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DRY DEPOSITION OF REDUCED AND REACTIVE NITROGEN: A SURROGATE SURFACES APPROACH. (R826647)
Citation:
Shahin, U. M., X. Zhu, AND T. M. Holsen. DRY DEPOSITION OF REDUCED AND REACTIVE NITROGEN: A SURROGATE SURFACES APPROACH. (R826647). ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 33:2113-2117, (1999).
Description:
Nitrogen dry deposition causes pH modification of ecosystems, promotes
eutrophication in some water bodies, interferes with the nutrient geochemical
cycle on land, and has a deteriorating effect on buildings. In this study, a
water surface sampler (WSS) and knife-leading-edge surrogate surface (KSS)
covered with both a Nylasorb filter and a greased disk were used to directly
measure nitrate dry deposition in Chicago between May and October 1997.
Concurrently, the KSS covered with both a citric acid-coated paper filter and a
greased disk and the WSS were used to measure ammonia dry deposition. The
average measured dry deposition flux for HNO3 was 3.78 ? 1.24 mg
m-2 day-1; for particulate nitrate,
it was 1.46 ? 0.3 mg m-2 day-1; and
for ammonia gas, it was 2.64 ?1.15 mg m-2
day-1. Nitrate fluxes to the WSS and Nylasorb filter on
the KSS were statistically equal, as were the total ammonia fluxes to the WSS
and the citric acid-impregnated filter on the KSS. The experimental measurements
indicated that HNO3 and particulate nitrate were the major species
responsible for the nitrate flux to the WSS and that ammonia gas was the major
source of deposited ammonia. The average mass transfer coefficients (MTCs) of
HNO3 and NH3 to the WSS were 1.5 ? 0.22 and 2.46 ? 1 cm/s,
respectively. SO2 and HNO3 MTCs were statistically the
same. After adjusting for the differences in molecular weights, the
HNO3 and NH3 mass transfer coefficients were statistically
equal to the SO2 MTC.