| Popis: |
The deposition velocity of ammonium(bi)sulphate (MMD 0.8 μm, σg 2) was derived from vertical concentration gradients using flux-profile relationships. The deposition velocity has a near-linear dependency on u* and an average value of 0.012–0.015 m s−1. The dry deposition of 214Pb was investigated by measuring airborne activity and activity accumulated on Douglas fir branches. This radioisotope is a natural tracer for submicron aerosol (AMD 0.4 μm, σg 3). The correlation of Vd with u* is poor. The average deposition velocity ranges from 0.0061–0.0110 m s−1, with a best estimate of 0.0073 m s−1, a factor 1.6–2.1 smaller than the deposition velocity for sulphate. The difference is regarded to be due to the difference in size distributions of 214Pb and sulphates. |
