Sasha D. Hafner, Ph.D.
Owner and Senior Scientist
My training and interests are broadly in environmental science and ecology. In graduate school, I studied biology and ecology, as well as environmental, agricultural, and biological engineering. After completing graduate school, I worked as a scientist for an ENR 200 environmental engineering and consulting firm (HydroQual) on modeling metal toxicity. Following that work, I've worked for the USDA Agricultural Research Service on modeling emission of air pollutants from farms.
In all of my previous work, my main strength has been an ability to understand physical, chemical, biological, or ecological processes, and develop algorithms for simulating and analyzing them. For example, I developed statistical programs and chemical speciation models in Fortran during my graduate work.
At HydroQual, I developed the code for a model on pulsed exposure of aquatic organisms to metals. With USDA-ARS, I've developed transport and emission models for methane and volatile organic compounds. Most recently, I've used R for combined speciation and transport models. You can get an idea of the wide range of topics I've worked on from the list of publications given below.
- Ph.D., Agricultural and Biological Engineering (major), Ecology and Evolutionary Biology (minor), Cornell University, 2007
- M.S., Environmental and Forest Biology, Ecology concentration, State University of New York, College of Environmental Science and Forestry, 2003
- B.S., Environmental and Forest Biology, Ecology concentration, State University of New York, College of Environmental Science and Forestry, 2001
- Senior Scientist, Hafner Consulting, 2011-present
- Research Associate, USDA Agricultural Research Service, 2008-2012
- Scientist, HydroQual, 2007-2008
- Adjunct Professor, Le Moyne College, 2008
Hafner, S.D., Montes, F., Rotz, C.A. 2012. A mass transfer model for VOC emission from silage. Atmospheric Environment 54: 134-140.
Hafner, S.D., Meisinger, J., Mulbry, W., Ingram, S. 2012. A pH-based method for measuring
gaseous ammonia. Nutrient Cycling in Agroecosystems.92: 195-205
Hafner, S.D., Montes, F., Rotz, C.A. 2012. Role of carbon dioxide in emission of ammonia from
manure. Atmospheric Environment. doi: 10.1016/j.atmosenv.2012.01.026
Quaye, A. K., Volk, T. A., Hafner, S. D., Leopold, D. J., Schirmer, C. 2011. Impacts of paper
sludge and manure on soil and biomass production of willow. Biomass and Bioenergy 35:
Hafner, S.D., Montes, F., Rotz, C.A., Mitloehner, F. 2010. Ethanol emission from loose corn silage and exposed silage particles. Atmospheric Environment 44: 4172-4180.
El-Mashad H.M., Zhang, R., Rumsey, T., Hafner, S., Montes, F., Rotz, C.A., Arteaga, V., Zhao,
Y., Mitloehner, F.M. 2010. A mass transfer model of ethanol emission from thin layers of
corn silage. Transactions of the ASABE 53: 1903-1909.
Montes, F., Hafner, S.D., Rotz, C.A., Mitloehner, F. 2010. Temperature and air velocity effects on ethanol emission from corn silage with the characteristics of the exposed face of a bunker silo. Atmospheric Environment 44: 1987-1995.
Farrell, J., Murray, B., Leopold, D., Halpern, A., Rippke, M., Godwin, K., Hafner, S. 2009.
Water-level regulation and coastal wetland vegetation in the upper St. Lawrence River:
inferences from historical aerial imagery, seed banks, and Typha dynamics.
Hydrobiologia 647: 127-144.
Hafner, S.D., Bisogni, J.J. Jr. 2009. Modeling of ammonia speciation in anaerobic digesters.
Water Research 43: 4105-4114. Journal
Hafner, S.D. 2007. Biological hydrogen production from nitrogen-deficient substrates.
Biotechnology and Bioengineering 97: 435-437.
Hafner, S.D., Bisogni, J.J. Jr. 2007. A simple method for measurement of inorganic carbon
concentration and carbonate system alkalinity in anaerobic digesters. Agricultural
Engineering International: The CIGR Ejournal IX.
Hafner, S.D., Bisogni, J.J. Jr., Jewell, W.J. 2006. Measurement of un-ionized ammonia in
complex mixtures. Environmental Science and Technology 40: 1597-1602.
Hafner, S.D., Jewell, W.J. 2006. Predicting nitrogen and phosphorus removal in wetlands due to detritus accumulation: a simple mechanistic model. Ecological Engineering 27: 13-21.
Forrester, J.A., Leopold, D.J., Hafner, S.D. 2005. Maintaining critical habitat in a heavily managed landscape: effects of power line corridor management on Karner blue butterfly (Lycaeides Melissa samuelis) habitat. Restoration Ecology 13(3): 488-498.
Hafner, S.D., Groffman, P.M. 2005. Soil nitrogen cycling under litter and coarse woody debris in a mixed forest in New York State. Soil Biology and Biochemistry 37: 2159-2162.
Hafner, S.D., Groffman, P.M., Mitchell, M.J. 2005. Leaching of dissolved organic carbon,
dissolved organic nitrogen, and other solutes from coarse woody debris and litter in a
mixed forest in New York State. Biogeochemistry 74: 257-282.
Hafner, S.D. 2003. Is fertilizer efficiency misleading? Nature 422: 397-
Hafner, S.D. 2003. Trends in maize, rice, and wheat yields for 188 nations over the past 40 years:
a prevalence of linear growth. Agriculture, Ecosystems, and Environment 97: 275-283.
Godwin, K.S., Hafner, S.D., Buff, M.F. 2003. Long-term trends in sodium and chloride in the
Mohawk River, New York: the effect of fifty years of road salt application.
Environmental Pollution 124: 273-281.