Analysis of commented vs. uncommented samples from the Clean Air Status and Trends Network (CASTNet)

Ambient gaseous and particulate concentration data from the Clean Air Status and Trends Network (CASTNet) dry deposition monitoring program are examined with respect to whether data from samples containing comment codes may be different than data from samples with no codes. The questions of whether commented samples may yield values that appear to be too high and whether concentrations from samples with wet filters differ from those from uncommented samples are addressed. Data were analyzed for each of the various monitored chemical species on a site-by-site basis. Generally, the results suggest that there are differences between samples that have comments and those that do not.