Kolefnisbinding í mómýrum í síbreytilegu umhverfi - lífræn efni í jarðvegi undir áhrifum eldvirkni - verkefni lokið

Fréttatilkynning verkefnisstjóra

28.7.2022

Rannsóknin einblíndi á víxlverkanir milli einkenna lífræns jarðvegs (e. histic soil properties) og eldfjallaeinkenna jarðvegs (e. andic soil properties), og hver áhrif samspil þessara einkenna eru á stöðugleika kolefnis. Vanalega er talið að ferli kolefnis í mójörð (jarðvegi mómýra) og öðrum lífrænum jarðvegi séu að mestu leyti stýrð af vatnsbúskap og súrefnisframboði, og af efnasamsetningu lífræns efnis í jarðvegi. En þessi rannsókn sýnir að steinefni hafa einnig áhrif á ferli kolefnis í óframræstum mómýrum á eldvirkum svæðum. Málmjónir járns (Fe) og áls (Al), sem berast í mýrar með gosefnum virðast stuðla að kolefsniuppsöfnun. Á sama tíma virðist steinefnainnihald mómýra hafa áhrif á viðkvæmni kolefnis fyrir hitastigsbreytingum. Kolefni, sem einkennist af viðkvæmum kolefnishópum (e. labile carbon compounds) var viðkvæmari fyrir hitastigsbreytingum en kolefni, sem einkennist af stöðugum kolefnishópum (e. recalcitrant carbon compounds), sem er andstætt niðurstöðum fyrri rannsókna á svæðum án eldvirkni. Þessar niðurstöður eru sérstaklega áhugaverðar í ljósi þess að rannóknin sýnir einnig jákvæða fylgni milli uppsöfnunar viðkvæmra kolefnishópa, eldfjallaeinkenna jarðvegs og gjóskulaga í jarðvegi. Þá má draga þá ályktun að á sama tíma og eldfjallaeinkenni virðast stuðla að aukinni kolefnisuppsöfnun í tiltölulega óröskuðum mómýrum, er aukin hætta á kolefnislosun úr sömu mýrum, verði þær fyrir raski (t.d. framræslu, auknu áfoki og/eða hlýnun loftslags).

English:
This research has improved our understanding of the impact of volcanism on soil development and carbon dynamics in relatively undisturbed peatlands in Iceland. Three undrained peatlands in Austur Húnavatnssýsla in Northwest Iceland were investigated, along a transect from the coast to the highlands. The focus was on interactions between histic and andic (volcanic) soil properties and their implications for carbon stability in these ecosystems. While carbon turnover of Histosols and other soils of wetlands is usually considered to be predominantly governed by hydrology and oxygen availability, and the chemical composition of the soil organic carbon, this research provides strong evidence that mineral deposits impact carbon dynamics in undrained peatlands of volcanic regions. For instance, a positive feedback between metal elements like Al and Fe and soil organic carbon accumulation may occur. At the same time, mineral material within the peat column seems to affects the temperature sensitivity of carbon mineralization. Contrary to the results of various previous studies in non-volcanic regions, higher temperature sensitivity of soil organic carbon dominated by labile carbon compounds than of soil organic carbon dominated by recalcitrant forms was detected in this study. This is particularly interesting in light of a significant relationship between the accumulation of labile carbon compounds, andic soil properties and tephra deposits. Hence, while volcanic impact factors may enable increased carbon accumulation in relatively undisturbed peatlands, there is a risk of accelerated carbon emissions from the same peatlands upon disturbance (i.e. artificial drainage, increased dust deposition and/or climate warming).

A short easily understandable description of the project, its results and impact
Peatlands belong to the greatest terrestrial carbon stores worldwide. Their organic soils possess
exceptional capacities for long-term carbon storage. Peatlands in Iceland are unusual as they receive comparatively great amounts of windborne mineral material from volcanic eruptions or sparsely vegetated and eroded drylands. These mineral additions of volcanic origin to the otherwise organic substrate of the peatlands shape their soils and vegetation characteristics. Additional to characteristics typical for organic soils in other Nordic peatlands, Icelandic peatlands possess characteristics of mineral soils of volcanic regions. At the core of this study was to investigate the impact of these rare interactions between characteristics of organic soils and mineral volcanic soils on the peatlands carbon stores. The aim was to increase our knowledge on carbon storage of peatlands in volcanic regions. We compared soils from three peatlands in northwest Iceland, and found strong indications that decomposition processes are slower in soils with stronger characteristics of mineral volcanic soils. In undisturbed (anaerobic) peatlands, this seems to impact long-term carbon storage positively, but in disturbed (aerobic) peatlands, it might pose a threat of accelerated carbon emissions.

Information on how the results will be applied
Upon degradation, peatlands exert an unusually strong impact on the global carbon cycle. Indeed,
greenhouse gas emissions from organic soils of disturbed peatlands in Iceland are estimated to
contribute the greatest part of emissions from the LULUCF sector, which, in turn is estimated to
contribute more than double the combined emissions from all other sectors. However, considerable uncertainty is inherent in these estimates. There is a need of more country specific information, not least more detailed information on the pedogenic environment of the soil organic carbon. Our research contributes to the knowledge of the pedogenic environment in Icelandic peatlands, and the impact of active volcanism on carbon storage in these ecosystems. But at the same time as this research has improved our understanding of the impact of volcanism on soil development and carbon dynamics in relatively undisturbed (i.e. undrained) peatlands, the results call for an investigation of the fate of carbon dynamics of peatlands under pressure (i.e. under pressure by artificial drainage, increased dust deposition and/or climate warming) within similar environmental settings. Therefore, this project builds the foundation of a consecutive project on the impact of volcanism and soil erosion on carbon dynamics of disturbed peatlands in Iceland. To pursue ongoing research on carbon cycling of peatlands in volcanic regions is not only important to understand carbon storage of peatlands in Iceland, but also in volcanic regions elsewhere.

A list of the project’s outputs
The project has hitherto led to the publication of two peer-reviewed papers in international scienctific journals and one manuscript to be published in a peer-reviewed international scientific journal (compare section “Publications” above). The project was also presented at various international and national workshops and conferences. It was part of a contribution to the news comment programme „Kveikur“ of RÚV, and a presentation at the Icelandic Wetland Association „Votlendissjóður“.

Currently, Susanne Claudia Möckel is working on her final PhD thesis, which is based on this project. The two publications and the manuscript listed above will be included in the thesis. Two scientific publications, which are closely related to this project were also published.

Heiti verkefnis: Kolefnisbinding í mómýrum í síbreytilegu umhverfi - lífræn efni í
jarðvegi undir áhrifum eldvirkni / Carbon storage in peatlands within an ever-changing environment – soil organic matter dynamics in the context of active volcanism
Verkefnisstjóri: Susanne Claudia Möckel, Háskóla Íslands
Tegund styrks: Doktorsnemastyrkur
Styrktímabil: 2018-2020
Fjárhæð styrks: 19,825 millj. kr. alls
Tilvísunarnúmer Rannís: 184778