HR: 0800h
AN: H31F-0727    [Abstracts]
TI: Denitrification Hotspots: Hydrology and Biogeochemistry
AU: * Molodovskaya, M
EM: mm433@cornell.edu
AF: Cornell University, Biological & Environmental Engineering, Ithaca, NY 14850-5701,
AU: Singurindy, O
EM: os43@cornell.edu
AF: Cornell University, Biological & Environmental Engineering, Ithaca, NY 14850-5701,
AU: Faulkner, J W
EM: jwf24@cornell.edu
AF: Cornell University, Biological & Environmental Engineering, Ithaca, NY 14850-5701,
AU: Zhang, W
EM: wz47@cornell.edu
AF: Cornell University, Biological & Environmental Engineering, Ithaca, NY 14850-5701,
AU: Richards, B K
EM: bkr2@cornell.edu
AF: Cornell University, Biological & Environmental Engineering, Ithaca, NY 14850-5701,
AU: Anderson, T R
EM: tra8@cornell.edu
AF: Cornell University, Biological & Environmental Engineering, Ithaca, NY 14850-5701,
AU: Geohring, L D
EM: ldg5@cornell.edu
AF: Cornell University, Biological & Environmental Engineering, Ithaca, NY 14850-5701,
AU: Steenhuis, T S
EM: tss1@cornell.edu
AF: Cornell University, Biological & Environmental Engineering, Ithaca, NY 14850-5701,
AU: Walter, M
EM: mtw5@cornell.edu
AF: Cornell University, Biological & Environmental Engineering, Ithaca, NY 14850-5701,
AB: Nitrogen (N) is a critical pollutant in many northeastern US watersheds and globally. Many forms of N, especially NO3, pose serious threats to coastal marine ecosystems. Agricultural land that receives fertilizers or animal manures is a principal source of anthropogenic N loading to the environment. The most effective mechanism to reduce N in streams is probably microbial denitrification, i.e., the transformation of nitrate into gaseous N2 or, in some cases, smaller amounts of N2O. Unfortunately, N2O is a greenhouse gas that may contribute to global warming. Currently, magnitudes of denitrification rates at landscape scales are "tentative" at best, largely based on watershed-scale budgets in which denitrification was estimated by difference. Denitrification and N2O net production strongly depend on both natural (temperature, soil moisture, microbial activity, soil organic matter) and anthropogenic (nitrogen fertilization, crop type, tillage) parameters. Denitrification occurs primarily under anaerobic conditions by heterotrophic microbes and is expected to be vigorous in wet soils high in organic carbon. There is good evidence that these conditions correlate strongly with hydrological sensitivity or high propensity for saturated conditions, thus by juxtaposing hydrology and biogeochemistry we can elucidate the distribution of denitrification hotspots across the landscape. Upon this hydrologic-biogeochemical framework we can ultimately develop BMPs to meet the program research priorities to improve water resource protection and promote sustainable agricultural systems that minimize environmental impact. The Cornell Soil and Water and Ecohydrology Research Groups have engaged in a variety of projects to elucidate the primary controls or quantify denitrification rates for different ecohydrological conditions including those that have been specifically designed to reduce N loading to streams. This presentation highlights recent findings of rates, controls, and spatio-temporal distributions of dentirification as well as N mineralization and other N fluxes.
DE: 0402 Agricultural systems
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0469 Nitrogen cycling
DE: 0478 Pollution: urban, regional and global (0345, 4251)
DE: 1813 Eco-hydrology
SC: Hydrology [H]
MN: 2007 Fall Meeting