Historical data available for the Connecticut Hill Atmospheric and Precipitation Chemistry Research and Monitoring Facility:

• Long-term record of N depostion (wet and dry)
• One of the original locations to measure regionally representative dry deposition in the U.S. (1987)
• Studies of throughfall versus inferentially measured dry deposition of N and sulfur species
• Isotopic studies (15N, 18O and 17O) of wet and dry deposition to understand the sources of NOx deposition (e.g., vehicle emissions vs. non-vehicle sources)
• Impact of changing emissions of SO2 and NOx on wet and dry deposition of sulfur, nitrogen, and acidity.

Data to be collected for this project:

• Improve measurement of dry deposition of N, especially gaseous NO2, NH3. At least 1/3 of the measured total N deposition at the sites is in the form of dry deposition, but not all components have yet been measured.
• MARGA (Monitoring instrument for aerosols and gases) hourly sampling for gaseous NH3, HNO3, and HNO2, and particulate NH4+ and NO3-; ThermoElectron 42C-Y chemiluminescence detector for hourly sampling for NOy
• Passive gas sampler monitoring for dry deposition of NH3, NO2, NOx, HNO3
• Comparison of data from passive samplers and CASTNet filter packs
• Further tests of spatial variability of dry deposition components