FIGURE 2-11 Wet deposition of NH4+ and NO3− averaged for 1990-1996 data from the National Atmospheric Deposition Program in each of the 133 accounting units that make up the Mississippi River basin.
NOTE: Blue circles indicate where NADP and CASTNet (Clean Air Status and Trends Network) sites are co-located.
SOURCE: Goolsby et al. (1999).
