Denitrification across landscapes and waterscapes : a synthesis
Seitzinger, Sybil P.
Harrison, John A.
Bohlke, John K.
Bouwman, A. F.
Lowrance, R. Richard
Peterson, Bruce J.
Tobias, Craig R.
Van Drecht, G.
MetadataShow full item record
KeywordContinental shelf; Denitrification; Estuaries; Lakes; Nitrogen; Oxygen minimum zones; Rivers; Sediments; Soils
Denitrification is a critical process regulating the removal of bioavailable nitrogen (N) from natural and human-altered systems. While it has been extensively studied in terrestrial, freshwater, and marine systems, there has been limited communication among denitrification scientists working in these individual systems. Here, we compare rates of denitrification and controlling factors across a range of ecosystem types. We suggest that terrestrial, freshwater, and marine systems in which denitrification occurs can be organized along a continuum ranging from (1) those in which nitrification and denitrification are tightly coupled in space and time to (2) those in which nitrate production and denitrification are relatively decoupled. In aquatic ecosystems, N inputs influence denitrification rates whereas hydrology and geomorphology influence the proportion of N inputs that are denitrified. Relationships between denitrification and water residence time and N load are remarkably similar across lakes, river reaches, estuaries, and continental shelves. Spatially distributed global models of denitrification suggest that continental shelf sediments account for the largest portion (44%) of total global denitrification, followed by terrestrial soils (22%) and oceanic oxygen minimum zones (OMZs; 14%). Freshwater systems (groundwater, lakes, rivers) account for about 20% and estuaries 1% of total global denitrification. Denitrification of land-based N sources is distributed somewhat differently. Within watersheds, the amount of land-based N denitrified is generally highest in terrestrial soils, with progressively smaller amounts denitrified in groundwater, rivers, lakes and reservoirs, and estuaries. A number of regional exceptions to this general trend of decreasing denitrification in a downstream direction exist, including significant denitrification in continental shelves of N from terrestrial sources. Though terrestrial soils and groundwater are responsible for much denitrification at the watershed scale, per-area denitrification rates in soils and groundwater (kg N·km−2·yr−1) are, on average, approximately one-tenth the per-area rates of denitrification in lakes, rivers, estuaries, continental shelves, or OMZs. A number of potential approaches to increase denitrification on the landscape, and thus decrease N export to sensitive coastal systems exist. However, these have not generally been widely tested for their effectiveness at scales required to significantly reduce N export at the whole watershed scale.
Author Posting. © Ecological Society of America, 2006. This article is posted here by permission of Ecological Society of America for personal use, not for redistribution. The definitive version was published in Ecological Applications 16 (2006): 2064–2090, doi:10.1890/1051-0761(2006)016[2064:DALAWA]2.0.CO;2.
Showing items related by title, author, creator and subject.
De Pol-Holz, Ricardo; Ulloa, Osvaldo; Lamy, Frank; Dezileau, Laurent; Sabatier, Pierre; Hebbeln, Dierk (American Geophysical Union, 2007-05-01)We present high-resolution bulk sedimentary δ 15N data from the southern edge of the present-day oxygen minimum zone of the eastern South Pacific. The record is interpreted as representing changes in water column nitrogen ...
Response of benthic metabolism and nutrient cycling to reductions in wastewater loading to Boston Harbor, USA Tucker, Jane; Giblin, Anne E.; Hopkinson, Charles S.; Kelsey, Samuel W.; Howes, Brian L. (Elsevier, 2014-10-02)We describe the long-term response of benthic metabolism in depositional sediments of Boston Harbor, MA, to large reductions in organic matter and nutrient loading. Although Boston Harbor received very high loadings of ...
Glacial-interglacial modulation of the marine nitrogen cycle by high-latitude O2 supply to the global thermocline Galbraith, Eric D.; Kienast, Markus; Pedersen, Thomas F.; Calvert, Stephen E. (American Geophysical Union, 2004-10-16)An analysis of sedimentary nitrogen isotope records compiled from widely distributed marine environments emphasizes the global synchrony of denitrification changes and provides evidence for a strong temporal coupling of ...