NO2 dry deposition velocity in a wheat [Triticum aestvum] field
2006
Zhang, S.(Tokyo Univ. of Agriculture and Technology, Fuchu (Japan)) | Nonaka, K. | Horie, K. | Matsuura, S. | Aoki, M. | Komori, D. | Matsuda, K.
Long-term continuous measurements of NO2 flux, NO2 dry deposition velocity (Vd) and various microclimate factors were carried out from February to June of both 2002 and 2003 on a wheat field located in Saiwai-cho, Fuchu-shi, Tokyo, Japan. The Bowen ratio technique was used to measure NO2 flux. Average values of daytime data were used to analyze Vd and the relationship between Vd and other factors such as solar radiation. Vd average values during the daytime were in the range of 0.03-1.11 cms(-1), were smaller in winter, and were larger in spring. Vd tended to increase along with wheat growth. Vd was affected primarily by leaf area index (LAI), and the relationship between Vd and each microclimate factor was different in LAI of each growing stage. With LAI less than 2, Vd was affected mainly by wind speed, and increased with an increase in wind speed. With LAI greater than 2, Vd was affected mainly by solar radiation, air temperature and vapor pressure deficit, and increased as these factors increased. In the maturing season (with LAI of approximately 5), the relationships between Vd and solar radiation, air temperature and vapor pressure deficit became stronger than during the previous growing periods. The average value of NO2 flux in the daytime during all growing periods was approximately 462 mu gm(-2)h(-1). The amount of NO2 deposition during all growing periods was approximately 0.29 gNm(-2).
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