The global cycles of nitrogen and phosphorus represent the foundation for all terrestrial ecosystems. Human activity has impacted the nitrogen through the use of fertilizers and combustion of fossil fuels. The cycling of P has also been impacted by humans particularly through the use of fertilizers. For these reasons, the atmospheric cycling and deposition of N is a critical research topic and there is growing evidence that the atmospheric cycling of P may also have been impacted by humans (through aerosol concentrations). These are active research areas in the lab.
Research Results for Nutrient Deposition to Ecosystems
Our work on nutrient deposition takes a number of forms. In many cases, it is impossible to study biogeochemical cycling without attention to atmospheric imputs. In recent years, our focus has been increasingly on the deposition of dust to ecosystems; a process with the potential to dramatically affect how some ecosystems function, but the lab has also done work on the global cycling of N.
Dust Studies
J.C. Neff, A.P. Ballantyne, G.L. Famer, N.M. Mahowald, J.L. Conroy, C.C. Landry, J.T. Overpeck, T.H. Painter, C.R. Lawrence, and R.L. Reynolds.(2008). Recent increase in eolian dust deposition related to human activity in the Western United States. Nature - Geosciences. This study uses lake sediment records from the San Juan Mountains of Colorado to document the h istory of dust deposition to this region. The results of these cores suggest that dust fall increased 4-7X following the settlement of the western US in the mid-1800s. These rates have declined somewhat to the present but remain greatly elevated relative to the historical background flux. The sediment studies also suggest changes in the chemistry of dust deposition that may reflect the use of agricultural fetilizers and air polution. Please email for PDF
Goldstein, H.L., Reynolds, R.L., Reheis, M.C., Yount, J.C., and Neff, J.C. (2008). Compositional trends in eolian dust along a transect across the southwestern United States. Journal of Geophysical Research, Earth Surface.doi:10.1029/2007JF000751. This study examines the chemical and isotopic properties of 'potholes' (small depressions in bedrock exposed to atmospheric deposition) along a gradient of sites from the Mojave to Colorado Plateau. PDF.
Reynolds, R.L., M.C. Reheis, J.C. Neff, H. Goldstein, and J. Yount. (2006). Late Quaternary eolian dust in surficial deposits of a Colorado Plateau Grassland: Controls on distribution and ecologic effects. Catena v66(3), 251-266. This study is one of a set of studies carried out in locations in and around Canyonlands National Park, UT. This particular study documents the presence of dust in OSL dated layers of soil and highlights periods of historical dust accumulation in this region. PDF.
Reynolds R., J.C. Neff, M. Reheis, and P. Lamothe. Atmospheric dust in modern soil on aeolian sandstone, Colorado Plateau (USA): Variation with landscape position and contribution to potential plant nutrients. Geoderma 130:108-123. This study provides an estimate of the dust fraction of surface soils in a study sity in Canyonlands National Park, UT. Using magnetic minerals as a tracer for dust, the study shows that surface soils are dominatly eolian in origin and also uses mixing models to show that most of the plant-essential elements in these surface soils are also derived from dust. PDF.
Nutrient Cycling and Deposition Studies
Parton W.J., J.C. Neff and P.M. Vitousek , Modeling phosphorus dynamics in terrestrial ecosystems. 2005. In Organic Phosphorus and the Environment ( BL Turner, E Frossard, ETH Lindau, DS Baldwin eds) Oxford University Press. 350 pages. pp 325-347. This book chapter reviews the mechanisms involved in P cycling and tests these mechanisms along a tropical soil age gradient using the Century Ecosystem Model. The results suggest that atmospheric deposition and/or release of occluded P is required to sustain observed patterns in troipcal productivity.
Neff J.C. , E.A. Holland, F.J. Dentener, W.H. McDowell and K.M.Russel (2002). Atmospheric organic nitrogen; Implications for the global N cycle. Biogeochemistry. 57/58: 99-136. This article reviews all the available data related to organic forms of nitrogen deposition globally. The results suggest that, on average, 30% of N deposition occurs in organic forms that may be missed by conventional measurement techniques. We also use a global atmsopheric chemisry tracer model to examine the distribution and fate of a number of organic molecules in the atmosphere and suggest how types of pollution may contribution to the global organic N flux in precipitation. PDF.
Research Results for Nutrient Deposition to Ecosystems
Our work on nutrient deposition takes a number of forms. In many cases, it is impossible to study biogeochemical cycling without attention to atmospheric imputs. In recent years, our focus has been increasingly on the deposition of dust to ecosystems; a process with the potential to dramatically affect how some ecosystems function, but the lab has also done work on the global cycling of N.
Dust Studies
J.C. Neff, A.P. Ballantyne, G.L. Famer, N.M. Mahowald, J.L. Conroy, C.C. Landry, J.T. Overpeck, T.H. Painter, C.R. Lawrence, and R.L. Reynolds.(2008). Recent increase in eolian dust deposition related to human activity in the Western United States. Nature - Geosciences. This study uses lake sediment records from the San Juan Mountains of Colorado to document the h istory of dust deposition to this region. The results of these cores suggest that dust fall increased 4-7X following the settlement of the western US in the mid-1800s. These rates have declined somewhat to the present but remain greatly elevated relative to the historical background flux. The sediment studies also suggest changes in the chemistry of dust deposition that may reflect the use of agricultural fetilizers and air polution. Please email for PDF
Goldstein, H.L., Reynolds, R.L., Reheis, M.C., Yount, J.C., and Neff, J.C. (2008). Compositional trends in eolian dust along a transect across the southwestern United States. Journal of Geophysical Research, Earth Surface.doi:10.1029/2007JF000751. This study examines the chemical and isotopic properties of 'potholes' (small depressions in bedrock exposed to atmospheric deposition) along a gradient of sites from the Mojave to Colorado Plateau. PDF.
Reynolds, R.L., M.C. Reheis, J.C. Neff, H. Goldstein, and J. Yount. (2006). Late Quaternary eolian dust in surficial deposits of a Colorado Plateau Grassland: Controls on distribution and ecologic effects. Catena v66(3), 251-266. This study is one of a set of studies carried out in locations in and around Canyonlands National Park, UT. This particular study documents the presence of dust in OSL dated layers of soil and highlights periods of historical dust accumulation in this region. PDF.
Reynolds R., J.C. Neff, M. Reheis, and P. Lamothe. Atmospheric dust in modern soil on aeolian sandstone, Colorado Plateau (USA): Variation with landscape position and contribution to potential plant nutrients. Geoderma 130:108-123. This study provides an estimate of the dust fraction of surface soils in a study sity in Canyonlands National Park, UT. Using magnetic minerals as a tracer for dust, the study shows that surface soils are dominatly eolian in origin and also uses mixing models to show that most of the plant-essential elements in these surface soils are also derived from dust. PDF.
Nutrient Cycling and Deposition Studies
Parton W.J., J.C. Neff and P.M. Vitousek , Modeling phosphorus dynamics in terrestrial ecosystems. 2005. In Organic Phosphorus and the Environment ( BL Turner, E Frossard, ETH Lindau, DS Baldwin eds) Oxford University Press. 350 pages. pp 325-347. This book chapter reviews the mechanisms involved in P cycling and tests these mechanisms along a tropical soil age gradient using the Century Ecosystem Model. The results suggest that atmospheric deposition and/or release of occluded P is required to sustain observed patterns in troipcal productivity.
Neff J.C. , E.A. Holland, F.J. Dentener, W.H. McDowell and K.M.Russel (2002). Atmospheric organic nitrogen; Implications for the global N cycle. Biogeochemistry. 57/58: 99-136. This article reviews all the available data related to organic forms of nitrogen deposition globally. The results suggest that, on average, 30% of N deposition occurs in organic forms that may be missed by conventional measurement techniques. We also use a global atmsopheric chemisry tracer model to examine the distribution and fate of a number of organic molecules in the atmosphere and suggest how types of pollution may contribution to the global organic N flux in precipitation. PDF.