uu.seUppsala University Publications
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Lake Dissolved Organic Matter Quantity and Quality: Variability across Temporal and Spatial Scales
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.ORCID iD: 0000-0003-2798-9018
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Surface waters receive large amounts of dissolved organic matter (DOM) via runoff from land. The DOM is rich in organic carbon that serves as an energy source for the aquatic biota. During uptake of this energy, aquatic organisms mineralize organic carbon. The resulting inorganic carbon is partially released to the atmosphere as carbon dioxide and methane that are greenhouse gases, and which are of concern for the ongoing global warming. The rate at which organic carbon is mineralized depends strongly on DOM quantity and quality that vary with respect to both time and space. In this thesis, DOM quantity and quality were addressed using spectroscopic methods that build on the absorptive and fluorescent properties of chromophoric DOM (CDOM). New techniques to measure CDOM absorption and fluorescence were applied and further developed that allowed us to present novel CDOM variability patterns. Addressing the lake-rich Scandinavian landscape, strong focus was placed on water retention by lakes that tightly links to lake DOM quantity and quality.

An analysis of 24,742 lakes from seven large Swedish river systems indicated that the majority of lakes in Sweden exchange their water within one year. From headwaters to the Sea, summed lake volumes in the catchments of lakes were found to increase at rates comparable to discharge, which indicated effective water renewal along flow. A strong relationship between lake water retention and CDOM was apparent and further investigated based on samples from a lake district to a regional scale.

Results from in situ high-frequency monitoring of CDOM absorption in a eutrophic humic lake showed intra-annual variability patterns known from oligotrophic lake systems. The patterns for CDOM absorption contrasted results obtained for synchronously measured partial pressures of carbon dioxide that showed diurnal signals. Measurements of CDOM fluorescence and DOC concentrations indicated lake-internal DOM production. A comparison of these results with results from addressing 560 lakes distributed across Sweden, showed that a well-calibrated CDOM fluorescence measurement captures signals from lake-internal DOM production. I conclude that improved CDOM fluorescence measurements are promising to address lake-internally produced DOM.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2015. , 37 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1225
Keyword [en]
dissolved organic matter, organic carbon, CDOM, lakes
National Category
Environmental Sciences
Research subject
Biology with specialization in Limnology
Identifiers
URN: urn:nbn:se:uu:diva-242335ISBN: 978-91-554-9163-5 (print)OAI: oai:DiVA.org:uu-242335DiVA: diva2:785075
Public defence
2015-03-27, Friessalen, Evolutionsbiologiskt Centrum (EBC), Norbyvägen 14, Uppsala, 10:00 (English)
Opponent
Supervisors
Available from: 2015-03-02 Created: 2015-01-24 Last updated: 2016-05-24Bibliographically approved
List of papers
1. Water renewal along the aquatic continuum offsets cumulative retention by lakes: implications for the character of organic carbon in boreal lakes
Open this publication in new window or tab >>Water renewal along the aquatic continuum offsets cumulative retention by lakes: implications for the character of organic carbon in boreal lakes
Show others...
2013 (English)In: Aquatic Sciences, ISSN 1015-1621, E-ISSN 1420-9055, Vol. 75, no 4, 535-545 p.Article in journal (Refereed) Published
Abstract [en]

The character of organic carbon (OC) in lake waters is strongly dependent on the time water has spent in the landscape as well as in the lake itself due to continuous biogeochemical OC transformation processes. A common view is that upstream lakes might prolong the water retention in the landscape, resulting in an altered OC character downstream. We calculated the number of lakes upstream for 24,742 Swedish lakes in seven river basins spanning from 56º to 68º N. For each of these lakes, we used a lake volume to discharge comparison on a landscape scale to account for upstream water retention by lakes (Tn tot). We found a surprisingly weak relationship between the number of lakes upstream and Tn tot. Accordingly, we found that the coloured fraction of organic carbon was not related to lake landscape position but significantly related to Tn tot when we analysed lake water chemical data from 1,559 lakes in the studied river basins. Thus, we conclude that water renewal along the aquatic continuum by lateral water inputs offsets cumulative retention by lakes. Based on our findings, we suggest integrating Tn tot in studies that address lake landscape position in the boreal zone to better understand variations in the character of organic carbon across lake districts.

Keyword
Lake, Landscape, Time, Organic carbon, Colour
National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-208615 (URN)10.1007/s00027-013-0298-3 (DOI)000324577500006 ()
Available from: 2013-10-04 Created: 2013-10-04 Last updated: 2017-12-06Bibliographically approved
2. Controls of dissolved organic matter quality: evidence from a large-scale boreal lake survey
Open this publication in new window or tab >>Controls of dissolved organic matter quality: evidence from a large-scale boreal lake survey
Show others...
2014 (English)In: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 20, no 4, 1101-1114 p.Article in journal (Refereed) Published
Abstract [en]

Inland waters transport large amounts of dissolved organic matter (DOM) from terrestrial environments to the oceans, but DOM also reacts en route, with substantial water column losses by mineralization and sedimentation. For DOM transformations along the aquatic continuum, lakes play an important role as they retain waters in the landscape allowing for more time to alter DOM. We know DOM losses are significant at the global scale, yet little is known about how the reactivity of DOM varies across landscapes and climates. DOM reactivity is inherently linked to its chemical composition. We used fluorescence spectroscopy to explore DOM quality from 560 lakes distributed across Sweden and encompassed a wide climatic gradient typical of the boreal ecozone. Six fluorescence components were identified using parallel factor analysis (PARAFAC). The intensity and relative abundance of these components were analyzed in relation to lake chemistry, catchment, and climate characteristics. Land cover, particularly the percentage of water in the catchment, was a primary factor explaining variability in PARAFAC components. Likewise, lake water retention time influenced DOM quality. These results suggest that processes occurring in upstream water bodies, in addition to the lake itself, have a dominant influence on DOM quality. PARAFAC components with longer emission wavelengths, or red-shifted components, were most reactive. In contrast, protein-like components were most persistent within lakes. Generalized characteristics of PARAFAC components based on emission wavelength could ease future interpretation of fluorescence spectra. An important secondary influence on DOM quality was mean annual temperature, which ranged between −6.2 and +7.5 °C. These results suggest that DOM reactivity depends more heavily on the duration of time taken to pass through the landscape, rather than temperature. Projected increases in runoff in the boreal region may force lake DOM toward a higher overall amount and proportion of humic-like substances.

National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-214177 (URN)10.1111/gcb.12488 (DOI)000332069500008 ()
Available from: 2014-01-07 Created: 2014-01-07 Last updated: 2017-12-06Bibliographically approved
3. Hourly, daily, and seasonal variability in the absorption spectra of chromophoric dissolved organic matter in a eutrophic, humic lake
Open this publication in new window or tab >>Hourly, daily, and seasonal variability in the absorption spectra of chromophoric dissolved organic matter in a eutrophic, humic lake
Show others...
2014 (English)In: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 119, no 10, 1985-1998 p.Article in journal (Refereed) Published
Abstract [en]

The short-term (hourly and daily) variation in chromophoric dissolved organic matter (CDOM) in lakes is largely unknown. We assessed the spectral characteristics of light absorption by CDOM in a eutrophic, humic shallow mixed lake of temperate Sweden at a high-frequency (30 min) interval and during a full growing season (May to October). Physical time series, such as solar radiation, temperature, wind, and partial pressures of carbon dioxide in water and air, were measured synchronously. We identified a strong radiation-induced summer CDOM loss (25 to 50%) that developed over 4 months, which was accompanied by strong changes in CDOM absorption spectral shape. The magnitude of the CDOM loss exceeded subhourly to daily variability by an order of magnitude. Applying Fourier analysis, we demonstrate that variation in CDOM remained largely unaffected by rapid shifts in weather, and no apparent response to in-lake dissolved organic carbon production was found. In autumn, CDOM occasionally showed variation at hourly to daily time scales, reaching a maximum daily coefficient of variation of 15%. We suggest that lake-internal effects on CDOM are quenched in humic lake waters by dominating effects associated with imported CDOM and solar exposure. Since humic lake waters belong to one of the most abundant lake types on Earth, our results have important implications for the understanding of global CDOM cycling.

Keyword
absorption spectra, CDOM, DOC, high frequency, photochemical degradation, lakes
National Category
Evolutionary Biology
Identifiers
urn:nbn:se:uu:diva-235286 (URN)10.1002/2014JG002719 (DOI)000345229700005 ()
Funder
Swedish Research CouncilFormas
Available from: 2014-10-30 Created: 2014-10-30 Last updated: 2017-12-05Bibliographically approved
4. Coherent color increases among 24 heterogeneous lakes in a poorly-buffered lake district
Open this publication in new window or tab >>Coherent color increases among 24 heterogeneous lakes in a poorly-buffered lake district
(English)Manuscript (preprint) (Other academic)
National Category
Environmental Sciences
Identifiers
urn:nbn:se:uu:diva-242334 (URN)
Available from: 2015-01-24 Created: 2015-01-24 Last updated: 2016-05-24

Open Access in DiVA

fulltext(724 kB)316 downloads
File information
File name FULLTEXT01.pdfFile size 724 kBChecksum SHA-512
e67f4bab43f56345ffd50058718a165c00af548c0bcf3110a22a09b63a7f8cd315a383d158f02a98e2e4c276c57a58214c3dce3aa77fa5a0b0f21c12c4913732
Type fulltextMimetype application/pdf
Buy this publication >>

Authority records BETA

Müller, Roger André

Search in DiVA

By author/editor
Müller, Roger André
By organisation
Limnology
Environmental Sciences

Search outside of DiVA

GoogleGoogle Scholar
Total: 316 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 1828 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf