, Volume 54, Issue 3, pp 251–278 | Cite as

Chemical and optical changes in freshwater dissolved organic matter exposed to solar radiation

  • Christopher L. Osburn
  • Donald P. Morris
  • Kevin A. Thorn
  • Robert E. Moeller


We studied the chemical and optical changes inthe dissolved organic matter (DOM) from twofreshwater lakes and a Sphagnum bog afterexposure to solar radiation. Stable carbonisotopes and solid-state 13C-NMR spectraof DOM were used together with optical andchemical data to interpret results fromexperimental exposures of DOM to sunlight andfrom seasonal observations of two lakes innortheastern Pennsylvania. Solar photochemicaloxidation of humic-rich bog DOM to smaller LMWcompounds and to DIC was inferred from lossesof UV absorbance, optical indices of molecularweight and changes in DOM chemistry. Experimentally, we observed a 1.2‰ enrichment in δ13$C and a 47% loss in aromaticC functionality in bog DOM samples exposed tosolar UVR. Similar results were observed inthe surface waters of both lakes. In latesummer hypolimnetic water in humic LakeLacawac, we observed 3 to 4.5‰enrichments in δ13C and a 30% increase inaromatic C relative to early spring valuesduring spring mixing. These changes coincidedwith increases in molecular weight and UVabsorbance. Anaerobic conditions of thehypolimnion in Lake Lacawac suggest thatmicrobial metabolism may be turning overallochthonous C introduced during springmixing, as well as autochthonous C. Thismetabolic activity produces HMW DOM during thesummer, which is photochemically labile andisotopically distinct from allochthonous DOM orautochthonous DOM. These results suggest bothphotooxidation of allochthonous DOM in theepilimnion and autotrophic production of DOM bybacteria in the hypolimnion cause seasonaltrends in the UV absorbance of lakes.

carbon stable isotopes DOM humic acids NMR photooxidation 


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  1. Amador JA,Alexander M &Zika RG (1991) Degradation of aromatic compounds bound to humic acid by the combined action of sunlight and microorganisms. Environ. Toxicol. Chem. 10: 475Google Scholar
  2. Amon RMW &Benner R (1996) Photochemical and microbial consumption of dissolved organic carbon and dissolved oxygen in the Amazon River system. Geochim. Cosmochim. Acta. 60(10): 1783-1792Google Scholar
  3. Benner R,Fogel ML,Sprague KE &Hodson RE (1987) Depletion of 13C in lignin and its implications for stable carbon isotope studies. Nature 329: 708–710Google Scholar
  4. Bertilsson S &Tranvik L (1998) Photochemically produced carboxylic acids as substrates for freshwater bacterioplankton. Limnol. Oceanogr. 43: 885–895Google Scholar
  5. Bourbonniere RA, Miller WL & Zepp RG (1997) Distribution, flux, and photochemical production of carbon monoxide in a boreal beaver impoundment. J. Geophys. Res. 102(D24): 29, 321–329, 329Google Scholar
  6. Boutton TW (1991) Stable carbon isotope ratios of natural materials: I. Sample preparation and mass spectrometric analysis. In: Coleman DC &Fry B (Eds) Carbon Isotope Techniques. Academic Press.Google Scholar
  7. Brophy JE &Carlson DJ (1989) Production of refractory dissolved organic carbon by natural seawater microbial populations. Deep-Sea Res. 36: 497–507Google Scholar
  8. Bunn SE &Boon PI (1993) What sources of organic carbon drive food webs in billabongs-a study based on stable isotope analysis. Oecologia. 69(1): 85–94Google Scholar
  9. Calvert JG &Pitts JN (1966) Photochemistry. John Wiley & Sons, New YorkGoogle Scholar
  10. Castellan A,Vanucci C &Bouas-Laurent H (1987) Photochemical degradation of lignin through ? C-O bond cleavage of non phenolic benzyl aryl ether units. A study of the photochemistry of ?(2", 4", 6"-trimethyl-phenoxy)-3, 4 dimethoxy toluene. Holzfouschung 41: 231–238Google Scholar
  11. Chen YS,Khan U &Schnitzer S (1978) Ultraviolet irradiation of dilute fulvic acid solutions. Soil Sci. Am. J. 42: 292–296Google Scholar
  12. Cherrier J,Bauer JE,Druffel ERM,Coffin RB &Chanton JP (1999) Radiocarbon in marine bacteria: Evidence for the age of assimilated organic matter. Limnol Oceanograph. 44(3): 730–736Google Scholar
  13. Clair TA,Sydor M,Kramer JR &Eaton DR (1991) Concentration of aquatic dissolved organic matter by reverse osmosis. Water Res. 15: 1033–1037Google Scholar
  14. DeHaan H (1993) Solar UV-light penetration and photodegradation of humic substances in peaty lake water. Limnol. Oceanogr. 38: 1072–1076Google Scholar
  15. DeHaan H &DeBoer T (1987) Applicability of light absorbance and fluorescence as measures of concentration and molecular size of dissolved organic carbon in humic Lake Tjeukemeer. Water Resour. 21: 731–734Google Scholar
  16. Ertel J (1990) Photochemistry of dissolved organic matter: An organic geochemical perspective. In: Effects of Solar Radiation on Biogeochemical Dynamics in Aquatic Environments. Woods Hole Oceanogr. Tech. Rep. WHOI-90-90Google Scholar
  17. Fry B &Sherr EB (1984) ? 13Cmeasurements as indicators of carbon flow in marine and freshwater ecosystems. Contrib. Mar. Sci. 27: 13–47Google Scholar
  18. Gelwicks JT,Risatti JB &Hayes JM (1994) Carbon isotope effects associated with aceticlastic methanogenesis. App. Env. Microb. 60: 467–472Google Scholar
  19. Gleixner G &Schmidt HL (1998) On-line determination of group-specific isotope ratios in model compounds and aquatic humic substances by coupling pyrolysis to GC-C-IRMS. In: Stankiewicz BA &van Bergen PF (Eds) Nitrogen-containing Macromolecules in the Bio-and Geosphere (pp 34–46). ACS Symposium Series 707Google Scholar
  20. Golterman HL (1971) Methods for Chemical Analysis of Fresh Waters. IBP Handbook No 8, 3rd Printing, Blackwell Scientific Publishers, Oxford.Google Scholar
  21. Graneli W,Lindell M &Tranvik L (1996) Photooxidative production of dissolved inorganic carbon in lakes of different humic content. Limnol. Oceanogr. 41: 698-706Google Scholar
  22. Harvey GR &Boran DA (1985) Geochemistry of humic substances in seawater. In: Aiken GR,McKnight DM,Wershaw RL &MacCarthy P (Eds) Humic Substances in Sediment, Soil, and Water: Geochemistry, Isolation, and Characterization (pp 233–249). J Wiley & Sons, New YorkGoogle Scholar
  23. Hedges JI,Keil RG &Benner R (1997) What happens to terrestrial organic matter in the ocean? Org. Geochem. 27: 195–212Google Scholar
  24. Herzceg AL (1988) Early diagenesis of organic matter in lake sediments: A stable carbon isotope study of pore waters. Chem. Geol. (Isot. Geosci. Sect.) 72: 199–209Google Scholar
  25. Kieber DJ,McDaniel J &Mopper K (1989) Photochemical source of biological substrates in seawater: Implications for carbon cycling. Nature. 341: 637–639Google Scholar
  26. Kieber RJ,Hydro LH &Seaton PJ (1997) Photooxidation of triglycerides and fatty acids in seawater: Implication toward the formation of marine humic substances. Limnol. Oceanogr. 42: 1454–1462Google Scholar
  27. Kinchesh P,Powlson DS,Randall EW (1995) European J. Soil Sci. 46: 125–138Google Scholar
  28. Kling GW,Kipphut GW &Miller MC (1991) Arctic lakes and streams as gas conduits to the atmosphere: Implications for tundra carbon budgets. Science. 251: 298–301Google Scholar
  29. Koussai AM &Zika RG (1992) Light-induced destruction of the absorbance property of dissolved organic matter in seawater. Toxicol. Environ. Chem. 35: 195–211Google Scholar
  30. Kulovaara M,Corin N,Backlund P &Tervo J (1996) Impact of UV254-radiation on aquatic humic substances. Chemosphere 33(5): 783–790Google Scholar
  31. Lindell M,Graneli W &Tranvik L (1995) Enhanced bacterial growth in response to photochemical transformation of dissolved organic matter. Limnol. Oceanogr. 40: 195–199Google Scholar
  32. Madronich S (1993) UV radiation in the natural and perturbed atmosphere. In: Tevini M (Ed.) UV-B Radiation and Ozone Depletion: Effects on Humans, Animals, Plants, Microorganisms, and Materials. LewisGoogle Scholar
  33. Miles CJ &Brezonik PL (1981) Oxygen consumption in humic-colored waters by a photochemical ferrous-ferric catalytic cycle. Environ. Sci. Technol. 15: 1089–1095Google Scholar
  34. Miller WM (1994) Recent advances in the photochemistry of natural dissolved organic matter. In: Helz GR, et al. (Eds) Aquatic and Surface Photochemistry (pp 111–128). Lewis Publishers, Boca RatonGoogle Scholar
  35. Miller WM &Zepp RG (1995) Photochemical production of dissolved inorganic carbon from terrestrial organic matter: Significance to the oceanic organic carbon cycle. Geophys. Res. Lett. 22: 417–420Google Scholar
  36. Molot LA &Dillon PJ (1996) Storage of terrestrial carbon in boreal lake sediments and evasion to the atmosphere. Global Biogeochem. Cycle. 10(3): 483–492Google Scholar
  37. Molot LA &Dillon PJ (1997) Photolytic regulation of dissolved organic carbon in northern lakes. Global Biogeochem. Cycles. 11(3): 357–365Google Scholar
  38. Morris DP,Zagarese HE,Williamson CE,Balseiro EG,Hargreaves BR,Modenutti B,Moeller RE &Queimalinos C (1995). The attenuation of solar UV radiation in lakes and the role of dissolved organic carbon. Limnol. Oceanogr. 40: 1381–1391Google Scholar
  39. Morris DP &Hargreaves BR (1997) The role of photochemical degradation of dissolved organic carbon in regulating the UV transparency of three lakes on the Pocono Plateau. Limnol. Oceanogr. 42(2): 239–349Google Scholar
  40. Mopper K,Zhou X,Kieber RJ,Sikorski RG &Jones RD (1991) Photochemical degradation of dissolved organic carbon and its impact on the oceanic carbon cycle. Nature 353: 60–62Google Scholar
  41. Opsahl S &Benner R (1998) Photochemical reactivity of dissolved lignin in river and ocean waters. Limnol. Oceanogr. 43(6): 1297–1304Google Scholar
  42. Osburn CL,Zagarese HE,Morris DP,Hargreaves BR &Cravero W (2000) Calculation of spectral weighting functions for the solar photobleaching of chromophoric dissolved organic matter in temperate lakes. Limnol Oceanogr. In pressGoogle Scholar
  43. Salonen K &Vähätalo A (1994) Photochemical mineralization of dissolved organic matter in Lake Skjervatjern. Environ. Int. 20: 307–312Google Scholar
  44. Schiff SL,Aravena R,Trumbore SE &Dillon PJ (1990) Dissolved organic carbon cycling in forested watersheds: a carbon isotope approach. Wat. Res. Research 26(12): 2949–2957Google Scholar
  45. Schmidt HL &Gleixner G (1998) Carbon isotope effects on key reactions in plant metabolism and 13C-patterns in natural compounds. In: Griffiths H (Ed.) Stable Isotopes (pp 13–25)Google Scholar
  46. Schulten HR &Gleixner G (1998) Analytical pyrolysis of humic substances and dissolved organic matter in aquatic systems: structure and origin. Wat. Res. 33(11): 2489–2498Google Scholar
  47. Sharp JH,Benner R,Bennett L,Carlson CA,Dow R &Fitzwater SE (1993) Reevaluation of high-temperature combustion and chemical oxidation measurements of dissolved organic carbon in seawater. Limnol. Oceanogr. 38(8): 1774–1782Google Scholar
  48. Stainton MP (1973) A syringe gas-stripping procedure for gas chromatographic determination of dissolved inorganic and organic carbon in fresh water and c carbonates in sediments. J. Fish. Res. Board Can. 30: 1441–1445Google Scholar
  49. Steinberg C &Muenster U (1985) Geochmeistry and ecological role of humic substances in lakewater. In: Aiken GR,McKnight DM,Wershaw RL &MacCarthy P (Eds) Humic Substances in Sediment, Soil, and Water: Geochemistry, Isolation, and Characterization (pp 105–147). J Wiley & Sons, New YorkGoogle Scholar
  50. Strome DJ &Miller MC (1978) Photolytic changes in dissolved humic substances. Verh. Internat. Verein. Limnol. 20: 1248–1254Google Scholar
  51. Tevini M (1993) UV-B Radiation and Ozone Depletion. LewisGoogle Scholar
  52. Thorn KA,Folan DW &MacCarthy P (1991) Characterization of the International Humic Substances Society standard and reference fulvic and humic acids by solution state carbon-13 and hydrogen-1 nuclear magnetic resonance spectrometry. USGS Water Resources Investigations Report 89–4196Google Scholar
  53. Thorn KA (1994) Nuclear-magnetic-resonance studies of fulvic and humic acids from the Suwannee River. In: Humic Substances in the Suwannee River, Georgia: Interactions, properties, and Proposed structures. USGS Water-Supply Paper 2373Google Scholar
  54. Thurman EM (1985) Organic Geochemistry of Natural Waters. Martinus Jijhoff/Dr. W. Junk PublishersGoogle Scholar
  55. Tranvik L (1993) Microbial transformation of labile dissolved organic matter into humic-like matter in seawater. FEMS Microb. Ecol. 12: 177–183Google Scholar
  56. Vähätalo AV,Salonen K,Salkinoja-Salonen M &Hatakka A (1999) Photochemical mineralization of synthetic lignin in lake water indicates enhanced turnover of aromatic organic matter under solar radiation. Biodegradation 10: 415–420Google Scholar
  57. Valentine RL &Zepp RG (1993) Formation of carbon monoxide from the photodegradation of terrestrial dissolved organic carbon in natural waters. Environ. Sci. Technol. 27: 409-412Google Scholar
  58. Waldron S,Watson-Craik IA,Hall A &Fallick AE (1998) The carbon and hydrogen stable isotopic composition of bacteriogenic methane: A laboratory study using a landfill inoculum. Geomicrob. 15: 157–169Google Scholar
  59. Wetzel RG (1983) Limnology, 2nd Ed. Saunders Publishing, Ft.WorthGoogle Scholar
  60. Zafiriou OC,Joussot-Dubien J,Zepp RG &Zika RG (1984) Photochemistry of natural waters. Environ. Sci. Technol. 18(2): 358A-371AGoogle Scholar
  61. Zepp RG (1988) Environmental photoprocesses involving natural organic matter. In: Frimmel FH &Christman RF (Eds) Humic Substances and their Role in the Environment (pp 193–214). J. Wiley & SonsGoogle Scholar
  62. Zepp RG,Callaghan TV &Erickson DJ (1995) Effects of increased solar ultraviolet radiation on biogeochemical cycles. Ambio. 24: 181–186Google Scholar

Copyright information

© Kluwer Academic Publishers 2001

Authors and Affiliations

  • Christopher L. Osburn
    • 1
  • Donald P. Morris
    • 2
  • Kevin A. Thorn
    • 3
  • Robert E. Moeller
    • 2
  1. 1.Department of Earth and Environmental SciencesLehigh UniversityBethlehemUSA
  2. 2.National Research Council-Naval Research Laboratory, Code 6115WashingtonUSA)
  3. 3.National Water Quality LaboratoryU.S. Geological SurveyDenverUSA

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