Measurement of NOx dry deposition. Final report

Technical Report · Mon Jun 01 04:00:00 EDT 1987

OSTI ID:7197386

Evilsizor, B; Stedman, D H; Stocker, D W

This study was undertaken to investigate dry deposition to a field of growing winter wheat at a field site in Eastern Colorado. From mid-January to the end of May 1986, the CRC supported the University of Denver's participation in a cooperative field study at the Rybicka farm field site. The study represents the first time an NOx flux intercomparison was conducted by more than a single investigator. It is also the first time a statistically significant set of long-term NO and NOx flux data was taken over a wide range of meteorological and surface conditions at a homogeneous site with minimal confounding influences of local roads. Wind components, temperature, NOx, NO, NO/sub 2/ and O/sub 3/ concentrations were continuously monitored. Consistent diurnal trends in the NOx concentrations were seen throughout the data collection period. During the data acquisition period, a diurnal variation in the NOx flux was observed, consisting of a downflux in the morning and an upflux in the afternoon. But unlike the NOx concentration, the magnitude and direction of the 5-day averages of the NOx varied with seasonal changes. The NOx flux in the winter (February) showed a net deposition at less than -1.0 ppb cm/s. Later in the year, the net flux changed to an upflux. In May, the upflux was at 6.0 ppb cm/s. The increase in the observed NOx upflux was apparently due to microbial activity in the soil or the maturing wheat plants, rather than to a seasonal warming that causes an increase in turbulent activity.

• Research Organization: Denver Univ., CO (USA). Dept. of Chemistry
• OSTI ID: 7197386
• Report Number(s): PB-88-193636/XAB
• Country of Publication: United States
• Language: English

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