Military activities on Department of Defense (DoD) installations in the southwestern United States are potentially large contributors of mineral dust to the atmosphere. These contributions can arise from wind erosion processes acting upon the large expanses of fragile desert soils and via testing and training activities. Developing cost-effective strategies to address particulate matter (PM) emissions and potential impacts requires identification of the main on-installation PM source contributions and an understanding of the environmental conditions that control the emissions. Following identification, it will be critical to define the relative contributions of these sources to ambient PM concentrations both within and external to DoD installations.
The objectives of this project were to (1) determine contributions from dust and other sources at Fort Bliss, Texas, to assess the regional impacts of these emissions on ambient PM levels; (2) develop a dust emission factor database for military wheeled vehicles traveling on unpaved surfaces; (3) develop and test a dust emission transport model that can determine the potential for longrange transport; (4) evaluate military vehicle disturbance effects on soil and surface properties and quantify the effects of disturbance on dust emission potential; (5) assess the potential visibility degradation off-installation; and (6) develop emission components that will be integrated with a geographic information system (GIS)- based emission model to estimate dust emission contributions from testing and training activities.
Contributions from dust and other sources were measured during an ambient air quality monitoring program at upwind and downwind boundary flux sites, combined with intensive monitoring during periods of active training. An emission factor database was developed using fastresponse instrumentation from both upwind-downwind and on-vehicle monitoring. Potential long-range transport of the emitted PM was assessed from field experiments designed to establish the relationship between the horizontal flux of dust emitted by vehicles in the near-field and its vertical flux component. Potential visibility degradation off-installation was determined with an intensive field measurement campaign using in-situ sensors to measure the light-absorption, light scattering, and the total extinction caused by aerosols exiting the installation. These data were combined with LIDAR measurements to describe the vertical and horizontal characteristics and flux of the aerosol plume exiting the installation.
Researchers quantified dust emissions by military vehicles, developed relationships between emission strength and surface properties, assessed the visibility degrading potential of the emissions, and evaluated how meteorological and surface conditions affect the transport and fate of dust. The results support the hypothesis that while specific DoD training activities may contribute to local PM and visibility issues, they may not be a major source of regional dust on an annual average time scale.
The emission factor data have been integrated into the Dust Emission and Transport (DUSTRAN) model developed under SERDP project RC-1195, providing the capability to predict contributions of fugitive dust from wheeled vehicle activity and to predict local and regional dust concentration levels. This understanding can be used to develop cost-effective strategies to mitigate these emissions and to help DoD maintain compliance with air quality regulations while having a positive impact on readiness. (Project Completed – 2005)