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Nitrogen dry deposition at an AmeriFlux site in a hardwood forest in the midwest
Author(s) -
Pryor S. C.,
Barthelmie R. J.,
Jensen B.
Publication year - 1999
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/1999gl900066
Subject(s) - nitric acid , aerosol , nitrate , ammonia , ammonium , deposition (geology) , nitrogen , flux (metallurgy) , ammonium nitrate , precipitation , chemistry , environmental chemistry , throughfall , reactive nitrogen , zoology , nitrification , analytical chemistry (journal) , atmospheric sciences , meteorology , inorganic chemistry , geology , biology , physics , paleontology , organic chemistry , sediment
This paper presents observations of ammonia, nitric acid and size segregated chemically speciated aerosols above the canopy of a secondary successional deciduous forest in Indiana during spring. Average nitric acid concentrations range between 0.1–1 µg m −3 and vertical gradients from 1 to 9 ng m −3 / m. The ammonia probability distribution indicates an average concentration of 0.8 µg m −3 , although concentrations in excess of 2 µg m −3 are observed. Aerosol measurements indicate ammonium is largely confined to the accumulation mode (0.1 < D p < 1.0 µm) with a mean concentration of 1 µg m −3 . Nitrate exhibits a bi‐modal distribution (with mass in both the accumulation and coarse (D p > 1.0 µm) modes), and is present at mean concentrations of 1.2 µg m −3 . Average dry deposition fluxes calculated from these measurements are: Nitric acid = 0.38 mg‐N m −2 dy −1 , ammonia = 1.07 mg‐N m −2 dy −1 , aerosol‐nitrate = 0.27 mg‐N m −2 dy −1 , aerosol‐ammonium = 0.25 mg‐N m −2 dy −1 . The total dry deposition nitrogen flux of over 1.9 mg‐N m −2 dy −1 is approximately equal to the flux in precipitation as measured at NADP sites in the region.