EPA Science Inventory

Factors influencing export of dissolved inorganic nitrogen by major rivers: A new seasonal, global-scale model

Citation:

McCrackin, M., J. Harrison, AND J. Compton. Factors influencing export of dissolved inorganic nitrogen by major rivers: A new seasonal, global-scale model. Presented at NSF Research Coordination Network, October 09 - 11, 2012.

Description:

Understanding sub-annual patterns of catchment dissolved inorganic nitrogen (DIN) export is critical for predicting and mitigating impacts of coastal eutrophication, such as algal blooms and hypoxic areas, which are often seasonal phenomena. We developed the first calibrated global model capable of predicting seasonal DIN export for >6,000 rivers (NEWS2-DIN-S). For model development, we compiled a dataset of observed seasonal DIN export and environmental variables for 73 large rivers. DIN export was positively related to runoff and negatively related to temperature. NEWS2-DIN-S used seasonal N-input budgets that we created by bringing together diverse datasets such as crop phenology and farmer fertilization practices. The sensitivity of modeled DIN export to changes in runoff did not differ among seasons, but sensitivity to temperature was greater for winter, spring, and fall than for summer. NEWS2-DIN-S was also used to understand potential changes in coastal DIN loads resulting from climate-related shifts in runoff and temperature.

Purpose/Objective:

Understanding seasonal patterns of catchment dissolved inorganic nitrogen (DIN) export is critical for predicting and mitigating impacts of coastal eutrophication, such as algal blooms and hypoxic areas, which are often seasonal phenomena. We developed the first calibrated global model capable of predicting seasonal DIN export for >6,000 rivers (NEWS2-DIN-S). For model development, we compiled a dataset of observed seasonal DIN export and environmental variables for 73 large rivers. DIN export was positively related to runoff and negatively related to temperature. NEWS2-DIN-S used seasonal N-input budgets that we created by bringing together diverse datasets such as crop phenology and farmer fertilization practices. The sensitivity of modeled DIN export to changes in runoff did not differ among seasons, but sensitivity to temperature was greater for winter, spring, and fall than for summer. NEWS2-DIN-S was also used to understand potential changes in coastal DIN loads resulting from climate-related shifts in runoff and temperature.

Record Details:

Record Type: DOCUMENT (PRESENTATION/ABSTRACT)
Record Last Revised: 10/15/2012
Record Created: 10/15/2012
Record Released: 10/15/2012
OMB Category: Other
Record ID: 246901

Organization:

U.S. ENVIRONMENTAL PROTECTION AGENCY

OFFICE OF RESEARCH AND DEVELOPMENT

NATIONAL HEALTH AND ENVIRONMENTAL EFFECTS RESEARCH LAB

WESTERN ECOLOGY DIVISION

FRESHWATER ECOLOGY BRANCH