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Black Carbon in Soils - Looking for the missing carbon

Description: Das Projekt "Black Carbon in Soils - Looking for the missing carbon" wird vom Umweltbundesamt gefördert und von Universität Zürich, Geographisches Institut durchgeführt. Burning fossil fuels releases large amounts of carbon dioxide into the atmosphere. However, researchers have found less of this greenhouse gas in the air than they ought to have according to their global carbon dioxide balance. Around half of the amount is missing. Scientists of Cologne University have been looking for this depression. 'The missing link here has long been suspected in the oceans. But we now believe that the missing carbon could occur in terrestrial ecosystems, especially in soils,' Dr. Michael Schmidt explains. Around 20 percent of the depression probably occurs owing to regular forest fires. The trees are not completely combustible but are charred. Largely, charcoal is left. Also, there are considerable amounts of soot that eventually rains down on the earth again. Charcoal and soot are simple terms for complicated organic molecules. They consist of graphite-like layers the arrangement of which always differs according to how they are formed. Scientists refer to them with the generic term of black carbon. This organic material accounts for up to half of the composition of soils. It is extremely resistant to chemicals. 'So far, examinations have only covered three to four years. During this period, black carbon is not decomposed at all,' Schmidt explains. 'But if nothing were to happen o it in the long run, we would be wading knee-deep in charcoal.' From this, he concludes that the decomposition rates are somewhere between 100,000 and a couple of years. In order to cover such huge expanses of time, the Cologne scientists have looked for an already existing model system. Although black carbon deposits do not exist in Sung, on the shores of Lake Onega in Russia, a similar substance does occur. A graphite rock called shungite has been deposited there over a period of around two billion years. This graphite and black carbon have analogous structures, so that the researchers can examine the decomposition behavior of such carbon compounds with the aid of the old rock. The graphite deposits cover an area of 9,000 square kilometers, which is around a quarter of the area of North Rhine-Westphalia. What is special about the area is that the shungite is a gigantic field experiment organized by nature, for ice scraped out this landscape 10,000 years ago, exposing the rock with a carbon content. This is precisely the period the researchers examine. It is only since then that the rock has weathered and new, fertile soil has formed. 'It is like in a supermarket. We can take our pick of graphite qualities,' says Schmidt. Since Shunga lies in a wide plain, no material from outside is washed or blown over the rock that would wear away the top layers. So the old carbon structures can decompose undisturbed. (abridged text)

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Origin: /Bund/UBA/UFORDAT

Tags: Köln ? Nordfriesland ? Fossiler Brennstoff ? Linde ? Ufer ? Naturwerkstoff ? Nordrhein-Westfalen ? Baummarder ? Brennstoff ? Graphit ? Holzkohle ? Kohlenstoffverbindung ? Waldbrand ? Seen ? Biogeochemie ? Kohlenstoffgehalt ? Zürich ? Bodenkohlenstoff ? Arzneimittel ? Baum ? Buchhaltung ? Kohlenstoff ? Russland ? THM-Prozess ? Material ? Black Carbon ? Verbrennung ? Brand ? Moorboden ? Tongrube ? Abrieb ? Ruß ? Ackerrandstreifen ? Technosol ? Absetzbare Stoffe ? Feststoff ? Gebäude ? Gesamtkohlenstoff ? Gelöster organischer Kohlenstoff ? Kohlendioxid ? Analyse ? Sediment ? Chemikalien ? Regen ? Meeresgewässer ? Boden ? Verwitterung ? Naturraum ? Systemanalyse ? Flachland ? Ökosystemforschung ? Stoff ? Terrestrisches Ökosystem ? Berechnungsverfahren ? Bilanz ? Landschaft ? Gestein ? Globale Aspekte ? Ökosystem ? Treibhausgas ? Feuerung ? Freilandversuch ? Atmosphäre ? Abdeckung ? Wetter ? Klimawandel ? Wald ? Biosphäre ? Küste ? Lohnform ? Bilanz [Betriebswirtschaft] ? Nassreinigung ?

License: cc-by-nc-nd/4.0

Language: Deutsch

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Time ranges: 2000-08-01 - 2002-07-31

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