Earth Scientist, Team Leader

1529 West Sequim Bay Road
Sequim, WA 98382

Earth Scientist, Team Leader

1529 West Sequim Bay Road
Sequim, WA 98382


Nick Ward studies how terrestrial and aquatic ecosystems function and interact across the continuum of land, inland waters, the ocean, and the atmosphere. He primarily focuses on carbon as the currency that gets exchanged across this continuum and seeks to understand how the flow of water, productivity of plants, and cycling of nutrients and redox sensitive species collectively mediate these carbon exchanges. A major goal of this research is establishing a baseline understanding of how ecosystems function naturally, which is needed to predict the influence of disturbances and human activities on hydrological, biogeochemical, and ecological processes. More information about his research can be found here:

Research Interest

  • Biogeochemical cycling
  • Ecosystem dynamics, sensitivity, and resilience
  • Sustainable natural resource management
  • Hydrology and hydrodynamics


  • PhD in Chemical Oceanography, University of Washington
  • MS in Chemical Oceanography, University of Washington
  • BS in Environmental Systems (Earth Science), University of California San Diego

Affiliations and Professional Service

  • Faculty Fellow, University of Washington, School of Oceanography
  • Associate Editor, Marine Chemistry
  • Associate Editor, PLOS One
  • American Association for the Advancement of Science
  • American Geophysical Union
  • Association for the Sciences of Limnology and Oceanography
  • Geochemical Society



  • Johnson, P., S. Merle, T. Bjorklund, S. Hautala, T. Baumberger, S. Walker, J. Liu, N.D. Ward, and C. Wang. 2022. "Methane Plume Emissions Associated With Puget Sound Faults in the Cascadia Forearc." Geochemistry, Geophysics, Geosystems 23 (1): Art. No. e2021GC010211. PNNL-SA-166987.
  • Richey, J.E., R.G. Spencer, T. Drake, and N.D. Ward. 2022. “Fluvial carbon dynamics across the land to ocean continuum of great tropical rivers: the Amazon and Congo.” In Congo Basin Hydrology Climate and Biogeochemistry: A Foundation for the Future. PNNL-SA-151991.
  • Wang, W., P. Zhang, H. Zhang, C. Grossiord, S.C. Pennington, M.J. Norwood, W. Li, A.L. Pivovaroff, L. Fernández-de-Uña, R. Leff, S.B. Yabusaki, S.R. Waichler, V. Bailey, N.D. Ward, and N. McDowell. 2022. “Severe declines in hydraulic capacity and associated carbon starvation drive mortality in seawater exposed Sitka-spruce (Picea sitchensis) trees.” Environmental Research Communications. PNNL-SA-171334.


  • Indivero J.L., A.N. Myers-Pigg, and N.D. Ward. 2021. "Seasonal changes in the drivers of water physico-chemistry variability of a small freshwater tidal river." Frontiers in Marine Science 8. PNNL-SA-146165.
  • Less D., N.D. Ward, J.E. Richey, and A. Cunha. 2021. “Seasonal and Daily Variation of Hydrodynamic Conditions in the Amazon River Mouth: Influence of Discharge and Tide on Flow Velocity.” Journal of Coastal Research 37 (6): 1181-1192. PNNL-SA-163631.
  • Li W., H. Zhang, W. Wang, P. Zhang, N.D. Ward, M.J. Norwood, A.N. Myers-Pigg, C. Zhao, R. Leff, S. Yabusaki, S. Waichler, V.L. Bailey, and N.G. McDowell. 2021. “Changes in carbon and nitrogen metabolism during seawater-induced mortality of Picea sitchensis trees.” Tree Physiology 41 (12): 2326-2340. PNNL-SA-156535.
  • Norwood, M.J., N.D. Ward, N.G. McDowell, A.N. Myers-Pigg, B. Bond-Lamberty, J.L. Indivero, S.C. Pennington, W. Wang, M.L. Kirwan, A.M. Hopple, and P. Megonigal. 2021. "Coastal forest seawater exposure increases stem methane concentration." Journal of Geophysical Research: Biogeosciences 126 (2): e2020JG005915. PNNL-SA-151190.
  • Regier, P.J., N.D. Ward, J.L. Indivero, C.A. Wiese Moore, M.J. Norwood, and A.N. Myers-Pigg. 2021. “Biogeochemical control points of connectivity between a tidal creek and its floodplain.” Limnology and Oceanography Letters. PNNL-SA-157526.
  • Sawakuchi, H.O., D. Bastviken, A. Enrich-Prast, N.D. Ward, P. Camargo, and J.E. Richey. 2021. "Low diffusive methane emissions from the main channel of a large Amazonian run-of-the-river reservoir attributed to high methane oxidation." Frontiers in Environmental Science 9. PNNL-SA-160843.
  • Sengupta, A., J.C. Stegen, B. Bond-Lamberty, A. Rivas-Ubach, J. Zheng, P. Handakumbura, C.G. Norris, M.J. Peterson, S.B. Yabusaki, V.L. Bailey, and N.D. Ward. 2021. "Antecedent conditions determine the biogeochemical response of coastal soils to seawater exposure." Soil Biology and Biochemistry 153. PNNL-SA-154783.
  • Tagestad, J.D., N.D. Ward, D. Butman, and J.C. Stegen. 2021. "Small Streams Dominate US Tidal Reaches and Will be Disproportionately Impacted by Sea-level Rise." Science of the Total Environment 753. PNNL-SA-145873.
  • Valerio, A., M. Kampel, N.D. Ward, H.O. Sawakuchi, A. Cunha, and J.E. Richey. 2021. "CO2 partial pressure and fluxes in the Amazon River Plume using in situ and remote sensing data." Continental Shelf Research 215. PNNL-SA-134274.
  • Valerio, A., M. Kampel, V. Vantrepotte, N.D. Ward, and J.E. Richey. 2021. "Optical classification of Lower Amazon waters based on in situ data and Sentinel-3 Ocean and Land Color Instrument imagery." Remote Sensing 13 (16): 3057. PNNL-SA-162771.
  • Zhang, H., X. Li, W. Wang, A.L. Pivovaroff, W. Li, P. Zhang, and N.D. Ward, A. Myers-Pigg, H.D. Adams, R. Leff, A. Wang, F. Yuan, J. Wu, S. Yabusaki, S. Waichler, V.L. Bailey, D. Guan, and N. McDowell. 2021. "Seawater exposure causes hydraulic damage in dying Sitka-spruce trees." Plant Physiology 187 (2): 873-885. PNNL-SA-156527.
  • Zhang, P., N.G. McDowell, X. Zhou, W. Wang, R.T. Leff, A.L. Pivovaroff, H. Zhang, P.S. Chow, N.D. Ward, J. Indivero, S.B. Yabusaki, S. Waichler, V.L. Bailey. 2021. "Declining carbohydrate content of Sitka-spruce trees dying from seawater exposure." Plant Physiology 185 (4): 1682-1696. PNNL-SA-156500.


  • da Silva, G., C. de Abreu, N.D. Ward, L.P. Belucio, D. Brito, H. Cunha, and A.C. da Cunha. 2020. “Environmental impacts of dam reservoir filling in the East Amazon.” Frontiers in Water 2. PNNL-SA-136441.
  • Schafer, T., N.D. Ward, P. Julian, K. Reddy, and T. Osborne. 2020. "Impacts of hurricane disturbance on water quality across the aquatic continuum of a black-water river to estuary complex." Journal of Marine Science and Engineering 8 (6): Article No. 412. PNNL-SA-137849.
  • Wang, W., N.G. McDowell, S.C. Pennington, C. Grossiord, R.T. Leff, A. Sengupta, N.D. Ward, U.U. Sezen, R. Rich, J.P. Megonigal, J. Patrick, J.C. Stegen, B. Bond-Lamberty, and V. Bailey. 2020. "Tree growth, transpiration, and water-use efficiency between shoreline and upland red maple (Acer rubrum) trees in a coastal forest." Agricultural and Forest Meteorology 295. PNNL-SA-153708.
  • Ward, N.D., J.L. Indivero, C.M. Gunn, W. Wang, V.L. Bailey, and N.G. McDowell. 2020. Longitudinal gradients in tree stem greenhouse gas concentrations across six Pacific Northwest coastal forests. PNNL-30257. Richland, WA: Pacific Northwest National Laboratory.
  • Ward, N.D., P. Megonigal, B. Bond-Lamberty, V.L. Bailey, D. Butman, E.A. Canuel, H.L. Diefenderfer, N.K. Ganju, M.A. Goñi, E.B. Graham, C.S. Hopkinson, T. Khangaonkar, J.A. Langley, N.G. McDowell, A.N. Myers-Pigg, R.B. Neumann, C.L. Osburn, R.M. Price, J. Rowland, A. Sengupta, M. Simard, P.E. Thornton, M. Tzortziou, R. Vargas, P.B. Weisenhorn, and L. Windham-Myers. 2020. "Representing the Function and Sensitivity of Coastal Interfaces in Earth System Models." Nature Communications 11. PNNL-SA-147328.
  • Ward, N.D., T.S. Bianchi, J. Martin, C. Quintero, H.O. Sawakuchi, and M. Cohen. 2020. "Pathways for methane emissions and oxidation that influence the net carbon balance of a subtropical cypress swamp." Frontiers in Earth Science 8. PNNL-SA-150215.
  • Yabusaki S.B., A.N. Myers-Pigg, N.D. Ward, S.R. Waichler, A. Sengupta, Z. Hou, X. Chen, Y. Fang, Z. Duan, J.A. Serkowski, J. Indivero, C. Wiese Moore, C.M. Gunn. 2020. "Floodplain inundation and salinization from a recently restored first-order tidal stream." Water Resources Research 56 (7): Article No. e2019WR026850. PNNL-SA-149723.
  • Zayas-Santiago, C., A. Rivas-Ubach, L. Kuo, N.D. Ward, and R.C. Zimmerman. 2020. "Metabolic profiling reveals biochemical pathways responsible for eelgrass response to elevated CO2 and temperature." Scientific Reports 10 (1): Article No. 4693. PNNL-SA-142954.


  • Araujo, K., H.O. Sawakuchi, D. Bertassoli, A.O. Sawakuchi, K. da Silva, T.B. Vieira, N.D. Ward, and T.S. Pereir. 2019. "Carbon dioxide (CO2) concentrations and emission in the newly constructed Belo Monte hydropower complex in the Xingu River, Amazonia." Biogeosciences 16 (18): 3527-3542. PNNL-SA-140925.
  • Arellano A., T.S. Bianchi, C. Osburn, E. D'Sa, N.D. Ward, D. Oveido-Vargas, I. Joshi, D.S. Ko, M.R. Shields, G. Kurian, and J. Green. 2019. "Mechanisms of Organic Matter Export in Estuaries with Contrasting Carbon Sources." Journal of Geophysical Research: Biogeosciences 124 (10): 3168-3188. PNNL-SA-137885.
  • Bianchi, T.S. and N.D. Ward. 2019. "Editorial: The Role of Priming in Terrestrial and Aquatic Ecosystems." Frontiers in Earth Science 7. PNNL-SA-148208.
  • Bond-Lamberty, B., S.C. Pennington, J. Jian, P. Megonigal, A. Sengupta, and N.D. Ward. 2019. "Soil respiration variability and correlation across a wide range of temporal scales." Journal of Geophysical Research: Biogeosciences 124 (11): 3672-3685. PNNL-SA-143258.
  • Chamberlain, C., T.S. Bianchi, A. Brown, M. Cohen, X. Dong, M. Flint, J. Martin, D. Mclaughlin, A.B. Murray, N.D. Ward, M. Flint, and J. Heffernan. 2019. "Mass Balance Implies Holocene Development of a Low-Relief Karst Patterned Landscape." Chemical Geology 527. PNNL-SA-128697.
  • Coppola, A., M. Seidel, N.D. Ward, D. Viviroli, G. Nascimento, N. Haghipour, B.N. Revels, S. Abiven, M.W. Jones, J.E. Richey, T.I. Eglinton, T. Dittmar, and M.W.I. Schmidt. 2019. "Marked isotopic variability within and between the Amazon River and marine dissolved black carbon pools." Nature Communications 10 (1): Article Number 4018. PNNL-SA-144923.
  • Kuhn, C., A. Valerio, N.D. Ward, L. Loken, H.O. Sawakuchi, M. Kampel, J.E. Richey, P. Stadler, J. Crawford, R. Striegl, E. Vermote, N. Pahlevan, and D. Butman. 2019. "Performance of Landsat-8 and Sentinel-2 surface reflectance products for river remote sensing retrievals of chlorophyll-a and turbidity." Remote Sensing of Environment. PNNL-SA-141044.
  • Sengupta, A., J.L. Indivero, C.M. Gunn, M.M. Tfaily, R.K. Chu, J.G. Toyoda, V.L. Bailey, N.D. Ward, and J.C. Stegen. 2019. "Spatial gradients in the characteristics of soil-carbon fractions are associated with abiotic features but not microbial communities." Biogeosciences 16 (19): 3911–3928. PNNL-SA-143361.
  • Valerio, A., M. Kampel, V. Vantrepotte, N.D. Ward, H.O. Sawakuchi, D. Less, V. Neu, A. Cunha, J.E. Richey. 2019. "Algoritmo regional para estimativa do material particulado em suspensao no baixo Amazonas." In Proceedings of XIX Brazilian Symposium on Remote Sensing, April 14–17, 2019, Santos, Sao Paulo, Brazil, 17: 636–639. PNNL-SA-138628.
  • Wang, W., N.G. McDowell, N.D. Ward, J.L. Indivero, C.M. Gunn, and V.L. Bailey. 2019. "Constrained tree growth and gas-exchange of seawater-exposed forests in the Pacific Northwest, USA." Journal of Ecology 107 (6):2541-2552. PNNL-SA-144278.
  • Ward, N.D., E. Morrison, Y. Liu, A. Rivas-Ubach, T. Osborne, A. Ogram, and T.S. Bianchi. 2019. "Marine microbial community responses related to wetland carbon mobilization in the coastal zone." Limnology and Oceanography: Letters 4 (1): 25–33. PNNL-SA-134462.
  • Ward, N.D., H.O. Sawakuchi, J.E. Richey, R.G. Keil, and T.S. Bianchi. 2019. "Enhanced aquatic respiration associated with mixing of clearwater tributary and turbid Amazon River waters." Frontiers in Earth Science 7. PNNL-SA-140620.
  • Ward, N.D., J.L. Indivero, C.M. Gunn, W. Wang, V.L. Bailey, and N.G. McDowell. 2019. "Longitudinal gradients in tree stem greenhouse gas concentrations across six Pacific Northwest coastal forests." Journal of Geophysical Research: Biogeosciences 124 (6): 1401–1412. PNNL-SA-138892.
  • Zhang, X., T.S. Bianchi, M. Cohen, J. Martin, C. Quintero, A. Brown, and A. Ares, et al. 2019. "Initiation and development of wetlands in southern Florida karst landscape associated with accumulation of organic matter and vegetation evolution." Journal of Geophysical Research: Biogeosciences 124 (6): 1604–1617. PNNL-SA-136524.


  • Dong, X., M. Cohen, J. Martin, D. Mclaughlin, A. Murray, N.D. Ward, M. Flint, and J.B. Heffernan. 2018. "Ecohydrologic processes and soil thickness feedbacks control limestone-weathering rates in a karst landscape." Chemical Geology 527 (2019): Article No. 118774. PNNL-SA-132178.
  • Galeron, M., O. Radakovitch, B. Charrière, F. Vaultier, J. Volkman, T.S. Bianchi, N.D. Ward, H.O. Sawakuchi, S. Tank, P. Kerhervé, and J.F Rontani. 2018. "Lipoxygenase-induced autoxidative degradation of terrestrial particulate organic matter in estuaries: A widespread process enhanced at high and low latitude." Organic Geochemistry 115. PNNL-SA-130078.
  • Valerio, A., M. Kampel, V. Vantrepotte, N.D. Ward, H.O. Sawakuchi, D. Less, V. Neu, A. Cuha, and J. Richey. 2018. "Using CDOM optical properties for estimating DOC concentrations and pCO2 in the Lower Amazon River." Optics Express 26 (14): A657–A677. PNNL-SA-131638.
  • Ward, N.D., H.O. Sawakuchi, and J.E. Richey. 2018. "The Amazon River's Ecosystem-Where Land Meets the Sea." Eos 99, January 18, 2018. PNNL-SA-128535.
  • Ward, N.D., H.O. Sawakuchi, V. Neu, D. Less, A. Valerio, A. Cunha, M. Kampel,  T.S. Bianchi, A.V. Krusche, J.E. Richey, and R.G. Keil. 2018. "Velocity-amplified microbial respiration rates in the lower Amazon River." Limnology and Oceanography: Letters 3 (3):265-274. PNNL-SA-123173.


  • Bianchi, T.S., D. Butman, P.A. Raymond, N.D. Ward, R. Kates, K. Flessa, H. Zamora, A.R. Arellano, J. Ramirez, and E. Rodriguez. 2017. "The Experimental Flow to the Colorado River Delta: Effects on Carbon Mobilization in a Dry Watercourse." Journal of Geophysical Research: Biogeosciences 122 (3): 607–327. PNNL-SA-124474.
  • Doherty, M., P. Yager, M. Moran, V. Coles, C.S. Fortunato, A. Krusche, P.M. Medeiros, J.P. Payet, J.E. Richey, B.M. Satinksy, H.O. Sawakuchi, N.D. Ward, and B.C. Crump. 2017. "Bacterial biogeography across the Amazon river-ocean continuum." Frontiers in Microbiology 8. PNNL-SA-125962.
  • Duan, S., Y. He, S.S. Kaushal, T.S. Bianchi, N.D. Ward, and L. Guo. 2017. "Impact of wetland decline on decreasing dissolved organic carbon concentrations along the Mississippi River continuum." Frontiers in Marine Science 3. PNNL-SA-124217.
  • Gagne-Maynard, W., N.D. Ward, R.G. Keil, H.O. Sawakuchi, A. Cunha, V. Neu, D. Brito, D.F. Da Silva Less, J.E.M. Diniz, A. DeMatos Valerio, M. Kampel, A.V. Krusche, and J.E. Richey. 2017. "Evaluation of primary production in the lower Amazon River based on a dissolved oxygen stable isotopic mass balance." Frontiers in Marine Science 4. PNNL-SA-123464.
  • Joshi, I., E. D'Sa, C. Osburn, T.S. Bianchi, D. Ko, D. Oveido-Vargas, A. Arellano, and N.D. Ward. 2017. "Assessing chromophoric dissolved organic matter (CDOM) distribution, stocks, and fluxes in Apalachicola Bay using combined field, VIIRS ocean color, and model observations." Remote Sensing of Environment 191. PNNL-SA-124218.
  • Satinsky, B., C. Smith, S. Sharma, N.D. Ward, A. Krusche, J.E. Richey, P. Yager, B.C. Crump, and M.A. Moran. 2017. "Patterns of Bacterial and Archaeal Gene Expression Through the Lower Amazon River." Frontiers in Marine Science 4. PNNL-SA-128662.
  • Sawakuchi, H.O., V. Neu, N.D. Ward, M.C. Barros, A. Valerio, W. Gagne-Maynard, A. Cunha, D.F.S. Less, J.E.M. Diniz, D.C.Brito, A.V. Krusche, and J. Richey. 2017. "Carbon dioxide emissions along the lower Amazon River." Frontiers in Marine Science 4. PNNL-SA-124475.
  • Silva, B., F. Coutinho, G. Gregoracci, L. Leomil, L. Oliveira, A. Fróes, D. Tschoeke, A.C. Soares, A.S. Cabral, N.D. Ward, J.E. Richey, A.V. Krusche, P.L. Yager, C. E. de Rezende, C.C. Thompson, and F.L. Thompson. 2017. "Virioplankton assemblage structure in the lower river and ocean continuum of the Amazon." mSphere 2 (5): e00366-17. PNNL-SA-128630.
  • Ward, N.D. 2017. "Editorial: Integrative Research on Organic Matter Cycling Across Aquatic Gradients." Frontiers in Marine Science 4. PNNL-SA-124200.
  • Ward, N.D., T.S. Bianchi, P.M. Medeiros, M. Seidel, J.E. Richey, R.G. Keil, and H.O. Sawakuchi. 2017. "Where carbon goes when water flows: Carbon cycling across the aquatic continuum." Frontiers in Marine Science 4. PNNL-SA-122717.
  • Ward, N.D., T.S. Bianchi, P.M. Medeiros, M. Seidel, R.G. Keil, and C. Robinson. 2017. Integrative Research on Organic Matter Cycling Across Aquatic Gradients. Lausanne: Frontiers Media SA. PNNL-SA-127485.

Selected Publications


  • Neu, V., N.D. Ward, A.V. Krusche, and C. Neill. 2016. “Dissolved organic and inorganic carbon flow paths in an Amazonian transitional forest.” Frontiers in Marine Science 3 (114).
  • Sawakuchi, H.O., D. Bastviken, A.O. Sawakuchi, N.D. Ward, C. Borges, S.M. Tsai, J.E. Richey, M.V.R. Ballester, and A.V. Krusche. 2016. “Oxidative mitigation of methane evasion in large Amazonian rivers.” Global Change Biology 22 (3): 1075–1085.
  • Seidel, M., T. Dittmar, N.D. Ward, A.V. Krusche, J.E. Richey, P.L. Yager,  and P.M. Medeiros. 2016. “Seasonal and spatial variability of dissolved organic matter in the lower Amazon River.” Biogeochemistry 131 (3): 281–302.
  • Ward, N.D., T.S. Bianchi, H.O. Sawakuchi, W. Gagne-Maynard, A.C. Cunha, D.C. Brito, V. Neu, A.M. Valerio, R. da Silva, A.V. Krusche, J.E. Richey, and R.G. Keil. 2016. “The reactivity of plant-derived organic matter and the potential importance of priming effects in the lower Amazon River.” Journal of Geophysical Research: Biogeosciences 121: 1522–1539.


  • Bianchi, T.S., D. Thornton, S. Yvon-Lewis, G. King, T. Eglinton, M. Shields, N.D. Ward, and J Curtis. 2015. “Positive priming of terrestrially-derived dissolved organic matter in a freshwater microcosm system.” Geophysical Research Letters 42 (13): 5460–5467.
  • Medeiros, P.M., M. Seidel, N.D. Ward, E.J. Carpenter, H.R. Gomes, J. Niggemann, A.V. Krusche, J.E. Richey, P.L. Yager, and T. Dittmar. 2015. “Fate of Amazon River dissolved organic matter in the Tropical Atlantic Ocean.” Global Biogeochemical Cycles 29 (5): 677–690.
  • Satinsky, B.M., C.S. Fortunato, M. Doherty, C.B. Smith, S. Sharma, J.E. Richey, N.D. Ward, A.V. Krusche, M.A. Moran, and B.C. Crump. 2015. “Metagenomic and metatranscriptomic inventories of the Amazon River, May 2011.” Microbiome 3 (39).
  • Seidel, M., P.L. Yager, N.D. Ward, E.J. Carpenter, H.R. Gomes, C.E. de Rezende, A.V. Krusche, J.E. Richey, T. Dittmar, and P.M. Medeiros. 2015. “Molecular level transformations of dissolved organic matter in the river to ocean continuum of the Amazon.” Marine Chemistry 177 (2): 218–231.
  • Ward, N.D. and R.J. Petrik-Finley. 2015. “Integrating local environmental research into an inquiry-based unit on biogeochemical principles in a high school science classroom.” The Earth Scientist-NESTA 31 (2): 21–28.
  • Ward, N.D., A.V. Krusche, H.O. Sawakuchi, D.C. Brito, A.C. Cunha, J.M.S. Moura, R. da Silva, P.L. Yager, R.G. Keil, and J.E. Richey. 2015. “The compositional evolution of dissolved and particulate organic matter along the lower Amazon River-Óbidos to the ocean.” Marine Chemistry 177 (2): 244–256.


  • Ward, N.D., R.J. Finley, R.G. Keil, and T.G. Clay. 2013. “Benefits and limitations of iPads in the high school science classroom and a trophic cascade lesson plan.” Journal of Geoscience Education 61(4): 378–384. 
  • Ward, N.D., R.G. Keil, P.M. Medeiros, D.C. Brito, A.C. Cunha, T. Dittmar, P.L. Yager, A.V. Krusche, and J.E. Richey. 2013. “Degradation of terrestrially derived macromolecules in the Amazon River.” Nature Geoscience 6 (7): 530–533.


  • Ward, N.D., R.G. Keil, and J.E. Richey. 2012. “Temporal variation in river nutrient and dissolved lignin phenol concentrations and the impact of storm events on nutrient loading to Hood Canal, Washington, USA.” Biogeochemistry 111 (1–3): 629–645.