Spatial variability of sulfur dioxide and sulfate over complex terrain in East Tennessee, USA

In 2004 and 2005, the East Tennessee Ozone Study (ETOS) enhanced its regional measurement program with annular denuder systems to quantify sulfur dioxide (SO2) and PM2.5 sulfate (SO42−) at five sampling sites that were representative of the complex terrain and physiographic features of East Tennessee. Intersite spatial variability was more defined for SO2 than for SO42−, which showed a fairly uniform structure in both daytime and nighttime measurements. Pollution roses indicated that two sites may have been influenced by the proximity of SO2 emission sources. The data suggest that SO2 is affected by nearby sources in the study area while the sources of SO42− are regionally distributed.