National Atmospheric Deposition Program

Canada, and Mexico (23). The National Atmospheric Deposition Program has established the nationwide sampling network of —100 stations in the United States. The sampler is shown in Fig. 14-9 with a wet collection container. The wet collection bucket is covered with a lid when it is not raining. A sensor for rain moves the lid to open the wet collector bucket and cover the dry bucket at the beginning of a rainstorm. This process is reversed when the rain stops. 

Precipitation over North America gradually becomes more acidic from west to east, especially in industrialized areas of the Northeast. This acid rain may be a result of the release of nitrogen and sulfur oxides into the atmosphere. The colors and numbers (see key) indicate pH measured at field laboratories in 2004. Data from National Atmospheric Deposition Program/National Trends Network http //nadp.sws.uiuc.edu. 

National Atmospheric Deposition Program Mercury Deposition Network... 

National Atmospheric Deposition Program (NADP), Environment Canada, 05/03/2006, http //nadp.sws.uiuc.edu/date. 

National Atmospheric Deposition Program (NRSP-3)/National Trends Network, NADP/NTN Coordination Office, Colorado State University Fort Collins, CO, 1992. 

Inputs and outputs to the lake have been measured to calculate net retention for the pre-acidified lake. Precipitation inputs of sulfate were based on data from wet collectors (1980-1983) compiled by the National Atmospheric Deposition Program (NADP). SO2 inputs were calculated from regional ambient air concentrations (22) usinga deposition velocity of 0.5 cm/sec. Aerosol sulfate was estimated from NADP dry bucket measurements and from dry bucket and snow core measurements made in this study (22). Groundwater inputs occur largely at the southeast corner of the lake and were calculated from modeled inseepage (21) and measured sulfate concentrations in a well located in the major inseepage area. Sulfate output was estimated from mean lakewater sulfate concentration and modeled outflows. 

Alaska (PF), Katherine, Australia (KA), Amsterdam Island, Indian Ocean, (AI), and Bermuda, Atlantic Ocean (BD). The eastern U.S. sites include Multistate Atmospheric Power Production Pollution Study (MAP3S) sites at Whiteface Mountain, NY (WH) Ithaca, NY (IT), Pennsylvania State University (PS), Charlottesville, VA (CV) and Urbana, IL (IL). The western states are National Atmospheric Deposition Program (NADP) sites with a continuous record between 1981-1984 (in Colorado, California, Washington, Oregon and Arizona). 

Several integral measurement methods were evaluated in the early stages of this program. The wet-chemistry bubbler system deployed in Europe for remote measurement purposes cannot distinguish different chemical species. Since the deposition velocity is very species dependent, clear distinction among different chemical species is required to derive dry deposition rates. Filterpack methods have limitations as well. At the 1982 Technical Committee meeting of the National Atmospheric Deposition Program, conducted in St. Louis, a... 

FIGURE 4-38 Mean pH of precipitation of the United States in 1990, based on weekly measurements at 170 sites (adapted from National Atmospheric Deposition Program, 1990). 

Since 1986, the National Atmospheric Deposition Program (NADP/NTN) has collected weekly precipitation samples from alx>ut 200 monitoring sites nationwide in the United States. Sites are away from major point sources and large urban centers to provide a more regional/national perspective on precipitation chemistry. 

Figure 8.6(b) Generalized isoconcentration contours for Cl (mg/L) in atmospheric precipitation of the contiguous United States in 1995, based on the plotted average Cl concentrations reported for stations in the National Atmospheric Deposition Program/National Trends Network ( 996). 

NADP Quality Assurance Plan for Deposition Monitoring", National Atmospheric Deposition Program, 1984. 

It is interesting to note that the surface used most widely in the United States is the Aerochem-Metrics bucket Since 1982, the buckets have been deployed at over 100 sites nationwide as part of the National Atmospheric Deposition Program (NADP) (8). This monitoring program has resulted in a sizeable dry deposition flux data base for numerous trace element and ionic species (12). 

National Atmospheric Deposition Program NAPD Data Report, Precipitation Chemistry. National Resource Ecology Laboratory. Colorado State University, Fort Collins, (1983-84). 

Fig. 13-3 Precipitation-weighted concentration of SO4 (mg/L) over the United States. 1987. Modified with permission from the National Atmospheric Deposition Program, 1988.

National Atmospheric Deposition Program/National Trend Network (NADP/NTN) Site Visitation Program (October 1989 through September 1990)... 

National Atmospheric Deposition Program (2001). 2000 Annual Summary. Washington, DC National Atmospheric Deposition Program. 

Galloway JN, Eiseneeich SJ and Scorr BC (1980) Toxic Substances in Atmospheric Deposition A Review and Assessment, National Atmospheric Deposition Program Report NC-141. U.S. Environmental Protection Agency Report EPA-5 60/ 5-80-001, 146 p. Washington, DC. 

The vast majority of measurements of nitrogen deposition in the United States—including those made by the National Atmospheric Deposition Program (NADP)—measure only wet deposition (i.e., N in rainfall and... 

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