You are here:
REGIONAL TRENDS IN RURAL SULFUR CONCENTRATIONS
Citation:
Holland, D M., P. Caragea, AND R. L. Smith. REGIONAL TRENDS IN RURAL SULFUR CONCENTRATIONS. ATMOSPHERIC ENVIRONMENT 38(11):1673-1684, (2004).
Impact/Purpose:
Our main objective is to assess the exposure of selected ecosystems to specific atmospheric stressors. More precisely, we will analyze and interpret environmental quality (primarily atmospheric) data to document observable changes in environmental stressors that may be associated with legislatively-mandated emissions reductions.
Description:
This paper presents an analysis of trends in atmospheric concentrations of sulfur dioxide (SO,) and particulate sulfate (SO42-) at rural monitoring sites in the Clean Air Act Status and Trends Monitoring Network (CASTNet) from 1990 to 1999. A two-stage approach is used to estimate regional trends and standard errors in the Midwest and Mid-Atlantic regions of the U.S. In the first stage, a linear regression model is used to estimate site-specific trends in data
adjusted for the effects of season and meteorology. In the second stage, kriging methodology based on maximum likelihood estimation is used to estimate regional trends and standard errors. This method is extended to include a Bayesian analysis to account for uncertainty in estimating the spatial covariance parameters. For both pollutants, significant improvement in air quality was detected that appears similar to the large drop in SO, power plant emissions. Spatial patterns of trends in S02 and S04 2- concentrations vary by location over the eastern U.S. For S02, trends at monitoring sites in the Midwest and Mid-Atlantic were in the -30% to -42% ranges with smaller changes in the South. Across most of the U.S., trends in S04 2- were smaller than for S02. Both spatial prediction techniques produced similar results in terms of regional trends and standard errors.