopes in ecology and environmental science. Ecological methods and concepts, 2nd edn, pp 1–21
Teodoru CR, del Giorgio PA, Prairie YT, Camire M (2009) Patterns in pCO2 in boreal streams and rivers of northern Quebec, Canada. Global Biogeochem Cycles 23:GB2012
Tranvik LJ, Olofsson H, Bertilsson S (1999) Photochemical effects on bacterial degradation of dissolved organic matter in lake water. Microbial biosystems: new frontiers. In: Proceedings of the 8th International Symposium on Microbial Ecology. Atlantic Canada Society for Microbial Ecology, Halifax, Canada
Twardowski MS, Boss E, Sullivan JM, Donaghay PL (2004) Modeling the spectral shape of absorption by chromophoric dissolved organic matter. Mar Chem 89:69–88
Tzortziou M, Osburn CL, Neale PJ (2007) Photobleaching of dissolved organic material from a tidal marsh-estuarine system of the Chesapeake Bay. Photochem Photobiol 83:782–792
Ugolini FC, Reanier RE, Rau GH, Hedges JI (1981) Pedological, isotopic, and geochemical investigations of the soils at the Boreal Forest and Alpine Tundra Transition in Northern Alaska. Soil Sci 131:359–374
Vähätalo AV, Jarvinen M (2007) Photochemically produced bioavailable nitrogen from biologically recalcitrant dissolved organic matter stimulates production of a nitrogen-limited microbial food web in the Baltic Sea. Limnol Oceanogr 52:132–143
Vähätalo AV, Wetzel RG (2008) Long-term photochemical and microbial decomposition of wetland-derived dissolved organic matter with alteration of 13C:12C mass ratio. Limnol Oceanogr 53:1387–1392
Vähätalo AV, Salonen K, Munster U, Jarvinen M, Wetzel RG (2003) Photochemical transformation of allochthonous organic matter provides bioavailable nutrients in a humic lake. Arch Hydrobiol 156:287–314
Vione D, Khanra S, Man SC, Maddigapu PR, Das R, Arsene C, Olariu R-I, Maurino V, Minero C (2009) Inhibition vs. enhancement of the nitrate-induced phototransformation of organic substrates by the •OH scavengers bicarbonate and carbonate. Water Res 43:4718–4728
Vodacek A, Blough NV, DeGrandpre MD, Peltzer ET, Nelson RK (1997) Seasonal variation of CDOM and DOC in the Middle Atlantic Bight: Terrestrial inputs and photooxidation. Limnol Oceanogr 42:674–686
Vogler EA, Hayes JM (1980) Carbon isotopic compositions of carboxyl groups of biosynthesized fatty acids. Phys Chem Earth 12:697–704
Waiser MJ, Robarts RD (2004) Photodegradation of DOC in a shallow prairie wetland: evidence from seasonal changes in DOC optical properties and chemical characteristics. Biogeochemistry 69:263–284
Waite TD, Morel FMM (1984) Ligand exchange and fluorescence quenching studies of the fulvic acid-iron interaction: effects of ph and light. Anal Chim Acta 162:263–274
Whitehead RF, de Mora S, Demers S, Gosselin M, Monfort P, Mostajir B (2000) Interactions of ultraviolet-B radiation, mixing, and biological activity on photobleaching of natural chromophoric dissolved organic matter: a mesocosm study. Limnol Oceanogr 45:278–291
Williams CJ, Yavitt JB (2003) Botanical composition of peat and degree of peat decomposition in three temperate peatlands. Ecoscience 10:85–95
Williams CJ, Yavitt JB, Wieder RK, Cleavitt NL (1998) Cupric oxide oxidation products of northern peat and peat forming plants. Can J Bot 76:51–62
Wipfli MS, Richardson JS, Naiman RJ (2007) Ecological linkages between headwaters and downstream ecosystems: transport of organic matter, invertebrates, and wood down headwater channels. JAWRA J Am Water Resour Assoc 43:72–85
WQMA (2000) Iron contours based on Canada-Newfoundland Water Quality Monitoring Agreement Data. Canada-Newfoundland Water Quality Monitoring Agreement; Environment Canada & Government of Newfoundland and Labrador (Department of Environment and Conserservation—Water Resources Management Division). http://www.env.gov.nl.ca/env/waterres/quality/background/Fe.pdf
Wu FC, Mills RB, Cai YR, Evans RD, Dillon PJ (2005) Photodegradation-induced changes in dissolved organic matter in acidic waters. Can J Fish Aquat Sci 62:1019–1027
Xie HX, Zafiriou OC, Cai WJ, Zepp RG, Wang YC (2004) Photooxidation and its effects on the carboxyl content of dissolved organic matter in two coastal rivers in the Southeastern United States. Environ Sci Technol 38:4113–4119
Zar JH (1996) Biostatistical analysis, 3rd edn. Prentice Hall, New Jersey
Zepp RG, Erickson DJ, Paul ND, Sulzberger B (2011) Effects of solar UV radiation and climate change on biogeochemical cycling: interactions and feedbacks. Photochem Photobiol Sci 10:261–279
Ziegler SE, Fogel ML (2003) Seasonal and diel relationships between the isotopic compositions of dissolved and particulate organic matter in freshwater ecosystems. Biogeochemistry 64:25–52
Acknowledgments
This project was supported by the Humber River Basin Project (HRBP), the Institute of Biodiversity, Ecosystem Science and Sustainability (IBES), Canada Research Chairs Program, and the Natural Science and Engineering Research Council (NSERC). The authors would like to thank Jennifer Bonnell, Nicholas Capps, Nicole DeBond, Aiden Dunne, Christopher Earle, Susan Hannan, Tiffany Lam, David Lyon, Claire Moore-Gibbons, Alexandra Rouillard, Alison Pye, Dean Strickland, and Geert Van Biesen for their support in the field and laboratory, and/or reviewing an earlier draft of this paper. The authors would also like to thank the anonymous reviewers for their useful suggestions, which strengthened this paper.
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Franke, D., Hamilton, M.W. & Ziegler, S.E. Variation in the photochemical lability of dissolved organic matter in a large boreal watershed. Aquat Sci 74, 751–768 (2012). https://doi.org/10.1007/s00027-012-0258-3
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DOI: https://doi.org/10.1007/s00027-012-0258-3