Deposition and Uptake of Nitrogen Oxides in Scots Pine needles (Pinus Sylvestris L.)

The deposition and uptake of nitrogen oxides in Scots pine needles were studied in exposure systems in the field and at the laboratory. For NO2 the deposition and uptake is a first order process determined by the stomatal conductance. The deposition velocities per needle area unit were during summer conditions determined to 0.65-1.67 mm x s-1 for daytime and 0.28 -0.78 m x s-1 for night time condition. Long term exposure of current needles to a concentration of 200 ug /m3 led to a decrease in transpration (stomatal conductance) after about 10 days exposure. One year old needles did not show any physiological effects at these concentrations. Short term studies of the deposition of NO showed that this was substantially lower than that for NO2

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