Interactions of wildland fire emissions with power plant and traffic emissions in Southeastern US

Abstract:

Emissions from wildland fires are a significant source of air pollutants and in certain parts of the world where air quality is already stressed by anthropogenic emissions they can lead to major health and environmental problems. The harmful effects can come simply from the increase of the preexisting primary pollutants in the region by the wildland fire emissions. Moreover, secondary pollutants can also form when wildland fire emissions coexist with emissions from other sources such as power plants and highways. In Southeastern US, where prescribed burning is routinely practiced both for ecosystem health and reduction of wildfire risk, smoke plumes from wildland fires frequently encroach urban areas where there is an abundance of other emissions. Up till now, assessments of the impacts of prescribed burning mostly focused on the primary pollutants and the interactions of wildland fire emissions with anthropogenic emissions has not been studied in detail.

Since November 2014, we have been forecasting the individual air quality impacts of two anthropogenic emission categories, namely electric generation and vehicular traffic, as well as prescribed burning using the Decoupled Direct Method (DDM) available in CMAQ version 5.0.2. We use special techniques to provide accurate emissions inputs to our forecasts, including a new weather-based prescribed burn forecasting system that mines a burn permit database for geographic burning patterns. We also use surface and satellite observations along with simulated concentrations and their sensitivities to emissions in an inverse modeling framework to continuously adjust input emissions. The impact forecasts include the interactions between emissions from different sources but do not distinguish their magnitudes.

In this study, using our forecasting system we simulated the impacts of power plants and on-road vehicles on ozone and PM2.5 concentrations first with and then without the prescribed burn emissions. Then, we attributed the difference between the two sets of simulated impacts to the interactions between the wildland fires and the two anthropogenic emissions categories. Results for periods of large prescribed burn impacts in urban areas during the 2015 burning season will be presented to establish bounds on potential interactions.