Biology:Colored dissolved organic matter

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Short description: Optically measurable component of the dissolved organic matter in water
"Yellow substance" redirects here. It is not to be confused with Yellowcake.
Variations in the concentration of colored dissolved organic matter as seen from space. The dark brown water in the inland waterways contains high concentrations of CDOM. As this dark, CDOM-rich water moves offshore, it mixes with the low CDOM, blue ocean water from offshore.

Colored dissolved organic matter (CDOM) is the optically measurable component of dissolved organic matter in water. Also known as chromophoric dissolved organic matter,[1] yellow substance, and gelbstoff, CDOM occurs naturally in aquatic environments and is a complex mixture of individual, unique organic matter molecules, which are primarily leached from decaying detritus and organic matter.[2] CDOM most strongly absorbs short wavelength light ranging from blue to ultraviolet, whereas pure water absorbs longer wavelength red light. Water with little to no CDOM, such as the open ocean, appears blue.[3] Waters containing high amounts of CDOM can range from brown, as in many rivers, to yellow and yellow-brown in coastal waters. CDOM is ubiquitous in the ocean and absorbs light energy, thus influencing water optics, phytoplankton photosynthesis, and photodegradation.[4] Levels of CDOM can also be used as a flexible indicator of salinity, primary productivity, and oceanic circulation.[4][5] CDOM influences water quality by both sequestering and producing harmful compounds.[5] Sources of CDOM vary between organic matter derived from terrestrial, marsh, and marine systems.[6][7][8] Different sources of organic matter have distinct CDOM signatures that may need to be considered when applying generalized models to CDOM measurements.[9][6][8] Measurement of CDOM is typically accomplished through spectroscopy and fluorometry, but new optical techniques have arisen including remote-satellite sensing.[4][10][7][11] Lastly, CDOM plays a role in global carbon cycling and may be impacted by anthropogenic forces and climate change.[12][13][14][15]

Significance

Peatland river water draining into coastal waters
South-East Asia is home to one of the world's largest stores of tropical peatland and accounts for roughly 10 % of the global land-to-sea dissolved organic carbon (DOC) flux. The rivers carry high coloured dissolved organic matter (CDOM) concentrations, shown here interfacing with ocean shelf water.[16]

The concentration of CDOM can have a significant effect on biological activity in aquatic systems. CDOM diminishes light intensity as it penetrates water.[4][5] Very high concentrations of CDOM can have a limiting effect on photosynthesis and inhibit the growth of phytoplankton,[17][18][19][20] which form the basis of oceanic food chains and are a primary source of atmospheric oxygen. However, the influence of CDOM on algal photosynthesis can be complex in other aquatic systems like lakes where CDOM increases photosynthetic rates at low and moderate concentrations, but decreases photosynthetic rates at high concentrations.[21][19][18][22] CDOM concentrations reflect hierarchical controls.[23] Concentrations vary among lakes in close proximity due to differences in lake and watershed morphometry, and regionally because of difference in climate and dominant vegetation.[24][23][25] CDOM also absorbs harmful UVA/B radiation, protecting organisms from DNA damage.[26]

Absorption of UV radiation causes CDOM to "bleach", reducing its optical density and absorptive capacity.[15] This bleaching (photodegradation) of CDOM produces low-molecular-weight organic compounds which may be utilized by microbes, release nutrients that may be used by phytoplankton as a nutrient source for growth,[27] and generates reactive oxygen species, which may damage tissues and alter the bioavailability of limiting trace metals.[5]

CDOM can be detected and measured from space using satellite remote sensing and often interferes with the use of satellite spectrometers to remotely estimate phytoplankton populations.[10] As a pigment necessary for photosynthesis, chlorophyll is a key indicator of the phytoplankton abundance. However, CDOM and chlorophyll both absorb light in the same spectral range so it is often difficult to differentiate between the two.

While there is interference between CDOM and chlorophyll measurements, CDOM levels monitored by remote satellites can serve as a proxy for water quality, salinity, primary productivity, and oceanic circulation.[2][4][5][10] CDOM can contaminate water by reacting with chlorine species to form disinfectants, or by decreasing amounts of dissolved oxygen which draws harmful metals out of sediments.[5] However, CDOM can also help purify water by sequestering trace metals and polyaromatic hydrocarbons.[5] CDOM is the only optical biomarker in water that has a significant relationship with salinity.[5] This is because CDOM is highest in freshwater systems and thus negatively correlated with salinity in coastal regions.[5] Satellite measurements of ocean color are useful for analyzing chlorophyll concentration and phytoplankton activity, but models often differ in the ways they account for the effect of CDOM, leading to a possible 30% discrepancy in global primary productivity values.[10] The amount of CDOM loading may also influence eutrophication by impacting the Secchi depth, which is a measure of water transparency.[28] Oceanic circulation influences subsurface levels of CDOM via the dynamic interaction of vertical ventilation and in situ generation.[4] Monitoring CDOM levels can thus be used as a tracer for global ocean circulation.[2][4][5]

Measurement

Traditional methods of measuring CDOM include UV-visible spectroscopy (absorbance) and fluorometry (fluorescence). Optical proxies have been developed to characterize sources and properties of CDOM, including specific ultraviolet absorbance at 254 nm (SUVA254) and spectral slopes for absorbance, and the fluorescence index (FI), biological index (BIX), and humification index (HIX) for fluorescence. Excitation emission matrices (EEMs)[29] can be resolved into components in a technique called parallel factor analysis (PARAFAC),[30] where each component is often labelled as "humic-like", "protein-like", etc. As mentioned above, remote sensing is the newest technique to detect CDOM from space.

Sources of CDOM

Organic matter is the primary source of CDOM in freshwater and saltwater ecosystems and can come from a variety of sources such as soils, plant matter, estuaries, tidal marshes, and the ocean itself. Typically, CDOM exhibits seasonal variation in spectral identity. Terrestrial carbon sources from fresh plant material dominate the spring and summer, when precipitation and melting is high, while older, more degraded carbon sources dominate the winter.[31][28] The source of organic matter for CDOM affects CDOM fluorescent (fDOM) measurement values used as a proxy. For example, there are significant differences between CDOM:fDOM ratios when comparing terrestrial sources to marsh sources, indicating that these carbon sources possess unique optical properties that cannot be generalized to a universal ratio.[7] Moreover, it has been shown that CDOM from tidal marshes is optically distinct relative to CDOM from nearby estuaries in terms of absorption, thus there is great variation in CDOM source and optical properties.[6]

Impacts of Anthropogenic Forces and Climate Change

Although variations in CDOM are primarily the result of natural processes including changes in the amount and frequency of precipitation, human activities such as logging, agriculture, effluent discharge, and wetland drainage can affect CDOM levels in fresh water and estuarine systems. Anthropogenic forces and climate change are predicted to synergistically increase levels of CDOM.[12] Increased precipitation from climate change may increase CDOM through increased base flow discharge of rivers emptying organic matter into the ocean.[31] In arctic regions, increased snowmelt and permafrost thawing from climate warming can increase CDOM from the release of stored carbon reserves in arctic soils.[31] Increased loading of CDOM from climate change may decrease the amount of light penetrating the ocean, decreasing the Secchi depth and limiting primary productivity.[12] Further, the combined effects of increased UV radiation from climate change, along with the increased stratification and the thinning of warmer ocean surface layers results in increased photodegradation of CDOM.[15] Increased photodegradation of CDOM has ramifications of producing more usable carbon fuel for microbial heterotrophs, allowing these bacteria to outcompete phytoplankton and further limit primary productivity.[31]

See also

References

  1. ↑ Hoge, FE; Vodacek, A; Swift, RN; Yungel, JK; Blough, NV (October 1995). "Inherent optical properties of the ocean: retrieval of the absorption coefficient of chromophoric dissolved organic matter from airborne laser spectral fluorescence measurements.". Applied Optics 34 (30): 7032–8. doi:10.1364/ao.34.007032. PMID 21060564. Bibcode: 1995ApOpt..34.7032H. ,
  2. ↑ 2.0 2.1 2.2 Coble, Paula (2007). "Marine Optical Biogeochemistry: The Chemistry of Ocean Color". Chemical Reviews 107 (2): 402–418. doi:10.1021/cr050350+. PMID 17256912. 
  3. ↑ "Ocean Color". https://science.nasa.gov/earth-science/oceanography/living-ocean/ocean-color. 
  4. ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 Nelson, Norman B.; Siegel, David A. (2013-01-03). "The Global Distribution and Dynamics of Chromophoric Dissolved Organic Matter" (in en). Annual Review of Marine Science 5 (1): 447–476. doi:10.1146/annurev-marine-120710-100751. ISSN 1941-1405. PMID 22809178. https://www.annualreviews.org/doi/10.1146/annurev-marine-120710-100751. 
  5. ↑ 5.00 5.01 5.02 5.03 5.04 5.05 5.06 5.07 5.08 5.09 Coble, Paula; Hu, Chuanmin; Gould, Richard W.; Chang, Grace; Wood, A. Michelle (2004). "Colored Dissolved Organic Matter in the Coastal Ocean: AN OPTICAL TOOL FOR COASTAL ZONE ENVIRONMENTAL ASSESSMENT AND MANAGEMENT". Oceanography 17 (2): 50–59. doi:10.5670/oceanog.2004.47. ISSN 1042-8275. Bibcode: 2004Ocgpy..17b..50C. https://www.jstor.org/stable/43925132. 
  6. ↑ 6.0 6.1 6.2 Tzortziou, Maria; Neale, Patrick J.; Osburn, Christopher L.; Megonigal, J. Patrick; Maie, Nagamitsu; JaffÉ, Rudolf (January 2008). "Tidal marshes as a source of optically and chemically distinctive colored dissolved organic matter in the Chesapeake Bay" (in en). Limnology and Oceanography 53 (1): 148–159. doi:10.4319/lo.2008.53.1.0148. ISSN 0024-3590. Bibcode: 2008LimOc..53..148T. 
  7. ↑ 7.0 7.1 7.2 Oestreich, W. K.; Ganju, N. K.; Pohlman, J. W.; Suttles, S. E. (2016-02-02). "Colored dissolved organic matter in shallow estuaries: relationships between carbon sources and light attenuation" (in en). Biogeosciences 13 (2): 583–595. doi:10.5194/bg-13-583-2016. ISSN 1726-4189. Bibcode: 2016BGeo...13..583O. https://bg.copernicus.org/articles/13/583/2016/. 
  8. ↑ 8.0 8.1 Song, Kaishan; Li, Lin; Tedesco, Lenore; Clercin, Nicolas; Li, Linhai; Shi, Kun (June 2015). "Spectral characterization of colored dissolved organic matter for productive inland waters and its source analysis" (in en). Chinese Geographical Science 25 (3): 295–308. doi:10.1007/s11769-014-0690-5. ISSN 1002-0063. Bibcode: 2015ChGpS..25..295S. http://link.springer.com/10.1007/s11769-014-0690-5. 
  9. ↑ Oestreich, W. K.; Ganju, N. K.; Pohlman, J. W.; Suttles, S. E. (2016-02-02). "Colored dissolved organic matter in shallow estuaries: relationships between carbon sources and light attenuation" (in en). Biogeosciences 13 (2): 583–595. doi:10.5194/bg-13-583-2016. ISSN 1726-4189. Bibcode: 2016BGeo...13..583O. https://bg.copernicus.org/articles/13/583/2016/. 
  10. ↑ 10.0 10.1 10.2 10.3 Siegel, D. A.; Maritorena, S.; Nelson, N. B.; Behrenfeld, M. J.; McClain, C. R. (October 2005). "Colored dissolved organic matter and its influence on the satellite-based characterization of the ocean biosphere" (in en). Geophysical Research Letters 32 (20). doi:10.1029/2005GL024310. ISSN 0094-8276. Bibcode: 2005GeoRL..3220605S. https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2005GL024310. 
  11. ↑ Siegel, D. A.; Maritorena, S.; Nelson, N. B.; Hansell, D. A.; Lorenzi-Kayser, M. (December 2002). "Global distribution and dynamics of colored dissolved and detrital organic materials" (in en). Journal of Geophysical Research: Oceans 107 (C12): 3228. doi:10.1029/2001JC000965. ISSN 0148-0227. Bibcode: 2002JGRC..107.3228S. https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2001JC000965. 
  12. ↑ 12.0 12.1 12.2 Harvey, E. Therese; Kratzer, Susanne; Andersson, Agneta (June 2015). "Relationships between colored dissolved organic matter and dissolved organic carbon in different coastal gradients of the Baltic Sea" (in en). Ambio 44 (S3): 392–401. doi:10.1007/s13280-015-0658-4. ISSN 0044-7447. PMID 26022322. 
  13. ↑ Coble, Paula; Hu, Chuanmin; Gould, Richard W.; Chang, Grace; Wood, A. Michelle (2004). "Colored Dissolved Organic Matter in the Coastal Ocean: AN OPTICAL TOOL FOR COASTAL ZONE ENVIRONMENTAL ASSESSMENT AND MANAGEMENT". Oceanography 17 (2): 50–59. doi:10.5670/oceanog.2004.47. ISSN 1042-8275. Bibcode: 2004Ocgpy..17b..50C. https://www.jstor.org/stable/43925132. 
  14. ↑ Tzortziou, Maria; Zeri, Christina; Dimitriou, Elias; Ding, Yan; Jaffé, Rudolf; Anagnostou, Emmanouil; Pitta, Elli; Mentzafou, Angeliki (July 2015). "Colored dissolved organic matter dynamics and anthropogenic influences in a major transboundary river and its coastal wetland" (in en). Limnology and Oceanography 60 (4): 1222–1240. doi:10.1002/lno.10092. ISSN 0024-3590. PMID 27656002. Bibcode: 2015LimOc..60.1222T. 
  15. ↑ 15.0 15.1 15.2 Lønborg, Christian; Carreira, Cátia; Jickells, Tim; Álvarez-Salgado, Xosé Antón (2020-06-23). "Impacts of Global Change on Ocean Dissolved Organic Carbon (DOC) Cycling". Frontiers in Marine Science 7. doi:10.3389/fmars.2020.00466. ISSN 2296-7745. Bibcode: 2020FrMaS...7..466L. 
  16. ↑ Martin, P., Cherukuru, N., Tan, A.S., Sanwlani, N., Mujahid, A. and Müller, M.(2018) "Distribution and cycling of terrigenous dissolved organic carbon in peatland-draining rivers and coastal waters of Sarawak, Borneo", Biogeosciences, 15(2): 6847–6865. doi:10.5194/bg-15-6847-2018. 50px Material was copied from this source, which is available under a Creative Commons Attribution 4.0 International License.
  17. ↑ Stedmon, C.A.; Markager, S.; Kaas, H. (2000). "Optical properties and signatures of chromophoric dissolved organic matter (CDOM) in Danish coastal waters". Estuarine, Coastal and Shelf Science 51 (2): 267–278. doi:10.1006/ecss.2000.0645. Bibcode: 2000ECSS...51..267S. 
  18. ↑ 18.0 18.1 Seekell, David A.; Lapierre, Jean-François; Ask, Jenny; Bergström, Ann-Kristin; Deininger, Anne; Rodríguez, Patricia; Karlsson, Jan (2015). "The influence of dissolved organic carbon on primary production in northern lakes" (in en). Limnology and Oceanography 60 (4): 1276–1285. doi:10.1002/lno.10096. ISSN 1939-5590. Bibcode: 2015LimOc..60.1276S. https://aslopubs.onlinelibrary.wiley.com/doi/abs/10.1002/lno.10096. 
  19. ↑ 19.0 19.1 Seekell, David A.; Lapierre, Jean-François; Karlsson, Jan (2015-07-14). "Trade-offs between light and nutrient availability across gradients of dissolved organic carbon concentration in Swedish lakes: implications for patterns in primary production" (in en). Canadian Journal of Fisheries and Aquatic Sciences 72 (11): 1663–1671. doi:10.1139/cjfas-2015-0187. Bibcode: 2015CJFAS..72.1663S. https://cdnsciencepub.com/doi/abs/10.1139/cjfas-2015-0187. 
  20. ↑ Carpenter, Stephen R.; Cole, Jonathan J.; Kitchell, James F.; Pace, Michael L. (1998). "Impact of dissolved organic carbon, phosphorus, and grazing on phytoplankton biomass and production in experimental lakes" (in en). Limnology and Oceanography 43 (1): 73–80. doi:10.4319/lo.1998.43.1.0073. ISSN 1939-5590. Bibcode: 1998LimOc..43...73C. 
  21. ↑ Hansson, Lars-Anders (1992). "Factors regulating periphytic algal biomass" (in en). Limnology and Oceanography 37 (2): 322–328. doi:10.4319/lo.1992.37.2.0322. ISSN 1939-5590. Bibcode: 1992LimOc..37..322H. 
  22. ↑ Kelly, Patrick T.; Solomon, Christopher T.; Zwart, Jacob A.; Jones, Stuart E. (2018-11-01). "A Framework for Understanding Variation in Pelagic Gross Primary Production of Lake Ecosystems" (in en). Ecosystems 21 (7): 1364–1376. doi:10.1007/s10021-018-0226-4. ISSN 1435-0629. Bibcode: 2018Ecosy..21.1364K. https://doi.org/10.1007/s10021-018-0226-4. 
  23. ↑ 23.0 23.1 Lapierre, Jean-Francois; Collins, Sarah M.; Seekell, David A.; Cheruvelil, Kendra Spence; Tan, Pang-Ning; Skaff, Nicholas K.; Taranu, Zofia E.; Fergus, C. Emi et al. (2018). "Similarity in spatial structure constrains ecosystem relationships: Building a macroscale understanding of lakes" (in en). Global Ecology and Biogeography 27 (10): 1251–1263. doi:10.1111/geb.12781. ISSN 1466-8238. Bibcode: 2018GloEB..27.1251L. 
  24. ↑ Lapierre, Jean-Francois; Seekell, David A.; Giorgio, Paul A. del (2015). "Climate and landscape influence on indicators of lake carbon cycling through spatial patterns in dissolved organic carbon" (in en). Global Change Biology 21 (12): 4425–4435. doi:10.1111/gcb.13031. ISSN 1365-2486. PMID 26150108. Bibcode: 2015GCBio..21.4425L. https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.13031. 
  25. ↑ Seekell, David A.; Lapierre, Jean-François; Pace, Michael L.; Gudasz, Cristian; Sobek, Sebastian; Tranvik, Lars J. (2014). "Regional-scale variation of dissolved organic carbon concentrations in Swedish lakes" (in en). Limnology and Oceanography 59 (5): 1612–1620. doi:10.4319/lo.2014.59.5.1612. ISSN 1939-5590. Bibcode: 2014LimOc..59.1612S. 
  26. ↑ Sommaruga, Ruben (2001-09-01). "The role of solar UV radiation in the ecology of alpine lakes" (in en). Journal of Photochemistry and Photobiology B: Biology 62 (1–2): 35–42. doi:10.1016/S1011-1344(01)00154-3. ISSN 1011-1344. PMID 11693365. Bibcode: 2001JPPB...62...35S. https://www.sciencedirect.com/science/article/abs/pii/S1011134401001543. 
  27. ↑ Helms, John R.; Stubbins, Aaron; Perdue, E. Michael; Green, Nelson W.; Chen, Hongmei; Mopper, Kenneth (2013). "Photochemical bleaching of oceanic dissolved organic matter and its effect on absorption spectral slope and fluorescence". Marine Chemistry 155: 81–91. doi:10.1016/j.marchem.2013.05.015. Bibcode: 2013MarCh.155...81H. 
  28. ↑ 28.0 28.1 Harvey, E. Therese; Kratzer, Susanne; Andersson, Agneta (2015-06-01). "Relationships between colored dissolved organic matter and dissolved organic carbon in different coastal gradients of the Baltic Sea" (in en). Ambio 44 (3): 392–401. doi:10.1007/s13280-015-0658-4. ISSN 1654-7209. PMID 26022322. PMC 4447701. https://doi.org/10.1007/s13280-015-0658-4. 
  29. ↑ "What is an Excitation Emission Matrix (EEM)?". https://www.horiba.com/en_en/technology/measurement-and-control-techniques/spectroscopy/fluorescence-spectroscopy/what-is-an-excitation-emission-matrix-eem/. 
  30. ↑ Beckmann, Christian. "Parallel Factor Analysis (PARAFAC)". https://www.fmrib.ox.ac.uk/datasets/techrep/tr04cb1/tr04cb1/node2.html. 
  31. ↑ 31.0 31.1 31.2 31.3 Stedmon, C. A.; Amon, R. M. W.; Rinehart, A. J.; Walker, S. A. (2011-03-20). "The supply and characteristics of colored dissolved organic matter (CDOM) in the Arctic Ocean: Pan Arctic trends and differences". Marine Chemistry 124 (1): 108–118. doi:10.1016/j.marchem.2010.12.007. ISSN 0304-4203. Bibcode: 2011MarCh.124..108S. https://www.sciencedirect.com/science/article/pii/S0304420311000065. 



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