Scientists also studied the southeast Asia fires in 1997. These fires were unique since they involved both the burning of above-ground vegetation and below-ground peata form of coal. Smoldering peat produces more gases and particulates than burning vegetation per unit area. These fires covered an area of more than 45,000 square kilometersan area comparable to the combined area of Rhode Island, Delaware, Connecticut, and New Jersey. The fire's thick smog cloud covered almost all of southeastern Asia, resulting in more than 20 million cases of smog-related health problems. Gases and particulates produced during the 1997 fires were measured as far away as Hawaii.
From these field experiments, scientists measured greenhouse gases (carbon dioxide, methane, and nitrous oxide), chemically active gases (carbon monoxide and nitric oxide), and particulates from diverse ecosystems. This research showed how the production of gases and particulates from fires varies with the type of ecosystem burned, the fire's characteristics, and the vegetation's moisture content. As a result of these measurements, LaRC researchers developed a fire combustion model to determine emissions from each ecosystem based on fire temperature. Knowing the amount of emissions is important for accurate estimates of the environmental impacts of these greenhouse gases. In addition, this model is useful for determining the contribution of biomass burning to the total production of green-house gases, a requirement for the Kyoto Treaty. This international treaty limits the amount of greenhouse gas emissions of certain industrialized nations.
Researchers also discovered that bacteria in soil enhance production of the greenhouse gas nitrous oxide. Nitrification is a biological process where bacteria convert ammonium, found naturally in soil and also in fire ash, to nitric oxide and nitrous oxide. They believe that the increased concentrations of ammonium in the ash lead to more nitrification after a fire, thereby releasing additional nitric oxide and nitrous oxide. The amount of these gases produced by bacteria after a fire may surpass the amount released during biomass burning.