This data set is a report of water chemistry from the stream draining the S1 peatland and surrounding uplands (the S1 catchment) at the Marcell Experimental Forest (MEF) in Itasca County, Minnesota. Stream water was collected biweekly, weekly, or more often, 2007 to ongoing. Samples were only collected when the intermittent stream had flowing water and samples were not collected when the stream was frozen (typically November or December to May).
Samples are measured for pH, specific conductivity, anions (chloride, sulfate), cations (calcium, magnesium, potassium, sodium, aluminum, iron, strontium), silicon, nutrients (ammonium, nitrate, soluble reactive phosphorus, total nitrogen, total phosphorus), and total organic carbon (TOC). Occasionally, stable isotopes of water and concentrations of ferrous and ferric iron have been measured.
The MEF is operated and maintained by the USDA Forest Service, Northern Research Station. Some of the samples were collected as part of the Spruce and Peatland Responses Under Changing Environments (SPRUCE) experiment. The SPRUCE experiment is a multi-year cooperative project among scientists of the Oak Ridge National Laboratory operated by UT-Battelle, LLC and the USDA Forest Service, Northern Research Station, with funding from the US Department of Energy, Biological and Environmental Research Program
SITE DESCRIPTION:
The S1 catchment has a 25.1-ha deciduous upland forest and a natural, undrained 8.1 ha peatland (raised-dome bog with a surrounding lagg). A stream forms in the lagg and flow is intermittent throughout the year (Verry et al. 2011). Streamflow occurs during and after snowmelt and rainfall events. In some years, there is streamflow from snowmelt to freeze-up during the following winter. In most years, there is a period of no flow during summer that may extend into fall or winter, and in most years, streamflow does not persist through winter.
Surface elevation ranges from 412 m a.s.l at the outlet to 430 m a.s.l. in the uplands.
The upland forest is dominated by aspen (Populus tremuloides), white birch (Betula papyrifera), red maple (Acer rubrum), and balsam fir (Abies balsamea), with some red oak (Quercus rubra), basswood (Tilia americana), and jack pine (Pinus banksiana). The upland forest was last harvested during the 1910s. In the uplands, a Warba sandy clay loam developed in glacial till atop deep (50 m) outwash sand deposits. The Warba soil series is a fine-loamy, mixed, superactive, frigid Haplic Glossudalfs; Alfisol (Nyberg 1987).
The peatland has a black spruce (Picea mariana)-tamarack (Larix laricina)-Sphagnum community. Below the overstory tree canopy, there is nearly complete coverage of ericaceous shrubs (primarily Rhododendron groenlandicum, Chamaedaphne calyculata, and Vaccinium angustifolium), cotton grass (Eriophorum spissum), and haircap moss (Polytrichum spp.). Three-leaved false Solomon’s seal (Maianthemum trifolium) is also abundant throughout the bog. The lagg has most of the same species but is richer in species than the bog (Verry and Janssens 2011). The more noticeable additional species include speckled alder (Alnus incana), paper birch (Betula papyrifera), and various Carex species.
Peat depth has been surveyed across the bog (Parsekian 2012). Peat is less than 1 m deep around the perimeter of the bog to >9 m deep at the deepest location, with 2 to 4 m of peat across much of the peatland. The Greenwood peat (Dysic, frigid Typic Haplohemists; a Histosol; Nyberg 1987) has accumulated in the last 10,000 yr since Wisconsin glaciation (Verry and Janssens 2011). The peatland surface has hummock and hollow microtopography. Hummocks are uneven, elevated areas that rise various heights, up to about 50 cm, above the adjacent hollows. Hollows have a relatively uniform elevation within a localized area, with an overall raised-dome profile to the entire bog surface. The peatland water table fluctuates from about 0.20 m above the surface to as much as 0.30 m below during a typical year.
The climate is continental with warm summers, cold winters, and a mean annual air temperature since 1961 of 3.5 deg C (1961 to 2019, Sebestyen et al. 2021). Mean annual precipitation since 1961 is 787 mm. Most precipitation occurs as rainfall during summer and a winter snowpack starts to accumulate around December and fully melts in March or April.
The peatland was harvested in successive stripcuts during an experimental study of streamflow, water table, water chemistry, and forest reproduction responses to that commercial harvesting practice (1969 and 1974; Perala and Verry 2011; Sebestyen and Verry 2011; Sebestyen, Verry and Brooks 2011).
At the S1 catchment, snow depth, snow water equivalent, ground frost, and water levels have been monitored since the 1960s (Sebestyen et al. 2021). Streamflow was measured from 1960 to 1980. Air temperature, precipitation, and other meteorological variables have been measured since 2010 (Hanson et al. 2015). Some chemistry (mostly unpublished) was measured as early as 1966. The SPRUCE (Spruce and Peatland Responses Under Changing Environments) experiment occurs on the S1 bog and started during 2014 when belowground warming was initiated in ten large enclosures (Wilson et al. 2016). Aboveground warming and elevated concentrations of carbon dioxide were added during 2015 and 2016, respectively (Hanson et al. 2017). The experiment is expected to last through 2025 for ten years of experimental warming and elevated carbon dioxide levels.
LOCATIONS OF WATER SAMPLING:
The stream water chemistry reported in this data release began during 2007 and stream water has been repeatedly sampled from a single location within 1 m of the spot where the channel forms. There is visual current in the stream under low streamflow in a channel that is about 40-cm wide where sampled during low streamflow. During periods of highest water levels, water may back up from a downstream peatland and into the S1 lagg and bog. During high streamflow after spring snowmelt or large rainfall events, the channel width is up to ~1.5 m wide and the water is up to about 30 cm deep.
The sampling location is about 3 m upstream of interlocking sheet piling that formed the headwall of a flume (with a type-H facing) that was present at the site prior to 1980 for the measurement of streamflow. Though the flume is no longer present, the site and samples from there are still named S1 flume.
There is an elevated boardwalk to access the main channel of the stream for sampling, particularly during high streamflow.
WATER SAMPLING:
Unfiltered surface water was ladled into new bottles for pH, specific conductivity, ion, nutrient, ferrous and ferric iron, and isotope analyses. All samples were dipped with a plastic kitchen ladle and poured into bottles. After about April 2010, the ladle or a dipper (CXBA00, Global Water Instrumentation, Phoenix, Arizona) with an approximately 1 m handle were used. The ladle or dipper was rinsed with 18 megaohm deionized water before the start of sampling. The ladle was rinsed with stream water that pooled behind the flume headwall, downstream of the sampling location. The rinse water was discarded downstream of the sampling location or in the uplands.
Unfiltered stream water was ladled or dipped in to a 250-ml LDPE bottle. An aliquot of most samples was collected in a 16-ml scintillation vial with a Polyseal cap for liquid water isotope analysis (stored at room temperature). Scintillation vials for water isotope samples were completely filled, with no headspace or bubbles. For some samples starting during 2015 (only SPRUCE samples) and all samples collected during and after 2019, a separate 60-ml aliquot was saved in a new, HDPE bottle solely for nutrient (nitrate, ammonium, soluble reactive phosphorus, total nitrogen, and total phosphorus,) analyses.
For all analyses except ferrous and ferric iron determination, sample bottles and vials were triple rinsed with sample water before filling. Samples bottles for ferrous and ferric iron analysis were not rinsed because each bottle received 0.5 ml (30-ml bottle) or 1 ml (60-ml) of 12 mol/L high-purity trace-metal grade hydrochloric acid in advance of sampling to preserve the samples.
When collected, date/time of retrieval, sample location, and associated notes were recorded on field data sheets. A unique serial ID number was assigned to all aliquots of the same sample for tracking purposes in the laboratory and data reporting. The serial ID, date/time, and sample location were also written on label tape on each sample bottle or vial. Sample ID numbers are five-digit or six-digit integers. Samples IDs are not necessarily consecutive because water from other sites at the MEF are interspersed in the numbering series. Since samples were sometimes collected for multiple research projects, several samples may have been collected on the same day. In general, the long-term sampling of the Forest Service at the MEF were collected every two weeks and were labelled in these series:
* 216037 to 216348 during 2007
* 217003 to 217426 during 2008
* 218030 to 218326 during 2009
* 219030 to 219358 during 2010
* 220002 to 220329 during 2011
* 221010 to 221282 during 2012
* 222027 to 222269 during 2013
* 223027 to 223216 during 2014
* 224041 to 224328 during 2015
* 225002 to 225362 during 2016
* 226005 to 226342 during 2017
* 227059 to 227272 during 2018
* 354362 to >354900 from 2019 to ongoing
As part of the SPRUCE project, separate weekly samples were also collected during pre-experimental monitoring phase (80000 to 82307 from 2011 to June 23, 2014), the belowground-only warming phase (82457 to 84076 from July 1, 2014 to August 10, 2015), and whole-ecosystem warming phase (belowground and aboveground heating with elevated atmospheric carbon dioxide concentrations, 84186 to >91000 from August 13, 2015 to ongoing).
Two additional samples (351652 and 351690) were collected during April 2013.
Weekly samples were collected from September 2016 to December 2018 (353008 to 354271), most of them for ferrous and ferric iron concentration determination at Iowa State University in addition to the core suite of measurements done at the Grand Rapids Laboratory.
Samples were transported on ice in a cooler to the Grand Rapids chemistry laboratory, and then were refrigerated (250-mL bottles), frozen (60-mL bottles for nutrient analysis), or stored at room temp (isotope vials) until analyzed. Bottles for ferric/ferrous iron analysis were either refrigerated or stored at room temperature, and later shipped to Iowa State University for analysis.
ANALYTICAL METHODS:
Water samples were analyzed for pH, specific conductivity, and concentrations of cations, silicon, anions, nutrients, and total organic carbon at the Forestry Science Laboratory in Grand Rapids, Minnesota. Water stable isotopes were analyzed at Oak Ridge National Laboratory or at the Forestry Science Laboratory. Samples were analyzed for ferrous and ferric iron concentrations at Iowa State University.
Unfiltered water was used for all laboratory analyses. It is important to keep in mind that surface waters in peatlands are free of inorganic particulates due to flowpaths through peat and slow transit times due to low hydraulic gradients that allow for deposition of particulates. For that reason, we have considered our unfiltered water samples of surface and peatland porewaters to be dissolved. The samples are likely to include colloids, but no inorganic particulates and rarely peat particles. Attempts are made to avoid or eliminate aquatic organisms (mostly mosquito larvae during late spring when abundant) or plant leaves and needles (after senescence).
Forestry Science Laboratory in Grand Rapids, Minnesota:
For each type of laboratory measurement, every tenth sample was run in duplicate followed by two reference standards. Reference standards were chosen to be within the range of calibration standards and optimized for particular solutes or suites of solutes to be within the range typical observed for waters of bog origin at the MEF. Most reference standards (except as noted below) were obtained as commercially prepared solutions and were not altered (e.g., diluted or mixed) before analysis. The vendors and concentrations did change over time, but that information is maintained in unpublished laboratory records for each batch of samples that were analyzed.
Analytical duplicates and the 10 preceding samples were acceptable for reporting when the relative error was less than 10 percent between duplicates. When reference standards differed by more than 5 percent from actual values, a batch of samples was reanalyzed. When a particular sample was higher in concentration than the highest calibration standard, that sample was diluted and re-run until within the range of the calibration standards.
Unless otherwise noted, autosamplers were used with instruments for analyses.
For each instrument and sample, we record the date and time of analysis and that information is stored in our unpublished records.
For anion, cation, silicon, nutrient, and TOC analyses, check and reference solutions were made in volumetric flasks with deionized water (18.0 megaohm/cm).
While we adhere to instrument operation in accordance with Standard Methods (APHA 2017), holding times of samples oftentimes does not meet those standards (as described below).
pH: A Mettler Toledo (Columbus, OH) DL53 Autotitrator was used to measure pH according to Standard Method 4500-H+ B (APHA 2017). A four-point calibration was performed before each batch of 15 samples. A sodium carbonate reference (prepared in-house) was run after every ten samples. Samples were only analyzed if the reference values were accurate to within 10 percent and pH is reported to the nearest tenth of a decimal place. Samples for pH analysis typically were analyzed within days of collection. Although rare, samples sometimes were held for weeks to several months while awaiting maintenance on the meter or for a replacement pH probe.
Specific conductivity: Conductivity was measured on a Yellow Springs Instruments (YSI; Yellow Spring, Ohio) Model 3100 meter. A YSI 3403 probe (cell constant = 1.0/cm) was used until March 2017 and a YSI 3253 probe (cell constant = 1.0/cm) thereafter. The meters were calibrated with a 46.7 microSiemen/cm standard, and periodically checked with 23.8, 84.0, or 150 microSiemen/cm references. The manually loaded cell of the conductivity probe was twice rinsed with sample water and then conductivity was measured on the third poured aliquot. Samples, the standard, and reference standards were measured in a laboratory maintained at 21 degree C. Conductivity values were recorded on paper. Specific conductivity (conductivity at 25 degree C) was calculated from conductivity (at 21 degree C) when values were transferred to spreadsheets. Samples for conductivity measurement typically were analyzed within days of collection. Although rare, samples sometimes were held for weeks to several months while awaiting maintenance on the meter or replacement of a probe.
Anions: Anion (chloride and sulfate) concentrations were measured using suppressed conductivity and conductimetric detection on two different ion chromatographs: on a Dionex (Sunnyvale, CA) DX-500 for samples collected through 2012 and a Thermo Scientific Dionex ICS-2100 thereafter. Samples were injected through 20 micrometer filter caps and through an IonPac AG14 pre-column and AS14 column (DX500) and AG22 pre-column and AS22 column (ICS-2100). Standard Method 4110-C was used (APHA 2017) and commercially available reference standards were analyzed with each batch of samples. The ion chromatograph was typically operated every business day. Daily throughput of samples is lower than the rate at which samples are sometimes collected. For that reason, samples for anion measurement were sometimes analyzed within several days of collection, but oftentimes held for months to a year before analysis.
Cations and silicon: Cation (calcium, magnesium, potassium, sodium, aluminum, iron, and strontium) and silicon concentrations were analyzed by inductively coupled optical emission spectroscopy (ICP-OES). A Thermo Electron Corporation (Waltham, Massachusetts) Iris Intrepid ICP-OES was used for all samples collected through 2015, and a Thermo Scientific (Waltham, Massachusetts) ICAP 7600 Duo for samples collected during and after 2016. Standard method 3120 was used (APHA 2017) and commercially available reference standards were analyzed with each batch of samples. Samples for cation and silicon analyses were typically run one to four times a year in large batches of samples; analysis occurred within several days of collection for some samples to a year from collection for those that were held longest.
Nutrients:
Ammonium was measured according to the Lachat (Milwaukee, Wisconsin) QuikChem 10-107-06-1-F method on a Lachat (Hach Company, Loveland, Colorado) QuickChem 8500 starting with samples collected during 2019. Ammonium is reported as the amount of nitrogen in ammonium. The Lachat methods are equivalent to the flow injection analysis method to form indephenol blue for colorimetric analysis (Standard Method 4500-NH3 H; APHA 2017).
Nitrate+nitrate was measured according to Lachat QuikChem 10-107-04-1-B on a QuickChem 8500 starting with samples collected during 2019. Nitrate was reduced to nitrite using the flow injection analysis (cadmium reduction) method and concentration was colorimetrically determined as the amount of nitrogen in the resulting nitrite (Standard Method 4500-NO3- I; APHA 2017). Though nitrite was not separately measured using this method, it has been rare in our experience to observe nitrite in MEF water samples. All samples were also analyzed by ion chromatography and nitrite peaks were not visible in sample chromatograms.
Total nitrogen (TN) concentrations were measured colorimetrically after in-line automated persulfate-ultraviolet oxidation to nitrate (Standard Method 4500-N B; APHA 2017). Concentrations were measured according to the Lachat QuikChem 10-107-04-1-P method on a Lachat QuickChem for samples collected before 2016 and Lachat QuikChem E10-107-04-3-D method on a Lachat QuickChem 8500 thereafter.
Soluble reactive phosphorus was measured according to the Lachat QuikChem 10-115-01-1-B method on a Lachat QuikChem 8000 for samples collected through 2012 and Lachat QuikChem 8500 thereafter. The Lachat methods are equivalent to the flow injection analysis method with ascorbic acid reduction (Standard Method 4500-P F; APHA 2017).
Total phosphorus (TP) concentrations were measured colorimetrically using automated persulfate-UV digestion and flow injection analysis with ascorbic acid reduction for colorimetric detection (Standard Method 4500-PI; APHA 2017). Concentrations were measured according to the Lachat QuikChem 10-115-01-3-A method on a Lachat QuickChem 8000 for samples collected before 2016 and Lachat QuikChem E10-115-01-3-A method on a Lachat QuickChem 8500 thereafter.
Samples for nitrogen and phosphorus chemistry were typically run once or twice a year in large batches of samples. Analysis occurred within several days of collection for some samples to a year from collection for those that were held longest.
Commercially available reference standards were analyzed with each batch of nutrient samples
Total organic carbon (TOC): Concentrations of TOC were measured by high-temperature combustion with infrared detection (Standard Method 5310-C, APHA 1995) on a Shimadzu TOC-V CPH with External Sparge Kit for samples collected through 2012. A Shimadzu (Columbia, Maryland) TOC-VCP was used for samples collected from 2013 onward. Concentrations were measured as total carbon minus inorganic carbon (TC-IC) before June 2010 and as non-purgeable organic carbon (NPOC) after that. Potassium hydrogen phthalate (KHP) was used for calibration and reference standards. Sebestyen et al. (2020) show that the TC-IC and NPOC are comparable to within 10% relative error as a measure of TOC concentration. We consider the two instruments and methods to be equivalent for our sites. Samples were typically measured within days of sample collection. Rarely, samples were held for weeks or months when the instrument needed maintenance or laboratory personnel were awaiting consumables such as compressed gas.
Liquid water isotopes: The glass scintillation vials for water isotope measurement are stored in a sample archive and are available for eventual analysis. Some samples have been analyzed on a Picarro Inc (Santa Clara, California) L11102-I at Oak Ridge National Laboratory or a Los Gatos Research (San Jose, California) T-LWIA-45-EP liquid water isotope analyzer at the Grand Rapids chemistry laboratory. Further information can be found in the data entity lab_info.csv in Stelling et al. (2021).
We report the relative abundance of deuterium (D) and oxygen-18 (O-18). The natural abundances of stable isotopes were measured using laser absorption spectroscopy (Lis et al. 2008). Both laboratories used similar procedures; 6-7 injections of 0.5-1.2 uL sample were analyzed. Isotopic values were scaled relative to the Vienna Standard Mean Ocean Water (VSMOW)-Standard Light Antarctic Precipitation (SLAP) scale. A series of secondary standards were calibrated to VSMOW and SLAP. Machine raw data were then post-processed to account for machine drift and between-sample memory (Wassenaar et al., 2014). Values for D and O-18 are reported in delta-notation (permil or per mil relative to VSMOW; Craig 1961).
Hall Laboratory, Iowa State University:
Total iron and ferrous iron concentrations were colorimetrically measured using a ferrozine method (Huang and Hall 2017) on a microplate spectrophotometer (Biotek Synergy HT, Winooski VT). Ferric iron concentration was calculated as the difference between total iron and ferrous iron concentrations (Huang and Hall 2017). The calculation of ferric iron concentration sometimes resulted in small negative values for samples with extremely low ferric iron concentrations. We defined the median absolute value of these negative numbers as the detection limit for ferric iron concentration (0.07 mg/L) and set positive ferric iron concentration values within this range to zero. Acidified samples were held for weeks or months to a year before analysis.
When a particular sample was higher in concentration than the highest calibration standard, that sample was diluted and re-run until within the range of the calibration standards.
The sum of ferrous and ferric iron concentrations from colorimetric analysis occasionally exceeded the total iron values measured by ICP-OES at the Grand Rapids Forestry Sciences Laboratory. This discrepancy is likely a consequence of greater release or dissolution of particulate iron from occasional peat fragments in the acidified (pH < 2) samples used for ferrous and ferric iron analysis. Samples for colorimetric analysis were collected in pre-acidified bottles to inhibit oxidation of ferrous iron to ferric iron during sample storage. Samples for ICP-OES analysis were not similarly acidified for storage and analysis.
REPORTED VALUES:
To document when a sample was collected, we include a laboratory ID, sample name, and date/time of collection. Sometimes chemistry values are assigned -9999 for individual solutes or for all analytes (i.e., pH, specific conductivity, and solute concentrations), which may have resulted from insufficient sample volume to complete all analyses, contamination that affected individual solutes or suites of analytes that were simultaneously measured on a single instrument for a particular sample, or contamination that affected all solutes for a particular sample. Samples pending analysis are also assigned a value of -9999.
Concentrations of nitrate and ammonium are only reported onward from 2016 or 2019 (depending on serial ID series) when aliquots were frozen for analysis (see above). Values are reported as -9999 prior to preservation with freezing.
Concentrations of ferrous and ferric iron are only reported between September 2016 to December 2018. Not all samples were analyzed, and some values are pending completion of analysis.
Data values below the detection limit are reported in the data file and are not flagged. Detection limits, as listed below, must be considered when using these data.
The method detection limits were:
- 0.01 mg chlorine/L,
- 0.02 mg sulfate/L,
- 0.05 mg calcium/L,
- 0.05 mg magnesium/L,
- 0.5 mg potassium/L,
- 0.1 mg sodium/L,
- 0.01 mg aluminum/L,
- 0.05 mg iron/L,
- 0.05 mg silicon/L,
- 0.01 mg strontium/L,
- 0.01 mg nitrogen/L for ammonium,
- 0.002 mg nitrogen/L for nitrate+nitrite,
- 0.001 mg phosphorus/L for soluble reactive phosphorus,
- 0.05 mg nitrogen/L for total nitrogen,
- 0.05 mg phosphorus/L for total phosphorus,
- 1 mg carbon/L for the TC-IC method, and 0.5 mg carbon/L for the NPOC method of TOC analysis,
- 0.04 mg iron/L for ferrous iron,
- 0.07 mg iron/L for ferric iron.
The analytical precision for water isotopes was:
- 0.5 permil for D and 0.1 permil for O-18 at Oak Ridge National Laboratory,
- 0.5 permil for D and 0.1 permil for O-18 at the Grand Rapids Forestry Sciences Laboratory.
MARCELL EXPERIMENTAL FOREST sites and data collection are described in further detail in:
Sebestyen, S.D., C. Dorrance, D.M. Olson, E.S. Verry, R.K. Kolka, A.E. Elling, and R. Kyllander (2011). Chapter 2: Long-Term Monitoring Sites and Trends at the Marcell Experimental Forest. In R.K. Kolka, S.D. Sebestyen, E.S. Verry, and K.N. Brooks (Ed.). Peatland Biogeochemistry and Watershed Hydrology at the Marcell Experimental Forest (pp 15-71). CRC Press, Boca Raton, FL. https://www.fs.usda.gov/treesearch/pubs/37979.
RELEVANT PUBLICATIONS
Griffiths, N. A., and Sebestyen, S. D. (2016), Dynamic vertical profiles of peat porewater chemistry in a northern peatland, Wetlands, 36(6), 1119-1130. https://doi.org/10.1007/s13157-016-0829-5
Stelling, J. M., Sebestyen, S. D., Griffiths, N. A., Mitchell, C. P. J., and Green, M. B. (2021, in press), The stable isotopes of natural waters at the Marcell Experimental Forest, Hydrol. Process. https://doi.org/10.1002/hyp.14336
Shelley, S. J., Brice, D. J., Iversen, C. M., Kolka, R. K., Sebestyen, S. D., and Griffiths, N. A. (2021, in press), Deciphering the shifting role of intrinsic and extrinsic drivers on moss decomposition in peatlands over a 5-year period, Oikos.
REFERENCES
APHA. (2017). Standard methods for the examination of water and wastewater (23rd ed.). Washington, DC: American Public Health Association.
Craig, H. (1961). Isotopic variations in meteoric waters. Science, 133(3465), 1702-1703. https://doi.org/10.1126/science.133.3465.1702
Hanson, P. J., Riggs, J. S., Nettles, R. W., Phillips, J. R., Krassovski, M. B., Hook, L. A., Gu, L., Richardson, A. D., Aubrecht, D. M., Ricciuto, D. M., Warren, J. M., and Barbier, C. (2017), Attaining whole-ecosystem warming using air and deep-soil heating methods with an elevated CO2 atmosphere, Biogeosciences, 14, 861-883. https://doi.org/10.5194/bg-14-861-2017
Hanson, P. J., Riggs, J. S., Dorrance, C., Nettles, R. W., and Hook, L. A. (2015), SPRUCE environmental monitoring data: 2010-2016, Oak Ridge National Laboratory, et al., Oak Ridge, TN. https://doi.org/10.3334/CDIAC/spruce.001
Huang, W., and Hall, S. J. (2017). Optimized high-throughput methods for quantifying iron biogeochemical dynamics in soil. Geoderma, 306, 67-72. https://doi.org/http://dx.doi.org/10.1016/j.geoderma.2017.07.013
Lis, G., Wassenaar, L. I., and Hendry, M. J. (2007). High-precision laser spectroscopy D/H and 18O/16O measurements of microliter natural water samples. Analytical Chemistry.
Nyberg, P. R. (1987). Soil survey of Itasca County, Minnesota. USDA Soil Conservation Service, St. Paul, MN.
Perala, D. A., and Verry, E. S. (2011), Forest management practices and silviculture, in Peatland biogeochemistry and watershed hydrology at the Marcell Experimental Forest, edited by Kolka, R. K., et al., pp. 371-400, CRC Press, Boca Raton, FL.
Sebestyen, S. D., Lany, N. K., Roman, D. T., Burdick, J. M., Kyllander, R. L., Verry, E. S., and Kolka, R. K. (2021). Hydrological and meteorological data from research catchments at the Marcell Experimental Forest, Minnesota, USA. Hydrological Processes, 35, e14092. https://doi.org/10.1002/hyp.14092
Sebestyen, S. D., and Verry, E. S. (2011), Water chemistry responses to watershed experiments at the Marcell Experimental Forest, in Peatland biogeochemistry and watershed hydrology at the Marcell Experimental Forest, edited by Kolka, R. K., et al., pp. 401-432, CRC Press, Boca Raton, FL.
Sebestyen, S. D., Verry, E. S., and Brooks, K. N. (2011), Hydrological responses to forest cover changes on uplands and peatlands, in Peatland biogeochemistry and watershed hydrology at the Marcell Experimental Forest, edited by Kolka, R. K., et al., pp. 433-458, CRC Press, Boca Raton, FL.
Stelling, J. M., Sebestyen, S. D., Griffiths, N. A., Mitchell, C. P. J., Green, M. B., and Lany, N. K. (2021), Marcell Experimental Forest stable isotopes of water, 2008 - ongoing, 1 ed., USDA Forest Service, Environmental Data Initiative. https://doi.org/10.6073/pasta/50a287716f80d2b1b602dcceac5a6e5c
Verry, E. S., Brooks, K. N., Nichols, D. S., Ferris, D. R., and Sebestyen, S. D. (2011). Watershed hydrology. In Kolka, R. K., Sebestyen, S. D., Verry, E. S., and Brooks, K. N. (Eds.), Peatland biogeochemistry and watershed hydrology at the Marcell Experimental Forest (pp. 193-212). Boca Raton, FL: CRC Press.
Verry, E. S., and Janssens, J. (2011). Geology, vegetation, and hydrology of the S2 bog at the MEF: 12,000 years in northern Minnesota. In Kolka, R. K., Sebestyen, S. D., Verry, E. S., and Brooks, K. N. (Eds.), Peatland biogeochemistry and watershed hydrology at the Marcell Experimental Forest (pp. 93-134). Boca Raton, FL: CRC Press.
Wassenaar, L. I., Coplen, T., and Aggarwal, P. K. (2014). Approaches for achieving long-term accuracy and precision of d18O and d2H for waters analyzed using laser absorption spectrometers. Environmental Science and Technology, 48(2), 1123-1131. https://doi.org/10.1021/es403354n
Wilson, R. M., Hopple, A. M., Tfaily, M. M., Sebestyen, S. D., Schadt, C. W., Pfeifer-Meister, L., Medvedeff, C. A., McFarlane, K. J., Kostka, J. E., Kolton, M., Kolka, R. K., Kluber, L. A., Keller, J. K., Guilderson, T. P., Griffiths, N. A., Chanton, J. P., Bridgham, S. D., and Hanson, P. J. (2016), Stability of peatland carbon to rising temperatures, Nature Communications, 7, 13723. https://doi.org/10.1038/ncomms13723
