AN EVALUATION OF AIR POLLUTANT EXPOSURES DUE TO THE 1991 KUWAIT OIL FIRES USING A LAGRANGIAN MODEL

A Lagrangian model was adapted to simulate the transport, dispersion, and deposition of pollutants from the Kuwait oil fires. Modifications to the model permitted radiative effects of the smoke plume to modify the pollutant's vertical mixing. Calculated SO2 (sulfur dioxide) air c oncentrations were compared with the observations from several intensi ve aircraft measurement campaigns as well as longer-term ground-based measurements. Model sensitivity tests and comparison to the aircraft m easurements confirmed (1) the magnitude of the tabulated emission rate s for SO2 and carbon soot; (2) the most appropriate value for the smok e's specific extinction coefficient was about 4 m2 g-1; (3) that the m odel was sensitive to the vertical mixing in the first 100 km downwind from the fires; (4) that the SO, conversion rate was about 6% h-1; an d (5) although there were large variations in the height of the initia l smoke plume and ground-level concentrations were most sensitive to t hat height, an average value of 1500 m a.g.l. (above ground level) pro vided reasonable model predictions. Six ground-level sampling location s, all along the Arabian Gulf Coast, were used for model evaluation. A lthough the measurements and model calculations were in qualitative ag reement, the highest space- and time-paired correlation coefficient wa s only 0.40. The monitoring stations were located in industrial areas, requiring the subtraction of a background concentration of anywhere f rom 5 to 34 mug m-3, which at some stations was larger than the contri bution from the oil fires smoke. The coastal location and lack of corr elation between some of the sites suggested that mesoscale flow featur es not properly represented in the coarse meteorological data used in the computations may have influenced the smoke transport.