Element composition of peat deposits in flat frost mound bogs of the Pyakupur River (northern taiga of West Siberia)

Abstract

<p>The content and the profile distribution of the element composition of the 1 meter high peat deposits in flat frost mound bogs are investigated. The botanical composition of peat is described. The results of the botanical composition analysis of peat showed that deposits consist mainly of sphagnum mosses, lichens, shrubs, green mosses, pine wood, as well as pine and birch bark. A good correlation between the degree of peat decomposition and the brightness of dry peat measured by the CIE L*a*b* color model is revealed. As a result of the study of peat samples’ color, it has been found that this parameter can be used as an express method for the rapid assessment of peat degree decomposition. The highest concentration of the organic carbon occurs at the base of the peat deposit (64.4±0.2%). The nitrogen concentration in permafrost peat is higher than in thawed (1.0 ± 0.2% and 0.7 ± 0.1%, respectively, the difference is significant at p = 0.001). The C / N ratio decreases from 72 ± 16 in 0-40 cm in the thawed layer to 50 ± 10 in the frozen part (40-100 cm). Within the bottom low boundary of the seasonally thawed layer, a local increase in the N concentration was detected, as well as an almost 2-fold decrease in the C/N ratio. It is most likely related to the high increase in the rate of microbial activity on the border between the thawed layer and the permafrost peat. It was revealed that most of the elements are concentrated in the upper (thawed) part of the peat deposit. Among them, only Na, Mg, Ca, Zn, Ba, As and Sb have a significant difference. Despite the fact that significant differences according to non-parametric U-criterion Mann-Whitney test were identified only for 7 elements, the distribution of the rest along elements the frozen and thawed peat layer is similar in nature. So for Na, Mg, Al, P, K, Ca, Ti, Fe, Zn, Ba, Li, B, V, Cr, Mn, Co, Ni, Cu, Ga, As, Rb, Sr, Y, Zr, Nb, Mo, Cd, Sb, Cs, the upper quartiles of concentrations in the seasonally thawed layer are 1.2 - 6.9 times higher than in the permafrost peat, and for C, N, Al, Ba, B, V, Co, Cu , Zr, Nb, Mo it is 1,0 - 0,6 times lower, respectively. Generally, according to the element composition, it is safe to say that the differences stem from the botanical composition. In general, according to the elemental composition it can be said that the differences are primarily due to the botanical composition. The active layer comprises mainly sphagnum mosses and lichens, the woody peat already appears in the lower permafrost part of the deposit. A correlation between the brightness of peat and the total content of ash elements (R2 = 0.65, excluding 1 sample) was revealed within the active layer. Taking into account the fact that the brightness correlates with the degree of decomposition, it may be concluded that higher upper quartile of the concentrations of elements in the active layer relates to the slower peat accumulation rate for the last 3 thousand years and, correspondingly, a large accumulation of dust components from the atmosphere by the peat layers.</p>

Microtopography Controls of Carbon and Related Elements Distribution in the West Siberian Frozen Bogs

“…Their deposition has been particularly enhanced by anthropogenic influences over the last century [71]. Therefore, the maximum dust stocks are confined to the upper parts of the peat deposits, which is confirmed by the distribution of chemical elements in the peat columns [72]. A significant contribution of atmospheric influences on the formation of springtime river fluxes of many metals has been shown at the study of snow [73].…”

Development history and composition of peatland in the Numto natural park in Western Siberia, Russia

“…For example, the eastern part of the Great Vasyugan Mire began to form during the late Atlanticthe early Subboreal (around 5500-5200 BP), but its prevailing peat deposits are much younger (3500-3000 yr BP) [18]. A greater age of 9983±157 yr BP has been identified in a flat frost mound bog of the Pyakupur River catchment, where autochthonous paludification and peat accumulation processes developed within a vast interfluve area [19]. The study of northern Pur-Taz interfluve shows that peat accumulation had the highest rate during the Borealearly Atlantic period and significantly slowed down in the Subboreal due to climate cooling [20].…”