ИСТИНА

Research on the organic geochemistry of black carbon became one of the priorities in the environmental Earth Sciences after publication of Goldberg's book "Black carbon in the environment" (Goldberg, 1985). In this paper, Goldberg suggested the idea of "black carbon" as a highly durable material remaining after combustion of biomass and suggested that "black carbon" has a very long characteristic time of existence, making a significant contribution to the slow cycle of the Earth's carbon pools. Organic geochemistry of "black carbon" has become even more relevant in connection with the matters of the carbon cycle and climate change, including long-term preservation of organic matter in ocean sediments and soils (Masiello, 2004). Geologists have shown that ancient sediments contain "carbon black" possibly of pyrogenic origin, which they believe might be separated from the carbon formed during the low temperature diagenesis (kerogen) (Song et al., 2002). Thus, initially in the literature "carbon black" was associated only with pyrogenic products, but nevertheless researchers soon have encountered so that combustion products varied widely in composition and stability depending on the combustion conditions, and that it was methodically difficult to distinguish between the products of low and high temperature organic matter oxidation (Schmidt et al., 2001). It has been proposed several methods of separation of "black carbon" from fossil and modern soil organic matter; all methods were based on the oxidation of organic matter by a set of acids, sometimes followed by heat treatment (100-375°C), or exposure to extreme ultraviolet radiation (Schmidt et al., 2001) . Different methods show different results on the order, which is associated with a wide range of properties and stability of combustion of organic matter. Many researchers (Skjemstad et al., 1996, 1999) succumbed to the temptation to include in the "black carbon" concept an extremely wide range of carbon-containing components and declare the pyrogenic origin of the major part of carbon in marine sediments and soils. Since much of the carbon in soil organic matter not extracted by acid and alkaline treatments has been regarded as "black carbon", a number of experts subjected the revision of existing views on the mechanisms of accumulation and transformation of organic matter in soils. In particular, it has been postulated that a significant proportion of dark-colored soils of chernozem type owes its color pyrogenic carbon (Skjemstad et al., 1996; Schmidt et al., 2001). Despite the apparent inconsistency of these statements to actual views on pedogenesis, this theory has spreaded and has been published in leading scientific journals, up to Nature (Schmidt et al., 2004). Also it was concluded that on the basis of the degree of stability of "black carbon" in the soil one can draw conclusions about the temperature of the combustion of organic matter that is separate carbon, formed as a result of fires and industrial high-temperature combustion (Skjemstad et al., 1999). So far it is not clear whether these views are unfounded. The main argument against the theory of the genesis of pyrogenic exclusively coal-like components in soil organic matter is that the geographical distribution of "black carbon" in the soil does not match the geography of wildfires in neither the present nor the past. We believe that a significant part of the so-called "black carbon" in the soil has a low-temperature origin, and therefore difficult to draw far-reaching conclusions based only on the availability of coal-like components in soil organic matter.