Citation:

Schwede, D., E. Cooter, J. Lin, J. Compton, AND J. Baron. CMAQ modeling in the nitrogen inventory study in the Nooksack-Abbotsford-Sumas Transboundary Region. NADP, San Diego, CA, October 30 - November 03, 2017.

Impact/Purpose:

Nitrogen release to the atmosphere may come from a variety of sources. In the transboundary Nooksack Basin in northwest Washington and southwest British Columbia, urban lands, croplands and dairies are located in close proximity to valuable streams, forests, shellfish beds and North Cascades National Park. This project brings together scientists from across EPA and USGS to examine the rates and drivers of atmospheric deposition in this basin. This is an invited talk for the NADP meeting in fall 2017.

Description:

Optimizing nitrogen (N) use for food production while minimizing the release of N and co-pollutants to the environment is an important challenge. The Nooksack-Abbotsford-Sumas Transboundary (NAS) Region, spanning a portion of the western interface of British Columbia, Washington State, the Lummi Nation and Nooksack Tribal lands, supports agriculture, estuarine fisheries, diverse wildlife, and vibrant urban areas. Excess N has contributed to surface and ground water pollution, shellfish closure, and impaired air quality (such as haze or smog) in some areas in the NAS Transboundary region. To reduce the release of N to the environment, collaborative approaches that engage all stakeholders and appropriate institutions are needed to integrate science, outreach and management efforts. The goal of the NAS Transboundary N inventory study is to quantify the sources and fate of N, including inputs and transfers within the watershed. We are synthesizing publicly available data on N sources including atmospheric deposition, sewage and septic inputs, fertilizer and manure applications, marine-derived N from salmon migrations, natural N-fixing vegetation, and more. CMAQv5.2 is used to estimate daily total nitrogen deposition as well as other air quality indicators in the target year (2014) at a 4-km grid resolution. An existing 12-km CMAQ model of Western US is employed to provide boundary conditions for the new model. The model domain is centered on the NAS Transboundary region, and includes nearly all of Washington State and the Fraser Valley in Canada. Bi-directional CMAQ ammonia flux will be presented from simulations that couple the USDA EPIC model which provides estimates of agricultural fertilizer application form, timing and amount based on the NLCD2011 land use classification and USDA regional cropping and agricultural management patterns, with the CMAQ model. The information on cross-boundary N inputs to the landscape will be coupled with stream and groundwater monitoring data and existing knowledge to estimate the N residual in the watershed and N transport out of the watershed. Results will inform N management in the search for the environmentally and economically viable and effective solutions. The NAS Transboundary Region study is one of seven international demonstration projects contributing knowledge of regional N budgets and collaborative approaches toward N management as part of the International Nitrogen Management System (INMS).

Record Details: