7-component PARAFAC model, dataset, and matlab code of aquatic dissolved organic matter composition in North American Great Lakes Region

DOM UV-visible absorbance and fluorescence characteristics were determined for 971 samples collected from a variety of surface water locations throughout the Great Lakes Region and Southern Ontario & Quebec Regions of North America.

Included in this repository

• The final saved Matlab data project for the model (11Jan2010Model7Ex250Em300AllData.mat)
• The original EEMs read into Matlab (OriginalData.mat & matlab.mat)
• The EEMs after removal of specific wavelengths and samples (CutData.mat)
• The split-half validation of the full model (SplitHalfTest1.mat)
• The Output of the full model and split-half validation (Model7Ex250Em300AllData_ResultsOutput.xlsx
  SpiltHalfValidation_FinalModel7.xls) &
• Contour plot images of the full model

Data used to construct the original parallel factor analysis model (PARAFAC) were treated as follows:

• Light absorbance was measured from 800 to 230 nm using a lambda 25 Perkin Elmer spectrophotometer
• Fluorescence excitation emission matrix (EEM) scans were measured using a Varian Cary Eclipse fluorometer
• Scan were made from 230 to 500 by 5 nm excitation and 270 to 600 by 2 nm emission with a bandwidth of 5 nm and at a scanning interval of 0.25 seconds.
• EEMs were corrected fully for inner filter effects, Milli-Q background, blank subtracted and instrument bias following the recommendations of (Cory et al. 2010; Murphy et al. 2010).
• Relative fluorescence units were converted to Raman units using the area under the Milli-Q scatter peak at 350 nm excitation.

For Parallel factor analysis (PARAFAC) modeling

• The DOMFluorv1_7 toolbox in Matlab 2007b (Mathworks) was used for analysis following the PARAFAC tutorial of Stedmon and Bro (2008).
• • Note: DOMFluor is no longer compatible with current versions of Matlab and has been replaced by the drEEM toolbox
• DOM samples. Prior to modeling, EEMs were trimmed to 250–500 excitation and 300–600 emission, first-order scatter was removed, and outlier EEMs were deleted.
• The PARAFAC model was validated using split-half analysis and Tucker congruence.
• The model was originally published in Williams, C.J., P.C. Frost and M.A. Xenopoulos. 2013. Beyond best management practices: Pelagic biogeochemical dynamics in urban stormwater ponds. Ecological Applications 23: 1384-1395. and is published on OpenFluor as GreatLakesRegion to be compared with other PARAFAC models
• This model has been used in multiple manuscripts and used to fit over 2000 EEMs collected after the initial model generation
• • King, S.S.E., P.C. Frost, S.B. Watson, and M.A. Xenopoulos. Transitions in dissolved organic phosphorus and dissolved organic carbon across a river-lake transect.
  • Begum, Most S., M. Kadjeski, C. Fasching and M.A. Xenopoulos. Temporal variability of dissolved organic matter composition export in streams.
  • Klemet-N’Guessan, S., M. Taskovic, N.J.T. Pearce and M.A. Xenopoulos. Fine ecological scales highlight the nonlinear relationship of animal nutrient excretion with dissolved organic matter.
  • Pearce, N.J.T., J.H. Larson, M.A. Evans, S.W. Bailey, P.C. Frost, W.F. James, and M.A. Xenopoulos. 2023. Dissolved organic matter transformations in a freshwater rivermouth. Biogeochemistry https://doi.org/10.1007/s10533-022-01000-z
  • Williams, C.J., P.C. Frost, B. Ginn, D. Lembcke, J. Marsalek, and M.A. Xenopoulos. 2023. Add a dash of salt? Effects of road de-icing salt (NaCl) on benthic respiration and nutrient fluxes in freshwater sediments. Limnetica. DOI: 10.23818/limn.42.17
  • Pearce, N.J.T., Dyczko, J.M. and M.A. Xenopoulos. 2022. Carbon and nutrients regulate greenhouse gas fluxes from oxic stream sediments. Biogeochemistry 160: 275-287 https://doi.org/10.1007/s10533-022-00955-3
  • Pearce, N.J.T., J.H. Larson, M.A. Evans, P.C. Frost, and M.A. Xenopoulos. 2021. Episodic nutrient addition affects water column nutrient processing rates in river-to-lake transitional zones Journal of Geophysical Research: Biogeosciences 126: e2021JG006374; DOI: 10.1029/2021JG006374
  • Kadjeski, M., C. Fasching and M.A. Xenopoulos. 2020. Synchronous biodegradability and production of dissolved organic matter in two streams of varying land use. Frontiers in Microbiology 11: 568629 (doi: 10.3389/fmicb.2020.568629).
  • Larson, J.H., W.F. James, F.A. Fitzpatrick, P.C. Frost, M.A. Evans, P.C. Reneau, and M.A. Xenopoulos. 2020. Phosphorus, nitrogen and dissolved organic carbon fluxes from sediments in freshwater rivermouths entering Green Bay (Lake Michigan; USA). Biogeochemistry 147: 179-197.
  • Fasching, C., C. Akotoye, M. Bižić-Ionescu, J. Fonvielle, D. Ionescu, S. Mathavarajah, L. Zoccarato, D.A. Walsh, H.-P. Grossart and M.A. Xenopoulos. 2020. Linking stream microbial community functional genes to dissolved organic matter and inorganic nutrients. Limnology and Oceanography. 65: S71-S87.
  • D’Amario, S.C., D.C. Rearick, C. Fasching, S. Kembel, E. Porter-Goff, D. Spooner, C.J. Williams, H.F. Wilson and M.A. Xenopoulos. 2019. The prevalence of non-linearity and detection of ecological thresholds across a land use gradient. Scientific Reports 9: 3878 (DOI: 10.1038/s41598-019-40349-4).
  • Williams, C.J., P.C. Frost, A.M. Morales-Williams, J.H. Larson, W.B. Richardson, A.S. Chiandet and M.A. Xenopoulos. 2016. Human activities cause distinct dissolved organic matter composition across freshwater ecosystems. Global Change Biology 22: 613-626.
  • Larson, J.H., P.C. Frost, M.A. Xenopoulos, C.J. Williams, A.M. Morales-Williams, J. Vallazza, J.C. Nelson and W.B. Richardson. 2014. Relationships between land cover and dissolved organic matter change along the river to lake transition. Ecosystems 17: 1413-1425
  • Williams, C.J., J.E. Van Eindhoven, E. Theberge, and M.A. Xenopoulos. 2014. Effects of golf course facilities on stream function in anthropogenically impacted streams. Anthropocene 3: 51-60.