colored dissolved organic matter

{{More citations needed section|date=January 2021}}

File:Interface between peatland draining river water and coastal waters.png 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.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 [https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International License].]]

The concentration of CDOM can have a significant effect on biological activity in aquatic systems. CDOM diminishes light intensity as it penetrates water. Very high concentrations of CDOM can have a limiting effect on photosynthesis and inhibit the growth of phytoplankton,{{Cite journal|last1=Stedmon|first1=C.A.|last2=Markager|first2=S.|last3=Kaas|first3=H.|date=2000|title=Optical properties and signatures of chromophoric dissolved organic matter (CDOM) in Danish coastal waters|journal=Estuarine, Coastal and Shelf Science|volume=51|issue=2|pages=267–278|doi=10.1006/ecss.2000.0645|bibcode=2000ECSS...51..267S }}{{Cite journal|last1=Seekell|first1=David A.|last2=Lapierre|first2=Jean-François|last3=Ask|first3=Jenny|last4=Bergström|first4=Ann-Kristin|last5=Deininger|first5=Anne|last6=Rodríguez|first6=Patricia|last7=Karlsson|first7=Jan|date=2015|title=The influence of dissolved organic carbon on primary production in northern lakes|url=https://aslopubs.onlinelibrary.wiley.com/doi/abs/10.1002/lno.10096|journal=Limnology and Oceanography|language=en|volume=60|issue=4|pages=1276–1285|doi=10.1002/lno.10096|bibcode=2015LimOc..60.1276S |hdl=11336/5573 |s2cid=84008509 |issn=1939-5590|hdl-access=free}}{{Cite journal|last1=Seekell|first1=David A.|last2=Lapierre|first2=Jean-François|last3=Karlsson|first3=Jan|date=2015-07-14|title=Trade-offs between light and nutrient availability across gradients of dissolved organic carbon concentration in Swedish lakes: implications for patterns in primary production|url=https://cdnsciencepub.com/doi/abs/10.1139/cjfas-2015-0187|journal=Canadian Journal of Fisheries and Aquatic Sciences|volume=72 |issue=11 |pages=1663–1671 |language=en|doi=10.1139/cjfas-2015-0187|bibcode=2015CJFAS..72.1663S |hdl=1807/69824|hdl-access=free}}{{Cite journal|last1=Carpenter|first1=Stephen R.|last2=Cole|first2=Jonathan J.|last3=Kitchell|first3=James F.|last4=Pace|first4=Michael L.|date=1998|title=Impact of dissolved organic carbon, phosphorus, and grazing on phytoplankton biomass and production in experimental lakes|journal=Limnology and Oceanography|language=en|volume=43|issue=1|pages=73–80|doi=10.4319/lo.1998.43.1.0073|issn=1939-5590|doi-access=free|bibcode=1998LimOc..43...73C }} 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.{{Cite journal|last=Hansson|first=Lars-Anders|date=1992|title=Factors regulating periphytic algal biomass|journal=Limnology and Oceanography|language=en|volume=37|issue=2|pages=322–328|doi=10.4319/lo.1992.37.2.0322|bibcode=1992LimOc..37..322H |issn=1939-5590|doi-access=free}}{{Cite journal|last1=Kelly|first1=Patrick T.|last2=Solomon|first2=Christopher T.|last3=Zwart|first3=Jacob A.|last4=Jones|first4=Stuart E.|date=2018-11-01|title=A Framework for Understanding Variation in Pelagic Gross Primary Production of Lake Ecosystems|url=https://doi.org/10.1007/s10021-018-0226-4|journal=Ecosystems|language=en|volume=21|issue=7|pages=1364–1376|doi=10.1007/s10021-018-0226-4|bibcode=2018Ecosy..21.1364K |s2cid=31266760 |issn=1435-0629|url-access=subscription}} CDOM concentrations reflect hierarchical controls.{{Cite journal|last1=Lapierre|first1=Jean-Francois|last2=Collins|first2=Sarah M.|last3=Seekell|first3=David A.|last4=Cheruvelil|first4=Kendra Spence|last5=Tan|first5=Pang-Ning|last6=Skaff|first6=Nicholas K.|last7=Taranu|first7=Zofia E.|last8=Fergus|first8=C. Emi|last9=Soranno|first9=Patricia A.|date=2018|title=Similarity in spatial structure constrains ecosystem relationships: Building a macroscale understanding of lakes|journal=Global Ecology and Biogeography|language=en|volume=27|issue=10|pages=1251–1263|doi=10.1111/geb.12781|issn=1466-8238|doi-access=free|bibcode=2018GloEB..27.1251L }} 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.{{Cite journal|last1=Lapierre|first1=Jean-Francois|last2=Seekell|first2=David A.|last3=Giorgio|first3=Paul A. del|date=2015|title=Climate and landscape influence on indicators of lake carbon cycling through spatial patterns in dissolved organic carbon|url=https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.13031|journal=Global Change Biology|language=en|volume=21|issue=12|pages=4425–4435|doi=10.1111/gcb.13031|pmid=26150108 |bibcode=2015GCBio..21.4425L |s2cid=205142736 |issn=1365-2486|url-access=subscription}}{{Cite journal|last1=Seekell|first1=David A.|last2=Lapierre|first2=Jean-François|last3=Pace|first3=Michael L.|last4=Gudasz|first4=Cristian|last5=Sobek|first5=Sebastian|last6=Tranvik|first6=Lars J.|date=2014|title=Regional-scale variation of dissolved organic carbon concentrations in Swedish lakes|journal=Limnology and Oceanography|language=en|volume=59|issue=5|pages=1612–1620|doi=10.4319/lo.2014.59.5.1612|bibcode=2014LimOc..59.1612S |issn=1939-5590|doi-access=free}} CDOM also absorbs harmful UVA/B radiation, protecting organisms from DNA damage.{{Cite journal|date=2001-09-01|title=The role of solar UV radiation in the ecology of alpine lakes|url=https://www.sciencedirect.com/science/article/abs/pii/S1011134401001543|journal=Journal of Photochemistry and Photobiology B: Biology|language=en|volume=62|issue=1–2|pages=35–42|doi=10.1016/S1011-1344(01)00154-3|issn=1011-1344|last1=Sommaruga |first1=Ruben |pmid=11693365 |bibcode=2001JPPB...62...35S |url-access=subscription}}

Absorption of UV radiation causes CDOM to "bleach", reducing its optical density and absorptive capacity. 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,{{Cite journal|last1=Helms|first1=John R.|last2=Stubbins|first2=Aaron|last3=Perdue|first3=E. Michael|last4=Green|first4=Nelson W.|last5=Chen|first5=Hongmei|last6=Mopper|first6=Kenneth|date=2013|title=Photochemical bleaching of oceanic dissolved organic matter and its effect on absorption spectral slope and fluorescence|journal=Marine Chemistry|volume=155|pages=81–91|doi=10.1016/j.marchem.2013.05.015|bibcode=2013MarCh.155...81H }} and generates reactive oxygen species, which may damage tissues and alter the bioavailability of limiting trace metals.

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. 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.

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.

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){{cite web |title=What is an Excitation Emission Matrix (EEM)? |url=https://www.horiba.com/en_en/technology/measurement-and-control-techniques/spectroscopy/fluorescence-spectroscopy/what-is-an-excitation-emission-matrix-eem/ |website=Horiba |access-date=17 December 2019}} can be resolved into components in a technique called parallel factor analysis (PARAFAC),{{cite web |last1=Beckmann |first1=Christian |title=Parallel Factor Analysis (PARAFAC) |url=https://www.fmrib.ox.ac.uk/datasets/techrep/tr04cb1/tr04cb1/node2.html |access-date=17 December 2019}} 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.{{Cn|date=February 2021}}

• Blackwater river
• Color of water
• Dissolved organic carbon (DOC)
• Ocean turbidity
• Secchi disk

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{{Wiktionary|gelbstoff}}

• [https://web.archive.org/web/20080921083712/http://nasascience.nasa.gov/earth-science/oceanography/living-ocean/ocean-color The Color of the Ocean] from science@NASA

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