Click on image to view larger version.
Figure 1. Sampling array for measuring number of pollen grains in a plume emitted from a plot of creeping bentgrass. Rotary impaction samplers were mounted on poles at heights of 0.5, 1.5, 2.5, and 4.0 m. The poles were set at 22.5° intervals along a 135° arc with a radius of 10 m, downwind from the center of a 6- by 6-m plot of creeping bentgrass. Two additional poles with samplers at 0.5 and 2.5 m height were placed upwind of the plot to measure background pollen concentrations. All samplers were run simultaneously during the sampling period of 15 or 30 min. To estimate total pollen passing through the downwind sampling array during the sampling period, the plume cross-section was divided conceptually into rectangles (indicated here in dashed lines). Pollen flux through each rectangle was derived by multiplying the spore concentration measured at the appropriate sampler by air volume moving through that rectangle. Air volume was calculated from measured or interpolated wind speed at sampler height, sampling duration, and cross-sectional area of the rectangle. The pollen fluxes of all rectangles were summed to produce the total flux.
