[Biogeosciences via ESS Open Archive] In the McMurdo Dry Valleys (MDV), Antarctica, microbial mats are responsible for primary productivity in both aquatic and terrestrial ecosystems; yet their influence on soil organic matter pools and turnover remains poorly understood.
We investigated the composition of carbon (C) turnover and nitrogen (N) cycling in three substrates: microbial mats, soils directly beneath microbial mats, and bare soils. We found that microbial mats have a substantial influence on the composition of organic matter.
While in microbial mats and bare soils we found broad and overlapping δ13C and δ15N values, in soils directly beneath microbial mats, we observed a distinct, elevated δ15N and a constrained δ13C signature.
Radiocarbon 14C analyses reveal that microbial mats and soils beneath microbial mats have modern 14C ages, with mean estimated residence times (MRT) of 5-25 years, while bare soils are associated with ancient 14C ages of 2494 to 4050 years BP.
Results from this study demonstrate that microbial mats clearly influence the provenance and composition of soil organic matter in the environments in which they occur, and in site fractionation of 13C and 15N as well as heterogenous sources of C and N have the potential to confound interpretation of stable isotope data.
Microbial Mats Influence the Isotopic Composition and Provenance of Soil Organic Matter in the McMurdo Dry Valleys, Antarctica, Journal of Geophysical Research – Biogeosciences via ESS Open Archive
Astrobiology,
