期刊
JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES
卷 122, 期 10, 页码 2593-2604出版社
AMER GEOPHYSICAL UNION
DOI: 10.1002/2017JG004006
关键词
permafrost; organic carbon; nitrogen; carbonates; McMurdo Dry Valleys; Antarctica
资金
- NASA's ASTEP grant
- NSERC Discovery grants
Little is known about the abundance and source of soil organic carbon and biogeochemical cycling in permafrost soils from the ultraxerous environment of the Dry Valleys of Antarctica. Here we investigate the distribution, source and cycling of organic carbon, total nitrogen and carbonates in the icy permafrost soils of University Valley, Quartermain Mountains. Results indicate that organic carbon content is lowest in icy soils from the perennially cryotic zone (<40gg(-1) dry soils) and higher in the icy soils from the seasonally noncryotic zone, where the highest concentrations were found in the warmer-wetter section of the valley and near a frozen pond (up to 313gg(-1) dry soils). The C-13(org) of organic carbon in the icy soils showed that it is derived from the weathering of Beacon Supergroup sandstone that hosts active endolithic communities. The C:N ratios in icy soils formed two populations: one with ratios <5 and the other with ratios near the Redfield ratios. The low C:N ratios suggest that physicochemical processes dominates these soils, as supported by the absence of microbial activity and atmospherically deposited NO3 with minimal postdeposition modification. The near Redfield C:N ratios can be explained by physical processes (translocation of SOC in the soils from snow meltwater) or balanced microbial activity. The latter is supported by the C-13(CaCO3) values of carbonates that suggest a contribution from microbially respired endolith-derived organic matter, providing indirect evidence of heterotrophic activity in permafrost soils from an ultraxerous environment.
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