Ozone uptake by an evergreen forest canopy: temporal variation and possible mechanisms

TY - JOUR

T1 - Ozone uptake by an evergreen forest canopy: temporal variation and possible mechanisms

AU - Mikkelsen, T N

AU - Ro-Poulsen, H

AU - Pilegaard, K

AU - Hovmand, M F

AU - Jensen, N O

AU - Christensen, C S

AU - Hummelshoej, P

N1 - Keywords: Ozone flux; Ozone deposition; Terpenes; Volatile organic compounds; Gradient and eddy correlation method

PY - 2000

Y1 - 2000

N2 - Patterns of ozone concentration ([O(3)]), O(3) deposition velocity (v(d)) and O(3) flux (F(c)) over an evergreen forest canopy are shown in relation to measuring method, physiological activity of the trees, and time of year. The gradient and eddy correlation methods were compared and showed similar diel v(d) patterns. Daytime F(c) was correlated with CO(2) and water vapour fluxes, while no correlation between [O(3)] in the range 10-70 ppb (nl l(-1)) and F(c) was seen in this study. F(c) was primarily driven by stomatal conductance, reactions with surfaces, particles and gases, and not by [O(3)]. On a monthly basis, [O(3)] was always highest in the afternoon while v(d) was typically higher in the morning, resulting in an equal F(c) over the day. Night-time F(c) was more than half of the daytime O(3) flux. The data reveal the importance of emissions of nitric oxide and terpenes as O(3) removal factors in evergreen forest dominated by Norway spruce.

AB - Patterns of ozone concentration ([O(3)]), O(3) deposition velocity (v(d)) and O(3) flux (F(c)) over an evergreen forest canopy are shown in relation to measuring method, physiological activity of the trees, and time of year. The gradient and eddy correlation methods were compared and showed similar diel v(d) patterns. Daytime F(c) was correlated with CO(2) and water vapour fluxes, while no correlation between [O(3)] in the range 10-70 ppb (nl l(-1)) and F(c) was seen in this study. F(c) was primarily driven by stomatal conductance, reactions with surfaces, particles and gases, and not by [O(3)]. On a monthly basis, [O(3)] was always highest in the afternoon while v(d) was typically higher in the morning, resulting in an equal F(c) over the day. Night-time F(c) was more than half of the daytime O(3) flux. The data reveal the importance of emissions of nitric oxide and terpenes as O(3) removal factors in evergreen forest dominated by Norway spruce.

U2 - 10.1016/S0269-7491(00)00045-2

DO - 10.1016/S0269-7491(00)00045-2

M3 - Journal article

C2 - 15092875

SN - 0269-7491

VL - 109

SP - 423

EP - 429

JO - Environmental Pollution

JF - Environmental Pollution

IS - 3

ER -