C  ∕ N ratio, stable isotope (<i>δ</i><sup>13</sup>C, <i>δ</i><sup>15</sup>N), and <i>n</i>-alkane patterns of brown mosses along hydrological gradients of low-centred polygons of the Siberian Arctic

Abstract

Abstract. Mosses are a major component of the arctic vegetation, particularly in wetlands. We present C ∕ N atomic ratio, δ13C and δ15N data of 400 brown-moss samples belonging to 10 species that were collected along hydrological gradients within polygonal mires located on the southern Taymyr Peninsula and the Lena River delta in northern Siberia. Additionally, n-alkane patterns of six of these species (16 samples) were investigated. The aim of the study is to see whether the inter- and intraspecific differences in C ∕ N, isotopic compositions and n-alkanes are indicative of habitat, particularly with respect to water level. Overall, we find high variability in all investigated parameters for two different moisture-related groups of moss species. The C ∕ N ratios range between 11 and 53 (median: 32) and show large variations at the intraspecific level. However, species preferring a dry habitat (xero-mesophilic mosses) show higher C ∕ N ratios than those preferring a wet habitat (meso-hygrophilic mosses). The δ13C values range between −37.0 and −22.5 ‰ (median = −27.8 ‰). The δ15N values range between −6.6 and +1.7 ‰ (median = −2.2 ‰). We find differences in δ13C and δ15N compositions between both habitat types. For some species of the meso-hygrophilic group, we suggest that a relationship between the individual habitat water level and isotopic composition can be inferred as a function of microbial symbiosis. The n-alkane distribution also shows differences primarily between xero-mesophilic and meso-hygrophilic mosses, i.e. having a dominance of n-alkanes with long (n-C29, n-C31) and intermediate (n-C25) chain lengths, respectively. Overall, our results reveal that C ∕ N ratios, isotopic signals and n-alkanes of studied brown-moss taxa from polygonal wetlands are characteristic of their habitat.

Fluvial and permafrost history of the lower Lena River, north‐eastern Siberia, over late Quaternary time

“…Biplot of δ 13 C and TOC/TN (total organic carbon/total nitrogen) from SAM18‐01 bulk organic matter (green dots). Colourized rectangles for comparison; POC 1 = particulate organic carbon measured from fluvial samples of the Lena Delta (Winterfeld et al ., 2015), Moss 2 from the central Lena Delta (Zibulski et al ., 2017), lake algae 3 and SOM 3 = soil organic matter from Transbaikalia (Prokopenko et al ., 1993), LD 4 = Lena Delta Yedoma (MIS 3–2) and Holocene cliff exposure (Wetterich et al ., 2008, 2020), W‐LD 5 = western Lena Delta fluvial deposits (MIS 3–2) from cliff exposure (Schirrmeister et al ., 2011). …”

“…Individual samples with high TOC/TN are associated with drift wood particles (Meyers & Teranes, 2001). Typical values of moss (Zibulski et al ., 2017) as known from the central delta (Samoylov Island) or POC (particulate organic carbon) as known from river water sampling (Winterfeld et al ., 2015) are not met with SAM18‐01 bulk organic matter. This is also true for Transbaikal lake algae (Prokopenko et al ., 1993), which all have lighter isotope signatures with δ 13 C < −29‰.…”

Concordant changes in late Holocene hydroclimate across southern Patagonia modulated by westerly winds and the El Niño–Southern Oscillation

“…We argue that, as carbon isotope discrimination in Sphagnum is related to water retention capacity, the signal becomes more apparent under drier conditions (Williams & Flanagan, 1996); the signal may thus lose part of its significance towards the wetter end of the range. Assuming that these extremely wet signatures indicate submersed Sphagnum, there may be a complex origin of plant-available carbon from varying dissolved inorganic carbon sources, some of which could have been enriched in the heavy isotope ("hard-water effect"), making it difficult to interpret the values of Sphagnum samples with small "apparent" discrimination (Hammarlund et al, 1997;Zibulski et al, 2017).…”

Plant wax isotopes in Greenland lakes record widespread CH4 uptake during Holocene warming

“…Short-term culturing experiments documenting this symbiosis using 13 C-labelled CH4 have shown that conservatively 30% to 40% of C in new biomass in Sphagnum and Scorpidium, respectively, is derived from CH4 15,16 . CH4-derived C is most strongly incorporated in submerged mosses (compared to nonsubmerged mosses) regardless of the species 15,42,43,46 . Using a C isotope mass balance model, we estimate that during the middle Holocene up to ~25% of the C in aquatic moss waxes at TS was derived from CH4 (Extended Data Fig.…”

“…A symbiotic relationship between both Sphagnum (Class: Sphagnopsida, Family: Sphagnaceae) and brown mosses and methanotrophic bacteria is well-documented 15,16,41 . Mossassociated methane-oxidizing bacteria (MAMO) form dense colonies within moss cells and on moss surfaces 16 , where they oxidize CH4 using O2 produced during photosynthesis, and in turn provide the moss CO2 and H2O 15,16,42,43 . Data from Siberian ponds has demonstrated that 60-99% of the CH4 produced by sedimentary methanogens in anoxic ponds is oxidized within aquatic brown moss layers, 44 demonstrating MAMO are highly efficient at consuming CH4 in the water column.…”