peer-reviewed publications

 

*indicates postdoc, graduate, or undergraduate advisee

  1. Katz, S.D., Osterholz, H., *Barton, R., Druffel, E.R.M., Gao, X., Masiello, C.A., Santin, C., Serafim, T.S.G., Wagner, S., Zabel, M., Lohmann, R. (2025) Changes in pyrogenic tracers over the last 15,000 years in the Congo River catchment through multi‐method analysis. Journal of Geophysical Research: Biogeosciences doi.org/10.1029/2025JG008772

  2. Giggy, L., *Barton, R., Wagner, S., Zimmer, M. (2025). Distinct streamflow and nutrient export dynamics in wildfire‐impacted nonperennial streams in central coastal California. Journal of Geophysical Research: Biogeosciences doi.org/10.1029/2024JG008553

  3. Slentz, A.E., McKenna, A.M., Kellerman, A.M., Holt, A.D., Burns, A.J., *Miller, M.G., Wagner, S., Tzortziou, M., Smith, H., Mannino, A., Chanton, J.P., Spencer, R.G.M. (2025) Signatures of Arctic change: Molecular‐level composition and bioavailability of shifting dissolved organic matter sources. Journal of Geophysical Research: Biogeosciences doi.org/10.1029/2025JG008899

  4. *Collins, A., *Hubbard, J., Wagner, S. (2025) Hydrologic management convolutes expected spatiotemporal patterns of dissolved organic matter in the Hudson River. Journal of Geophysical Research: Biogeosciences doi.org/10.1029/2024JG008131

  5. Holt, A.D., *Barton, R., Wagner, S., McKenna, A.M., Fellman, J., Hood, E., Battin, T.I., Hannes, P., Vanishing Glaciers Field Team, Spencer, R.G.M. (2025) Widespread black carbon deposition of varied origin exported from glaciers. Global Biogeochemical Cycles doi.org/10.1029/2024GB008359

  6. Brown, E., Wagner, S., Hunt, B.P.V. (2025) Interplay of seasonal hydrology and landscape topography drives black carbon export in the Fraser River. Journal of Geophysical Research: Biogeosciences doi.org/10.1029/2024JG008627

  7. Myers-Pigg, A. Grieger, S., Roebuck, J.A., Barnes, M.E., Bladon, K.D., Bailey, J.D., *Barton, R., Chu, R.K., Graham, E.B., Homolka, K.K., Kew, W., Lipton, A.S., Scheibe, T., Toyoda, J.G., Wagner, S. (2024) Experimental open air burning of vegetation enhances organic matter chemical heterogeneity compared to laboratory burns. Environmental Science and Technology doi.org/10.1021/acs.est.3c10826

  8. Bambakidis, T., Crump, B.C., Yoon, B., Kyzivat, E., Aho, K.S., Leal, C.F., Fair, J.H., Stubbins, A., Wagner, S., Raymond, P.A., Hosen, J.D. (2024) Temperature, water travel time, and dissolved organic matter structure river microbial communities in a large temperate watershed. Limnology and Oceanography doi:10.1002/lno.12591

  9. *Goranov, A.I., Swinton, M.W., Winkler, D.A., Farrell, J.L., Nierzwicki-Bauer, S.A., Wagner, S. (2024) Assessing the spatiotemporal variability of dissolved organic matter fluorescence characteristics in the Lake George, NY watershed. Biogeochemistry doi.org/10.1007/s10533-024-01147-x

  10. *Barton, R., *Winston, I., Wagner, S. (2024) The presence of free benzenepolycarboxylic acids (BPCAs) may result in the overestimation of dissolved black carbon in aqueous samples. Organic Geochemistry 190, 104765. doi.org/10.1016/j.orggeochem.2024.104765

  11. Richardson, C., Montalvo, M., Wagner, S., *Barton, R., Paytan, A., Redmond, M., Zimmer, M. (2024) Exploring the complex effects of wildfire on stream water chemistry: Insights from concentration-discharge relationships. Water Resources Research doi:10.1029/2023WR034940

  12. *Barton, R., Richardson, C., *Pae, E., Montalvo, M., Redmond, M., Zimmer, M., Wagner, S. (2023) Hydrology, rather than wildfire burn extent, determines post-fire organic and black carbon export from mountain rivers in central coastal California. Limnology and Oceanography Letters doi.10.1002/lol2.10360

  13. Bisson, K., Gasso, S., Mahowald, N., Wagner, S., Koffman, B., Carn, S., Gazel, E., Kramer, S., Krotkov, N., Mitchell, C., Pritchard, M., Stamieszkin, K., Wilson, C. (2023) Observing ocean ecosystem responses to volcanic ash. Remote Sensing of Environment 296, 113749. doi.org/10.1016/j.rse.2023.113749

  14. Coppola, A.I., Wagner, S., Lennartz, S.T., Seidel, M., Ward, N., Dittmar, T., Santin, C., Jones, M. (2022) The black carbon cycle and its role in the Earth system. Nature Reviews Earth and Environment doi.org/10.1038/s43017-022-00316-6

  15. *Barton, R., Wagner, S. (2022) Measuring dissolved black carbon in water via aqueous, inorganic, high-performance liquid chromatography of benzenepolycarboxylic acid (BPCA) molecular markers. PLoS ONE 17, e0268059. doi.org/10.1371/journal.pone.0268059

  16. Holt, A., Kellerman, A., Li, W., Stubbins, A., Wagner, S., McKenna, A., Fellman, J., Hood, E., Spencer, R.G.M. (2021) Assessing the role of photochemistry in driving the composition of dissolved organic matter in glacier runoff. Journal of Geophysical Research: Biogeosciences 126, e2021JG006516. doi.org/10.1029/2021JG006516

  17. *Goranov, A.I., Schaller, M. F., Long, J.A., Podgorski, D.C., Wagner, S. (2021) Characterization of asphaltenes and petroleum using benzenepolycarboxylic acids and compound-specific stable carbon isotopes. Energy and Fuels doi.org/10.1021/acs.energyfuels.1c02374

  18. Bauters, M., Drake, T., Wagner, S., Baumgartner, S., Makelele, I., Bode, S., Verheyen, K., Verbeeck, H., Ewango, C., Ntaboba, L.C., Van Oost, K., Boeckx, P. (2021) Fire-derived phosphorus fertilization of African tropical forests. Nature Communications 12, 5129. doi.org/10.1038/s41467-021-25428-3

  19. Wagner, S., Harvey, E., Baetge, N., McNair, H., Arrington, E., Stubbins, A. (2021) Investing atmospheric inputs of dissolved back carbon to the Santa Barbara Channel during the Thomas Fire (California, USA). Journal of Geophysical Research: Biogeosciences 126, e2021JG006442. doi.org/10.1029/2021JG006442

  20. Wagner, S., Coppola, A.I., Stubbins, A., Dittmar, T., Niggemann, J., Drake, T.W., Seidel, M., Spencer, R.G.M., Bao, H. (2021) Questions remain about the biolability of dissolved black carbon along the combustion continuum. Nature Communications 12, 4281. doi.org/10.1038/s41467-021-24477-y

  21. Podgorski, D.C., Zito, P., Kellerman, A.M., Bekins, B.A., Cozzarelli, I.M., Smith, D.F., Cao, X., Schmidt-Rohr, K., Wagner, S., Stubbins, A., Spencer, R.G.M. (2021) Hydrocarbons to carboxyl-rich alicyclic molecules: A continuum model to describe biodegradation of petroleum-derived dissolved organic matter in contaminated groundwater plumes. Journal of Hazardous Materials 402, doi.org/10.1016/j.jhazmat.2020.123998

  22. Drake, T.W., Wagner, S., Stubbins, A., Wabakanghanzi, J.N., Dinga, J.B., Six, J., Spencer, R.G.M. (2020) Du feu à l'eau: Source and flux of dissolved black carbon from the Congo River. Global Biogeochemical Cycles 34, e2020GB006560. doi.org/10.1029/2020GB006560

  23. Wagner, S., Schubotz, F., Kaiser, K., Hallmann, C., Waska, H., Rossel, P.E., Hansman, R., Elvert, M., Middelburg, J.J., Engel, A., Blattmann, T.M., Catalá, T.S., Lennartz, S.T., Gomez-Saez, G.V., Pantoja-Gutiérrez, S., Bao, R., Galy, V. (2020) Soothsaying DOM: A current perspective on the future of oceanic dissolved organic carbon. Frontiers in Marine Science 7:341. doi:10.3389/fmars.2020.00341

  24. Bisson, K., Baetge, N., Kramer, S.J., Catlett, D., Girling, G., McNair, H., Arrington, E., Hayes, D., Jacobs, C., James, A., Closset, A., Fischer, A.D., Wagner, S., Reading, M., Comstock, J., Amiri, S., Harvey, E., Carlson, C., Gaube, P., Drushka, K., Valentine, D.L. (2020) California wildfire burns boundaries between science and art. Oceanography 33:16–19. doi.org/10.5670/oceanog.2020.110

  25. Wagner, S., Brantley, S., Stuber, S., Van Stan, S., Whitetree, A., Stubbins, A. (2019) Dissolved black carbon in throughfall and stemflow in a fire-managed longleaf pine woodland. Biogeochemistry 146:191–207. doi.org/10.1007/s10533-019-00620-2

  26. Wagner, S., Brandes, J., Spencer, R.G.M., Ma, K., Rosengard, S.Z., Moura, J.M.S., Stubbins, A. (2019) Isotopic composition of oceanic dissolved black carbon reveals non-riverine source. Nature Communications 10. doi:10.1038/s41467-019-13111-7

  27. Wagner, S., Fair, J.H., Matt, S., Hosen, J., Raymond, P., Saiers, J., Shanley, J.B., Dittmar, T., Stubbins, A. (2019) Molecular hysteresis: Hydrologically driven changes in riverine dissolved organic matter chemistry during a storm event. Journal of Geophysical Research: Biogeosciences 123. doi.org/10.1029/2018JG004817

  28. Wagner, S., Jaffé, R., Stubbins, A. (2018) Dissolved black carbon in aquatic ecosystems. Limnology and Oceanography: Letters doi:10.1002/lol2.10076

  29. Wagner, S., Brandes, S., Goranov, A., Drake, T.W., Spencer, R.G.M., Stubbins, A. (2017) Online quantification and compound-specific stable isotopic analysis of black carbon in environmental matrices via liquid chromatography-isotope ratio mass spectrometry. Limnology and Oceanography: Methods 15:995–1006. doi:10.1002/lom3.10219

  30. Wagner, S., Ding, Y., Jaffé, R. (2017) A new perspective on the apparent solubility of dissolved black carbon. Frontiers in Earth Science 5:75. doi:10.3389/feart.2017.00075

  31. Van Stan, J.T., Wagner, S., Guillemette, F., Whitetree, A., Lewis, J., Silva, L., Stubbins, A. (2017) Temporal dynamics in the concentration, flux, and optical properties of tree-derived dissolved organic matter (tree-DOM) in an epiphyte-laden oak-cedar forest. Journal of Geophysical Research: Biogeosciences 122:2982–2997. doi:10.1002/2017JG004111

  32. Santos, F., Wagner, S., Rothstein, D., Jaffé, R., Meisel, J. (2017) Impact of a historical fire event on pyrogenic carbon stocks and dissolved pyrogenic carbon in spodosols in Northern Michigan. Frontiers in Earth Science 5:80. doi:10.3389/feart.2017.00080

  33. Roebuck, J.A., Podgorski, D.C., Wagner, S., Jaffé, R. (2017) Photodissolution of charcoal and fire-impacted soil as a potential source of dissolved black carbon in aquatic environments. Organic Geochemistry 112:16–21. doi:10.1016/j.orggeochem.2017.06.018

  34. Khan, A., Wagner, S., Jaffé, R., Xian, P., Williams, M., Armstrong, R., McKnight, D. (2017) Dissolved black carbon in the global cryosphere: concentrations and chemical signatures. Geophysical Research Letters 44:6226–6234. doi:10.1002/2017GL073485

  35. Kaal, J., Wagner, S., Jaffé, R. (2016) Molecular properties of ultrafiltered dissolved organic matter and dissolved black carbon in headwater streams as determined by pyrolysis-GC-MS. Journal of Analytical and Applied Pyrolysis 118:181–191. doi:10.1016/j.jaap.2016.02.003

  36. Wagner, S., Jaffé, R., Cawley, K., Dittmar, T., Stubbins, A. (2015) Associations between the molecular and optical properties of dissolved organic matter in the Florida Everglades, a model coastal wetland system. Frontiers in Chemistry 3:66. doi:10.3389/fchem.2015.00066

  37. Wagner, S., Riedel, T., Niggemann, J., Vähätalo, A.V., Dittmar, T., Jaffé, R. (2015) Linking the molecular signature of heteroatomic dissolved organic matter to watershed characteristics in world rivers. Environmental Science and Technology 49:13798–13806. doi:10.1021/acs.est.5b00525

  38. Wagner, S., Jaffé, R. (2015) Effect of photodegradation on molecular size distribution and quality of dissolved black carbon. Organic Geochemistry 86:1–4. doi:10.1016/j.orggeochem.2015.05.005

  39. Wagner, S., Cawley, K.M., Rosario-Ortiz, F.L., Jaffé, R. (2015) In-stream sources and links between particulate and dissolved black carbon following a wildfire. Biogeochemistry 124:145–161. doi:10.1007/s10533-015-0088-1

  40. Wagner, S., Dittmar, T., Jaffé, R. (2015) Molecular characterization of dissolved black nitrogen by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry. Organic Geochemistry 79:21–30. doi:10.1016/j.orggeochem.2014.12.002

 

The Aluminum Nitric-acid Keg (TANK)

During oxidation of black carbon samples to produce benzenepolycarboxylic acids, pressure buildup within glass ampules can cause them to explode, resulting in sample loss, injury to ovens, or a "domino-effect" where breakage of one ampule shatters adjacent ones.

Here we provide schematics and detailed instructions for the manufacturing of The Aluminum Nitric-acid Keg, or TANK. This apparatus was designed to isolate individual samples during black carbon sample prep and to stop the domino-effect, decreasing sample loss and limiting the release of nitric acid fumes. Since it’s development, TANK also seems to reduce the occurrence of explosions overall, likely due to more consistent heating of samples in the aluminum block.

 
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Molecular Tales of Marine Dissolved Organic Matter

by *Evelyn Pae and Sasha Wagner

A zine about chemistry, adventure, and the deep blue sea! This story follows four molecules, who tell tales about their journey to the ocean. Scientists reveal and share the tales of these dissolved organic matter molecules to better understand the past, present, and future of biogeochemistry and carbon cycling on our planet.

The zine is freely available and can be viewed as an e-booklet or downloaded as a PDF file.

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CONTACT

Dr. Sasha Wagner

Rensselaer Polytechnic Institute

Department of Earth and Environmental Sciences

110 8th Street, Troy, NY 12180

Contact: wagnes3@rpi.edu