EMISSIONS FROM MESOSCALE IN-SITU OIL FIRES - THE MOBILE 1991 EXPERIMENTS

A series of 14 mesoscale burns were conducted in 1991 to study various aspects of oil burning in situ. Extensive sampling and monitoring of these burns were conducted to determine the emissions. This was done a t two downwind ground stations, one upwind ground station and in the s moke plume using a blimp and a remote-controlled helicopter. Particula te samples in air were taken and analyzed for polycyclic aromatic hydr ocarbons (PAHs), PAHs were found to be lower in the soot than in the s tarting oil. Metals in the oil were found concentrated in the residue and could not be measured in soot samples using conventional industria l hygiene sampling techniques, Particulates in the air were measured b y several means and found to be greater than recommended exposure Leve ls only up to 150 m downwind at ground level. Combustion gases includi ng carbon dioxide, sulphur dioxide and carbon monoxide did not reach e xposure level maximums. These gases were emitted over a broad area aro und the fire and are not directly associated with the plume trajectory . Volatile organic compound (VOCs) emissions are extensive from fires, but the levels are less than those emitted from a non-burning test sp ill. Over 50 compounds were identified and quantified, several at poss ible levels of concern up to 200 m downwind. Water under the burns was analyzed; no analytes of concern could be found at the detection leve ls of the methods. The burn residue was analyzed for the same compound s as the air particulate samples. The residue contained elevated amoun ts of metals, PAHs were at a lower concentration in the residue than i n the starting oil, however there is a slight differential concentrati on increase in some higher molecular weight species. Overall, indicati ons from these mesoscale trials are that emissions from in situ burnin g are low in comparison to other sources of emissions and result in co ncentrations of air contaminants that are below exposure limits beyond 500 m downwind. (C) 1997 Elsevier Science Ltd.