In 1997, the Clean Air Status and Trends Network (CASTNet) monitored atmospheric concentrations of sulfur dioxide, nitric acid, and particulate sulfate and nitrate at six PRIMENet sites; Big Bend, Canyonlands, Glacier, Rocky Mountain, Sequoia/Kings Canyon, and Shenandoah NPs. CASTNet filter pack systems have subsequently been installed in the remaining PRIMENet parks, with the exception of Hawaii Volcanoes, which is scheduled for July 1999.
CASTNet Filter Pack and Meteorological Station Site Information. Data available HERE.
Atmospheric concentration data are collected at each site with open-faced, 3-stage filter packs. The filter pack contains a teflon filter for collection of particulate species, a nylon filter for nitric acid and a base-impregnated cellulose filter for sulfur dioxide. Filter packs are exposed for 1-week intervals at a flow rate of 1.5 liters per minute (3.0 liters per minute for western sites), and sent to the laboratory for chemical analysis.
The following graphs, compare atmospheric concentrations of sulfur dioxide and particulate sulfate, and nitric acid and particulate nitrate, respectively. Again only one year of data is presented because operation dates were highly variable. Shenandoah NP had the highest sulfur concentrations, while Shenandoah and Sequoia/Kings Canyon NPs had the highest nitrogen concentrations.
Atmospheric Concentration of Sulfur Dioxide and Particulate Sulfate in 1997.
Atmospheric Concentrations of Nitric Acid and Particulate Nitrate in 1997.
To estimate total deposition to a park site, both wet and dry deposition must be monitored. As part of CASTNet, dry deposition rates will be calculated using a multi-layer version of the NOAA "big leaf" model, with the parameters of atmospheric concentration, meteorological data and information on land use, vegetation, and surface conditions. Dry deposition estimates for each site will be available when runs of the model are complete. Updated information on CASTNet is available.