01262nas a2200133   4500008004100000245006600041210006400107300001500171490000800186520080500194100001800999700001901017856009201036       1990                        eng d00aSite-specific underestimation of wetfall NH+4 using NADP data0 aSitespecific underestimation of wetfall NH4 using NADP data  a3093 -30950 v24A3 a<p>Estimates of NH4+ in weekly composited wetfall samples were measured by two laboratories, one at Kansas State University and that operated by the National Atmospheric Deposition Program (NADP) in Illinois. NH4+ samples were lower in the NADP estimates and exhibited a strong seasonal difference in concentrations. Losses were likely not due to volatilization; microbial immobilization of NH4+ likely occurred during transport of samples. Differences in estimates of annual ammonium ion deposition were larger than those observed for average weekly concentrations because of seasonal rainfall patterns. NADP values will require site-specific corrections for models describing or predicting regional or national patterns of nitrogen inputs in wetfall. Key words: Ammonium, NADP, nitrate, wetfall</p>1 aRamundo, R.A.1 aSeastedt, T.R.  uhttp://129.130.186.12/content/site-specific-underestimation-wetfall-nh4-using-nadp-data