Bryan Downing

Biography

I am a research hydrologist at the USGS California Water Science Center, with a principal interest in studying aquatic organic matter (dissolved and particulate) and nutrients to better understand their impact on ecosystem functioning. My research involves the use of optical measurements (attenuation, absorbance, fluorescence and backscatter) to better understand complex biogeochemical cycling of organic matter and nutrients in rivers, estuaries and the coastal ocean. Measuring water quality using optical sensor technology represents a significant new direction in water quality research, where cycling of nutrients and organic matter can be measured in-situ, on time scales ranging from seconds to years. One of my study goals is to help provide enhanced optical instrumentation and methodologies, to improve real-time measurements of nitrate, phosphate, fluorescent dissolved organic matter (FDOM), algal pigments (chlorophyll-a and phycocyanin - a common blue-green algae proxy) and detection of harmful algal blooms (HABs). Currently, my colleagues and I have developed a boat based, high speed mapping system that measures transects of nutrients, WQ, stable water isotopes (δ2H, δ18O) with GPS location at sampling frequencies of 1Hz in real time. 

 

CURRENT PROJECTS

  • Interactions between physical processes, nutrient cycling and ecosystem functioning in the Sacramento-San Joaquin Delta
  • Water and particle properties as measures of habitat quality in the Sacramento-San Joaquin Delta
  • High-resolution mapping of water residence time using stable isotopes (δ2H, δ18O)
  • High speed mapping of water quality, water isotopes in the Lower South San Francisco Bay
  • Dynamics of zooplankton in the Cache Slough Complex
  • High-speed, high-resolution biogeochemical mapping in the SF Bay-Delta
  • Elucidating Physical and Biological Drivers of Fish Populations to Inform Management and Habitat Restoration Actions
  • Spatially explicit mapping of water residence time and water quality to determine effects of an emergency drought barrier
  • Nutrients and physics as drivers of production and aquatic habitat conditions in the SF Bay-Delta
  • Assessing Particle Quality on the Fly: a novel approach to in situ particle measurements

 

EDUCATION

2004 M.S., CA State University Sacramento, Hydrogeology/Geology.

2002 B.S., CA State University Sacramento, Geology.

 

PROFESSIONAL EXPERIENCE

2010-present: Research Hydrologist (RGE), USGS, CA Water Science Center, Sacramento, CA.

2002–2010: Hydrologist, USGS, CA Water Science Center, Sacramento, CA.

1999–2002: Student Hydrologist, USGS, CA Water Science Center, Sacramento, CA.

 

 

 

 

Publications:

Bergamaschi, B.A., Downing, B.D., Kraus, T.E.C., and Pellerin, B.A., 2017, Designing a high-frequency nutrient and biogeochemical monitoring network for the Sacramento–San Joaquin Delta, northern California: U.S. Geological Survey Scientific Investigations Report 2017–5058, 40 p., https://doi.org/10.3133/sir20175058.

Downing, B.D., Bergamaschi, B.A., and Kraus, T.E.C., 2017, Synthesis of data from high-frequency nutrient and associated biogeochemical monitoring for the Sacramento–San Joaquin Delta, northern California: U.S. Geological Survey Scientific Investigations Report 2017–5066, 28 p., https://doi.org/10.3133/sir20175066.

Kraus, T.E.C., Bergamaschi, B.A., and Downing, B.D., 2017, An introduction to high-frequency nutrient and biogeochemical monitoring for the Sacramento–San Joaquin Delta, northern California: U.S. Geological Survey Scientific Investigations Report 2017–5071, 41 p., https://doi.org/10.3133/sir20175071.

Kraus, T.E.C.,   K.D. Carpenter, B.A. Bergamaschi, A.E. Parker, E.B. Stumpner, B.D. Downing, N. M. Travis, F.P. Wilkerson, C. Kendall, and T.D. Mussen, 2017. A river-scale Lagrangian experiment examining controls on phytoplankton dynamics in the presence and absence of treated wastewater effluent high in ammonium. Limnology and Oceanography. doi: 10.1002/lno.10497

Downing, B.D., Bergamaschi, B.A., Kendall, C., Kraus, T.E.C., Dennis, K.J., Carter, J.A., & Von Dessonneck, T.S. 2016. Using Continuous Underway Isotope Measurements to Map Water Residence Time in Hydrodynamically Complex Tidal Environments. Environmental Science & Technology. doi:10.1021/acs.est.6b05745 https://pubs.acs.org/doi/abs/10.1021/acs.est.6b05745

Saraceno, J. F., Shanley, J. B., Downing, B. D., & Pellerin, B. A. (2017). Clearing the waters: Evaluating the need for site-specific field fluorescence corrections based on turbidity measurements. Limnology and Oceanography-Methods, 15(4), 408-416. doi:10.1002/lom3.10175 https://aslopubs.onlinelibrary.wiley.com/doi/abs/10.1002/lom3.10175

Byrd, K.B., Windham-Myers, L., Leeuw, T., Downing, B., Morris, J.T., & Ferner, M.C. 2016. Forecasting tidal marsh elevation and habitat change through fusion of Earth observations and a process model. Ecosphere, 7(11), e01582. doi:10.1002/ecs2.1582

Hansen, A.M., Kraus, T.E.C., Pellerin, B.A., Fleck, J.A., Downing, B.D., & Bergamaschi, B.A. 2016. Optical properties of dissolved organic matter (DOM): Effects of biological and photolytic degradation. Limnology and Oceanography, 61(3), 1015-1032. doi:10.1002/lno.10270

Fichot, C. G., Downing, B. D., Bergamaschi, B. A., Windham-Myers, L., Marvin-DiPasquale, M. C., Thompson, D. R., & Gierach, M. (2015). High-resolution remote sensing of water quality in the San Francisco Bay-Delta Estuary. Environ Sci Technol. doi:10.1021/acs.est.5b03518 [Download File]

Fleck, J. A., Gill, G., Bergamaschi, B. A., Kraus, T. E., Downing, B. D., and Alpers, C. N., 2014, Concurrent photolytic degradation of aqueous methylmercury and dissolved organic matter: Science of The Total Environment, v. 484, p. 263-275. http://dx.doi.org/10.1016/j.scitotenv.2013.03.107 [Link]

BA Pellerin, BA Bergamaschi, RJ Gilliom, CG Crawford, J Saraceno, CP Frederick, BD Downing and JC Murphy. 2014. Mississippi River Nitrate Loads from High Frequency Sensor Measurements and Regression-Based Load Estimation. Environmental Science and Techology, dx.doi.org/10.1021/es504029c. [Download File]

Carpenter, Kurt D.; Kraus,Tamara E.C.; Goldman, Jami H.; Saraceno, John Franco; Downing, Bryan D.; Bergamaschi, Brian A.; McGhee, Gordon; Triplett, Tracy, 2013. Sources and characteristics of organic matter in the Clackamas River, Oregon, related to the formation of disinfection by-products in treated drinking water. U.S. Geological Survey Scientific Investigations Report 2013-5001, Report: x, 78 p.; Appendixes: .XLSX file [Link]

Pellerin, Brian A.; Bergamaschi, Brian A.; Downing, Bryan D.; Saraceno, John Franco; Garrett, Jessica D.; Olsen, Lisa D., 2013. Optical techniques for the determination of nitrate in environmental waters: Guidelines for instrument selection, operation, deployment, maintenance, quality assurance, and data reporting. U.S. Geological Survey Techniques and Methods 1-D5, vi, 37 p. [Link]

Zamora, Celia; Dahlgren, Randy A.; Kratzer, Charles R.; Downing, Bryan D.; Russell, Ann D.; Dileanis, Peter D.; Bergamaschi, Brian A.; Phillips, Steven P., 2013. Groundwater contributions of flow, nitrate, and dissolved organic carbon to the lower San Joaquin River, California, 2006-08. U.S. Geological Survey Scientific Investigations Report 2013-5151, Report: xii, 105 p.; Appendix 4: CSV file; Appendix 5: CSV file; Appendix 6: CSV file; Appendix 7: CSV file; Appendix 8: CSV file [Link]

Fleck J.A, Gary Gill, Brian A. Bergamaschi, Tamara E.C. Kraus, Bryan D. Downing, and Charles N. Alpers. 2013. Concurrent photolytic degradation of aqueousmethylmercury and dissolved organic matter, Sci Total Environ http://dx.doi.org/10.1016/j.scitotenv.2013.03.107 [Download File]

Bergamaschi, Brian A.; Fleck, Jacob A.; Downing, Bryan D.; Boss, Emmanuel; Pellerin, Brian A.; Ganju, Neil K.; Schoellhamer, David H.; Byington, Amy A.; Heim, Wesley A.; Stephenson, Mark; Fujii, Roger, 2012. Mercury dynamics in a San Francisco estuary tidal wetland: assessing dynamics using in situ measurements. Springer , 13 p. [Link]

Downing, B. D., B. A. Pellerin, B. A. Bergamaschi, J. F. Saraceno, and T. E. C. Kraus. 2012. Seeing the light: The effects of particles, dissolved materials, and temperature on in situ measurements of DOM fluorescence in rivers and streams. Limnology and Oceanography: Methods 10:767-775. [Link]

Downing, B. D., B. A. Pellerin, B. A. Bergamaschi, J. F. Saraceno, and T. E. C. Kraus. 2012. Seeing the light: The effects of particles, dissolved materials, and temperature on in situ measurements of DOM fluorescence in rivers and streams. Limnology and Oceanography: Methods 10:767-775. [Link]

Kraus, Tamara E.C.; Bergamaschi, Brian A.; Hernes, Peter J.; Doctor, Daniel H.; Kendall, Carol ; Downing, Bryan D.; Losee, Richard F., 2011. How reservoirs alter drinking water quality: Organic matter sources, sinks, and transformations. Taylor and Francis , 12 p. [Link]

Bergamaschi, B. A.; Fleck, J. A.; Downing, B. D.; Boss, E.; Pellerin, B.; Ganju, N. K.; Schoellhamer, D. H.; Byington, A. A.; Heim, W. A.; Stephenson, M. ; Fujii, R., 2011. Methyl mercury dynamics in a tidal wetland quantified using in situ optical measurements. Association for the Sciences of Limnology and Oceanography , 17 p. [Link]

Pellerin, Brian A.; Bergamaschi, Brian A.; Murdoch, Peter S.; Downing, Bryan D.; Saraceno, JohnFranco ; Aiken, George R.; Striegl, Robert G., 2011. The aquatic real-time monitoring network; in-situ optical sensors for monitoring the nation's water quality. U.S. Geological Survey Fact Sheet 2011-3061, 2 p. [Link]

Bergamaschi BA, BD Downing, BA Pellerin and J Saraceno. 2010. In Situ Sensors for Dissolved Organic Matter Fluorescence: Bringing the Lab to the Field. USGS Water Resources Discipline Instrument News, 125: 1-2. [Download File]

Kraus, T. E. C., C. A. Anderson, K. Morgenstern, B. D. Downing, B. A. Pellerin, and B. A. Bergamaschi. 2010. Determining Sources of Dissolved Organic Carbon and Disinfection Byproduct Precursors to the McKenzie River, Oregon. Journal of Environmental Quality 39: 2100-2112. [Download File]

Downing, B. D., E. Boss, B. A. Bergamaschi, J. A. Fleck, M. A. Lionberger, N. K. Ganju, D. H. Schoellhamer, and R. Fujii. 2009. Quantifying fluxes and characterizing compositional changes of dissolved organic matter in aquatic systems in situ using combined acoustic and optical measurements. Limnol. Oceanogr. Meth. 7: 119-131. [Link]

Pellerin, B. A., B. D. Downing, C. Kendall, R. A. Dahlgren, T. E. C. Kraus, J. Saraceno, R. G. M. Spencer, and B. A. Bergamaschi. 2009. Assessing the sources and magnitude of diurnal nitrate variability in the San Joaquin River (California) with an in situ optical nitrate sensor and dual nitrate isotopes. Freshwater Biology 54: 376-387. [Link]

Saraceno, J. F., B. A. Pellerin, B. D. Downing, E. Boss, P. a. M. Bachand, and B. A. Bergamaschi. 2009. High-frequency in situ optical measurements during a storm event: Assessing relationships between dissolved organic matter, sediment concentrations, and hydrologic processes. Journal of Geophysical Research-Biogeosciences 114: G00F09, doi: 10.1029/2009jg000989. [Link]

Downing, B. D., B. A. Bergamaschi, D. G. Evans, and E. Boss. 2008. Assessing contribution of DOC from sediments to a drinking-water reservoir using optical profiling. Lake and Reservoir Management 24: 381-391. [Download File]

Spencer, R. G. M., B. A. Pellerin, B. A. Bergamaschi, B. D. Downing, T. E. C. Kraus, D. R. Smart, R. A. Dahgren, and P. J. Hernes. 2007. Diurnal variability in riverine dissolved organic matter composition determined by in situ optical measurement in the San Joaquin River (California, USA). Hydrological Processes 21: 3181-3189. [Link]