Abood, Paul听1听;听Williams, Mark听2听;听Tonnessen, Kathy听3听;听Morris, Kristi听4
1听University of Colorado, 麻豆影院
2听University of Colorado, 麻豆影院
3听Rocky Mountains CESU, National Park Service
4听Air Resources Division, National Park Service
NADP/NTN data are used to characterize the "chemical climate" of the US and observe its changes over time. However, NADP sites collect "wet" only deposition because of the much greater costs and analytical uncertainty involved in sampling "dry" deposition. An outstanding question is the contribution of "dry" deposition to total annual chemical deposition. Here we evaluate the role of dry deposition in total deposition at Park Research and Intensive Monitoring of Ecosystems Network (PRIMENet) sites. We report on the percent contribution of dry deposition to total deposition, year-to-year variations in the ratio of wet to dry deposition at each site, and evaluate whether the results support converting NADP wet deposition values to total deposition by using a simple wet:dry ratio.
Dry N deposition, as a percentage of total N deposition, generally decreases with increasing precipitation amount. However, the inverse relationship between precipitation and dry deposition percentage does not hold for all park locations. Dry S deposition as a percentage of total S deposition depended less on precipitation amounts and more on factors such as local emission sources.
Wet to dry deposition ratios vary on a yearly basis at most of the locations. This is also the case for wet to dry deposition ratios within seasons across years.
In its simplest form, this ratio does not appear to be stable enough to accurately reflect total deposition if only wet deposition is measured.