N-Alkanes in Permafrost Peatlands

In this study, high-performance liquid chromatography (HPLC) methods were utilised to identify and quantify C21-C33 n-alkanes in permafrost peatlands located within the Eastern European and Western Siberian cryolithozone. The total content of n-alkanes in Europe is 7.4 times higher compared to Siberian permafrost peatlands, and was estimated at 282 ± 145 (range from 74 to 709) μg/kg and 38 ± 12 (10-66) μg/kg, respectively. In the European cryolithozone, CPI alkane 9.5 ± 2.4 (3.7-18.6) and HPA 0.10 ± 0.03 (0.05-0.23) indicate a relatively higher share of higher plants and a higher stage of peat decomposition decree, with 6.9 ± 2.1 (3.1-12.9) and 0.15 ± 0.05 (0.06-0.29) in the Siberian region. In contrast, the Western Siberian peat plateaus were formed under conditions of constant excess moisture, a distinction from the Eastern European peatlands, where moisture and permafrost conditions were subject to constant change. This is further corroborated by the values of Paq, C23/C29 and C23(C27 + C31), which are 0.90 ± 0.05 (0.69-0.99); 11.1 ± 8.9 (0.84-61.6); 1.53 ± 0.80 (0.21-4.72) and 0.47 ± 0.12 (0.08-0.71); 0.64 ± 0.32 (0.08-1.48); and 0.43 ± 0.21 (0.04-1.26), respectively. The n-alkanes and peat physicochemical properties show no significant correlation. In the European part, permafrost degradation occurred repeatedly during the warming periods. Nevertheless, only slight subsidence of the permafrost table was observed, and peat continued to accumulate (up to 0.1 mm/year) in the West Siberian peat plateaus. Consequently, the variation in the quantitative and qualitative composition of n-alkanes in permafrost peatlands is determined not only by the different botanical composition of the plant remains forming the peat strata, but also by the consequence of lower mean annual temperatures in Western Siberia compared to the European nNortheast, and such a climatic difference persisted throughout the Holocene.