A peat fire is a slow-burning, smoldering fire that occurs in peatlands, which are types of wetlands. These fires are distinct from typical forest or grass fires because they burn below the surface, within the organic soil itself. They can persist for extended periods, often weeks or months, even after surface flames have disappeared.
The Science of Peat and Combustion
Peat is a partially decomposed organic material that accumulates over thousands of years in waterlogged, low-oxygen environments like bogs and fens. Its high carbon content makes it a flammable fuel source when dry.
The porous structure of peat allows air to penetrate deep into the material. When dry, this enables smoldering combustion, a slow, low-temperature burning process without flames. Unlike flaming combustion, which involves rapid oxidation and visible flames, smoldering relies on a slower reaction at the solid fuel’s surface. This process releases heat and gases, allowing the fire to spread stealthily underground.
Ignition and Spread of Peat Fires
Peat fires can ignite from natural occurrences and human activities. Lightning strikes during prolonged dry periods are a natural cause. Human actions are also a source of ignition, including uncontrolled agricultural burning, unattended campfires, or carelessly discarded cigarettes that contact dry peat.
Once ignited, peat fires spread slowly underground. The fire follows seams of dry peat, moving through the porous material beneath the ground. This allows the fire to creep across vast areas without visible smoke or flames above ground, making it challenging to track and predict.
Environmental and Health Consequences
Peat fires release large amounts of carbon and other greenhouse gases into the atmosphere. Peatlands store vast quantities of ancient carbon, accumulated over millennia, which is released as carbon dioxide and methane when burned. The destruction of peatland ecosystems also eliminates unique habitats and reduces biodiversity.
The smoke produced by these fires forms a thick, prolonged haze that can blanket vast regions. This smoke contains high levels of harmful particulate matter, such as PM2.5, which are tiny particles less than 2.5 micrometers in diameter. Inhaling these particles can lead to respiratory illnesses, including asthma attacks and bronchitis, and can exacerbate existing heart conditions. The smoke also contains toxic gases like carbon monoxide and various volatile organic compounds.
Detection and Extinguishing Challenges
Detecting peat fires presents difficulties because they burn primarily underground. They are frequently discovered only when the ground above them subsides, or when smoke begins seeping from cracks in the ground far from the initial ignition point. Fires can smolder for weeks or months before becoming apparent, making early intervention challenging.
Extinguishing peat fires is difficult. Applying water to the surface is often ineffective, as it tends to run off without penetrating deep into the water-repellent dry peat layers where the fire burns. Effective methods involve prolonged flooding of the affected area, requiring large volumes of water and time. Another approach involves digging deep trenches down to the mineral soil or water table to create physical barriers. Both methods demand substantial time, effort, and resources.