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Glacial chronologies from the Pamir may not only provide insights into past changes in temperature, but also into past changes in precipitation related to the northern-hemispheric westerlies and the monsoonal circulation. We present 18 new exposure ages from the Bogchigir Valleys that complement and refine our previous studies in these valleys. The most extensive dated glaciation in the area occurred ~. 100. ka, during Marine Oxygen Isotope Stage (MIS) 5, and indicates increased precipitation likely from both the westerlies and the monsoonal circulation. A subsequent glacier advance, which deposited characteristic 'chukur' moraine lobes, occurred at ~. 80-75. ka. Circumstantial evidence points to glacial advances at ~. 65 and 40. ka, the latter likely also documenting increased monsoonal moisture supply during MIS 3. Less extensive glacial advances occurred during MIS 2 at ~. 28 and 24. ka and reflect the aridization trend during the course of the last glacial cycle. Deglaciation started ~. 21. ka, interrupted by minor stillstands or readvances at ~. 16 and 12. ka. Local calibration sites and glacier-climate modeling would be very helpful to reduce the systematic methodological uncertainties (still at least 10%) and to draw more detailed paleoclimatic conclusions.

Despite increased paleoenvironmental studies in Northern Yakutia (ANDREEV et al. 2002 and references therein), little is known of past climatic and environmental fluctuations during the Middle and Late Weichselian (Karginsky interstadial and Sartan stage). New pollen and radiocarbon data from the Verkhoyansk Mountains document the Late Pleistocene and early Holocene environmental history of the area.The climate of the region is extreme continental and arid. In Yakutsk the absolute minimum temperature reaches -64°C, absolute maximum +38°C, and annual precipitation is 180-250 mm. But more than 350-400 mm vapors from June to September (GAVRILOVA 1973). Today larch (Larix dahurica) forest (taiga) with herbs dominate the vegetation. Few other trees (Betula pendula, Pinus sylvestris, Picea obovata) and shrubs (Alnus fruticosa, Pinus pumila, Betula nana) also grow in the area. The samples came from a site at the Tumara River valley (63N, 130W).The pollen spectra show that open tundra-like Poaceae and Cyperaceae associations with some other herbs (Caryophyllaceae, Ranunculaceae, and Asteraceae) dominated the area about 50-40 14C ka ago. Steppe-like communities with Artemisia, Cichoriaceae, Thalictrum, and rare shrubby tundra communities with Salix and Betula sect. Nanae were also present in the vegetation cover. An increase of Chenopodiaceae pollen and Equisetum spore contents, which are mainly pioneer species on disturbed soils, and the presence of charcoal particles in the sediments dated ca 48-50 14C ka most likely reflect fire activity at that time.Higher content of Salix pollen, Polypodiaceae and Lycopodium spores during ca 48-30 14C ka may reflect climate conditions warmer and wetter than during the previous interval. A find of Linum perenne pollen grains indicate the existence of dry steppe habitats in the area as well. The presence of this species reflects that temperatures were at least 12.5°C during the growing season. This relatively warm interval corresponds wel

Despite increased paleoenvironmental studies in the Northern Siberia, little is known of past climatic and environmental fluctuations during the Karga (Middle Weichselian) Interstadial. New pollen and radiocarbon data from the Verkhoyansk Mountains document the Late Pleistocene and Holocene environmental history of the area. The pollen spectra show that open tundra-like Poaceae and Cyperaceae associations with some other herbs (Caryophyllaceae, Ranunculaceae, Asteraceae) dominated the area about 50-30 14C ka. Steppe-like communities with Artemisia, Cichoriaceae and Thalictrum and shrubby tundra communities with Salix and Betula sect. Albae also were present in the vegetation cover. An increase of Chenopodiaceae pollen and presence of charcoal particles in the sediments dated ca 48-50 14C ka most likely reflect a fire at that time. Higher content of Salix pollen, Polypodiaceae and Lycopodium spores between 48-30 14C ka may reflect some climate amelioration. This relatively warm interval seems to correspond well with the Karga Interstadial. Selaginella rupestris spores, indicators of very dry environment are also common in the Late Pleistocene spectra. Higher tree pollen contents (mostly Salix and Betula sect. Albae) in the Alleröd- early Holocene (ca 11-9 14C ka) reflect that the more favorable climate conditions during that interval. This data are in good agreement with other pollen records from the region.

The performance of a gas chromatography-combustion-isotope ratio mass spectrometry system (GC-C-IRMS) with respect to the dependence of d13C values on the amount of sample is presented. Particular attention is paid to the localization of the amount-dependent isotopic fractionation within the system. Injection experiments with varying amounts of gases (CO2, n-hexane, and toluene) revealed that neither the detector unit nor the combustion reactor, but rather the conditions in the split/splitless injector, contributed to this effect. Although optimization of injector parameters was performed and a reduction of this adverse effect from 3 to 1 was achieved, it was not possible to eliminate isotopic fractionation completely. Consequently, additional injector parameters have to be considered and adjusted to achieve injection conditions free of fractionation. For routine analysis of the compound-specific d13C analysis of different biomarkers in many environmental samples, perfect optimization may not always be reached. Therefore, in order to prevent systematic errors in the measured d13C values due to different sample concentrations, it is suggested that correction for the remaining unknown amount-dependent fractionation can be made by means of co-analyzing standards of varying analyte concentrations and known d13C values. Residual overall amount-dependent isotope-fractionation can thus be corrected mathematically.

Rapid turnover of organic matter leads to a low efficiency of organic fertilizers applied to increase and sequester C in soils of the humid tropics. Charcoal was reported to be responsible for high soil organic matter contents and soil fertility of anthropogenic soils (Terra Preta) found in central Amazonia. Therefore, we reviewed the available information about the physical and chemical properties of charcoal as affected by different combustion procedures, and the effects of its application in agricultural fields on nutrient retention and crop production. Higher nutrient retention and nutrient availability were found after charcoal additions to soil, related to higher exchange capacity, surface area and direct nutrient additions. Higher charring temperatures generally improved exchange properties and surface area of the charcoal. Additionally, charcoal is relatively recalcitrant and can therefore be used as a long-term sink for atmospheric CO2. Several aspects of a charcoal management system remain unclear, such as the role of microorganisms in oxidizing charcoal surfaces and releasing nutrients and the possibilities to improve charcoal properties during production under field conditions. Several research needs were identified, such as field testing of charcoal production in tropical agroecosystems, the investigation of surface properties of the carbonized materials in the soil environment, and the evaluation of the agronomic and economic effectiveness of soil management with charcoal.

Die isotopische Zusammensetzung einer Substanz ist eine Stoffeigenschaft und nicht von der gemessenen Konzentration abhängig. Dennoch fanden wir bei der substanzspezifischen d13C-Analyse von phenolischen Ligninoxidationsprodukten eine Abhängigkeit des d13C-Wertes von der injizierten Substanz-Menge. Durch systematische Untersuchung der einzelnen Gerätekomponenten der Gaschromatographie-Verbrennungs-Isotopenmassenspektrometrie-(GC-C-IRMS)-Konfiguration konnten die Ursachen des mengenabhängigen Isotopen-Signals lokalisiert und mittels geeigneter Parameterwahl weitgehend minimiert werden. Die durchgeführten Experimente ergaben, dass die Isotopenfraktionierung weder am IRMS noch am Oxidationsreaktor stattfindet. Allerdings führen Veränderungen der Injektionsparameter, wie Splitfluss-Rate, Splitless-Zeit und die Spritzenlänge und deren Eintauchtiefe zu deutlich veränderter Abhängigkeit des d13C-Wertes von der injizierten Stoffmenge. Durch Optimierung dieser Parameter konnte die Injektionsmengenabhängigkeit reduziert, jedoch nicht vollständig eliminiert werden, die verbleibende Abhängigkeit konnte durch Anpassung logarithmischer Kalibrierfunktionen rechnerisch korrigiert werden. Angewandt wurde die so optimierte Methode zur substanzspezifischen Bestimmung des d13C-Wertes von phenolischen Ligninoxidationsprodukten als terrestrischen Biomarker höherer Pflanzen innerhalb einer Paläostudie.

Rapid turnover of organic matter leads to a low efficiency of organic fertilizers applied to increase and sequester C in soils of the humid tropics. Charcoal was reported to be responsible for high soil organic matter contents and soil fertility of anthropogenic soils (Terra Preta) found in central Amazonia. Therefore, we reviewed the available information about the physical and chemical properties of charcoal as affected by different combustion procedures, and the effects of its application in agricultural fields on nutrient retention and crop production. Higher nutrient retention and nutrient availability were found after charcoal additions to soil, related to higher exchange capacity, surface area and direct nutrient additions. Higher charring temperatures generally improved exchange properties and surface area of the charcoal. Additionally, charcoal is relatively recalcitrant and can therefore be used as a long-term sink for atmospheric CO2. Several aspects of a charcoal management system remain unclear, such as the role of microorganisms in oxidizing charcoal surfaces and releasing nutrients and the possibilities to improve charcoal properties during production under field conditions. Several research needs were identified, such as field testing of charcoal production in tropical agroecosystems, the investigation of surface properties of the carbonized materials in the soil environment, and the evaluation of the agronomic and economic effectiveness of soil management with charcoal.

Minerals may protect organic matter against microbial decay, either by direct chemical and physical interactions or by inhibitory effects on the soil microbial community. To clarify the effects of minerals on organic matter cycling by microorganisms, we used amino sugars as tracers for C and N in dead microbial cells after 0, 15, 29, 90, 239, and 498 days of incubation of beech leaf litter mixed with quartz sand, Fe oxide, Al hydroxide, or Mn oxide. Beech leaf litter without addition of any mineral phases was used as the control. The results show that amino sugar concentrations increased as litter decomposition proceeded. Decreasing ratios of glucosamine to muramic acid and of glucosamine to galactosamine indicated that bacterial products accumulated increasingly relative to fungal cells with increasing incubation time. As the presence of Mn oxide promoted losses of plant-derived C, there was a more pronounced selective accumulation of the microbial-derived amino sugar C than in the other treatments. Aluminium hydroxide and Fe oxide inhibited synthesis of bacterial amino sugars by a factor of two. This resulted in lower amino sugar C proportions compared with the other treatments. Consequently, the amino sugar C proportions were sensitive to both increasing amino sugar synthesis and C mineralization rates. In contrast, the amino sugar N proportions were not affected by any mineral additions. Thus, the mere presence of minerals did not affect the cycling of N through the amino sugar pool, but minerals altered the relative proportions of N sequestered within residues of bacteria and fungi.