Jeffrey R. White
Professor of Environmental Sciences
Aquatic Chemistry, Biogeochemistry, and Limnology
Office: MSBII S2-412
- Ph.D., 1984, Syracuse University
- M.S., 1979, Rutgers University
- B.A., 1977, Gettysburg College
White and his group are interested in processes controlling the cycling of elements in aquatic and terrestrial systems and in the potential impact of human activity on element cycles. They study cycling of elements at sediment/water interfaces in fresh water systems and within soils of agricultural systems. They also contribute to interdisciplinary research on changes in the biology and chemistry of lake/watershed systems.
Increased deposition of atmospheric sulfate is affecting the cycling of sulfur, iron, manganese, and carbon in lake ecosystems of northeastern North America. They have been investigating these effects by measuring chemical changes over short distances (1 cm) at the sediment/water interface of acidic lakes in the Adirondack Mountain region of New York State. Evidence of changes in element cycling is drawn from chemical diffusion gradients, chemical mass balances, sediment geochemistry, and stable isotopic analyses. White's group have accumulated evidence of profound changes in the importance of sulfate reduction P and, thus, the cycling of carbon P in remote lakes, and have found that the cycling of trace metals has also been altered.
Additionally, they have begun work on methane cycling in wetlands. Freshwater wetland environments are particularly conducive to methanogenesis because they are often rich in organic matter and depleted in O2 and sulfate. On a molar basis, each increment of CH4 emitted to the atmosphere is 25-fold more efficient at energy retention than are corresponding additions of CO2. With atmospheric methane concentrations increasing at a rate of 1% per year, the role of methane as a greenhouse gas is of major concern. To improve understanding of natural sources of atmospheric methane, they are currently investigating a number of wetland types. The role of local climate (temperature, insolation, and water level) in controlling methane budgets is being studied using chemical mass balances, stable isotopic analyses, isolation of specific bacterial populations, and continuous records of climatic variables. They aim to develop mechanistic models that will describe methane cycling in detail and which will allow prediction of responses of natural rates of methane production to climatic change.
Other areas of research include: the development of stable isotopes of nitrogen as a "fingerprinting" tool to identify the sources of ammonia and nitrate in surface water; improvement of sampling and analysis techniques for trace metals in gravel sediments; and development of new isolation techniques for microbial communities inhabiting wetland sediments.
Tang, J., Zhuang, Q., Shannon R.D. and White, J.R. "Quantifying Wetland Methane Emissions with Process-Based Models of Different Complexities." Biogeosciences, Vol. 7, 2010, pp. 3817-3837.
White, J. R., Shannon, R.D., Weltzin, J.F., Pastor, J., and Bridgham, S.D. “Effects of Soil Warming and Drying on Methane Cycling in a Northern Peatland Mesocosm Study,” J. Geophysical Research, Vol. 113, 2008, G00A06, doi:10.1029/2007JG000609.
Herrman, K.S. and White, J.R. “Denitrification in a constructed wetland: comparison of mass balance and stable isotopic methods,” Applied Geochemistry, 2008, DOI 10.1016/j.apgeochem.2008.04.024, 2008.
Keller, J.K.,, Bridgham, S.D., Pastor, J. "Climate Change Effects on Carbon and Nitrogen Mineralization in Peatlands Through Changes in Soil Quality," (2004). Global Change Biology, Vol. 10, pp. 1053-1064.
Avery, B., Shannon, R.D.,, Martens, C.S., and Alperin, M.J. "Controls on Methane Production in a Tidal Freshwater Estuary and a Peatland: Methane Production via Acetate Fermentation and CO2 Reduction," (2002). Biogeochemistry, Vol. 62, pp. 19-37.
Avery, B., Shannon, R.D.,, Martens, C.S., and Alperin, M.J., "Effect of Seasonal Changes in the Pathways of Methanogenesis on the del13C Values of Pore Water Methane in a Michigan Peatland," (1999). Global Biogeochemical Cycles, Vol. 13, pp. 475-484.
, and R.D. Shannon, "Modeling Organic Solutes in Peatland Soils Using Acid Analogs" (1997). Soil Science Society of America Journal, Vol. 61, 1257-1263.
Walter, B.P., M. Heimann, R.D. Shannon,, "A process-based model to derive methane emissions from natural wetlands," (1996). Geophysical Research Letters, Vol. 23, 3731-3734.
Shannon, R.D., and, "The Effects of Spatial and Temporal Variations in Acetate and Sulfate on Methane Cycling in Two Michigan Peatlands" (1996). Limnology and Oceanography, Vol. 41(3), 1996, 435-443.
Shannon, R.D.,, J.E. Lawson, and B.S. Gilmour, "Methane efflux from emergent vegetation in peatlands" (1996). J. Ecology, Vol. 84, 239-246.
Shannon, R.D. and, "A three-year study of controls on methane emissions from two Michigan peatlands," (1994). Biogeochemistry, Vol. 27, 35-60.
Shannon, R.D., and, "The Selectivity of a Sequential Extraction Procedure for Iron Oxyhydroxide and Sulfides in Freshwater Sediments" (1991). Biogeochemistry, Vol. 14, 193-208.
Gubala, C.P., D.R. Engstrom, and, "Effects of Iron Cycling on 210Pb Dating of Sediments in an Adirondack Lake, U.S.A." (1990). Canadian J. Fisheries and Aquatic Sciences, Vol. 47, 1821-1829.
and C. P. Gubala, "Sequentially Extracted Metals from Adirondack Lake Sediment Cores," (1990). J. Paleolimnology, Vol. 3, 243-252.
, C.P. Gubala, B. Fry, J. Owen, and M.J. Mitchell, "Sediment Biogeochemistry of Iron and Sulfur in an Acidic Lake," (1989). Geochimica et Cosmochimica Acta, Vol. 53, 2547-2559.