Atmospheric Deposition is
a term that collectively refers to two processes, one of which is more commonly characterized as "acid
rain". Acid rain, or wet deposition, may occur as a result of
precipitation such as rain, snow, sleet, hail, or fog; dry deposition may
also occur as dry particles or dust settling out of the
atmosphere. The gasses in the atmosphere that contribute to the
development of these acids come from both natural sources, such as
volcanoes or the decomposition of organic matter, and from
anthroprogenic, or man-made sources such as automobiles and
boilers. Samples from this program are composites of precipitation events collected over
a one week period. Samples are usually collected at 9:00 AM each
Tuesday. Field chemistry measurements are then taken before the sample is
shipped to the Central Analytical Laboratory in Illinois where
additional measurements are taken. Final data can be accessed at
the National Atmospheric Deposition Program web site.
Field chemistry measurement data is available from the DEP sponsored sites
highlighted below. Data from the other sites can be obtained from
the NADP web site.
