Grantee Research Project Results

1999 Progress Report: Quantification of the Dry Deposition Flux and Air Water Exchange of Reactive and Reduced Nitrogen

EPA Grant Number: R826647
Title: Quantification of the Dry Deposition Flux and Air Water Exchange of Reactive and Reduced Nitrogen
Investigators: Holsen, Thomas M.
Institution: Clarkson University
EPA Project Officer: Aja, Hayley
Project Period: October 1, 1998 through September 30, 2001
Project Period Covered by this Report: October 1, 1998 through September 30, 1999
Project Amount: $309,104
RFA: Exploratory Research - Environmental Chemistry (1998) RFA Text |  Recipients Lists
Research Category: Sustainable and Healthy Communities , Land and Waste Management , Air , Safer Chemicals

Objective:

This research project is using a newly developed instrument, the Water Surface Sampler (WSS), to directly measure the dry deposition flux of reactive and reduced nitrogen. These species are responsible for acidification and eutrophication of many of our waterways. The specific objectives of the research are to: (1) use the WSS to directly measure the dry deposition of both reactive and reduced nitrogen that exist in the gas and particulate phases, (2) characterize the collection properties of the water surface for these compounds, (3) develop techniques to analyze the data collected, and (4) compare this technique to indirect methods currently being developed. This work will be performed in Potsdam, NY (Clarkson University) and at the Chesapeake Biological Station (University of Maryland) in Solomons Island, MD. In upstate New York, nitrogen deposition is contributing to the acidification of many Adirondack Lakes; in the Chesapeake Bay region, nitrogen deposition is causing eutrophication of the Bay.

Progress Summary:

To date, work has focused on building the new samplers, refining analysis techniques, and obtaining samples in both Potsdam, NY, and Solomons Island, MD. Two new water surface samplers were constructed. Ammonia sampling and analysis techniques have been improved by using a new HEPA filter clean bench containing citric acid coated foam filters to lower ammonia levels in the work area and decrease blank levels. Ion chromatography is being optimized to improve ammonia detection limits.

First year field sampling has been completed. Sampling near the Chesapeake Bay took place in May. Approximately 20 12-hour samples were obtained. During the summer and fall, an additional 20 samples were obtained in Potsdam. In these sampling campaigns, dry deposition samples were collected with both an aerodynamically smooth water surface (WSS) and a knife-edge surrogate surface (KSS) (Table 1). These samples will be collected during periods of no rain or threat of rain. Ambient reactive and reduced nitrogen measurements, and meteorological data were obtained concurrently at the site. Particulate reactive and reduced nitrogen fluxes were measured by extracting and analyzing samples collected on greased strips contained on the KSS. Dry deposition samples from the water surface, and nylon and citric acid coated paper filters exposed on the KSS were analyzed for reactive and reduced nitrogen.

Table 1: Summary of Analytical and Experimental Methods Used in this Research.

Compound	Phase	Sampling Methods Dry Deposition Flux	Sampling Methods Ambient Concentration	Analytical Technique
HNO3	Gas	WSS, Nylon Filter	Denuder Tube	IC##
SO2	Gas	WSS	Denuder Tube	IC
NH3	Gas	WSS, Paper Filter#	Denuder Tube	IC
Fine NO3-*	Particulate	KSS	Back-up Filter	IC
Fine SO42-*	Particulate	KSS	Back-up Filter	IC
Fine NH4+*	Particulate	KSS	Back-up Filter	IC
Coarse NO3-*	Particulate	KSS	Filter	IC
Coarse SO42-**	Particulate	KSS	Filter	IC
Coarse NH4+**	Particulate	KSS	Filter	IC

* Aerodynamic diameter <2.5 µm.
** Aerodynamic diameter >2.5 µm.
# Paper filter will be citric acid impregnated.
## IC ? ion chromatography

Preliminary results indicate that nitrate fluxes to the WSS and Nylasorb filter on the KSS were 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 approximately 1.5 cm/sec, and 2.5 cm/sec, respectively. The SO2 and HNO3 MTCs were approximately the same. After adjusting for the differences in molecular weights, the NH3 MTC was approximately equal to the SO2 MTC.

Future Activities:

Sampling, chemical analysis, and data interpretation will continue. Sampling will occur in the Chesapeake Bay region in March and will continue in Potsdam through the spring, summer, and fall.

Journal Articles on this Report : 1 Displayed | Download in RIS Format

Publications Views

Other project views:	All 1 publications	1 publications in selected types	All 1 journal articles

Publications

Type	Citation	Project	Document Sources
Journal Article	Shahin UM, Zhu X, Holsen TM. Dry deposition of reduced and reactive nitrogen: A surrogate surfaces approach. Environmental Science & Technology 1999;33(12):2113-2117.	R826647 (1999)	not available

Supplemental Keywords:

ambient air, atmosphere, acid deposition, chemical transport, particulates, nitrogen oxides, sulfates, acid rain, environmental chemistry, engineering, monitoring, analytical, measurement methods, northeast, Chesapeake Bay., RFA, Scientific Discipline, Air, Water, Nutrients, particulate matter, Environmental Chemistry, Air Deposition, Engineering, Chemistry, & Physics, fate and transport, eutrophication, hydrological stability, dry deposition studies, environmental monitoring, reactive contaminant transport, particulates, aerosol particles, atmospheric particles, gas phase nitrogen deposition, chemical transport, chemical transport modeling, atmospheric nitrogen deposits, nutrient stress, chemical kinetics, nutrient cycling, meterology, atmospheric loading, water surface sampler, atmospheric deposition

Progress and Final Reports:

Original Abstract

2000

Final