Dissolved organic carbon and related environmental data from ponds and lakes in the circumpolar North

Frozen tundra soils hold one of the Earth’s largest pools of organic carbon. With global warming, permafrost is thawing at an accelerated rate, promoting the formation of thermokarst ponds. These ponds have become increasingly abundant in high latitude areas, representing up to 90% of all lakes in some regions. They act as recipients of the huge amount of carbon stored in permafrost that, due to thawing, is transported to aquatic ecosystems. Originally transparent ponds with high oxygen production by benthic algae and general net autotrophy are receiving increasing amounts of terrestrial organic material from the changing watershed with consequences for the ecosystem metabolism. Increasing reliance to terrestrial carbon and nutrients stimulate bacteria production and respiration and decrease the light availability to benthic primary production, contributing to making an increasing number of circumpolar freshwaters an important source of greenhouse gases to atmosphere. The combined effect of increasing humic compounds from the watershed and the modifications in the pond metabolism contribute to changes in the composition of the carbon pool in water. The extent and rate of this change are however unknown although shallow ponds are the major freshwater ecosystem type in the circumpolar North and constitute an integral component in the carbon cycling at high latitudes. In order to investigate the influence of permafrost thaw to the stocks and composition of dissolved organic material (DOM) in circumpolar North freshwater systems, we used a suite of chemical (DOC), biological (chlorophyll a), optical (spectrophotometric indexes, EEMs, PARAFAC) and stable isotopic (d13C and d2H) indicators. During the summer periods from 2002 to 2016, we sampled a total of 253 ponds distributed in 14 circumpolar regions, for a total of 356 samples, a fraction of ponds being sampled more than one time during these 15 years. The regions span over a very wide geographic area, covering ~200° in longitude (from Alaska to Russia) and ~30° in latitude (from Subarctic to High Arctic), and resulting in a large range of thawing permafrost influence. We divided the ponds into three categories according to their exposure to permafrost thaw: (1) bedrock ponds, characterized by a bedrock catchment and not directly affected by thawing permafrost; (2) tundra, not impacted by permafrost thaw, but characterized by forest, shrub or desert tundra watersheds, depending on the region; and (3) thaw ponds, directly affected by thawing permafrost.

Data and Resources

Dataset extent

Map data © OpenStreetMap contributors
Source http://www.cen.ulaval.ca/nordicanad/dpage.aspx?doi=10.5885/45520CE-0A48ADE0E2194290
Version 1.0
Citation Wauthy, M., Rautio, M., Christoffersen, K.S., Forsström, L., Laurion I., Mariash, H., Peura, S., Vincent, W.F. 2017. Dissolved organic carbon and related environmental data from ponds and lakes in the circumpolar North, v. 1.0 (2002-2016). Nordicana D31, doi: 10.5885/45520CE-0A48ADE0E2194290.
Authors
  • Author Name: Maxime Wauthy
  • Author Name: Milla Rautio
  • Author Name: Kirsten S Christoffersen
  • Author Name: Laura Forsström
  • Author Name: Isabelle Laurion
  • Author Name: Heather Mariash
  • Author Name: Sari Peura
  • Author Name: Warwick F Vincent
Temporal coverage
  • Temporal coverage start: 2002-07-07  Temporal coverage end: 2016-09-03
Spatial coverage { "coordinates": [ -149.6, 68.6333 ], "type": "Point" }
Station cen-whapmagoostui-kuujuarapik-research-station
Collaborator
Variable measured
  • Variable name: Absorbance  Variable description: Absorbance measured at a specific wavelength. We measured CDOM absorbance between 250 and 800 nm using a UV-visible Cary 100 (Agilent, Santa Clara, CA), Cary 300 (Agilent, Santa Clara, CA) or LAMBDA 650 (PerkinElmer, Waltham, MA) spectrophotometer, depending on the sample origin. After subtracting the blank spectrum, we applied a null-point adjustment, using the mean value from 750 to 800 nm.  Variable unit: Absorbance unit  Variable URL: http://www.cen.ulaval.ca/nordicanad/infounitedonnees.aspx?id=579185
  • Variable name: Absorption coefficient at 320 nm  Variable description: We reported CDOM as the absorption coefficient at 320 nm (a320) according to the equation: a320 = 2.303 × A320/ L, where a320 is the absorption coefficient (m-1) at 320 nm, A320 the absorbance corrected at 320 nm and L the path length of the cuvette (m).  Variable unit: 1 / meter  Variable URL: http://www.cen.ulaval.ca/nordicanad/infounitedonnees.aspx?id=579167
  • Variable name: Absorption coefficient at 440 nm  Variable description: We reported CDOM as the absorption coefficient at 440 nm (a440) according to the equation: a440 = 2.303 × A440/ L, where a440 is the absorption coefficient (m-1) at 440 nm, A440 the absorbance corrected at 440 nm and L the path length of the cuvette (m).  Variable unit: 1 / meter  Variable URL: http://www.cen.ulaval.ca/nordicanad/infounitedonnees.aspx?id=579168
  • Variable name: Cuvette size  Variable description: Size of the cuvette used for the absorbance scans on the spectrophotometer (2 sizes: 1 or 10 cm)  Variable unit: Centimeter  Variable URL: http://www.cen.ulaval.ca/nordicanad/infounitedonnees.aspx?id=579165
  • Variable name: d13C Mean  Variable description: Mean of the d13C signature for the type of sample and pond corresponding.  Variable unit: Per thousand  Variable URL: http://www.cen.ulaval.ca/nordicanad/infounitedonnees.aspx?id=579186
  • Variable name: d13C Standard deviation  Variable description: Standard deviation of the d13C signature for the type of sample and pond corresponding.  Variable unit: Per thousand  Variable URL: http://www.cen.ulaval.ca/nordicanad/infounitedonnees.aspx?id=579187
  • Variable name: d2H Mean  Variable description: Mean of the d2H signature for the type of sample and pond corresponding.  Variable unit: Per thousand  Variable URL: http://www.cen.ulaval.ca/nordicanad/infounitedonnees.aspx?id=579188
  • Variable name: d2H Standard deviation  Variable description: Standard deviation of the d2H signature for the type of sample and pond corresponding.  Variable unit: Per thousand  Variable URL: http://www.cen.ulaval.ca/nordicanad/infounitedonnees.aspx?id=579189
  • Variable name: Dissolved organic carbon concentration (DOC)  Variable description: We filtered surface water through pre-rinsed cellulose acetate filters (0.2 µm) and stored samples in acid-washed and combusted glass vials, at 4°C in the dark. DOC quantification was carried out using a carbon analyzer TOC-5000A or TOC-VCPH (Shimadzu, Kyoto, Japan).  Variable unit: Milligramm per liter  Variable URL: http://www.cen.ulaval.ca/nordicanad/infounitedonnees.aspx?id=579164
  • Variable name: Fluorescence index  Variable description: Ratio of fluorescence emission intensities at 450 nm and 500 nm for an excitation at 370 nm.  Variable unit: unitless
  • Variable name: Maximum fluorescence of the component C1  Variable description: Maximum fluorescence of the component C1 identified by our PARAFAC model.  Variable unit: Raman unit  Variable URL: http://www.cen.ulaval.ca/nordicanad/infounitedonnees.aspx?id=579172
  • Variable name: Maximum fluorescence of the component C2  Variable description: Maximum fluorescence of the component C2 identified by our PARAFAC model.  Variable unit: Raman unit  Variable URL: http://www.cen.ulaval.ca/nordicanad/infounitedonnees.aspx?id=579173
  • Variable name: Maximum fluorescence of the component C3  Variable description: Maximum fluorescence of the component C3 identified by our PARAFAC model.  Variable unit: Raman unit  Variable URL: http://www.cen.ulaval.ca/nordicanad/infounitedonnees.aspx?id=579174
  • Variable name: Maximum fluorescence of the component C4  Variable description: Maximum fluorescence of the component C4 identified by our PARAFAC model.  Variable unit: Raman unit  Variable URL: http://www.cen.ulaval.ca/nordicanad/infounitedonnees.aspx?id=579175
  • Variable name: Maximum fluorescence of the component C5  Variable description: Maximum fluorescence of the component C5 identified by our PARAFAC model.  Variable unit: Raman unit  Variable URL: http://www.cen.ulaval.ca/nordicanad/infounitedonnees.aspx?id=579176
  • Variable name: Pelagic chlorophyll a concentration (Chla)  Variable description: We filtered surface water onto GF/F filters to determine pelagic chlorophyll a (Chla) concentration following Nusch (1980). Nusch, E. A. 1980. Comparison of different methods for chlorophyll and phaeopigments determination. Archiv für Hydrobiologia 14:14-35.  Variable unit: Microgram per liter  Variable URL: http://www.cen.ulaval.ca/nordicanad/infounitedonnees.aspx?id=579132
  • Variable name: pH  Variable description: Potential of hydrogen , measured from surface water samples.  Variable unit: unitless
  • Variable name: Relative abundance of the component C1  Variable description: Relative abundance of the component C1 identified by our PARAFAC model.  Variable unit: Percentage  Variable URL: http://www.cen.ulaval.ca/nordicanad/infounitedonnees.aspx?id=579178
  • Variable name: Relative abundance of the component C2  Variable description: Relative abundance of the component C2 identified by our PARAFAC model.  Variable unit: Percentage  Variable URL: http://www.cen.ulaval.ca/nordicanad/infounitedonnees.aspx?id=579179
  • Variable name: Relative abundance of the component C3  Variable description: Relative abundance of the component C3 identified by our PARAFAC model.  Variable unit: Percentage  Variable URL: http://www.cen.ulaval.ca/nordicanad/infounitedonnees.aspx?id=579180
  • Variable name: Relative abundance of the component C4  Variable description: Relative abundance of the component C4 identified by our PARAFAC model.  Variable unit: Percentage  Variable URL: http://www.cen.ulaval.ca/nordicanad/infounitedonnees.aspx?id=579181
  • Variable name: Relative abundance of the component C5  Variable description: Relative abundance of the component C5 identified by our PARAFAC model.  Variable unit: Percentage  Variable URL: http://www.cen.ulaval.ca/nordicanad/infounitedonnees.aspx?id=579182
  • Variable name: Slope ratio  Variable description: We determined spectral slopes (S) following Loiselle <i>et al.</i> (2009) for the intervals 275-295 (S285) and 350-400 nm (S375). We performed the regression calculations on SciLab v 5.5.2. The slope ratio (SR) is S285 divided by S375. Loiselle, S. A., L. Bracchini, A. Cózar, A. M. Dattilo, A. Tognazzi, and C. Rossi. 2009. Variability in photobleaching yields and their related impacts on optical conditions in subtropical lakes. Journal of Photochemistry and Photobiology B: Biology 95:129-137.  Variable unit: unitless
  • Variable name: Specific ultraviolet absorbance at 254 nm  Variable description: We calculated the specific ultraviolet absorbance at 254 nm (SUVA254) from DOC normalized A254 values. In order to remove the iron effect on SUVA254, we applied the following equation when the Fe concentration was higher than 2 mg L-1: A254 corrected= A254 measured - (0.0653 × [Fe] )  Variable unit: Liter / (mg of carbone x meter)  Variable URL: http://www.cen.ulaval.ca/nordicanad/infounitedonnees.aspx?id=579166
  • Variable name: Spectral slope for the interval 279-299 nm  Variable description: We determined spectral slopes (S) following Loiselle <i>et al.</i> (2009) for the intervals 279-299 (S289). We performed the regression calculations on SciLab v 5.5.2. Loiselle, S. A., L. Bracchini, A. Cózar, A. M. Dattilo, A. Tognazzi, and C. Rossi. 2009. Variability in photobleaching yields and their related impacts on optical conditions in subtropical lakes. Journal of Photochemistry and Photobiology B: Biology 95:129-137.  Variable unit: 1 / nanometer  Variable URL: http://www.cen.ulaval.ca/nordicanad/infounitedonnees.aspx?id=579170
  • Variable name: Sum of the maximum fluorescence  Variable description: Sum of the maximum fluorescence of the 5 components identified by our PARAFAC model for the corresponding sample.  Variable unit: Raman unit  Variable URL: http://www.cen.ulaval.ca/nordicanad/infounitedonnees.aspx?id=579177
  • Variable name: Sum of the relative abundance  Variable description: Sum of the relative abundance of the 5 components identified by our PARAFAC model for the corresponding sample. Must equal 100%.  Variable unit: Percentage  Variable URL: http://www.cen.ulaval.ca/nordicanad/infounitedonnees.aspx?id=579183
  • Variable name: Total dissolved iron concentration  Variable description: Total dissolved iron concentration, measured from surface water samples. For ponds without Fe measures, we used mean values from the literature, if they exist.  Variable unit: Milligramm per liter  Variable URL: http://www.cen.ulaval.ca/nordicanad/infounitedonnees.aspx?id=579161
  • Variable name: Total nitrogen concentration  Variable description: Total nitrogen concentration, measured from surface water samples.  Variable unit: Milligramm per liter  Variable URL: http://www.cen.ulaval.ca/nordicanad/infounitedonnees.aspx?id=579163
  • Variable name: Total phosphorus concentration  Variable description: Total phosphorus concentration, measured from surface water samples.  Variable unit: Microgram per liter  Variable URL: http://www.cen.ulaval.ca/nordicanad/infounitedonnees.aspx?id=579162
  • Variable name: Wavelength  Variable description: Wavelengths  Variable unit: Nanometer  Variable URL: http://www.cen.ulaval.ca/nordicanad/infounitedonnees.aspx?id=579184
Measurement Technique
    Date published 2017-09-11
    Date modified 2017-09-11
    Status Public
    Publisher
    • Publisher name: Nordicana D  Publisher URL: http://www.cen.ulaval.ca/nordicanad/en_index.aspx
    Provider
    • Provider name: Centre d'études Nordiques (CEN)  Provider URL: http://www.cen.ulaval.ca/
    License http://www.cen.ulaval.ca/nordicanad/en_modalite.aspx