TY - JOUR
T1 - Anthropogenic nitrogen sources and relationships to riverine nitrogen export in the northeastern U.S.A.
AU - Boyer, Elizabeth W.
AU - Goodale, Christine L.
AU - Jaworski, Norbert A.
AU - Howarth, Robert W.
N1 - Funding Information:
This work was initiated as part of the International SCOPE Nitrogen Project, which received support from both the Mellon Foundation and from the National Center for Ecological Analysis and Synthesis. Thanks to T. Kittel & N. Rosenblum for sharing the VEMAP II climate data. We are grateful to Douwe Van Dam for literature regarding agricultural N fixation rates. We thank the following for their helpful discussions: Richard Alexander, Frank Dentener, Jim Galloway, Leo Hetling, Kate Lajtha, Gary Lovett, Jason Neff, Sybil Seitzinger, Nico van Breemen, Douwe Van Dam, and Hal Walker. The thoughtful comments of 4 reviewers – Jill Baron, Walter Boynton, Max Holmes, and Tom Fischer – substantially improved the manuscript.
PY - 2002
Y1 - 2002
N2 - Human activities have greatly altered the nitrogen (N) cycle, accelerating the rate of N fixation in landscapes and delivery of N to water bodies. To examine relationships between anthropogenic N inputs and riverine N export, we constructed budgets describing N inputs and losses for 16 catchments, which encompass a range of climatic variability and are major drainages to the coast of the North Atlantic Ocean along a latitudinal profile from Maine to Virginia. Using data from the early 1990's, we quantified inputs of N to each catchment from atmospheric deposition, application of nitrogenous fertilizers, biological nitrogen fixation, and import of N in agricultural products (food and feed). We compared these inputs with N losses from the system in riverine export. The importance of the relative sources varies widely by catchment and is related to land use. Net atmospheric deposition was the largest N source (>60%) to the forested basins of northern New England (e.g. Penobscot and Kennebec); net import of N in food was the largest source of N to the more populated regions of southern New England (e.g. Charles & Blackstone); and agricultural inputs were the dominant N sources in the Mid-Atlantic region (e.g. Schuylkill & Potomac). Over the combined area of the catchments, net atmospheric deposition was the largest single source input (31%), followed by net imports of N in food and feed (25%), fixation in agricultural lands (24%), fertilizer use (15%), and fixation in forests (5%). The combined effect of fertilizer use, fixation in crop lands, and animal feed imports makes agriculture the largest overall source of N. Riverine export of N is well correlated with N inputs, but it accounts for only a fraction (25%) of the total N inputs. This work provides an understanding of the sources of N in landscapes, and highlights how human activities impact N cycling in the northeast region.
AB - Human activities have greatly altered the nitrogen (N) cycle, accelerating the rate of N fixation in landscapes and delivery of N to water bodies. To examine relationships between anthropogenic N inputs and riverine N export, we constructed budgets describing N inputs and losses for 16 catchments, which encompass a range of climatic variability and are major drainages to the coast of the North Atlantic Ocean along a latitudinal profile from Maine to Virginia. Using data from the early 1990's, we quantified inputs of N to each catchment from atmospheric deposition, application of nitrogenous fertilizers, biological nitrogen fixation, and import of N in agricultural products (food and feed). We compared these inputs with N losses from the system in riverine export. The importance of the relative sources varies widely by catchment and is related to land use. Net atmospheric deposition was the largest N source (>60%) to the forested basins of northern New England (e.g. Penobscot and Kennebec); net import of N in food was the largest source of N to the more populated regions of southern New England (e.g. Charles & Blackstone); and agricultural inputs were the dominant N sources in the Mid-Atlantic region (e.g. Schuylkill & Potomac). Over the combined area of the catchments, net atmospheric deposition was the largest single source input (31%), followed by net imports of N in food and feed (25%), fixation in agricultural lands (24%), fertilizer use (15%), and fixation in forests (5%). The combined effect of fertilizer use, fixation in crop lands, and animal feed imports makes agriculture the largest overall source of N. Riverine export of N is well correlated with N inputs, but it accounts for only a fraction (25%) of the total N inputs. This work provides an understanding of the sources of N in landscapes, and highlights how human activities impact N cycling in the northeast region.
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U2 - 10.1023/A:1015709302073
DO - 10.1023/A:1015709302073
M3 - Article
AN - SCOPUS:18544403514
VL - 57-58
SP - 137
EP - 169
JO - Biogeochemistry
JF - Biogeochemistry
SN - 0168-2563
ER -