Surface Environment, Mine Ventilation and Underground Hazards · Surface Environment · 2 marks · Numerical answer
CO is emitted at ground level at 25 g/s. Wind speed is 5 m/s; horizontal and vertical Gaussian dispersion coefficients are 150 m and 200 m. Find ground-level centreline concentration in μg/m³, to two decimals.
For a ground-level point source and receiver on the centreline, reflection doubles the Gaussian term, giving C=Q/(πuσyσz). Convert 25 g/s to 25000000 μg/s. Then C=25000000/(π×5×150×200)=53.0516 μg/m³, or 53.05. Omitting the ground-reflection factor would halve the concentration.
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