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Spatially Resolved Organomineral Interactions across a Permafrost Chronosequence
- Source :
- Environmental Science & Technology. 54:2951-2960
- Publication Year :
- 2020
- Publisher :
- American Chemical Society (ACS), 2020.
-
Abstract
- Permafrost contains a large (1700 Pg C) terrestrial pool of organic matter (OM) that is susceptible to degradation as global temperatures increase. Of particular importance is syngenetic Yedoma permafrost containing high OM content. Reactive iron phases promote stabilizing interactions between OM and soil minerals and this stabilization may be of increasing importance in permafrost as the thawed surface region ("active layer") deepens. However, there is limited understanding of Fe and other soil mineral phase associations with OM carbon (C) moieties in permafrost soils. To elucidate the elemental associations involved in organomineral complexation within permafrost systems, soil cores spanning a Pleistocene permafrost chronosequence (19,000, 27,000, and 36,000 years old) were collected from an underground tunnel near Fairbanks, Alaska. Subsamples were analyzed via scanning transmission X-ray microscopy-near edge X-ray absorption fine structure spectroscopy at the nano- to microscale. Amino acid-rich moieties decreased in abundance across the chronosequence. Strong correlations between C and Fe with discrete Fe(III) or Fe(II) regions selectively associated with specific OM moieties were observed. Additionally, Ca coassociated with C through potential cation bridging mechanisms. Results indicate Fe(III), Fe(II), and mixed valence phases associated with OM throughout diverse permafrost environments, suggesting that organomineral complexation is crucial to predict C stability as permafrost systems warm.
- Subjects :
- chemistry.chemical_classification
Pleistocene
Spatially resolved
Chronosequence
Yedoma
Permafrost
General Chemistry
010501 environmental sciences
Ferric Compounds
01 natural sciences
Carbon
Active layer
Soil
chemistry
Environmental chemistry
Soil water
Environmental Chemistry
Organic matter
Alaska
0105 earth and related environmental sciences
Subjects
Details
- ISSN :
- 15205851 and 0013936X
- Volume :
- 54
- Database :
- OpenAIRE
- Journal :
- Environmental Science & Technology
- Accession number :
- edsair.doi.dedup.....4f65fdf50e63488dc8da89d673eaccfc