TY - JOUR

T1 - Stability of soil organic matter in Cryosols of the maritime Antarctic

T2 - Insights from 13C NMR and electron spin resonance spectroscopy

AU - Abakumov, E.

AU - Alekseev, I.

PY - 2018/11/19

Y1 - 2018/11/19

N2 - Previously, the structure and molecular composition of the Antarctic soil organic matter (SOM) has been investigated using 13C-NMR methods, which showed that in typical organo-mineral soils the aliphatic carbon prevails over the aromatic one, owing to the non-ligniferous nature of its precursor material. In this study, the SOM was analysed from different sample areas (surface level and partially isolated supra-permafrost layer) of the tundra-barren landscape of the Fildes Peninsula, King George Island, Western Antarctica. We found that the humic acids (HAs) of the cryoturbated, buried areas had lower amounts of alkyl aromatic and protonized aromatic compounds. In contrast, the HAs from the surface layers contain less alkyl carbon components. The free-radical content was higher in the surface layers than in the buried layers due to the presence of fresh organic remnants in superficial soil samples. New data on SOM quality from these two representative Cryosols will enable a more precise assessment of SOM stabilization rate in sub-Antarctic tundras. Comparison of the 13C-NMR spectra of the HAs and the bulk SOM revealed that humification occurs in the Antarctic and results in accumulation of aromatic and carboxylic compounds and reductions in alkylic ones. This indicates that humification is one of the ways of soil organic matter stabilization.

AB - Previously, the structure and molecular composition of the Antarctic soil organic matter (SOM) has been investigated using 13C-NMR methods, which showed that in typical organo-mineral soils the aliphatic carbon prevails over the aromatic one, owing to the non-ligniferous nature of its precursor material. In this study, the SOM was analysed from different sample areas (surface level and partially isolated supra-permafrost layer) of the tundra-barren landscape of the Fildes Peninsula, King George Island, Western Antarctica. We found that the humic acids (HAs) of the cryoturbated, buried areas had lower amounts of alkyl aromatic and protonized aromatic compounds. In contrast, the HAs from the surface layers contain less alkyl carbon components. The free-radical content was higher in the surface layers than in the buried layers due to the presence of fresh organic remnants in superficial soil samples. New data on SOM quality from these two representative Cryosols will enable a more precise assessment of SOM stabilization rate in sub-Antarctic tundras. Comparison of the 13C-NMR spectra of the HAs and the bulk SOM revealed that humification occurs in the Antarctic and results in accumulation of aromatic and carboxylic compounds and reductions in alkylic ones. This indicates that humification is one of the ways of soil organic matter stabilization.

KW - SOUTH-SHETLAND ISLANDS

KW - HUMIC ACIDS

KW - MOLECULAR COMPOSITION

KW - BYERS PENINSULA

KW - CLIMATE-CHANGE

KW - LIVINGSTON ISLAND

KW - PERMAFROST CARBON

KW - WESTERN SIBERIA

KW - TUNDRA SOILS

KW - RAW PEAT

UR - http://www.scopus.com/inward/record.url?scp=85056855502&partnerID=8YFLogxK

U2 - 10.5194/se-9-1329-2018

DO - 10.5194/se-9-1329-2018

M3 - Article

AN - SCOPUS:85056855502

VL - 9

SP - 1329

EP - 1339

JO - Solid Earth

JF - Solid Earth

SN - 1869-9510

IS - 6

ER -