Evaluating habitat vulnerability to hazardous air pollutants in the southeastern United States

Long term protection and maintenance of ecological communities and populations must consider the effect of atmospheric pollutants in addition to stressors that occur on the ground. We describe a technique for identifying species ranges and ecosystems across the landscape where there could be potential effects from air toxics releases. We modified the ranking equations for hazardous air pollutants (HAPs) from the Chemical Scoring and Ranking Assessment Model (SCRAM) to come up with a weighted relative toxicity value. The model combines toxicity rankings from SCRAM, chemical ambient air concentration data from the Assessment System for Population Exposure Nationwide model, and species richness data from the Southeast Gap Analysis Project. The final output was a 30-m pixel grid of potential vulnerability to HAP exposures. We found that the model, in general, resulted in a circular pattern around major urban areas with vulnerability decreasing with distance from the urban center. Those areas having high acreage of federal, state, and locally protected lands were also highlighted by the models added weight for species richness. Since the final toxicity maps were in a raster format the data can be aggregated into any number of assessment units for use by multiple levels of decision makers including federal and state entities who want to compare relative toxicity exposures across a region and local groups who want to evaluate the vulnerability of lands under their management.