Dissolved organic carbon vertical movement and carbon accumulation in West Siberian peatlands

Abstract

Abstract. Dissolved organic carbon is an additional path of carbon cycle but there is a lack of information about its distribution in peatland and rates of downward movement. We dated seven peat cores (separately the dissolved (DOC) and particulate (POC) organic carbon) from Mukhrino peatland (typical zonal oligotrophic bog) in western Siberia to assess the date distribution between those two peat fractions. Our results revealed that the DOC is younger than POC for the surface peatland layers (0–150 cm) and older for the deeper layers. The date differences increases with depth and reaches 2000–3000 years at the bottom layer (430–530 cm). In our hypothesis this date discrepancy caused by more young DOC moving to the deeper and older peat layers. The estimated average value of DOC downward movement was 0.047 ± 0.019 cm yr−1. Th oldest dates found at the lake bottom and ancient riverbed were 10 053 and 10 989 cal yr BP correspondingly. For the whole period of peatland functioning the average peat accumulation rate was estimated as 0.067 ± 0.018 cm yr−1 (0.013–0.332 cm yr−1), the carbon accumulation rate was estimated as 38.56 ± 12.21 g С m−2 yr−1 (28.46–57.91 g С m−2 yr−1).

Methane in West Siberia terrestrial seeps: Origin, transport, and metabolic pathways of production

“…The stable isotope compositions of both carbon and hydrogen in the methane indicate that it is of the primary microbial origin (Figure 4a). Radiocarbon age of the seep methane reflects its origin from early to mid‐Holocene organic matter and is lower than the basal peat organic carbon ages in peatlands of the region (Kremenetski et al, 2003; Turunen et al, 2001; Zarov et al, 2021). Stable isotope composition of CO 2 in seep gas provides further evidence for the peatland origin of seep methane, as the CO 2 is believed to come from the same source.…”

“…It is noteworthy that in advection‐dominated raised bogs, deeper‐peat methane production is at least partly fueled by recently photosynthesized organic matter; this methane is typically half the age of the peat at any given depth (Aravena et al, 1993; Chanton et al, 1995; Glaser et al, 2016). Hence, fast migration via advective transport, which is suggested to occur on a decadal timescale (Glaser et al, 2016), would likely result in seep methane age of less than 2–4 thousand years BP, half the average age of the peat at depths of 1.5–4 m in West Siberian boreal zone (Kremenetski et al, 2003; Turunen et al, 2001; Zarov et al, 2021).…”

“…Seep methane radiocarbon age comprises the age of organic matter used for CH 4 production and migration time of CH 4 from peatlands to the seeps. The early to mid‐Holocene radiocarbon age of seep methane could be solely explained by the age of organic matter at depths of 1.5–4 m in West Siberian peatlands (Kremenetski et al, 2003; Turunen et al, 2001; Zarov et al, 2021). If seep methane is indeed produced in these deep peat layers, then methane migration time should be negligible relative to its age.…”