Particulate emissions from fires in central Siberian Scots pine forests

Abstract

Siberian boreal forest fires burn large areas annually, resulting in smoke that releases large amounts of particulate emission into the atmosphere. We sampled aerosol emissions from experimental fires on three Scots pine (Pinus sylvestris L.) forest sites of central Siberia. Emissions from ground-based aerosol samples were 0.1-0.7 t/ha. This value represented 1%-7% of the total biomass (10-30 t/ha) consumed during the experimental fires. We were able to classify the chemical composition of 77%-90% of the mass of particulate fire emissions. Chemical analysis indicated that an average of 8%-17% of the particulate composition was of mineral origin. Carbonaceous aerosols created because of incomplete combustion ranged from 50% to 70% of the total aerosol mass. The fraction of aerosols containing elemental carbon (EC) (i.e., graphite, soot, and charcoal) was 7%-15%. As our samples were taken near the ground surface, these results represent freshly emitted fire aerosols that have not yet had time to react with atmospheric moisture or to undergo postfire chemical or physical-chemical changes. In a typical year, where 12 × 10 6 -14 × 10 6 ha burn in Russia, we estimate that 3 × 10 6 -10 × 10 6 t of particulate matter may be emitted into the atmosphere.Résumé : À chaque année, les incendies brûlent de vastes zones de forêt boréale en Sibérie. Ces incendies produisent de la fumée qui relâche dans l'atmosphère de grandes quantités de particules. Ils ont échantillonné les émissions d'aérosols provenant de feux expérimentaux dans trois forêts de pin sylvestre (Pinus sylvestris L.) du centre de la Sibérie. Sur la base d'échantillons d'aérosols prélevés au sol, les émissions atteignent 0,1-0,7 t/ha. Cette valeur représente 1 % -7 % de la biomasse totale (10-30 t/ha) consumée par les feux expérimentaux. Les auteurs ont pu classer la composition chimique de 70 % -90 % de la masse des émissions de particules dues au feu. L'analyse chimique a montré que 8 % -17 % des particules sont d'origine minérale. Les aérosols carbonés provenant de la combustion incomplète comptent pour 50 % -70 % de la masse totale d'aérosols. La proportion des aérosols contenant du carbone élémentaire (c.-à-d. du graphite, de la suie et du charbon) est de 7 % -15 %. Étant donné que nos échantillons ont été prélevés près de la surface du sol, ces résultats représentent les aérosols fraîchement émis par le feu qui n'ont pas eu le temps de réagir avec l'humidité atmosphérique ou subir des modifications chimiques ou physico-chimiques à la suite du feu. Au cours d'une année typique en Russie, où 12 × 10 6 -14 × 10 6 ha de forêt sont détruites par le feu, ils estiment que 3 × 10 6 -10 × 10 6 t de particules seraient émises dans l'atmosphère.[Traduit par la Rédaction] Samsonov et al. 2217

Black (pyrogenic) carbon: a synthesis of current knowledge and uncertainties with special consideration of boreal regions

“…In the latter study of particles up to 2.5 µm diameter, the BC/TC ratio was found to be 0.085 for the flaming stage and 0.0087 for the smouldering stage, but EFs were not determined. However, more information is recently available from experimental fires in three Scots pine sites of central Siberia (Samsonov et al, 2005). Aerosol emissions corresponded to 1%-7% of the mass of fire-consumed biomass, with EC constituting 7-15% of total aerosol mass.…”

“…Techniques for visual assessment of char are well-established, but there appear to be no studies with a complete accounting of char in any boreal forest site, and we found no quantitative information on BC storage in boreal peatlands. Integrated projects and interdisciplinary approaches are required, so that, for example, measurements of PyC production could be integrated into experimental fire studies such as the ICFME and FIRE BEAR (Samsonov et al, 2005), and the painstaking efforts to assess char abundance in peat cores could also be used to develop estimates of area-based char stocks. Increased application of 14 C dating is also necessary to assess the turnover time of different fractions of PyC.…”

Coupling of Vegetation Growing Season Anomalies and Fire Activity with Hemispheric and Regional-Scale Climate Patterns in Central and East Siberia

“…Forest fires play an important role in global atmospheric chemistry. Aerosol emissions from ground-based air samples at three Pinus sylvestris (L.) forest sites in central Siberia that were burned in an experiment ranged from 0.1 to 0.7 t ha Ϫ1 or 1%-7% of the total biomass (10-30 t ha Ϫ1 ) consumed during the experimental fires (Samsonov et al 2005). Anomalies in atmospheric trace gas concentrations from the Commonwealth Scientific and Industrial Research Organisation's (CSIRO) global sampling network in 1994/95 and 1997/98 are consistent with gas emission pulses from extreme fires in the Tropics and the boreal biome (Langenfelds et al 2002).…”

The role of forest floor in migration of metals and artificial nuclides during forest fires in Siberia

“…The area of the burn was 26 thousand ha. Average concen trations of the metals in the reference area were as fol lows: Cd, 0.161; Pb, 10 (2) do not imply that all the amounts were transferred far beyond the burn. I showed above that surface fires merely redistributed metals within a burned site or lower forest layers.…”

“…Forest understory (grasses and shrubs) added about 5 t/ha on average. The forest floor load reaches 30 t/ha or more for some parts of Central Siberia [10].…”